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Pentamethylcyclopentadienyl Halfsandwich Complexes of Rhodium and Iridium Containing l,l'-Ferrocene Dichalcogenido LigandsMax Herberhold* and Guo-Xin JinLaboratorium für Anorganische Chemie der Universität Bayreuth, Postfach 101251,D-W-8580 Bayreuth

Arnold L. Rheingold and George F. Sheats+Department o f Chemistry, University o f Delaware, Newark, Delaware, 19716, U .S.A.Dedicated to Prof. H. L. Krauss on the occasion o f his 65 th birthdayZ. Naturforsch. 4 7b , 1091-1098 (1992); received February 17, 1992

Bimetallic Complexes, Rhodium and Iridium Halfsandwich Compounds,2-Metalla-[3]ferrocenophanes

A series o f 12 bimetallic complexes Cp*M(L)[(EC5H4)2Fe] (M(L) = Rh(PM e3), Ir(PMe3),Ir(PPh3) and Ir(CN'Bu); E = S, Se, Te) has been synthesized from the dichlorides Cp*M(L)Cl2.The new compounds have been characterized by their 'H, 13C and 31P N M R spectra in solu­tion. The mass spectra indicate that the two-electron ligand L is preferentially eliminated upon electron-impact. Oxidation by AgBF4 to give ferrocenium-type cations also occurs readily.An X-ray structure analysis o f Cp*Rh(PMe3)[(SC5H4)2Fe] ( l a ) confirms the presence o f a 1,l'-ferrocene dithiolate ligand with parallel and ecliptic cyclopentadienyl rings. The long Rh -Fe (430.4(1) pm) distance rules out any direct interaction between the rhodium center and the iron in the cavity o f the ferrocene sandwich.

Introduction

Heterobimetallic complexes in which the metals are held in close proximity have been extensively studied in recent years with respect to possible in­teractions between the metals [1-4], In this con­nection, ferrocene derivatives are of interest be­cause the redox-active iron center is buried be­tween the two cyclopentadienyl rings o f the sandwich structure and is, in general, not available for additional bonding interactions. Only a few complexes are known in which a ferrocene iron is connected to another transition metal, as in pal­lad iu m ^ ) and platinum(II) compounds contain­ing 1,l'-ferrocene dichalcogenate chelate ligands:

\< S 7 - 1Fe ------5Fe ------ -> M — P Ph,

✓

E

M = PdE = 0 151, S 16,71

M = PtE = S 171

Fe(C5H4E)2M(PPh3)

Present address: Department o f Chemistry, State U n i­versity o f New York, Plattsburgh, N Y 12901, U .S.A .Reprint requests to Prof. M. Herberhold.

Verlag der Zeitschrift für Naturforschung,D-W -7400 Tübingen0932-0776 /92 /0800- 1091/$ 01.00/0

According to X-ray structure determinations [5-7] the metal (M = Pd, Pt) has a slightly dis­torted square-planar coordination sphere. The cy­clopentadienyl rings are almost eclipsed and only slightly tilted with respect to the planar arrange­ment o f the ideal sandwich. Similar complexes have also been prepared with 1,l'-ruthenocene di­chalcogenate ligands, e.g. Ru(C5H4E)2M(PPh3) (M = Ni, E = S [5]; M = Pd, E = O [5], S [5, 7], Se [7]; M = Pt, E = S [7], Se [7]).

However, in most cases the 1,l'-ferrocene di­chalcogenate ligands are coordinated to the transi­tion metal through the two chalcogen atoms only, acting formally as dianionic 4-electron ligands. Al­ternatively, the heterobimetallic ferrocene deriva­tives can be considered as 1,3-dichalcogena-2-metalla-[3]ferrocenophanes:

M = Cp( * )V ( 0 ) ! E = S, Se 181 Mo(NO)L*, E = S 191

/ M (L* = H B (3 ,5 -M e 2C3N 2H)3)\ 0 > E Pd(PPh3) 2, E = 0 151

Pt(PPh3) 2, E = S 171, Se [71

We have recently been interested in chalcogen and chalcogenate derivatives of mononuclear half­sandwich metal compounds [10-13] in which one hemisphere of the coordination shell is completely shielded by a cyclopentadienyl (Cp) or penta-

1092 M. Herberhold et al. ■ Pentamethylcyclopentadienyl Halfsandwich Complexes

methylcyclopentadienyl (Cp*) ring. Halfsandwich compounds of this type are good models for metal- ligand interactions in the remaining hemisphere. So far, only vanadium halfsandwich complexes of1, l'-ferrocene dichalcogenate chelate ligands, i.e. Cp**)V(0)[(EC5H4)2Fe] (Cp<*> = /75-C5H 5, >75-C5Me5; E = S, Se), have been described [8]. We now report on pentamethylcyclopentadienyl complexes of the late transition metals rhodium and iridium with l,l'-ferrocene dithiolate, diselenolate and, for the first time, ditellurolate chelate ligands.

