Synthesis of a manganese germavinylidene complex from bis(germavinylidene)

Article abstract of DOI:10.1021/ic050969u

The reaction of bis(germavinylidene) [(Me₃SiN=PPh ₂)₂C=Ge→Ge= C(PPh₂=NSiMe₃) ₂] (1) with CpMn(CO)₂(THF) (Cp = η⁵-C ₅H₅) in THF afforded [(Me₃SiN=PPh ₂)₂C=Ge→Mn(CO)₂Cp] (2). Similar reaction of 1 with (cod)RhCl (cod = 1,5-cyclooctadiene) in THF gave [(Me ₃SiN=NPPh₂)₂{(cod)Rh}C-GeCl] (3). The results suggested that reactive germavinylidene may exist in solution. The X-ray structures of 2 and 3 have been determined.

Full text of DOI:10.1021/ic050969u

Inorg. Chem. 2005, 44, 7286−7288
Synthesis of a Manganese Germavinylidene Complex from
Bis(germavinylidene)
Wing-Por Leung,* Cheuk-Wai So, Kwok-Wai Kan, Hoi-Shan Chan, and Thomas C. W. Mak
Department of Chemistry, The Chinese UniVersity of Hong Kong, Shatin, New Territories,
Hong Kong, China
Received June 14, 2005
The reaction of bis(germavinylidene) [(Me3SiN
C(PPh2dNSiMe3)2] (1) with CpMn(CO)2(THF) (Cp ) η5-C5H5) in
THF afforded [(Me3SiN PPh2)2C Ge Mn(CO)2Cp] (2). Similar
reaction of 1 with (cod)RhCl (cod
gave [(Me3SiN NPPh2)2 (cod)Rh
d
PPh2)2C
d
Ge
f
Ge
d
NSiMe3)2] (1).5 Its role as a carbene ligand transfer reagent
has been demonstrated in the reaction of 1 with Mo(CO)5-
(THF) to form mer/fac-(Me3SiNdPPh2)2CdMo(CO)5.6 We
have also reported the synthesis of chalcogen-bridged dimers
of germaketene analogues [(Me3SiNdPPh2)2CdGe(µ-E)]2 (E
) S, Se, and Te) from the direct reaction of elemental
chalcogens with 1.7 However, monomeric germavinylidene
or its metal complex has not been structurally authenticated.
Because of the weak Ge-Ge interaction of 1 in solution,
we anticipated that it could be a potential source of the
reactive germavinylidene intermediate “:GedC(PPh2d
NSiMe3)2”. In this paper, we report the synthesis of a
manganese germavinylidene complex showing that germa-
vinylidene is stabilized by the CpMn(CO)2 moiety. The 1,2-
addition of germavinylidene with (cod)RhCl (cod ) 1,5-
cyclooctadiene) is also reported.
The reaction of 1 with 2 equiv of CpMn(CO)2(THF) (Cp
) η5-C5H5) in THF afforded [(Me3SiNdPPh2)2CdGef
Mn(CO)2Cp] (2; Scheme 1).8 The structure of 2 has been
confirmed by X-ray structure analysis. It showed that
compound 2 contains a germavinylidene as a neutral ligand
bonded to the Mn(I) center. The result suggested that a
solution of 1 may contain the monomeric germavinylidene
[(Me3SiNdPPh2)2CdGe:] by dissociation of the donor-
acceptor interaction between the germanium centers. The
germavinylidene thus acts as a two-electron ligand and
displaces THF in CpMn(CO)2(THF) to form compound 2.
Similar Lewis base type behavior of germanium(II) com-
plexes toward transition metals has been demonstrated.9 For
d
d
f
)
1,5-cyclooctadiene) in THF
GeCl] (3). The results sug-
d
{
}C
−
gested that reactive germavinylidene may exist in solution. The
X-ray structures of 2 and 3 have been determined.
Compounds containing a double bond between germanium
and carbon (>GedC<) have attracted much attention in the
