Synthesis of thiolate and phosphido bridged iron-manganese complexes; Molecular structure of cis-[FeMn(μ-CO)(μ-SEt)(CO)2(Cp)(C5H4Me)]

Article abstract of DOI:10.1016/S0022-328X(99)00106-0

The reaction of [Fe(CO)₂(SR)(Cp)] (R=Et, Ph; Cp=η-C₅H₅) with [Mn(CO)₂(thf)(C₅H₄Me)] (thf=tetrahydrofuran), under photolytic conditions, leads to the formation of the novel heterodinuclear bridged thiolate complexes [FeMn(μ-CO)(μ-SR)(CO)₂(Cp)(C₅H₄Me)] in low yields. [FeMn(μ-CO)(μ-SEt)(CO)₂(Cp)(C₅H₄Me)] consists of a mixture of cis and trans isomers which have been separated and characterized by IR and NMR spectroscopy. The μ-phosphido complex [FeMn(μ-CO)(μ-PPh₂)(CO)₂(Cp)(C₅H ₄Me)] has been prepared analogously from [Fe(CO)₂(PPh₂)(Cp)] and [Mn(CO)₂(thf)(C₅H₄Me)]. Variable temperature NMR spectra of the latter heterodinuclear complex, in CDCl₃, show the presence of an equilibrium mixture of the two interconverting cis and -trans isomers. The X-ray molecular structure of cis-[FeMn(μ-CO)(μ-SEt)(CO)₂(Cp)(C₅H₄Me)] shows a bonded Fe-Mn interaction [2.617(2) A] reinforced by a μ-CO and a μ-SEt ligands. The molecule contains chiral centers at the iron, manganese and sulfur atoms and the diastereoisomer under study exhibits optimized non bonded contacts between the alkyl groups.

Full text of DOI:10.1016/S0022-328X(99)00106-0

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 583 (1999) 28–33
Synthesis of thiolate and phosphido bridged iron–manganese
complexes; molecular structure of
cis-[FeMn(m-CO)(m-SEt)(CO)2(Cp)(C5H4Me)]ꢀ
Vincenzo G. Albano a, Luigi Busetto b,*, Magda Monari a, Valerio Zanotti b
a Dipartimento di Chimica ‘G. Ciamician’, Uni6ersita di Bologna, Via Selmi 2, I-40126 Bologna, Italy
b Dipartimento di Chimica, Fisica ed Inorganica, Uni6ersita di Bologna, V. le Risorgimento 4, I-40138 Bologna, Italy
Received 30 June 1998
Abstract
The reaction of [Fe(CO)2(SR)(Cp)] (R=Et, Ph; Cp=h-C5H5) with [Mn(CO)2(thf)(C5H4Me)] (thf=tetrahydrofuran), under
photolytic conditions, leads to the formation of the novel heterodinuclear bridged thiolate complexes [FeMn(m-CO)(m-
SR)(CO)2(Cp)(C5H4Me)] in low yields. [FeMn(m-CO)(m-SEt)(CO)2(Cp)(C5H4Me)] consists of a mixture of cis and trans isomers
which have been separated and characterized by IR and NMR spectroscopy. The m-phosphido complex [FeMn(m-CO)(m-
PPh2)(CO)2(Cp)(C5H4Me)] has been prepared analogously from [Fe(CO)2(PPh2)(Cp)] and [Mn(CO)2(thf)(C5H4Me)]. Variable
temperature NMR spectra of the latter heterodinuclear complex, in CDCl3, show the presence of an equilibrium mixture of the
two interconverting cis and -trans isomers. The X-ray molecular structure of cis-[FeMn(m-CO)(m-SEt)(CO)2(Cp)(C5H4Me)] shows
,
a bonded Fe–Mn interaction [2.617(2) A] reinforced by a m-CO and a m-SEt ligands. The molecule contains chiral centers at the
iron, manganese and sulfur atoms and the diastereoisomer under study exhibits optimized non bonded contacts between the alkyl
groups. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Dinuclear; Iron–manganese; Carbonyl complexes; m-Thiolate; m-Phosphido; Crystal structure
1. Introduction
the metal–metal bond is bridged by aminocarbyne
ligands [5]. Since only few other examples of Fe–Mn
complexes containing bridging ligands are known [6],
including bridging phosphido species [7], we have ex-
tended our work with the aim of obtaining new Fe–
Mn complexes containing bridging thiolato and
phosphido ligands.