Results and Discussion

1. Preparation o f the complexes

The synthesis of the new 1 ,l'-ferrocene dichalco­genate rhodium compounds l a - c is based on a straightforward reaction between the halfsand­wich rhodium dichloride Cp*Rh(PM e3)Cl2 (1) and the dilithium 1, l'-ferrocene dichalcogenates Fe(C5H4ELi)2 • «THF (E = S, Se, Te) in TH F solu­tion at room temperature.

M e ,P

,Rh—VCl

ciELi (THF)

Fe(C5H4ELi)2 Cp*Rh(PMe3)CI2 E = S (a), Se (b), Te (c)

1Cp*Rh(PMe3)l (EC5H4) 2Fe] E = S (1a), Se (1b), Te (1c)

An analogous reaction of the halfsandwich iridium dichlorides Cp*Ir(L)Cl2 (L = PMe3 (2), PPh3 (3), 'B u -N C (4)) leads to the correspond­ing triads of 1,l'-ferrocene dichalcogenate com­pounds, Cp*Ir(L)[(EC5H4)2Fe] (2 a -c , 3 a -c and 4 a -c ).

L = PMe3E = S (2a), Se (2b), Te (2c)

L = PPh3E = S i3a), Se (3b), Te (3c)

L = C s N -t BuE = S (4a), Se (4b), Te (4c)

The colour of the new 1,l'-ferrocene dichal­cogenate compounds is basically red; the rho­dium complexes are darker than the iridium com­plexes, and the colour in a given triad Cp*M(L)[(EC5H4)2Fe] becomes darker when the

chalcogen is changed in the series E = S < Se < Te. The iridium complexes are more stable than the rhodium complexes. In contrast to the solid sulfur and selenium compounds, the solid telluri­um analogues tend to decompose, especially in the presence of air.

2. Spectroscopic characterization

The 'H , l3C and 31P N M R spectroscopic data of the Cp*M(L)[(EC5H4)2Fe] compounds ( l a - c to 4 a -c ) are collected in Table I.

The Cp* ligands are easily recognized both in the ‘H and in the I3C NM R spectra by the intense signals of their methyl substituents. The methyl proton signal is split into a doublet in the case of the phosphane compounds (1 -3 and their deriva­tives) as a result of 31P - 'H spin-spin coupling (V(P,H) ca. 2 -3 Hz), whereas the 13C methyl sig­nal always appears as a singlet. The methyl signal is shifted to lower field in both the 'H and 13C NM R spectra if the chalcogen E is changed in the order E = S, Se, Te. On the other hand, the 13C chemical shift of the Cp* ring carbon atoms is re­markably insensitive with respect to the nature of the chalcogen E; in the case of the phosphane com­pounds the signal appears as a doublet due to 31P - 13C spin-spin coupling (2/(P ,C ) ca. 3 -4 Hz).

The 1,l'-ferrocene dichalcogenate ligands show the usual patterns in the ’H and 13C NM R spectra. From the intensity ratios and the systematic influ­ence of the chalcogens it can be concluded that the a protons (H 2, H5) are less shielded than the ß pro­tons (H3, H 4). The same conclusion holds for the a (C2, C5) and ß (C3, C4) carbon atoms, in agreement with our earlier studies on 1,l'-ferrocene dichalco- gen compounds [14-16]. As expected, the chemi­cal shifts o f ’H and 13C atoms in the a positions are more stongly influenced by the nature of the chal­cogen atoms than those of the atoms in the ß posi­tions. Thus, the chemical shifts of the ß carbons (C3,C 4) differ only slightly. Both a and ß ,3C sig­nals are somewhat shifted to lower fields when the heavier chalcogens are present. The less intense signal of the carbon atom C 1 to which the chalco­gen E is directly attached is progressively moving upfield in the order E = S, Se, Te (“heavy-atom ef­fect”, cf. refs. [15, 16]). Spin-Spin coupling 31P - 13C is only observed for C 1 and only in the case of the1,1 '-ferrocene dithiolate complexes la , 2 a and 3 a.

M. Herberhold et al. • Pentamethylcyclopentadienyl Halfsandwich Complexes 1093

Table I. N M R spectroscopic characterization (CDC13 solution, 0 °C).

Complex ‘H NM R<5(Cp*)(V(P,H))

<5(L)(2y (p ,h ))

<5(Fe(C5H4E)2)l3C NM R <5(Cp*) S(Cp*)

(V(P,C))<S(L)[•/(P,C)]

<5(Fe(C5H4E)2)(V(P,C))

31P N M R<5(31P){ ‘y(Rh,P)}

Cp*Rh(PM e3)Cl2 Lit. [19]a

1.63(3.6)

1.56(11.7)

- 9.2 s 98.1 d (6.5)

14.6[33.3]

- 7.50{136.5}

Cp*Rh(PMe3)[(SC5H4)2Fe] 1.81(3.0)

1.73(10.7)

3 .76(m ,4H )4 .36(m ,2H )4 .55(m ,2H )

9.6 s 100.0(3.4)

15.6[37.4]

65.7;67.0 74.2; 77.4 99.8C'(3.3)

