6
This work has been digitalized and published in 2013 by Verlag Zeitschrift für Naturforschung in cooperation with the Max Planck Society for the Advancement of Science under a Creative Commons Attribution 4.0 International License. Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschung in Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht: Creative Commons Namensnennung 4.0 Lizenz. Compounds of Complex Halo and Pseudohalo Acids of the Group II B Metals, Part I Etherate, Pyridine and Aniline Compounds of Zn(II) A. G. Galinos*, J. K. Kouinis, P. V. Ioannou, Th. F. Zafiropoulos, and S. P. Perlepes Department of Inorganic Chemistry, University of Patras, Patras, Greece Z. Naturforsch. 34b, 1101-1106 (1979); received May 11, 1979 Ether, Pyridine, Aniline, Thiocyanate, Zinc The preparation of sixteen new etherate, pyridine and aniline compounds of complex halo and pseudohalo acids of Zn(II) is reported. The study of some physical and chemical properties as well as the UV and IR spectra of these compounds are discussed. Tetrahedral structures are proposed for all compounds in the solid state. Introduction Although a large number of salts of the complex anions [M n X 3 ] - a n d [ M n X 4 ] 2 ~ is known, the situa- tion with regard to the corresponding acids is not very clear. The study of these acids is of special interest, since a great number o f t h e m is used in certain Friedel-Crafts reactions. The catalytic action of the etherate HAICI4 • 2 Et 2 0 has been studied [1]. The preparation of etherate and pyridine compounds of the acids HZnCl 2 Br, HZnBr 3 and HZnI 2 Br has been reported [2-4]. Recently, we prepared and studied the complex compounds HZnCl 3 • 3 A n , HZnBr 2 C l • 3 A n a n d H Z n I 2 C l • 3 A n , w h e r e A n = aniline [5]. The study of compounds of mixed complex metallohaloacids with pseudohalogens is of some theoretical interest. The isolation of the compounds HZnCl 2 ( C S N ) • 2 E t 2 0 and HZnBr 2 ( C S N ) • 2 E t 2 0 has been achieved in the past [6]**. The etherate, pyridine and aniline compounds of the acids HI11X3SCN (X = Cl, Br, I) have also been prepared and studied [7, 8]. As a continuation of the interest of our laboratory in the complex haloacids and their compounds in this paper we report the preparation, for the first time, of three etherate, five pyridine and eight aniline compounds of complex halo and pseudohalo acids of Zn(II). Thiocyanate was used as a pseudo- halogen. Experimental Reagents High purity reagents were used for the prepara- tion of the complex compounds. Diethyl ether was treated as usual for the removal of peroxides and moisture [9]. The organic bases, pyridine and aniline, were doubly distilled under atmospheric pressure. Preparation of the complexes The preparation of the etherate complexes HZnCl 2 I • 3 E t 2 0 (1) and HZnBr 2 I • 3 E t 2 0 (2) was carried out by the "etherohalogenosis" method [3]. As starting materials anhydrous ZnCl 2 and ZnBr 2 and an ether solution of HI, 0.3 N were used; the last reagent was in 20% excess. The experimental temperature was kept at — 5 0 °C (mixture of dry ice and acetone). The preparation of HZnI 2 ( C S N ) • 3 E t 2 0 (3) was achieved by a method previously described [7]. The ether solution of HSCN, 0.05 N, was added in 80% excess. The reaction products 1, 2 and 3, thick oily liquids, were purified by washing with small portions of absolute ether. For the preparation of the pyridine and aniline compounds the following procedure was used: To small amounts of freshly prepared etherate complex haloacids a slight excess of pyridine or aniline was added drop wise. The reaction was vigorous and exothermic and was accompanied by the evolution of vapours. Immediately after the addition of the base, the whole reaction mixture solidified. The addition of more base caused dissolution of the solid product and the appearance of a clear solution. Subsequently, the reaction vessel was placed in a vacuum desiccator over concentrated sulfuric acid. The final crystalline product was obtained by repeated pumping. The product was washed with small portions of absolute ether and heated to 35 °C for 15 min. Analyses a) Instruments and apparatus For the Potentiometrie determinations of the acidic hydrogen and the organic bases a pH meter Radiometer Copenhagen NV.-Type P H M 26 c and * Reprint requests to Prof. A. G. Galinos. ** Thiocyanate will be indicated as CNS whenever the actual mode of bonding is undetermined. 0340-5087/79/0800-1101/5 01.00/0

Compounds of Complex Halo and Pseudohalo Acids of the Group …zfn.mpdl.mpg.de/data/Reihe_B/34/ZNB-1979-34b-1101.pdf · 2018. 2. 9. · product and the appearance of a clear solution

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Page 1: Compounds of Complex Halo and Pseudohalo Acids of the Group …zfn.mpdl.mpg.de/data/Reihe_B/34/ZNB-1979-34b-1101.pdf · 2018. 2. 9. · product and the appearance of a clear solution

This work has been digitalized and published in 2013 by Verlag Zeitschrift für Naturforschung in cooperation with the Max Planck Society for the Advancement of Science under a Creative Commons Attribution4.0 International License.

Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschungin Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung derWissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht:Creative Commons Namensnennung 4.0 Lizenz.

Compounds of Complex Halo and Pseudohalo Acids of the Group II B Metals, Part I Etherate, Pyridine and Aniline Compounds of Zn(II)

A . G . G a l i n o s * , J . K . K o u i n i s , P . V . I o a n n o u , T h . F . Z a f i r o p o u l o s , a n d S. P . P e r l e p e s

Department of Inorganic Chemistry, University o f Patras, Patras, Greece

Z. Naturforsch. 34b , 1101-1106 (1979); received M a y 11, 1979

Ether, Pyridine, Aniline, Thiocyanate , Zinc

The preparation o f sixteen new etherate, pyridine and aniline c o m p o u n d s of complex halo and pseudohalo acids o f Z n ( I I ) is reported.