Herein we report on the synthesis, spectroscopic
characterization and stereochemistry of novel iron–
manganese complexes [FeMn(m-CO)(m-X)(CO)2(Cp)-
(C5H4Me)] (X=SEt, SPh and PPh2). The X ray
molecular structure of the –SEt derivative is de-
scribed.
Heterodinuclear organometallic compounds are an
area of active interest [1] because bonded M–M% units
can cooperate in producing new and distinct reactiv-
ity patterns [2]. Bridging ligands are introduced fre-
quently in order to prevent breaking of the
metal–metal bond, although growing interest is
placed in heterobimetallic unbridged compounds [3].
Our work in the area has led to the synthesis and
structural characterization of the thiocarbonyl com-
pound [FeMn(m-CO)(m-CS)(CO)5(Cp)] [4] and the din-
uclear W–M (M=Cu, Ag, Au) complexes, in which
2. Results and discussion
ꢀ The authors wish to dedicate the publication to Professor Alberto
Ceccon on the occasion of his 65th birthday.
Addition of [Fe(CO)2(SEt)(Cp)] [8] to a thf solution
* Corresponding author. Fax: +39-51-6443690.
E-mail address: busetto@ms.fci.unibo.it (L. Busetto)
of [Mn(CO)2(thf)(C5H4Me)] (thf=tetrahydrofuran) re-
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00106-0

V.G. Albano et al. / Journal of Organometallic Chemistry 583 (1999) 28–33
31
evidenced in the low temperature 13C-NMR spectrum
of 3, by the appearance of two sets of peaks of about
the same intensity for each resonance (e.g. for the Cp
carbons at 87.8 and 85.5 ppm, the C5H4Me methyl
carbons at 14.4 and 13.7 ppm, the FeCO at 213.9 and
212.8 ppm, the MnCO at 230.1 and 228.8 ppm).
The IR spectrum of 3 shows, in the CO region, bands
due to terminally bonded CO (1957s, 1937sh, 1894s,
cm−1) and one bridging w-CO (1762m cm−1). The
relative intensities of the absorptions changes in less
polar solvents (e.g. hexane: 1974w, 1941m 1903s and
1787m cm−1) that is consistent with the presence of an
equilibrium mixture of the two interconverting cis and
trans isomers, the first being favoured in more polar
solvents.
Finally, it should be mentioned that the reactions of
3 with HSO3CF3 and MeSO3CF3 have been investi-
gated. Both protonation and methylation occur at the P
atom promoting bridge opening and Fe–Mn fragmen-
tation, suggesting that the phosphido bridge largely
contributes to the stability of 3. The compounds
[Fp(PHPh2)]SO3CF3 (Fp=Fe(CO)2(Cp)) [19] and
[Fp(PMePh2)]SO3CF3 [20] have been identified among
the products of the reaction of 3 with HSO3CF3 and
MeSO3CF3, respectively, whereas it is still unknown the
fate of the Mn fragment.