9.55{148.6}

Cp*Rh(PMe3)[(SeC5H4)2Fe] 1.87(2.9)

1.79(10.5)

3 .87(m ,4H )4.13(m ,2H )4 .36(m ,2H )

10.1 s 99.2(4.3)

18.1[38.7]

67.1; 67.7 75.7; 77.5 83.1C 1

4.87{146.2}

Cp*Rh(PMe3)[TeC5H4)2Fe] 2.01(2.7)

1.91 ( 9.8)

3 .89(m ,2H )4.04(m ,2H )4.13(m ,2H )

11.2s 99.4 dd (3.4)

22.7[45.2]

69.1; 69.2 88.2; 88.4 6 1 .2 0

- 0.55 {148.6}

Cp*Ir(PMe3)Cl2 Lit. [19]a

1.67(2.3)

1.62(11.2)

— 8.9 s 91.0(3.4)

13.7[39.4]

— - 27.0

Cp*Ir(PMe3)[(SC5H4)2Fe] 1.87(1.8)

1.77(10.7)

3.77 (m ,4H ) 4.14(m ,2H ) 4.45 (m, 2 H)

9.1 s 94.9(3.4)

14.4[43.7]

66.5;66.9 73.7; 77.3 9 6 .3 0 (4 .3 )

- 29.9

Cp*Ir(PMe3)[(SeC5H4)2Fe] 1.89(2.3)

1.83(11.0)

3 .85(m ,4H ) 3.96(m ,2H ) 4.25 (m, 2 H)

9.4 s 94.2(3.2)

16.8[43.4]

67.5; 67.6 75.1;77.2 81.5C 1

- 42.2

Cp*Ir(PMe3)[(TeC5H4)2Fe] 2.02(2.0)

2.02(10.1)

3 .83(m ,2H )3.98(m ,4H )4.08(m ,2H )

10.4s 94.6(3.4)

21.0[45.2]

68.9; 69.4 79.4; 80.5 6 1 .9 0

- 43.9

Cp*Ir(PPh3)Cl2 1.34(2.1)

7.73 (m) 7.30(m)

8.3 d ( l . l ) b

92.6(2.7)

127.7 [ 10.9] 130.3 134.2134.7 [9.8]

+ 0.3

Cp*Ir(PPh3)[(SC5H4)2Fe] 1.57(2.4)

7.65 (m) 7.37 (m)

3 .55(m ,2H )3.63(m ,2H )3.68(m ,2H )4 .14(m ,2H )

8.8( l . l ) b

96.5(3.3)

127.6 [10.4]130.2 s134.7 [10.4]135.2 [9.8]

66.4; 66.6 73.7; 78.1 96.1C ‘(3.8)

- 3.8

Cp*Ir(PPh3)[(SeC5H4)2Fe] 1.61(1.8)

7.33 (m) 7.38(m)

3 .68(m ,2H ) 3 .74(m ,2H ) 3 .83(m ,2H ) 4.07 (m, 2 H)

9.4 95.9(3.3)

127.7 [10.1] 130.2134.8 [10.1]

67.0; 67.2 74.7; 78.0 8 2 .5 0 (4 .9 )

- 3.5

Cp*Ir(PPh3)[(TeC5H4)2Fe] 1.76(2.2)

7.37 (m) 7.80(m)

3 .73(m ,2H ) 3.80(m ,2 H) 3.87 (m ,4H )

10.5 96.1(3.6)

127.7 [7.4] 130.3 134.9 [9.2]

68.5;68.7 78.6; 80.4 6 8 .0 0

- 4.9

Cp*Ir(CN'Bu)Cl2 1.74 1.51 — 8.9 93.0 30.8 (Me) 57.3 (CMe3)

—

Cp*Ir(CN'Bu)[(SC5H4)2Fe] 1.83 1.63 3.81 (m ,2H ) 3 .96(m ,2H ) 4.14(m ,2H ) 4.19(m ,2H )

8.2 95.3 31.157.7

66.7; 67.9 73.8; 77.3 9 0 .6 0

Cp*Ir(CN'Bu)[(SeC5H4)2Fe] 1.87 1.59 3.86(m ,2H ) 3 .95(m ,2H ) 4 .10(m ,4H )

8.7 94.5 31.357.7

67.3; 68.2 76.9; 77.6 8 0 .4 0

Cp*Ir(CN'Bu)[(TeC5H4)2Fe] 2.06 1.54 3 .92(m ,2H ) 4.00 (m, 2 H) 4 .16(m ,4H )

10.2 95.3 31.551.5

68.7; 69.1 79.9; 81.7 6 9 .5 0

a The 'H and 13C N M R spectroscopic data reported in the literature for 1 [19] and 2 [19] are in reasonable agreement with the data o f the present study; b the coupling constant 3/ ( 31Pl3C) =1. 1 Hz was observed in the 300 MHz spectrum.