past 15 years, and they have been the focus of several
reviews.1 It was found that the thermal stability of the Ged
C bond is intrinsically low and they can undergo oligomer-
ization readily.2 Nevertheless, stable germenes R2GedCR′2
have been synthesized by incorporating sterically bulky
substituents at both germanium and carbon.3 These germenes
are highly reactive and can undergo 1,2-addition and [2 +
n] cycloaddition.4 In contrast, the related germavinylidenes
(>CdGe:) are scarcely known. Because they lack any bulky
substitutents at the germanium(II) center, germavinylidenes
are expected to oligomerize more readily.
The unusual structure and the unknown reactivity of
germavinylidenes have attracted our interest. Recently, we
have communicated the synthesis and structure of bis-
(germavinylidene) [(Me3SiNdPPh2)2CdGefGedC(PPh2d
* To whom correspondence should be addressed. E-mail:
kevinleung@cuhk.edu.hk.
(1) For selected recent reviews and examples of germenes, see: (a) Barrau,
J.; Escudie´, J.; Satge´, J. Chem. ReV. 1990, 90, 283. (b) Driess, M.;
Gru¨tzmacher, H. Angew. Chem., Int. Ed. Engl. 1996, 35, 828. (c)
Escudie´, J.; Ranaivonjatovo, H. AdV. Organomet. Chem. 1999, 44,
113. (d) Couret, C.; Escudie´, J.; Satge´, J.; Lazraq, M. J. Am. Chem.
Soc. 1987, 109, 4411. (e) Anselme, G.; Escudie´, J.; Couret, C.; Satge´,
J. J. Organomet. Chem. 1991, 403, 93. (f) Lazraq, M.; Couret, C.;
Escudie´, J.; Satge´, J. Polyhedron 1991, 10, 1153.
(2) Bravo-Zhivotovskii, D.; Zharov, I.; Kapon, M.; Apeloig, Y. J. Chem.
Soc., Chem. Commun. 1995, 1625.
(3) (a) Meyer, H.; Baum, G.; Massa, W.; Berndt, A. Angew. Chem., Int.
Ed. Engl. 1987, 26, 798. (b) Lazraq, M.; Escudie´, J.; Couret, C.; Satge´,
J.; Dra¨ger, M.; Dammel, R. Angew. Chem., Int. Ed. Engl. 1988, 27,
828. (c) Couret, C.; Escudie´, J.; Delpon-Lacaze, G.; Satge´, J.
Organometallics 1992, 11, 3176.
(5) Leung, W.-P.; Wang, Z.-X.; Li, H.-W.; Mak, T. C. W. Angew. Chem.,
Int. Ed. 2001, 40, 2501.
(6) Leung, W.-P.; So, C.-W.; Wang, J.-Z.; Mak, T. C. W. J. Chem. Soc.,
Chem. Commun. 2003, 248.
(7) Leung, W.-P.; So, C.-W.; Wang, Z.-X.; Wang, J.-Z.; Mak, T. C. W.
Organometallics 2003, 22, 4305.
(8) A solution of CpMn(CO)3 (0.21 g, 1.03 mmol) in 80 mL of THF
with stirring was irradiated by a 125-W medium-pressure mercury
lamp for ca. 6 h, and then 1 (0.65 g, 0.52 mmol) in 80 mL of THF
was added. The mixture was stirred at room temperature for ca. 2
days. THF was removed under reduced pressure, and the residue was
extracted with ether. After filtration and concentration of the filtrate,
2 was obtained as yellow crystals. Yield: 0.52 g (63%).
(9) For selected recent reviews, see: (a) Petz, W. Chem. ReV. 1986, 86,
1019. (b) Lappert, M. F.; Rowe, R. S. Coord. Chem. ReV. 1990, 100,
267.
(4) Escudie´, J.; Couret, C.; Ranaivonjatovo, H.; Satge´, J. Coord. Chem.
ReV. 1994, 130, 427.
7286 Inorganic Chemistry, Vol. 44, No. 21, 2005
10.1021/ic050969u CCC: $30.25
© 2005 American Chemical Society
Published on Web 09/20/2005