The study of some physical and chemical properties as well as the U V and I R spectra o f these compounds are discussed. Tetrahedral structures are proposed for all c ompounds in the solid state.

Introduct ion

A l t h o u g h a l a r g e n u m b e r o f s a l t s o f t h e c o m p l e x

a n i o n s [ M n X 3 ] - a n d [ M n X 4 ] 2 ~ is k n o w n , t h e s i t u a -

t i o n w i t h r e g a r d t o t h e c o r r e s p o n d i n g a c i d s is n o t

v e r y c l e a r . T h e s t u d y o f t h e s e a c i d s is o f s p e c i a l

i n t e r e s t , s ince a g r e a t n u m b e r o f t h e m is u s e d i n

c e r t a i n F r i e d e l - C r a f t s r e a c t i o n s . T h e c a t a l y t i c a c t i o n

o f t h e e t h e r a t e HAICI4 • 2 E t 2 0 h a s b e e n s t u d i e d [1] .

T h e p r e p a r a t i o n o f e t h e r a t e a n d p y r i d i n e c o m p o u n d s

o f t h e a c i d s H Z n C l 2 B r , H Z n B r 3 a n d H Z n I 2 B r h a s

b e e n r e p o r t e d [2-4] . R e c e n t l y , w e p r e p a r e d a n d

s t u d i e d t h e c o m p l e x c o m p o u n d s H Z n C l 3 • 3 A n ,

H Z n B r 2 C l • 3 A n a n d H Z n I 2 C l • 3 A n , w h e r e A n =

a n i l i n e [5].

T h e s t u d y o f c o m p o u n d s o f m i x e d c o m p l e x

m e t a l l o h a l o a c i d s w i t h p s e u d o h a l o g e n s is o f s o m e

t h e o r e t i c a l i n t e r e s t . T h e i s o l a t i o n o f t h e c o m p o u n d s

H Z n C l 2 ( C S N ) • 2 E t 2 0 a n d H Z n B r 2 ( C S N ) • 2 E t 2 0

h a s b e e n a c h i e v e d i n t h e p a s t [6]** . T h e e t h e r a t e ,

p y r i d i n e a n d a n i l i n e c o m p o u n d s o f t h e a c i d s

H I 1 1 X 3 S C N ( X = Cl , B r , I ) h a v e a l s o b e e n p r e p a r e d

a n d s t u d i e d [7, 8].

A s a c o n t i n u a t i o n o f t h e i n t e r e s t o f o u r l a b o r a t o r y

i n t h e c o m p l e x h a l o a c i d s a n d t h e i r c o m p o u n d s i n

t h i s p a p e r w e r e p o r t t h e p r e p a r a t i o n , f o r t h e f i rs t

t i m e , o f t h r e e e t h e r a t e , f i v e p y r i d i n e a n d e i g h t

a n i l i n e c o m p o u n d s o f c o m p l e x h a l o a n d p s e u d o h a l o

a c i d s o f Z n ( I I ) . T h i o c y a n a t e w a s u s e d a s a p s e u d o -

h a l o g e n .

Exper imenta l

Reagents H i g h p u r i t y r e a g e n t s w e r e u s e d f o r t h e p r e p a r a -

t i o n o f t h e c o m p l e x c o m p o u n d s . D i e t h y l e t h e r w a s t r e a t e d as u s u a l f o r t h e r e m o v a l o f p e r o x i d e s a n d m o i s t u r e [9]. T h e o r g a n i c b a s e s , p y r i d i n e a n d a n i l i n e , w e r e d o u b l y d i s t i l l e d u n d e r a t m o s p h e r i c p r e s s u r e .

Preparation of the complexes T h e p r e p a r a t i o n o f t h e e t h e r a t e c o m p l e x e s

H Z n C l 2 I • 3 E t 2 0 (1) a n d H Z n B r 2 I • 3 E t 2 0 (2) w a s c a r r i e d o u t b y t h e " e t h e r o h a l o g e n o s i s " m e t h o d [3]. A s s t a r t i n g m a t e r i a l s a n h y d r o u s Z n C l 2 a n d Z n B r 2

a n d a n e t h e r s o l u t i o n o f H I , 0.3 N w e r e u s e d ; t h e l a s t r e a g e n t w a s i n 2 0 % e x c e s s . T h e e x p e r i m e n t a l t e m p e r a t u r e w a s k e p t a t — 5 0 °C ( m i x t u r e o f d r y i ce a n d a c e t o n e ) . T h e p r e p a r a t i o n o f H Z n I 2 ( C S N ) • 3 E t 2 0 (3) w a s a c h i e v e d b y a m e t h o d p r e v i o u s l y d e s c r i b e d [7]. T h e e t h e r s o l u t i o n o f H S C N , 0.05 N , w a s a d d e d i n 8 0 % e x c e s s . T h e r e a c t i o n p r o d u c t s 1 , 2 a n d 3, t h i c k o i l y l i q u i d s , w e r e p u r i f i e d b y w a s h i n g w i t h s m a l l p o r t i o n s o f a b s o l u t e e t h e r .

F o r t h e p r e p a r a t i o n o f t h e p y r i d i n e a n d a n i l i n e c o m p o u n d s t h e f o l l o w i n g p r o c e d u r e w a s u s e d : T o s m a l l a m o u n t s o f f r e s h l y p r e p a r e d e t h e r a t e c o m p l e x h a l o a c i d s a s l i g h t e x c e s s o f p y r i d i n e or a n i l i n e w a s a d d e d d r o p w i s e . T h e r e a c t i o n w a s v i g o r o u s a n d e x o t h e r m i c a n d w a s a c c o m p a n i e d b y t h e e v o l u t i o n o f v a p o u r s . I m m e d i a t e l y a f t e r t h e a d d i t i o n o f t h e b a s e , t h e w h o l e r e a c t i o n m i x t u r e so l id i f ied . T h e a d d i t i o n o f m o r e b a s e c a u s e d d i s s o l u t i o n o f t h e s o l i d p r o d u c t a n d t h e a p p e a r a n c e o f a c l e a r s o l u t i o n . S u b s e q u e n t l y , t h e r e a c t i o n v e s s e l w a s p l a c e d i n a v a c u u m d e s i c c a t o r o v e r c o n c e n t r a t e d s u l f u r i c a c i d . T h e f i n a l c r y s t a l l i n e p r o d u c t w a s o b t a i n e d b y r e p e a t e d p u m p i n g . T h e p r o d u c t w a s w a s h e d w i t h s m a l l p o r t i o n s o f a b s o l u t e e t h e r a n d h e a t e d t o 3 5 °C f o r 1 5 m i n .