1094 M. Herberhold et al. ■ Pentamethylcyclopentadienyl Halfsandwich Complexes

The heavy-atom effect of the heavier chalcogens is also evident in the 31P NM R spectra where the signal of the tellurium compounds is always found at highest field. In the rhodium compounds a doublet is observed due to 103R h - 31P spin-spin coupling. The coupling constant increases if the two chloro ligands in Cp*Rh(PMe3)Cl2 (1, '7(Rh,P) 136.5 Hz) are replaced by the 1,1'-ferro­cene dichalcogenate chelate ligand to give Cp*Rh(PM e3)[(EC5H4)2Fe] ( la - c , >./(Rh,P) 146—149 Hz).

The electron-impact (El) mass spectra generally contain the peak of the molecular ion (M +). A par­ticularly intense signal is observed for the ion Cp*M[EC5H 4)2Fe]+ which has lost the two-elec­tron ligand L (L = PMe3, PPh3 or CN'Bu). In the case of Cp*Ir(PPh3)[(TeC5H4)2Fe] (3c), which de­composes under EI-MS conditions, a field desorp­tion (FD) mass spectrum has confirmed the com­position of the complex, showing (among other peaks) the molecular ion with the expected isotope pattern.

3. Reactivity o f the phosphane complexes

The stable triphenylphosphane compounds, Cp*Ir(PPh3)[(EC5H4)2Fe] (E = S (3a) and Se (3b)), react with elemental sulfur to give phosphane-free products (5a, b). According to a preliminary X-ray structure analysis of 5 b, the abstraction of PPh3 from 3 a, b leads to dimerization via the 1,1'- ferrocene dichalcogenate ligand which is able to bridge two iridium centers. In the solid state, direct iridium-iron bonds are definitely absent in 5 b. However, the El mass spectra of 5a, b contain the monomeric ion {Cp*Ir[(EC5H4)2Fe]} + as the base peak (rel. intensity 100%).

The di-iridium complexes 5 a, b take up PMe, to give 2 a, b. The PPh3 ligand in 3 a, b can also be di­rectly replaced by PMe3 and, although more slow­ly, by 'BuNC to give 2 a, b and 4a, b, respectively.

Chemical oxidation of the phosphane complex­es, for example lb and 3a, by AgBF4 takes place rapidly in TH F solution. The 'H NM R spectra of the paramagnetic salts ( lb +) BF4~ and (3a+) BF4~ are in agreement with the assumption that the positive charge is essentially localized at the iron center. The protons at the ferrocene unit are no longer observed in the cations although the Cp* protons are still visible as a broad absorption which is somewhat (up to 1 ppm) shifted to higher field with respect to the neutral compound. In a similar manner, the salts obtained from Cp*V(0)[(EC5H4)2Fe] in the reactions with AgBF4 do not show ferrocene protons in the ’H NMR spectra although a vanadium signal is still ob­served in the 51V N M R spectra [8],

AgBF4, -A g Cp*Rh(PM e3)[(SeC5H4)2Fe] .

lb, red (Na2S20 3){Cp*Rh(PMe3)[(SeC5H4)2Fe]+BF4-

( lb +) BF4~, violet

The ferrocenium cations lb + and 3 a + are recon­verted to the neutral complexes lb and 3a by var­ious reducing agents, for example by aqueous thiosulfate solutions.

4. X-Ray structure analysis o f Cp*Rh(PM e3) [ ( S C 5H4) 2Fe] (1 a)

The molecular structure of l a is presented in Fig. 1, and some relevant distances and angles are given in Table II. The complex possesses nearly perfect mirror symmetry defined by the plane of the metal atoms and phosphorus. The geometry of1 a is similar to that of the oxo-vanadium complex Cp*V(0)[(SeC5H4)7Fe] (6b) described previously [8],

E = S (5a), Se (5b)

2 a,bC p*Rh(PMe3) [ (S C 5H4) 2Fe] C p * V (0 ) l (S e C 5H4)2Fel

( 1a) (6 b) [8 ]

M. Herberhold et al. • Pentamethylcyclopentadienyl Halfsandwich Complexes 1095

Fig. 1. ORTEP drawing and labelling scheme for Cp*Rh(PMe3)[(SC5H4)2Fe] (1 a).

Table II. Selected bond distances and bond angles for Cp*Rh(PMe3)[(SC5H4)2Fe] (1 a)a.

Bond length (pm) Bond angles

R h -P 224.6(1) P - R h - S ( l ) 84.7(1)R h -S (l) 236.7(1) P -R h -S (2 ) 82.9(1)R h -S (2 ) 236.0(1) S ( l ) -R h -S (2 ) 104.9(1)R h -C N T (l) 187.6(5) C N T (1 )-R h -P 132.0(2)F e-C N T (2) 163.7(5) C N T (1 )-R h -S ( l) 121.1(2)F e—CNT(3) 163.8(5) C N T (1 )-R h -S (2 ) 121.3(2)S ( l ) -C ( l ) 175.7(5) R h -S (2 )-C (2 ) 116.9(2)S(2)—C(2) 174.6(5) C N T (2 )-F e-C N T (3 ) 179.7(2)R h -C ( l l ) 227.0(5)R h-C (12) 225.6(5)R h-C (13) 220.1(5)R h-C (14) 223.0(5)R h-C (15) 219.4(5)Rh -Fe 430.4(1)

a CNT = center o f the ring ligand; C N T (l) = centroid o f atoms C (11) to C(15) (Cp* ring); CNT(2) = centroid o f atoms C (l) to C(5) and CNT(3) = centroid o f atoms C(6) to C(10) (ferrocenylene unit).