(thf)(C5H4Me)] which has been obtained by irradiating
[Mn(CO)3(C5H4Me)] (1.13 g, 5.18 mmol) in thf (200
ml). The mixture was stirred for 1 h and the resulting
dark-brown solution was photolyzed for 30 min under
a stream of Argon. Further stirring for 1 h and filtra-
tion on an allumina pad gave a brown solution which
was evaporated to dryness under vacuum. The residue
was chromatographed on an alumina column (5×30
cm) with Et2O:Petroleum ether (b.p. 40–70°C) 1:3 (v/v)
as eluent. A first fraction, containing some unreacted
[Mn(CO)3(C5H4Me)] was discharged. A second yellow–
brown fraction was collected, evaporated to dryness
and crystallized from CH2Cl2 layered with n-pentane at
−20°C affording [Fe(CO)(SEt)(Cp)]2 (66 mg, 9% yield)
which was identified by comparison with the spectro-
scopic properties reported in the literature [8,9]. Further
elution gave a red fraction that was collected and
evaporated to dryness affording trans-1. Yield (148 mg,
10%). Analysis. Found: C, 48.02; H, 4.24%.
C16H17FeMnO3S requires: 48.03; H, 4.28%. IR
(CH2Cl2) wmax (cm−1) 1952m, 1899s and 1776m (CO).
NMR: lH (CDCl3): 4.78 (5 H, s, CpFe), 4.53, 4.45,
4.39, 4.32 (4 H, s, MeC5H4Mn), 3.16 (1 H, m,
SCH2CH3), 2.09 (1 H, m, SCH2CH3), 1.92 (3 H, s,
MeC5H4Mn) and 1.54 (3 H, t, SCH2CH3) ppm. lC
(CDCl3): 268.7 (m-CO), 230.0 (Mn–CO), 212.7 (Fe–
CO), 105.6, 89.2, 88.5, 87.6, 84.5 (MeC5H4Mn), 86.6
(CpFe), 39.2 (SCH2CH3), 19.0 (SCH2CH3) and 13.6
(MeC5H4Mn) ppm.
3. Experimental
Finally, a green-brown fraction was collected, evapo-
rated to dryness and crystallized from Et2O layered
with n-pentane at −20°C yielding cis-1 (0.45 g, 32%).
Analysis. Found: C, 48.10; H, 4.22%. C16H17FeMnO3S
3.1. General
All reactions were carried out routinely under argon
using standard Schlenk techniques. Solvents were dis-
tilled immediately before use under nitrogen from ap-
propriate drying agents. Glassware was oven-dried
before use. Infrared spectra were recorded on a Perkin–
Elmer 983-G spectrophotometer, 1H- and 13C-NMR
spectra on a Varian Gemini 300. The shiftless relax-
ation reagent [Cr(acac)3] (acac=acetylacetonate) was
added to solution studied by 13C-NMR spectroscopy.
All reagents were commercial products (Aldrich) of the
highest purity available and used as received. Com-
pound [Mn(CO)2(thf)(C5H4Me)] was prepared in situ
by irradiating a thf solution of [Mn(CO)3(C5H4Me)]
under a stream of Ar. Compounds [Fe(CO)2(SR)(Cp)]
(R=Et, Ph) were obtained with a slight modification
of the procedure described in the literature [8].
requires: C, 48.03; H, 4.28%. IR (CH2Cl2) wmax(cm−1
)
1958s, 1897m and 1774m (CO). NMR: lH (CDCl3):
4.70 (5 H, s, CpFe), 4.39, 4.31, 4.10 (4 H, s,
MeC5H4Mn), 2.35 (2 H, m, SCH2CH3), 2.10 (3 H, s,
MeC5H4Mn) and 1.45 (3 H, t, SCH2CH3) ppm. lC
(CDCl3): 269.0 (m-CO), 229.7 br (Mn–CO), 213.4 (Fe–
CO), 103.7, 87.2, 87.1, 85.9, 85.6 (MeC5H4Mn), 84.4
(CpFe), 38.6 (SCH2CH3), 19.3 (SCH2CH3) and 13.9
(MeC5H4Mn) ppm.