Analyses a) I n s t r u m e n t s a n d a p p a r a t u s

F o r t h e P o t e n t i o m e t r i e d e t e r m i n a t i o n s o f t h e a c i d i c h y d r o g e n a n d t h e o r g a n i c b a s e s a p H m e t e r R a d i o m e t e r C o p e n h a g e n N V . - T y p e P H M 26 c a n d

* Reprint requests to Prof . A . G. Galinos. ** Thiocyanate will be indicated as CNS whenever

the actual m o d e of bonding is undetermined. 0340-5087/79/0800-1101/5 01.00/0

Page 2: Compounds of Complex Halo and Pseudohalo Acids of the Group …zfn.mpdl.mpg.de/data/Reihe_B/34/ZNB-1979-34b-1101.pdf · 2018. 2. 9. · product and the appearance of a clear solution

1102 A. G. Galinos et al. • Etherate, Pyridine and Aniline Compounds of Zn(II)

g l a s s a n d c a l o m e l e l e c t r o d e s w e r e e m p l o y e d . I n t h e d e t e r m i n a t i o n s o f t h e a c i d i c h y d r o g e n in t h e p y r i d i n e a n d a n i l i n e c o m p o u n d s t h e s a t u r a t e d a q u e o u s solu-t i o n K C l o f t h e c a l o m e l e l e c t r o d e w a s r e p l a c e d b y a m e t h a n o l i c o n e [10]. F o r t h e P o t e n t i o m e t r i e d e t e r -m i n a t i o n s o f t h e h a l o g e n s a n d t h e t h i o c y a n a t e a p o t e n t i o m e t e r C o r n i n g - E e l , m o d e l 12 w a s u s e d w i t h c a l o m e l a n d su l f ide e l e c t r o d e s , b) A n a l y t i c a l p r o c e d u r e s

F o r t h e q u a n t i t a t i v e d e t e r m i n a t i o n o f t h e e t h e r a t e c o m p o u n d s a s o l u t i o n w a s p r e p a r e d b y d e c o m p o s i n g a d e f i n i t e a m o u n t o f e a c h c o m p o u n d w i t h w a t e r . T h e a c i d i c h y d r o g e n w a s d e t e r m i n e d p o t e n t i o m e t r i -c a l l y w i t h a s t a n d a r d 0.1 N K O H s o l u t i o n [ 1 1 a ] . T h e h y d r o l y s i s o f Z n ( I I ) w a s t a k e n i n t o a c c o u n t . Z i n c w a s d e t e r m i n e d v o l u m e t r i c a l l y w i t h a 0.05 M E D T A s o l u t i o n [ l i b ] . T h e t o t a l h a l o g e n w a s d e t e r m i n e d v o l u m e t r i c a l l y b y t h e V o l h a r d m e t h o d [ 1 1 c ] a n d p o t e n t i o m e t r i c a l l y w i t h a 0.1 N A g N 0 3 s o l u t i o n [12] . T h e i o d i d e i o n i n t h e p r e s e n c e o f c h l o r i d e o r b r o m i d e w a s d e t e r m i n e d b y t h e P d C l 2 m e t h o d [ l i d ] . T h e s u m o f i o d i d e a n d t h i o c y a n a t e i o n s a s w e l l a s e a c h o f t h e m i n t h e p r e s e n c e o f t h e o t h e r w e r e d e t e r m i n e d p o t e n t i o m e t r i c a l l y w i t h a 0.1 N A g N 0 3 s o l u t i o n [12]. E t h e r w a s d e t e r m i n e d b y w e i g h t d i f f e r e n c e .

T h e a c i d i c h y d r o g e n o f t h e p y r i d i n e a n d a n i l i n e c o m p o u n d s w a s d e t e r m i n e d p o t e n t i o m e t r i c a l l y w i t h a 0.1 N K O H s o l u t i o n , a f t e r d i s s o l v i n g t h e m i n a b s o l u t e D M S O [10]. T h e c o n t e n t o f t h e o r g a n i c b a s e w a s d e t e r m i n e d b y d i s s o l v i n g t h e c o m p o u n d i n g l a c i a l C H 3 C O O H a n d P o t e n t i o m e t r i e t i t r a t i o n w i t h a 0.1 M H C I O 4 s o l u t i o n i n C H 3 C O O H o r s i m p l e t i t r a t i o n w i t h 0.1 M H C I O 4 a n d C r y s t a l v i o l e t a s t h e i n d i c a t o r [ 1 3 ] ; t o t h e s a m p l e b e i n g a n a l y z e d w e r e a d d e d 5 - 8 m l o f 6 % H g ( C H 3 C O O ) 2 s o l u t i o n i n C H 3 C O O H . Z i n c w a s d e t e r m i n e d as d e s c r i b e d a b o v e ; a 1 5 % a q u e o u s s o l u t i o n o f C 2 H 5 O H w a s e m p l o y e d a s a s o l v e n t . T h e h a l o g e n s a n d t h i o c y a n a t e w e r e d e t e r m i n e d a s d e s c r i b e d a b o v e , t h e s a m p l e s b e i n g d i s s o l v e d i n 2 N H N 0 3 . T h e c h l o r i d e a n d b r o m i d e ions , t h e c h l o r i d e a n d t h i o c y a n a t e ions , a n d t h e b r o m i d e a n d t h i o c y a n a t e i o n s w e r e d e t e r m i n e d p o t e n t i o m e t r i c a l l y [12],

Stability test for the pyridine and aniline compounds [4]

A s m a l l a m o u n t o f t h e c o m p o u n d w a s d i s s o l v e d i n a b s o l u t e e t h a n o l . N o p r e c i p i t a t e a p p e a r e d b y t h e a d d i t i o n o f a 0 . 5 % e t h a n o l i c s o l u t i o n o f A g C 1 0 4 . A s l i g h t c l o u d i n e s s a p p e a r e d a f t e r a f e w m i n u t e s . D i l u t i o n w i t h w a t e r c a u s e d t h e A g ( I ) h a l i d e s a n d A g S C N t o p r e c i p i t a t e .