As may be seen from Fig. 1, the central rhodium atom in 1 a contains the Cp* ring, the phosphorus atom of the PMe3 group, and the two sulfur atoms of the 1, l'-ferrocene dithiolate ligand in a distorted tetrahedral coordination sphere. Compared with6 b, the distortion of the tetrahedron is larger, i.e., the angles at Rh (from 83.8(2) av. for P - R h - S to 132.0(2)° for C N T (l) -R h -P ) deviate more from the tetrahedral angle (109.5°) than those at V (from 100.0(1) for S e(l)-V -S e(2 ) and 103.3(4) av.

for O -V -S e to 124.8(3) for C N T (l)-V -O ). This is certainly due to the more voluminous PMe3 li­gand in 1 a as compared with the slim oxo ligand in6 b; similar steric effects become obvious in the comparison of the pentasulfido chelate complexes CpCo(PM e3)(S5) [17], CpRh(PM e3)(S5) [18] and Cp*V(0)(S5) [10]. The Cp*-free complex fragment {Rh(PMe3)[(SC5H4)2Fe]} contains a symmetry plane involving Fe, Rh and P and bisecting the 1,l'-ferrocene dithiolate ligand. The cyclopenta­dienyl rings of the sandwich ligand are nearly eclipsed (with a torsion angle S ( l ) -C ( l) -F e /F e - C (6)-S(2) of 2.3°) and almost exactly parallel (with a dihedral angle between the ring planes of 0.7°); the analogous angles in 6b are 0.0(1)° and 0.8°, respectively. The folding angle defined by the RhS2 and [S(l), C(l), C(6), S(2)] planes is 24.9°.

As in 6 b [8], the Cp* ring ligand in 1 a is unsym- metrically attached to the metal (cf. differing R h -C bond lengths, Table II), and the methyl substituents are bent slightly outwards, away from the metal.

The R h -S bond lengths in Cp*Rh(PM e3)[(SC5H4)2Fe] ( la ) are normal; very similar distances were observed for the rhodium complexes [18] CpRh(PPh3)(S5) (235.9(2), 235.1(2)), CpRh(PPh3)(S6) (233.5(3), 234.5(3)) and (C5H4COOM e)Rh(PPh3)(S4) (235.4(1), 235.0(1) pm) as well as for the I r -S bond distances in Cp*Ir(PM e3)(S6) (235.8(2); 234.5(2) pm) [13], The R h - S - C angles (115.9(2) and 116.9(2)°) in l a are larger than the V -S e -C angles (101.5(4)°) in 6b. The Rh-- - Fe nonbonding distance (430.4(1) pm) is remarkably long; the corresponding V -Fe dis­tance was found to be 401.4(2) pm in 6b [8],

ExperimentalAll manipulations were routinely carried out

under argon using Schlenk techniques. Argon was deoxygenated and dehydrated over BTS catalyst and molecular sieve, respectively. Solvents (hex­ane, toluene, tetrahydrofuran) were kept under re­flux over N a/K alloy and then distilled off in a stream of argon. Merck Kieselgel 60 (0.06-0.2 mm) was activated at temperatures > 600 °C over night and stored ander argon before use.

The parent Cp* complexes Cp*Rh(PMe3)Cl2 (1) [19], Cp*Ir(PM e3)Cl2 (2) [19,20], Cp*Ir(PPh3)Cl2(3) [19] and Cp*Ir(CN'Bu)Cl2 (4) [21] and the dili- thio 1, l'-ferrocene dichalcogenates Fe(C5H 4ELi)2 • 2 THF (E = S [22], Se [22] and Te

1096 M. Herberhold et al. ■ Pentamethylcyclopentadienyl Halfsandwich Complexes

[15, 23] were prepared according to literature p ro­cedures. Other chemicals were used as purchased.

Preparation o f the 1 ,1 '-ferrocene dichalcogenate complexes General procedure

A solution of the dichloride Cp*M(L)Cl2 ( l - 4) (ca. 0 .3 -0 .8 mmol) in 30 ml TH F was slowly ad­ded to a THF solution (100 ml) containing an equimolar amount of the l,l'-ferrocenedichalco- genate, Fe(C5H4ELi)2, at -7 8 °C. The reaction mixture was allowed to warm up to room tempera­ture and kept stirring for additional 3 h. Then the solvent THF was removed and the product puri­fied by column chromatography over silica, using CH2C12 for elution. Recrystallization from CHC13/ hexane or toluene/hexane at -7 8 °C gave intensely coloured crystals which are soluble in most organ­ic solvents (CHC13, CH2C12, toluene, tetrahydro- furan, acetone and dimethylformamide) but only sparingly soluble in pentane and hexane.