3.3. Synthesis of [FeMn(v-CO)(v-SPh)(CO)2(Cp)-
(C5H4Me)] 2
Complex 2 was obtained following the same proce-
dure described for the preparation of 1 starting from
[Fe(CO)2(SPh)(Cp)] (2.4 mmol), prepared from
[Fe(CO)2(Cp)(thf)] and NaSPh, and a slight excess of
[Mn(CO)2(thf)(C5H4Me)] (3.0 mmol). Yield (145 mg,
13%). Analysis. Found: C, 53.46; H, 3.90%.
C20H17FeMnO3S requires: C, 53.60; H, 3.82%. IR
(CH2Cl2) wmax (cm−1) 1968s, 1905m and 1774m (CO).
NMR: lH (CD2Cl2): 7.65–7.00 (5 H, m, SPh), 4.83 (5
H, s, Cp), 4.77–4.40 (4 H, m, MeC5H4Mn) and 2.16 (3
3.2. Synthesis of [FeMn(v-CO)(v-SEt)(CO)2(Cp)-
(C5H4Me)] 1
A thf (20 ml) solution of [Fe(CO)2(SEt)(Cp)] (3.55
mmol), freshly prepared from [Fe(CO)2(thf)(Cp)]-
SO3CF3 and NaSEt, was transferred, by cannula, into a
UV immersion lamp reactor containing [Mn(CO)2-

32
V.G. Albano et al. / Journal of Organometallic Chemistry 583 (1999) 28–33
H, s, MeC5H4Mn) ppm. lC (CD2Cl2): 267.1 (v-CO),
229.2 (Mn–CO), 212.9 (Fe–CO), 146.8, 133.0, 128.1,
127.1 (Ph), 104.5, 88.1, 87.8, 86.7, 86.2 (MeC5H4Mn),
84.9 (CpFe) and 14.4 (MeC5H4Mn) ppm.
fects. No decay correction was necessary. An empirical
absorption correction was applied by using the az-
imuthal scan method [21]. The positions of the metal
atoms were found by direct methods using the
SHELXS 86 program [22] and all the non-hydrogen
atoms located in Fourier syntheses. The hydrogen
atoms were located in successive Fourier-difference
maps but added in calculated positions and allowed to
ride the pertinent carbon atoms during the refinement.
Although manganese and iron atoms were recognized
unambigously by the non equivalence of their chemical
environments a refinement was made with inverted
assignement of the metal atoms. Interestingly, this cal-
culation gave an R factor of 0.0504 against 0.0474 of
the correct structure. Our data were therefore able to
discriminate contiguous metal atoms in the periodic
table. The final refinement on F2 proceeded by full-ma-
trix least-squares calculations (SHELXL 93) [23] using
anisotropic thermal parameters for all the non-hydro-
gen atoms. The methyl and methylene H atoms were
assigned an isotropic thermal parameter 1.3 times Ueq
of the carbon atoms to which they were attached. In the
final difference Fourier synthesis the electron density
3.4. Synthesis of [FeMn (v-CO)(v-PPh2)(CO)2(Cp)-
(C5H4Me)] 3
Complex 3 was obtained following the same proce-
dure described for the preparation of
1 using
[Fe(CO)2(PPh2)(Cp)] (2.8 mmol), prepared from [Fe-
(CO)2(thf)(Cp)] and LiPPh2, in place of [Fe(CO)2-
(SEt)(Cp)] and a slight excess of [Mn(CO)2(thf)-
(C5H4Me)] obtained by photolysis of [Mn(CO)3-
(C5H4Me)] (0.70 g, 3.2 mmol). Chromatography of the
reaction products on alumina column, with CH2Cl2-
hexane as eluent (1:3, v/v) gave a first yellow fraction of
[Mn(CO)3(C5H4Me)] (0.18 g) was followed by some
[Fe2(CO)4(Cp)2]. Further elution with thf gave third
reddish-brown fraction of 3 which was collected and
crystallized at −20°C from CH2Cl2 layered with n-pen-
tane. (Yield 0.34 g, 23%). Analysis. Found: C, 59.67; H,
4.31%. C26H22FeMnO3S requires: C, 59.57; H, 4.23%.