Physicochemical measurements T h e m . p . o f t h e p y r i d i n e a n d a n i l i n e c o m p o u n d s

w e r e o b t a i n e d i n a B ü c h i 5 1 0 a p p a r a t u s . F o r t h e c o n d u c t i v i t y m e a s u r e m e n t s 10~3 M s o l u t i o n s w e r e p r e p a r e d i n C H 3 N O 2 , w h i c h w a s p r o p e r l y p r e t r e a t e d [14]. A c o n d u c t i v i t y a p p a r a t u s , E h r h a r d t - M e t z g e r

N a c h f . t y p e L 2 1 , w a s e m p l o y e d . T h e ce l l c o n s t a n t w a s C = 1 c m - 1 a n d t h e m e a s u r e m e n t s w e r e c a r r i e d o u t a t 2 5 ± 0.1 °C. T h e U V s p e c t r a o f t h e p y r i d i n e a n d a n i l i n e c o m p o u n d s w e r e t a k e n i n a B a u s c h L o m b - S h i m a d z u S p e c t r o n i c 2 1 0 U V d o u b l e b e a m s p e c t r o p h o t o m e t e r w i t h a d e u t e r i u m l a m p . T h e s o l v e n t w a s s p e c t r o s c o p i c q u a l i t y C 2 H 5 O H , t h e con-c e n t r a t i o n s 1 0 - 5 - 1 0 - 4 M a n d t h e r e g i o n s c a n n e d 2 1 0 - 3 2 0 n m . T h e I R s p e c t r a o f t h e s e c o m p o u n d s w e r e r e c o r d e d i n P e r k i n - E l m e r s p e c t r o p h o t o m e t e r s 4 5 7 a n d 5 7 7 . T h e s a m p l e s w e r e u s e d i n t h e f o r m o f K B r p e l l e t s . T h e s p e c t r a c o v e r e d t h e r e g i o n 4 0 0 0 - 2 5 0 c m - 1 .

Results and Discussion F o r t h e p r e p a r a t i o n o f c o m p o u n d s 1 a n d 2 a l o w

t e m p e r a t u r e is r e q u i r e d , s i n c e a t h i g h t e m p e r a t u r e s

e t h e r is c l e a v e d b y H I [15] . T h e e t h e r a t e s f u m e i n

a i r a n d a r e i n s o l u b l e i n n o n p o l a r s o l v e n t s . T h e

p y r i d i n e a n d a n i l i n e c o m p o u n d s a r e f o r m e d b y t h e

c o m p l e t e r e p l a c e m e n t o f t h e e t h e r b y p y r i d i n e or

a n i l i n e :

P y

H Z n I 2 ( C S N ) • 3 E t 2 0 + 3 P y >

e x c e s s

H Z n l a S C N • 3 P y + 3 E t 2 0

w h e r e P y = p y r i d i n e . T h e p y r i d i n e a n d a n i l i n e

c o m p o u n d s a r e c r y s t a l l i n e so l ids a n d s t a b l e i n t h e

a i r . T h e y a r e i n s o l u b l e i n n o n p o l a r s o l v e n t s , s o m e -

w h a t s o l u b l e i n w a t e r a n d a l c o h o l s a n d s o l u b l e i n

o t h e r p o l a r s o l v e n t s . T h e y d i s s o l v e r e a d i l y i n d i l u t e

m i n e r a l a c i d s .

T h e a n a l y t i c a l r e s u l t s , c o l o r s , m e l t i n g p o i n t s

( u n c o r r e c t e d ) a n d A m v a l u e s a r e g i v e n i n T a b l e I .

T h e s t a b i l i t y t e s t f o r t h e p y r i d i n e a n d a n i l i n e

c o m p o u n d s l e n d s a s t r o n g s u p p o r t t o t h e a s s u m p t i o n

t h a t a l l h a l i d e i o n s a n d t h e t h i o c y a n a t e a r e co-

o r d i n a t e d t o Z n ( I I ) ; t h e n e w c o m p o u n d s , t h e r e f o r e ,

a r e c o m p l e x c o m p o u n d s a n d n o t d o u b l e sa l ts [4].

T h e s l i g h t c l o u d i n e s s , a p p e a r i n g a f t e r a s h o r t t i m e ,

is a t t r i b u t e d t o t h e s l i g h t d i s s o c i a t i o n o f t h e c o m p l e x

i o n s i n e t h a n o l .

F r o m t h e A m v a l u e s o b t a i n e d , i t is c o n c l u d e d t h a t

a l l p y r i d i n e a n d a n i l i n e c o m p l e x e s in n i t r o m e t h a n e

b e h a v e a s 1 : 1 e l e c t r o l y t e s [16].