Cp*Rh(PM e3)[(SC5H4)9Fe] (la): red needles, m.p. 205-206 °C. Y ield'58%. E I-M S: m/e (rel. int.) 562(6) M +, 486(100) (M -P M e3)+.

Cp*Rh(PM e3)[(SeC5H4)2Fe] (lb): dark-red crys­tals, m.p. 210-211 °C. Yield 50%. E I-M S : m/e (rel. int.) 658(10) M +, 582(100) (M -P M e3)+.

Cp*Rh(PM e3)[(TeC5H4)2Fe] (lc): black crys­tals, m.p. 235 °C. Yield 15%. E I-M S: m/e (rel. int.): 754(20) M +, 678(100) (M -P M e3)+, 550(26) (M -P M e3-T e )+.

Cp*Ir(PMe3)[(SC5H4)2Fe] (2 a): orange-red needles, m.p. 132 °C. Yield 60%. E I-M S: m/e (rel. int.) 652(18) M \ 576(100) (M -P M e3)+.

Cp*Ir(PMe3)[(SeC5H4)-,Fe] (2b): red plates, m.p. 140-141 °C. Yield 47%" E I-M S : m/e (rel. int.) 746(3) (M +), 670(21) (M -P M e3)+.

Cp*Ir(PM e3)[(TeC5H4)2Fe] (2c): dark-red crys­tals, m.p. 185 °C (dec.). Yield 48%. E I-M S : m/e (rel. int.): 844(23) M +, 768(27) (M -P M e3)+, 640(100) (M -P M e3-T e )+.

Cp*Ir(PPh3)[(SC5H4)2Fe] (3 a): orange-red needles, m.p. 132 °C (dec.). Yield 52%. E I-M S : mle (rel. int.) 576(100) (M -P P h 3)+, 544(11) (M -P P h 3- S ) +, 479(23) (M -P P h 3-S C 5H 5)+.

Cp*Ir(PPh3)[(SeC5H4),Fe] (3b): red plates, m.p.150 °C (dec.). Yield 47%. E I-M S : m/e (rel. int.) 670(44) (M -P P h 3)+, 590(100) (M -P P h 3-S e )+, 525(62) (M -P P h 3-S eC 5H 5).

Cp*Ir(PPh3)[(TeC5H4),Fe] (3c): dark-red crys­tals, m.p. 190 °C (dec.). Yield 47%. F D -M S : m/e 1028 (M +).

Cp*Ir(CN'Bu)[(SC5H4)-,Fe] (4a): red crystals, m.p. 187-188 °C. Yield 65%. E I-M S: m/e (rel. int.) 576(45) (M -C N 'B u)+; 41(100).

Cp*Ir(CN'Bu)[(SeC5H4)-,Fe] (4b): red crystals, m.p. 169-170 °C (dec.). Y~ield 48%. E I-M S: m/e (rel. int.) 753(31) M +, 670(100) (M -C N 'B u)+.

Cp*Ir(CN'Bu)[(TeC5H4)2Fe] (4c): dark-red crystals, m.p. 245 °C (dec.). Yield 66%. E I-M S: m/e (rel. int.) 851(20) M +, 768(24) (M -C N 'Bu); 640(35) (M -C N 'B u -T e )+, 56(100) (C4Hg)+.

Reactions o f the 1,1'-ferrocene dichalcogenate complexesa) Oxidation

0.05 g (0.26 mmol) AgBF4 were added to the red solution of 0.14 g (0.21 mmol) Cp*Rh(PM e3)[(SeC5H4)2Fe] (lb ) in 50ml THF. The colour of the mixture turned violet immediate­ly, and a violet precipitate was formed. The mix­ture was poured on top of a N a2S 0 4 layer, and the violet solid washed with TH F (to remove lb). Elu­tion using CH2C12 produced a violet solution which contained 0.15 g (94.6%) (lb +)BF4~. Re­crystallization from CHCl3/hexane mixtures at -2 5 °C gave violet needles, m.p. 203-205 °C, sol­uble in chloromethanes and acetonitrile, insoluble in pentane, hexane, toluene and THF.

A solution 0.08 g (0.11 mmol) ( lb +)BF4~ in 40 ml acetonitrile was treated with an aqueous so­lution of 0.05 g (0.2 mmol) N a2S20 3-5H 20 . The violet colour changed to red, and workup by chro­matography over silica led to the recovery of 0.06 (85% )red lb .

In a similar manner Cp*Ir(PPh3)[(SC5H4)2Fe] (3a) was oxidized by AgBF4 in THF solution to a green-brown salt, (3 a+)BF4~, m.p. 191-193 °C, in 88% yield. Reduction of the cation 3 a+ (in aceto­nitrile) by an aqueous solution of Na2S20 3-5H 20 gave 72% recovery of red 3 a.

b) Substitution o f triphenylphosphane in Cp*Ir(PPh3) [ (S e C 5H4) 2Fe] (3 b)

An orange solution of 0.10 g (0.11 mmol) 3b in 30 ml THF was treated with excess (30 p\) trime- thylphosphane. The solution was stirred over night (16 h), brought to dryness, and the residue chromatographed over silica. Elution with CH2C12 produced a red band which contained 0.07 g (87.5%) Cp*Ir(PM e3)[(SeC5H4)2Fe] (2b).