IR (CH2Cl2) wmax (cm−1) 1957s, 1937sh, 1894s and
1762s (CO). NMR: lH (CDCl3, 233 K): 7.71–6.98 (10
H, m, Ph), 4.67, 4.51 (5 H, s, CpFe), 4.88, 4.77, 4.75,
4.30, 4.14, 3.94, 3.88, 3.62 (3 H, s, MeC5H4Mn), 2.16
and 2.06 (3 H, s, MeC5H4Mn) ppm; cis-trans isomers in
about 1:1 ratio; (CDCl3, 295 K): 7.70–7.32 (10 H, m,
Ph), 4.55 (ꢀ5 H, s br, CpFe), 4.75, 3.95, 3.70 (s, br
MeC5H4Mn) 4.02 (ꢀ1 H, s, br MeC5H4Mn) and 2.10
(ꢀ3 H, s, br, MeC5H4Mn). lH (CDCl3, 313 K): 7.70–
7.31 (10 H, m, Ph), 4.55 (ꢀ5 H, s, CpFe), 4.01 (ꢀ1 H,
s, br MeC5H4Mn), (3 H, m, MeC5H4Mn), and 2.10 (3
H, s, MeC5H4Mn) ppm. lC (CDCl3, 253 K) cis and
trans isomers: 275.6, 274.4 (m-CO), 230.1 (d, JCP=19.4
Hz), 228.8 (d, JCP=19.4 Hz) (Mn–CO), 213.9 (d,
was found in the range −0.66 to 0.92 e A−3. A
,
Table 2
Crystal data and experimental details for [FeMn(m-CO)(m-
SEt)(CO)2(Cp)(C5H4Me)]
Formula
Formula weight
Temperature (K)
C16H17FeMnNO3S
400.15
200(2)
,
Wavelength (A)
0.71069
Triclinic
Crystal symmetry
Space group
(
P1 (No. 2)
Unit cell dimensions
,
a (A)
6.732(6)
9.303(8)
13.261(6)
80.35(2)
83.33(3)
82.98(2)
809(1)
,
b (A)
,
c (A)
J
CP=15.0 Hz), 212.8 (d, JCP=16.3 Hz) (Fe–CO),
h (°)
i (°)
k (°)
137.0–128.3 (m, Ph), 103.3, 101.1, 89.7, 89.2, 88.2, 86.4,
85.9, 85.6, 84.6 (MeC5H4Mn), 87.8, 85.5 (CpFe), 14.4,
and 13.7 (MeC5H4Mn) ppm. lP (CDCl3, 295 K) cis and
trans isomers: (CDCl3) 300 Mhz: 219.6, and 209.7 ppm.
MS m/e: 524 (M+), 496 (–CO), 468 (–2CO), 448
(–3CO, base peak).
3
,
Cell volume (A )
Z
2
Dc (Mg m−3
)
1.643
1.814
408
m(Mo–Ka) (mm−1
F(000)
)
Crystal size (mm)
q limits (°)
Scan mode
0.20×0.25×0.30
2–27
v
3506 (9h, 9k, +l)
2489
1.050
0.0474, 0.1269
a=0.0728,
b=1.2486 b
0.916 and −0.656
3.5. X-ray structure determination of
[FeMn(v-CO)(v-SEt)(CO)2(Cp)(C5H4Me)] 1
Reflections collected
Unique observed reflections [Fo\4|(Fo)]
Goodness of fit on F2
R1 (F) a, wR2 (F2) b
Crystal data and details of the data collection for
[FeMn(m-CO)(m-SEt)(CO)2(Cp)(C5H4Me)] are given in
Table 2. The diffraction experiments were carried out at
200 K on a fully automated Enraf-Nonius CAD-4
diffractometer using graphite-monochromated Mo–Ka
radiation. The unit cell parameters were determined by
a least-squares fitting procedure using 25 reflections.