T h e U V s p e c t r a o f t h e p y r i d i n e c o m p o u n d s s h o w

a b s o r p t i o n m a x i m a a t 233, 240, 245, 250, 257 a n d

2 6 3 n m . T h e s e m a x i m a a r e a t t r i b u t e d t o n -> n * a n d

n - + 7 i * e l e c t r o n i c t r a n s i t i o n s [ 1 7 , 18]. T h e m a x i m u m

a t 290 n m i n t h e s p e c t r a o f c o m p o u n d s 4, 5 a n d 8

is v e r y p e c u l i a r ; i t c a n n o t b e d u e t o a n n -> 71*

t r a n s i t i o n [ 1 7 , 18]. T h e U V s p e c t r u m o f p u r e a n i l i n e

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1103 A. G. Galinos et al. • Etherate, Pyridine and Aniline Compounds of Zn(II)

Table I. Analytical results, colors, m.p. and /IM values of the new etherate, pyridine and aniline compounds of the complex halo and pseudohalo acids of Zn(II).

No. Compound [%] Acidic hydro-gen

Zn Cl Br I SCN B Color m.p. [°C] [S cm2 mol -1]

1 HZnCl2I • 3 Et20 Calcd 0.20 13.44 14.57 26.08 45.70 crimson Found 0.18 13.70 14.33 25.60 46.19

2 HZnBr2I • 3 Et20 Calcd 0.17 11.36 27.77 22.05 38.64 crimson Found 0.16 10.99 27.02 21.96 39.87

8 HZnI2(CSN) • 3 Et20 Calcd 0.17 10.88 42.31 9.66 36.98 orange-Found 0.17 10.53 43.18 9.86 36.29 red

4 HZnCl2I • 3 Py Calcd 0.20 13.04 14.14 25.30 47.32 yellow 110 72 Found 0.17 13.93 14.28 23.15 48.23

yellow

5 HZnBr2I • 3 Py Calcd 0.17 11.07 27.07 21.49 40.19 straw 117 86 HZnBr2I • 3 Py Found 0.17 11.28 27.72 20.45 41.22

6 HZnCl2SCN • 3 Py Calcd 0.23 15.12 16.42 13.41 54.81 flesh 191 84 HZnCl2SCN • 3 Py Found 0.23 16.02 16.79 13.69 53.33

7 HZnBr2SCN • 3 Py Calcd 0.19 12.54 30.69 11.12 45.45 straw 210 79 HZnBr2SCN • 3 Py Found 0.18 13.01 31.18 11.31 43.06

8 HZnI2SCN • 3 Py Calcd 0.16 10.63 41.27 9.42 38.51 grey 182 76 HZnI2SCN • 3 Py Found 0.16 11.03 42.96 10.21 38.24

grey

9 HZnCl2Br • 3 An Calcd 0.20 13.17 14.28 16.09 56.26 white 185d 69 Found 0.18 13.38 13.74 17.28 54.15

10 HZnBr3 • 3 An Calcd 0.17 11.17 40.94 47.72 pale 162d 87 Found 0.17 10.99 40.46 47.97 pink

11 HZnI2Br • 3 An Calcd 0.15 9.62 11.76 37.35 41.12 light beige

168- 73 Found 0.15 9.88 12.34 35.11 42.52

light beige 170

12 HZnCl2I • 3 An Calcd 0.18 12.03 13.04 23.34 51.40 whitish- 150d 81 Found 0.16 12.80 13.12 23.02 51.05 yellow

13 HZnBr2I • 3 An Calcd 0.16 10.34 25.27 20.06 44.17 yellowish 162- 68 Found 0.15 10.43 26.13 19.25 43.79

yellowish 165d

14 HZnCl2NCS • 3 An Calcd 0.21 13.78 14.97 12.23 58.81 flesh 238d 77 Found 0.21 14.03 15.06 12.18 58.59

15 HZnBr2NCS • 3 An Calcd 0.18 11.61 28.40 10.29 49.52 pale 245 74 Found 0.17 12.10 29.04 10.21 50.52 pink

16 HZnlaNCS • 3 An Calcd 0.15 9.95 38.64 8.82 42.44 yellow 217 81 Found 0.16 10.17 39.04 9.04 43.58

yellow

B = Et20, Py, An. a Values of molar conductance for 10~3 M solutions in CH3N02 at 25 °C. d = decomposes.

Table II. IR spectral assignments of some absorption bands of diagnostic value for the pyridine complexes.

Complex v(C-N) f(C-S) <5(NCS) Vibrations of the pyridine ring

i»(Zn-Cl)t »(Zn-Br)t

4 632 s 420 s 413 sh 323 s 290 s 5 631s 421s 411 sh 251 s 6 2078 s overlapped by absorption 638 vs 422 s 325 s 295 s 7 2078 s bands of the coordinated 638 vs 422 s 418 s 255 s 8 2078 m pyridine 640 s 425 s 418 m s = strong, sh = shoulder, m = medium, vs = very strong.

Table III. IR spectral assignments of some absorption bands of diagnostic value for the aniline complexes.

Complex v(C-N) v(C-S) <5(NCS) J'asym(N-H) f s y m (N-H) v(Zn-An) i>(Zn-Cl)t v(Zn-Br)t

9 3270 m 3225 m 400 sh 357 s 290 s 274 sh <250 10 3263 m 3220 m 399 sh 355 s 250 s 11 3262 m 3219 m 400 sh 341 s 253 m 12 3265 m 3220 m 400 w 358 s 290 s 275 sh 13 3270 m 3224 m 400 sh 347 m 252 m 14 2090 s overlapped 477 m 3260 vs 3220 vs 405 m 365 s 296 s 15 2090 s by bands of the 475 m 3260 vs 3220 vs 400 s 357 s <250

coordinated 16 2080 s aniline 471 m 3265 s 3215 s 395 m 343 s

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1104 A. G. Galinos et al. • Etherate, Pyridine and Aniline Compounds of Zn(II)

i n e t h a n o l s h o w s a b s o r p t i o n m a x i m a a t 2 3 5 a n d

285 n m . T h e s p e c t r a o f t h e s a l t s A n H X ( X = C l ,

B r , I , S C N ) i n e t h a n o l a l s o s h o w r e g u l a r m a x i m a a t

2 3 5 a n d 2 8 5 n m a s w e l l a s s u c c e e d i n g a b s o r p t i o n s i n

t h e f o r m o f s h o u l d e r s a t 2 5 5 , 260 a n d 2 6 5 n m . T h e s e

s h o u l d e r s a r e d u e t o t h e A n H + i o n [19] . T h e m a x i m a

a t 230 a n d 285 n m i n t h e s p e c t r a o f a l l a n i l i n e

c o m p l e x e s o b t a i n e d a r e d u e t o e l e c t r o n i c t r a n s i t i o n s

o f a n i l i n e , s i n c e t h e y a p p e a r i n t h e s p e c t r a o f a n i l i n e ,

A n H X a n d c o o r d i n a t i o n c o m p o u n d s o f a n i l i n e [20].