The analogous reaction of 0.12 g (0.14 mmol)3 b with excess (50 p\, 0.52 mmol) tert-butyl isoni- trile in 30 ml THF for 20 h led to the red complex Cp*Ir(CN'Bu)[(SeC5H4)2Fe] (4b) in 81% yield.

M. Herberhold e t al. • Pentamethylcyclopentadienyl Halfsandwich Complexes 1097

Elimination o f triphenylphosphane from Cp*Ir(PPh3) [ ( SC5H4) 2Fe] (3a)

A CH 2C12 solution (30 ml) containing 0.12 g (0.13 mmol) 3a and 0.02 g (0.08 mmol) S8 was heated under reflux for 3 h. Separation of the product mixture by column chromatography gave Ph3PS (colourless, eluted by C H 2Cl2/pentane 1:1), unchanged 3 a (orange, eluted with CH2C12) and finally a complex of the composition Cp*Ir[(SC5H4)2Fe] (5 a) (dark-red, eluted with CH2C12). Recrystallization from CHCl3/hexane at -2 5 °C gave dark-red prisms, dec. > 250 °C. Yield 0.06 g (73.2%). E I-M S : m/e (rel. int.) 576(100) M +, 544(6), (M -S )+, 480(18) (M -C 5H4S)+.

'H N M R (CDC13, 0°C), 1.71 (s, 15H, Cp*);3.79, 3.98, 4.18, 4.60 (m, 2H each, ferrocene pro­tons). 13C NM R (CDC13), 8.95 and 92.7 (Cp*), 66.3, 71.9, 76.3 and 82.9 (C2- C 5), 96.2 (C1).

Table III. Crystallographic data for Cp*Rh(PMe3)[(SC5H4)2Fe] (la).

a) Crystal ParametersFormula C13H r PS-,FeRhFormula weight 562.35Crystal system orthorhombicSpace group P bca«[A] 16.156(4)M f] 17.096(4)d A j 17.219(5)V\A>] 4756.0(24)7 8Cryst. dimens, [mm] 0.39x0.42x0.47Cryst. color dark redD (calc.) [g em -3] 1.571/j(M oK a) [cm-1] 15.23Temp. [K] 296Transm. [T (max ) /T (min)] 1.115

b) Data CollectionDiffractometer Nicolet R 3 mMonochromator graphiteRadiation M oK a (A = 0.71073 A)20 scanrange, deg. 4 -5 6Data collected (h, k, 1) + 22, +23, +23Rflns. collected 5335Indpt. rflns. 4820Indpt. obsvd. rflns. 3349

F0 >h<7(F0) (n = 5)Std. rflns. 3 std ./197 rflns.Var. in stds. <1

c) Refinement

R{F) [%] 3.58R(wF) [%] 3.90A o {max) 0.017/1(g) [eÄ~3] 0.412N JN V 13.2GOOF 0.996

Table IV. Atomic coordinates (* 1 0 4) and equivalent isotropic displacement parameters (Ä2* 103).

X y z u*

Rh 2105.5(2) 5968.4(2) 6574.7(2) 30.6(1)Fe 412.7(4) 7376.4(4) 5244.0(4) 45.6(2)S(D 827(1) 6471(1) 7025(1) 40(1)S(2) 2456(1) 6763(1) 5504(1) 43(1)P 2665(1) 6957(1) 7254(1) 41(1)C (l) 199(3) 6919(3) 6321(3) 39(1)C(2) - 295(3) 6538(3) 5750(3) 51(2)C(3) - 802(3) 7107(4) 5380(3) 64(2)C(4) - 635(3) 7830(4) 5717(3) 66(2)C(5) - 19(3) 7726(3) 6295(3) 54(2)C(6) 1640(3) 7201(3) 5001(3) 41(1)C(7) 1131(3) 6848(3) 4426(3) 54(2)C(8) 635(4) 7432(4) 4082(3) 72(2)C(9) 818(4) 8142(4) 4440(3) 72(2)C(10) 1438(3) 8008(3) 5006(3) 55(2)C (ll) 2202(3) 4847(3) 5875(3) 49(2)C( 12) 1603(3) 4744(3) 6445(3) 46(2)C(13) 1976(3) 4848(3) 7192(3) 45(2)C( 14) 2827(3) 4978(3) 7076(3) 47(2)C(15) 2971(3) 5030(3) 6265(3) 46(2)C( 16) 2095(4) 4793(4) 5014(3) 68(2)C( 17) 711(4) 4520(3) 6329(4) 70(2)C(18) 1548(4) 4718(3) 7952(3) 75(2)C(19) 3493(4) 4982(4) 7688(4) 75(2)C(20) 3795(3) 5124(3) 5875(4) 72(2)C(21) 2608(4) 6835(4) 8287(3) 63(2)C(22) 3751(3) 7114(4) 7064(3) 61(2)C(23) 2232(4) 7926(3) 7126(4) 75(2)

* Equivalent isotropic U defined as one third o f the trace o f the orthogonalized tensor.