Data were corrected for Lorentz and polarization ef-
Weighting scheme
−3
,
Largest difference peak and hole, (e A
)
a R1=S ꢀ ꢀ Fo ꢀ–ꢀ Fc ꢀ/S ꢀ Fo ꢀ.
b wR2=[S w(F2o−F2c)2/S w(Fo2)2]1/2 where w=1/[|2(F2o)+(aP)2+
bP] where P=(F2o+2Fc2)/3.

V.G. Albano et al. / Journal of Organometallic Chemistry 583 (1999) 28–33
33
(g) Z. Qiu, J. Sun. J. Chen, Organometallics 17 (1998) 600.
complete list of bond lengths and angles and a table of
anisotropic displacement parameters have been de-
posited at the Cambridge Crystallographic Data Centre
(CCDC).
[7] (a) J.T. Lin, A.C. Yeh, Y.C. Chou, T.Y.R. Tsai, Y.S. Wen, J.
Organomet. Chem. 486 (1995) 147. (b) R.P. Rosen, J.B. Hoke,
R.B. Whittle, G.L. Geoffroy, J.P. Hutchinson, J.A. Zubieta,
Organometallics 3 (1984) 846. (c) M. Muller, H. Vahrenkamp,
Chem. Ber. 116 (1983) 2322.
[8] M. Ahmad, R. Bruce, G.R. Knox, J. Organomet. Chem. 6
(1966) 1.
[9] R.J. Haines, J.A. De Beer, R. Greatex, J. Organomet. Chem. 85
(1975) 89.
Acknowledgements
We thank the Consiglio Nazionale delle Ricerche,
Ministero dell’Universita’e della ricerca Scientifica e
Tecnologica and the University of Bologna (projects
‘Sintesi Modelli e Caratterizzazione per Materiali Fun-
zionali’ and ‘Molecole ed aggregati Molecolari Intelli-
genti’) for financial support.
[10] (a) J.G. Bullit, F.A. Cotton, T. Marks, Inorg. Chem. 11 (1972).
(b) R.D. Adams, F.A. Cotton, J. Am. Chem. Soc. 95 (1973)
6602.
[11] (a) E.W. Abel, G.W. Farrow, K.G. Orrell, V. Sik, J. Chem. Soc.
Dalton Trans. (1977) 42. (b) G. Natile, L. Maresca, G. Bor,
Inorg. Chim. Acta 23 (1977) 37. (c) S.D. Killops, S.A.R. Knox,
J. Chem. Soc. Dalton Trans. (1978) 1260.
[12] R.H. Fong, C.H. Lin, H. Idmoumaz, W.H. Hersh, Organometal-
lics 12 (1993) 503.
[13] (a) J.C.T.R. Burkett-St.Laurent, M.R. Caira, R.B. English, R.J.
Haines, L.R. Nassimbeni, J. Chem. Soc. Dalton Trans. (1977)
1077. (b) P.A. Shapley, W.A. Reinerth, Organometallics 15
(1996) 5090.
[14] R.B. English, L.R. Nassimbeni, R.J. Haines, J. Organomet.
Chem. 135 (1977) 351.
[15] A. Winter, G. Huttner, M. Gottlieb, I. Jibril, J. Organomet.
Chem. 286 (1985) 317.
[16] P. Oudet, M.M. Kubicki, C. Mo¨ıse, Organometallics 13 (1994)
4278 and Refs. therein.
[17] R.J. Haines, C.R. Nolte, J. Organomet. Chem. 36 (1972) 163.
[18] (a) S.G. Shyu, P.J. Lin, Y.S. Wen, J. Organomet. Chem. 443
(1993) 115. (b) S.G. Shyu, P.J. Lin, T.Y. Dong, Y.S. Wen, J.
Organomet. Chem. 460 (1993) 229.