T h e s h o u l d e r a t 260 n m i n t h e s p e c t r a o f m o s t ani -

l i n e c o m p l e x e s is a t t r i b u t e d t o t h e A n H + i o n [19] .

S o m e c h a r a c t e r i s t i c a n d o f d i a g n o s t i c v a l u e I R

f r e q u e n c i e s ( c m - 1 ) o f t h e p y r i d i n e a n d a n i l i n e

c o m p l e x e s a r e g i v e n i n T a b l e s I I a n d I I I , r e s p e c -

t i v e l y .

Study of IR spectra of the pyridine complexes T h e t w o o r t h r e e w e a k a b s o r p t i o n b a n d s i n t h e

r e g i o n 3 2 2 0 - 3 1 0 0 c m - 1 i n t h e s p e c t r a o f t h e p y r i d i n e

c o m p l e x e s a r e d u e t o t h e P y H + i o n ; t h e i r l o w

i n t e n s i t y i n d i c a t e s t h a t t h e P y H + i o n is i n v o l v e d i n

h y d r o g e n b r i d g i n g [ 2 1 ] . T h e a b s e n c e , a l so , o f a

s t r o n g b r o a d b a n d j u s t b e l o w 3000 c m - 1 e x c l u d e s

t h e p r e s e n c e o f h y d r o g e n b o n d i n g o f t h e c a t i o n -

a n i o n t y p e , N + - H - - - X - [ 2 1 ] ; t h i s is , o f c o u r s e ,

e x p e c t e d s i n c e , a l l h a l i d e i o n s a n d t h e t h i o c y a n a t e

a r e c o o r d i n a t e d t o Z n ( I I ) . T h e p r e s e n c e o f P y H + i o n

i n t h e m o l e c u l e s o f t h e p r e p a r e d c o m p l e x e s is

c l e a r l y i n d i c a t e d b y t h e a b s o r p t i o n b a n d s a t 1630,

1600, 1 5 2 5 , 1480, 1 3 2 5 , 1 2 4 0 a n d 1 1 8 5 c m - 1 [22, 23],

T h e t w o a b s o r p t i o n b a n d s a t 1 5 7 0 a n d 1 4 4 5 c m - 1

a s w e l l a s t h e s t r o n g o n e s a t 1 2 1 5 , 1 1 5 0 , 1065, 1040,

1 0 1 0 , 7 5 0 a n d 6 9 5 c m - 1 a r e d u e t o c o o r d i n a t e d

p y r i d i n e [23]. T h e s t r o n g b a n d s a t 6 3 5 a n d 420 c m - 1

a r e t h o u g h t o f b e i n g s h i f t s o f t h e b a n d s a t 604 ( a n

i n - p l a n e r i n g d e f o r m a t i o n ) a n d 4 0 5 ( a n o u t - o f - p l a n e

r i n g d e f o r m a t i o n ) c m - 1 o f f r e e p y r i d i n e . T h e s h i f t i n g

o f t h e s e b a n d s t o h i g h e r f r e q u e n c i e s i n d i c a t e s co-

o r d i n a t e d p y r i d i n e [22, 2 4 ] ; c o n s i s t e n t w i t h t h i s is

t h e s p l i t t i n g o f t h e b a n d a t 420 c m - 1 i n t h e s p e c t r a

o f t h e c o m p l e x e s 4, 5 , 7 , a n d 8 [22, 24], T h e b a n d a t

635 c m - 1 i n d i c a t e s a t e t r a h e d r a l e n v i r o n m e n t a r o u n d

Z n ( I I ) [24, 25] . A b s o r p t i o n b a n d s d u e t o Z n - N ( P y )

s t r e t c h i n g v i b r a t i o n s a p p e a r b e l o w 2 5 0 c m - 1 [ 2 4 - 2 6 ] .

T h e s t r o n g b a n d s i n t h e r e g i o n 3 2 5 - 2 9 0 c m - 1 i n

t h e s p e c t r a o f c o m p o u n d s 4 a n d 6 a r e a t t r i b u t e d t o

Z n - C l t e r m i n a l s t r e t c h i n g v i b r a t i o n s , r ( Z n - C l ) t ,

s ince t h e y a r e a b s e n t i n t h e s p e c t r a o f c h l o r i n e - f r e e

c o m p l e x e s ; t h e f r e q u e n c i e s o f t h e s e b a n d s c l e a r l y

s h o w t h a t t h e s t r u c t u r e o f c o m p o u n d s 4 a n d 6 is

t e t r a h e d r a l [24, 26], L i k e w i s e , t h e s t r o n g b a n d s a t

2 5 1 a n d 2 5 5 c m - 1 i n t h e s p e c t r a o f 5 a n d 7 , r e s p e c -

t i v e l y a r e a t t r i b u t e d t o v ( Z n - B r ) t a n d t h e i r f re-

q u e n c i e s i n d i c a t e a t e t r a h e d r a l l i g a n d a r r a n g e m e n t

a r o u n d Z n ( I I ) [24]. T h e Z n - I s t r e t c h i n g v i b r a t i o n s

o c c u r b e l o w 250 c m - 1 [24].