X-Ray crystal structure analysis o f l aThe crystallographic data are collected in

Table III, and the atomic coordinates and equiva­lent isotropic displacement parameters are given in Table IV. The crystal was obtained by very slow evaporation of pentane from a pentane solution of l a into a nonane (C9H 20) reservoir at room tem­perature during one month.

Further details of the structure determination may be obtained from Fachinformationszentrum Karlsruhe, Gesellschaft für wissenschaftlich- technische Information mbH, D-W-7514 Eggen- stein-Leopoldshafen 2, by quoting the registry number CSD 56213, the names of the authors and the journal citation.

Financial support by the Deutsche Forschungs­gemeinschaft and the Fonds der Chemischen In­dustrie is gratefully acknowledged. We thank Fa. Pluto, Herne, for a gift of ferrocene. Guo-Xin Jin is particularly grateful for a postdoctoral fellow­ship granted by the Alexander von Humboldt Foundation.

1098 M. Herberhold et al. ■ Pentamethylcyclopentadienyl Halfsandwich Complexes

[1] R. M. Bullock and C. P. Casey, Acc. Chem. Res. 20, 167(1987).

[2] D. W. Stephan, Coord. Chem. Rev. 95, 41 (1989).[3] T. A. Work and D. W. Stephan, Organometallics 8,

2836(1989); Inorg. Chem. 29, 1731 (1990).[4] N. A. Compton, R. J. Errington, and N. C. N or­

man, Adv. Organomet. Chem. 31 ,91 (1990).[5] S. Akabori, T. Kumagai, T. Shirahige, S. Sato, K.

Kawazoe, C. Tamura, and M. Sato, Organometal­lics 6,2105(1987).

[6] D. Seyferth, B. W. Harnes, T. G. Rucker, M. Cowie, and R. S. Dickson, Organometallics 2, 472 (1983); M. Cowie and R. S. Dickson, J. Organomet. Chem. 326, 269(1987).

[7] S. Akabori, T. Kumagai, T. Shirahige, S. Sato, K. Kawazoe, C. Tamura, and S. Sato, Organometallics 6, 526(1987).

[8] M. Herberhold, M. Schrepfermann, and A. L. Rheingold, J. Organomet. Chem. 394, 113 (1990).

[9] R. P. Sidebotham, P. D. Beer, T. A. Hamor, C. J. Jones, and J. A. McCleverty, J. Organomet. Chem. 371, C31 (1989).

[10] Vanadium: M. Herberhold, M. Kuhnlein, M. L. Ziegler, and B. Nuber, J. Organomet. Chem. 349, 131 (1988).

[11] Chromium, Molybdenum and Tungsten: M. Her­berhold, G.-X. Jin, W. Kremnitz, A. L. Rheingold, and B. S. Haggerty, Z. Naturforsch. 46b, 500 (1991).

[12] Manganese and Rhenium: M. Herberhold, and B. Schmidkonz, J. Organomet. Chem. 308, 35 (1986); ibid. 358, 301 (1988);M. Herberhold, B. Schmidkonz, M. L. Ziegler, and O. Serhadle, Z. Naturforsch. 42b, 739 (1987).

[13] Iridium: M. Herberhold, G.-X. Jin, and A. L. Rheingold, Chem. Ber. 124, 2245 (1991).

[14] M. Herberhold, C. Dörnhöfer, H. I. Hayen, and B. Wrackmeyer, J. Organomet. Chem. 355, 325 (1988).

[15] M. Herberhold, P. Leitner, C. Dörnhöfer, and J. Ott-Lastic, J. Organomet. Chem. 377, 281 (1989).

[16] M. Herberhold and P. Leitner, J. Organomet. Chem. 366, 153 (1987); ibid 411, 233 (1991).

[17] C. Burschka, K. Leonhard, and H. Werner, Z. An­org. Allg. Chem. 464, 30 (1980).

[18] Y. Wakatsuki, H. Yamazaki, and C. Cheng, J. Or­ganomet. Chem. 372,437 (1989).

[19] J. W. Kang, K. Moseley, and P. M. Maitlis, J. Am. Chem. Soc. 91, 5970(1969).

[20] R. G. Ball, W. A. G. Graham, D. M. Heinekey, J. K. Hoyano, A. D. McMaster, B. M. Mattson, and S. T. Michel, Inorg. Chem. 29, 2023 (1990).

[21] W. D. Jones, R. P. Duttweiler, and F. J. Feher, In­org. Chem. 29, 1505(1990).

[22] R. Broussier, A. Abdulla, and B. Gautheron, J. Or­ganomet. Chem. 332, 165 (1987).

[23] M. Herberhold, P. Leitner, and U. Thewalt, Z. Na- turforsch. 45b, 1503 (1990).