[19] P.M. Treichel, W.K. Dean, W.M. Douglas, J. Organomet.
Chem. 42 (1972) 145.
[20] The compound [Fp(PMePh2)]SO3CF3 [Fp=Fe(CO)2(Cp)] was
identified by comparison of its spectroscopic properties with
those of a sample prepared from [Fp(thf)]SO3CF3 and PMePh2:
IR (CH2Cl2) wmax (cm−1) 2058s and 2014s (CO). NMR: lH
(CD2Cl2): 7.81–7.40 (10 H, m, Ph), 5.35 (5 H, s, Cp) and 2.40 (3
H, d, PPh2Me, JPH 9.9 Hz) ppm. lC (CDCl3): 209.6 (d, JPC 24.9
Hz, CO), 133.2–130.7 (Ph), 88.7 (Cp) and 20.0 (d, JPC 35.3 Hz
PPh2Me) ppm.
References
[1] (a) D.A. Roberts, G.L. Geoffroy, in: G. Wilkinson, F.G.A.
Stone, E.W. Abel (Eds.), Comprehensive Organometallic Chem-
istry, vol. 6, Pergamon Press, Oxford, 1982, p. 763. (b) M.J.
Chetchuti, in: G. Wilkinson, F.G.A. Stone, E.W. Abel (Eds.),
Comprehensive Organometallic Chemistry II, vol. 10, Pergamon
Press Oxford, 1995, p. 23. (c) D.W. Stephan, Coord. Chem. Rev.
95 (1989) 41.
[2] (a) E. Sappa, A. Tiripicchio, P. Braunstein, Coord. Chem. Rev.
65 (1985) 219. (b) C. Fraser, R. Ostrander, A.L. Rheingold, C.
White, B. Bosnich, Inorg. Chem. 33 (1994) 324. (c) B.T. Steren-
berg, R.W. Hilts, G. Moro, R. McDonald, M. Cowie, J. Am.
Chem. Soc. 117 (1995) 245. (d) M.A. Esteruelas, M.P. Garcia,
A.M. Lopez, L.A. Oro, Organometallics 10 (1991) 127. (e) A.M.
Baranger, R.G. Bergman, J. Am. Chem. Soc. 116 (1994) 3822.
[3] M. Herberhold, G.X. Jin, Angew. Chem. Int. Ed. Engl. 33
(1994) 964.
[4] V.G. Albano, M. Monari, L. Busetto, L. Carlucci, V. Zanotti,
Gazz. Chim. Ital. 122 (1992) 201.
[5] V.G. Albano, L. Busetto, M.C. Cassani, P. Sabatino, A.
Schmitz, V. Zanotti, J. Chem. Soc. Dalton Trans. (1995) 2087.
[6] Significant examples include: (a) S.M. Gadol, R.E. Davis,
Organometallics 1 (1982) 1607. (b) J. Keijsper, P. Grimberg, G.
van Koten, K. Vrieze, B. Kojic-Prodic, A.L. Spek, Organometal-
lics 4 (1985) 438. (c) W. Ehrl, H. Vahrenkamp, Chem. Ber. 106,
(1973) 2563. (d) M. Akita, A. Takabuchi, M. Terada, N. Ishii,
M. Tanaka, Y. Moro-oka, Organometallics 13 (1994) 2516. (e)
R.H. Fong, W.H. Hersh, Organometallics 4 (1985) 1468. (f) Y.
Yu, J. Chen, P. Zheng, J. Chem. Soc. Dalton Trans. (1996) 1443.
[21] A.C.T. North, D.C. Philips, F.S. Mathews, Acta Crystallogr.
Section A 24 (1968) 351.
[22] G.M. Sheldrick, SHELXS 86, Program for crystal structure solu-
tion, University of Gottingen, 1986.
[23] G.M. Sheldrick, SHELXL 93, Program for crystal structure refine-
ment, University of Gottingen, 1993.
.
.