T h e t h i o c y a n a t e g r o u p h a s t h r e e d i a g n o s t i c I R

r e g i o n s ; C - N s t r e t c h i n g v ( C - N ) , C - S s t r e t c h i n g

v ( C - S ) a n d N C S b e n d i n g <5(NCS). T h e a b s o r p t i o n

b a n d s i n t h e s e r e g i o n s a r e a f f e c t e d b y d i f f e r e n t

t y p e s o f c o o r d i n a t i o n . T h e a b s o r p t i o n b a n d s i n t h e

C N r e g i o n a p p e a r a t 2078 c m - 1 i n o u r s p e c t r a , a f a c t

i n d i c a t i n g t h e a b s e n c e o f b r i d g e d - S C N - g r o u p s [27]

or f r e e t h i o c y a n a t e i o n s [28]. T h e C - S s t r e t c h i n g

r e g i o n h a s b e e n w e l l d e a l t w i t h i n t h e c h e m i c a l

l i t e r a t u r e a n d h a s b e e n u s e d as a d i a g n o s t i c r e g i o n

f o r t h e t y p e o f b o n d i n g o f t h e t h i o c y a n a t e g r o u p i n

t h e c o m p l e x e s . T u r c o a n d P e c i l e [29], s t u d y i n g I R

s p e c t r a o f c o m p l e x e s o f k n o w n s t r u c t u r e s h o w e d

t h a t t h e r ( C - S ) f o r t h e S - b o n d e d c o m p l e x e s o c c u r s

i n t h e r e g i o n 6 9 0 - 7 2 0 c m - 1 a n d i n t h e r e g i o n 7 8 0 -

860 c m - 1 f o r t h e N - b o n d e d o n e s . S i n c e o u r s p e c t r a

d o n o t s h o w a b s o r p t i o n b a n d s i n t h e r e g i o n 7 8 0 -

860 c m - 1 , t h e p r e s e n c e o f Z n - N C S b o n d is e x c l u d e d .

T h e a s s i g n m e n t o f r ( C - S ) i n t h e r e g i o n 6 9 0 - 7 2 0 c m - 1

is i m p o s s i b l e d u e t o t h e s i m u l t a n e o u s a p p e a r a n c e o f

a b s o r p t i o n b a n d s o f c o o r d i n a t e d p y r i d i n e . T h e

t h i o c y a n a t e c o m p l e x e s s h o w a b s o r p t i o n b a n d s i n

t h e r e g i o n 4 4 0 - 4 0 0 c m - 1 a n d t h e i s o t h i o c y a n a t e

o n e s i n t h e r e g i o n 4 9 0 - 4 5 0 c m - 1 [30, 3 1 ] . I n o u r

case , t h e a b s e n c e o f a b a n d i n t h e r e g i o n 4 9 0 -

450 c m - 1 e x c l u d e s or r u l e s o u t t h e p r e s e n c e o f

Z n - N C S b o n d ; i n t h e r e g i o n 4 4 0 - 4 0 0 c m - 1 co-

o r d i n a t e d p y r i d i n e a b s o r b s t o o .

C a r e f u l e x a m i n a t i o n o f t h e s p e c t r a o f a l l p r e p a r e d

p y r i d i n e c o m p o u n d s c l e a r l y s h o w s t h e a b s e n c e o f

c h a r a c t e r i s t i c b a n d s o f f r e e p y r i d i n e ; h e n c e t h e s e

c o m p o u n d s c o n t a i n n o l a t t i c e p y r i d i n e [32].

Study of IR spectra of the aniline complexes T h e s p e c t r a o f a l l a n i l i n e c o m p l e x e s s h o w t w o

s t r o n g a n d b r o a d b a n d s a t 2850 a n d 2580 c m - 1 ,

w h i c h a r e i n d i c a t i v e o f t h e A n H + i o n i n v o l v e d i n

h y d r o g e n b r i d g i n g [33, 34]. T h e n u m e r o u s w e a k

b a n d s i n t h e r e g i o n 2 5 5 0 - 1 6 5 0 c m - 1 a r e m a i n l y

c o m b i n a t i o n b a n d s a n d o v e r t o n e s , s o m e o f w h i c h

a r e d u e t o t h e a b s o r p t i o n o f t h e - N H 3 + g r o u p

[33, 35]. T h e a s s i g n m e n t s i n t h e r e g i o n 1620 t o

1500 c m - 1 a r e d i f f i c u l t , s i n c e b a n d s i n t h i s r e g i o n

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1105 A . G. Galinos et al. • Etherate, Pyridine and Aniline Compounds o f Z n ( I I )

a r e d u e t o s t r e t c h i n g v i b r a t i o n s o f t h e b e n z e n e r i n g

a n d b e n d i n g v i b r a t i o n s o f t h e - N H 3 + g r o u p [33].

T h e b a n d s a t 1600, 1 5 6 0 , 1 5 1 5 , 1490, 1 4 6 5 , 1 3 2 5 ,

1290, 1 1 9 0 , 1 1 7 5 , 1 1 5 0 , 1 1 1 0 , 1080, 1025, 1000, 960,

900, 840, 800, 740, 680, 6 1 5 , 5 2 5 a n d 380 c m - 1 a r e

d u e t o A n H + i o n s i n c e t h e s e a p p e a r a l s o i n t h e

s p e c t r a o f A n H X .

T h e s p e c t r u m a l s o s h o w s t h a t a n i l i n e is co-

o r d i n a t e d t o Z n ( I I ) . A l l s p e c t r a s h o w t w o a b s o r p t i o n

b a n d s i n t h e r e g i o n 3 3 0 0 - 3 2 0 0 c m - 1 . T h e b a n d a t

t h e h i g h e r f r e q u e n c y is a t t r i b u t e d t o - N H 2 a n t i -

s y m m e t r i c s t r e t c h i n g v i b r a t i o n w h i l e t h e o n e a t t h e

l o w e r f r e q u e n c y t o - N H 2 s y m m e t r i c s t r e t c h i n g

v i b r a t i o n . T h e f r e q u e n c i e s o f t h e s e b a n d s (signifi-

c a n t l y l o w e r t h a n t h e c o r r e s p o n d i n g i n f r e e a n i l i n e )

i n d i c a t e c o o r d i n a t e d a n i l i n e [20, 36]. T h e s h i f t i n g

a n d s p l i t t i n g o f t h e b a n d s a t 740, 680, 6 1 5 a n d

5 2 5 c m - 1 s h o w a l s o c o o r d i n a t e d a n i l i n e [37]. T h e

t w o b a n d s i n t h e r e g i o n 4 0 5 - 3 4 1 c m - 1 o f e v e r y

s p e c t r u m a r e a t t r i b u t e d t o Z n - N ( A n ) s t r e t c h i n g

v i b r a t i o n o r t o v i b r a t i o n m o d e s o f a n i l i n e ; t h e l a t t e r

h a v e , p o s s i b l y , s h i f t e d o r b e c o m e i n f r a r e d a c t i v e

u p o n t h e c o o r d i n a t i o n o f a n i l i n e [36, 38].

F r o m t h e j>(Zn-Cl)t a n d v ( Z n - B r ) t v a l u e s (see

T a b l e I I I ) i t is c o n c l u d e d t h a t t h e c o m p l e x e s 9, 10,

1 1 , 1 2 , 1 3 a n d 1 4 h a v e t e t r a h e d r a l s t r u c t u r e [24, 26,

36, 38]. T h e a b s e n c e o f a b a n d , d u e t o Z n - B r

s t r e t c h i n g v i b r a t i o n , a b o v e 2 5 0 c m - 1 i n t h e spec-

t r u m o f c o m p o u n d 1 5 , is r e a s o n a b l e , s i n c e t h i s b a n d

o f t e n o c c u r s s l i g h t l y b e l o w 2 5 0 c m - 1 f o r t e t r a h e d r a l

c o m p l e x e s o f Z n ( I I ) [26, 38],

T h e p r e s e n c e o f t h e S C N g r o u p i n t h e i n n e r s p h e r e

o f t h e a n i l i n e c o m p l e x e s is s h o w n b y t h e a p p e a r a n c e

o f b a n d s a t 2090 a n d 4 7 5 c m - 1 .

T h e p o s i t i o n o f t h e C - N s t r e t c h i n g r u l e s o u t t h e

p r e s e n c e o f t h e t h i o c y a n a t e g r o u p i n t h e i o n i c o r

b r i d g e d f o r m . T h e p o s i t i o n a l s o o f t h e N C S b e n d i n g

s h o w s t h a t t h e b o n d i n g o f t h e t h i o c y a n a t e g r o u p t o

Z n ( I I ) is v i a t h e n i t r o g e n a t o m .

F i n a l l y , t h e a b s e n c e o f l a t t i c e a n i l i n e is c e r t a i n .

Correlation of the data regarding the stereochemistry of the pyridine and aniline complexes in the solid state

F r o m t h e s t a b i l i t y t e s t i t is c o n c l u d e d t h a t t h e

n e w c o m p o u n d s a r e c o m p l e x c o m p o u n d s ; t h e U V

s p e c t r a a l s o s h o w t h a t t h e a n i l i n e c o m p o u n d s

c o n t a i n t h e A n H + i o n .

F r o m t h e I R s p e c t r a l a n a l y s i s i t is c o n c l u d e d

t h a t :

a) A l l c o m p o u n d s c o n t a i n c o o r d i n a t e d o r g a n i c b a s e .

b) I n a l l c o m p l e x e s t h e P y H + a n d A n H + i o n s a r e

i n v o l v e d i n h y d r o g e n b o n d i n g .

c) A l l c o m p l e x a n i o n s a r e t e t r a h e d r a l m o n o m e r s .

d) N o n e o f the.se c o m p o u n d s c o n t a i n s l a t t i c e p y r i -

d i n e o r a n i l i n e .

e) N o n e o f t h e s e c o m p o u n d s c o n t a i n s i o n i c o r

b r i d g e d t h i o c y a n a t e . T h e p y r i d i n e c o m p l e x e s ,

c o n t a i n i n g t h e t h i o c y a n a t e , a r e S - b o n d e d , w h i l e

t h e c o r r e s p o n d i n g a n i l i n e c o m p l e x e s a r e N -

b o n d e d .

O n t h e b a s i s o f a l l t h e s e f i n d i n g s t h e f o l l o w i n g

g e n e r a l s t r u c t u r a l f o r m u l a is p r o p o s e d f o r t h e n e w

p y r i d i n e a n d a n i l i n e c o m p o u n d s :

[ Z n X 2 Y B ] - [ B - - - H - - - B ] + ,

w h e r e X = C1, B r , I ; Y = B r , I , S C N ; B = P y , A n .

T h e s y m b o l - - - r e p r e s e n t s a h y d r o g e n b r i d g e be-

t w e e n t h e p r o t o n i c h y d r o g e n a n d t w o n i t r o g e n

a t o m s o f t w o m o l e c u l e s o f t h e o r g a n i c b a s e i n t h e

o u t e r s p h e r e o f t h e c o m p l e x ; s u c h a h y d r o g e n b o n d

h a s b e e n o b s e r v e d i n n u m e r o u s c o m p o u n d s o f

c o m p l e x h a l o a c i d s [4, 5 , 7 , 8, 37] .

T h e a u t h o r s w i s h t o t h a n k t h e N a t i o n a l H e l l e n i c R e s e a r c h F o u n d a t i o n f o r t h e financial s u p p o r t o f p a r t o f t h i s w o r k . O n e o f u s ( S . P . P . ) is e s p e c i a l l y g r a t e f u l t o t h e s a i d F o u n d a t i o n f o r t h e financial s u p p o r t h e r e c e i v e d f o r t h e d u r a t i o n o f t h i s r e s e a r c h .

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1106 A. G. Galinos et al. • Etherate, Pyridine and Aniline Compounds of Zn(II)

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