COMMUNICATION
Scheme 1
example, [M(CO)5Ge{N(SiMe3)2}2] (M ) Cr, Mo, or W),10
[M(PR3)2Ge{N(SiMe3)2}2] (M ) Ni or Pd),11 and [Fe(CO)4-
Ge(OAr)2] {Ar ) 2,4,6-tris[(dimethylamino)methyl]phenyl}12
have been reported. Recently, Barrau and co-workers have
reported the synthesis of [(Salen)GefMn(CO)2(Cp)] from
the reaction of [(Salen)Ge] with CpMn(CO)2(THF).13
Figure 1. Molecular structure of 2 (30% probability ellipsoids). Selected
bond distances [Å] and angles [deg]: Ge1-Mn1, 2.236(1); Ge1-C1,
1.885(3); Ge1-N2, 1.939(2); C1-P1, 1.748(3); C1-P2, 1.713(3); P1-
N1, 1.549(3); P2-N2, 1.653(3); C66-O1, 1.160(5); C67-O2, 1.159(4);
Mn1-C66, 1.770(4); Mn1-C67, 1.774(4); C1-Ge1-Mn1, 145.4(8); N2-
Ge1-Mn1, 133.1(7); C1-Ge1-N2, 81.4(1); P1-C1-Ge1, 128.6(2); P2-
C1-Ge1, 91.5(1); P1-C1-P2, 136.5(2); Ge1-N2-P2, 91.5(1); Ge1-
Mn1-C66, 93.9(1); Ge1-Mn1-C67, 91.2(1).
A similar reaction of 1 with 2 equiv of (cod)RhCl in THF
gave [(Me3SiNdNPPh2)2{(cod)Rh}C-GeCl] (3).14 The X-
ray structure of 3 showed that (cod)RhCl underwent a 1,2-
addition with germavinylidene in solution. The GedC bond
inserted into the Rh-Cl bond underlining the nucleo-
philic character at the carbene center. This contrasts with
the results found in the reaction of [MCl2{C(PPh2dNSiMe3)2-
κC,κ2N,N′}], in which the electrophilic moiety was added
to the carbene center.15 The result is different from that of
[RhCl{Ge(NBut)2SiMe2}4]16 or cis-[RhCl{Ge(NR2)2}(PPh3)]
(R ) SiMe3),9b in which the germanium(II) center acted as
a Lewis base toward RhCl. The X-ray structure also showed
that the Ge-C bond distance is lengthened (by 0.191 Å)
significantly in 3, as compared with the Ge-C double bond
distance in 2. Therefore, the germavinylidene exists as a
vinylidene structure instead of an ylide-amide structure in
the solution.17 Compound 3 is a bimetallic bis(iminophos-
phorano)methanide complex. Other bimetallic examples such
as [(AlMe)2{µ2-C(Ph2PdNSiMe3)2-κ4C,C′,N,N′}]18 and [Cr{µ2-
rhodium bis(iminophosphorano)methanide complex [Rh{CH-
(PPh2dN-C6H4-4-CH3)2}(cod)] has also been synthesized.20
Compounds 2 and 3 were isolated as yellow crystalline
solids. They are air-sensitive, soluble in THF, and sparingly
soluble in Et2O. They have been characterized by NMR
spectroscopy and X-ray structure analysis.21 The 31P NMR
spectrum of 2 at 298 K showed one singlet at δ 32.37 ppm,
which does not correspond to the X-ray structure. This may
be due to the fluxional coordination of the imino nitrogen
atoms at the germanium center in solution. At 238 K, the
fluxional coordination slowed and the 31P NMR of 2
displayed two singlets at δ 5.06 and 62.42 ppm, consistent
with the X-ray structure. The 31P NMR spectrum of 3 showed
two signals at δ 45.53 and 58.43 ppm due to two different
phosphorus environments as in the solid-state structure.
The molecular structure of 2 is shown in Figure 1.22
Compound 2 is comprised of a monomeric germavinylidene
19
C(Ph2PdNSiMe3)2-κ4C,C′,N,N′}]2 have been reported. A
(10) Lappert, M. F.; Power, P. P. J. Chem. Soc., Dalton Trans. 1985, 51.
(11) (a) Bender, J. E.; Shusterman, A. J.; Banaszak Holl, M. M.; Kampf,
J. W. Organometallics 1999, 18, 1547. (b) Cygan, Z. T.; Bender, J.
E., IV; Litz, K. E.; Kampf, J. W.; Banaszak Holl, M. M. Organo-
metallics 2002, 21, 5373.
(12) Barrau, J.; Rima, G.; Amraoui, T. E. J. Organomet. Chem. 1998, 570,
163.
(20) Imhoff, P.; van Asselt, R.; Ernsting, J. M.; Vrieze, K.; Elsevier, C. J.;
Smeets, W. J. J.; Spek, A. L.; Kentgens, A. P. M. Organometallics
1993, 12, 1523.
(21) 2. Mp: 149.6 °C (dec). Anal. Calcd for C38H43GeMnN2O2P2Si2: C,
56.66; H, 5.38; N, 3.48. Found: C, 56.38; H, 5.13; N, 3.25. 1H NMR
(THF-d8): δ -0.11 (s, 18H, SiMe3), 4.33 (s, 5H, η5-C5H5), 7.30-
7.32 (m, 8H, Ph), 7.39-7.41 (m, 4H, Ph), 7.60-7.72 (m, 8H, Ph).
13C{1H} NMR (THF-d8): δ 3.79 (SiMe3), 81.13 (η5-C5H5), 129.06,
129.22, 131.52, 131.92, 132.68, 133.10, 133.24, 137.29 (Ph), 231.22
(CO). 31P{1H} NMR (298 K, THF-d8): δ 32.37. 31P{1H} NMR (238
K, THF-d8): δ 5.06, 62.42. IR (cm-1): νCO ) 1855 (w), 1897 (s),
2018 (s). 3. Mp: 144.5 °C (dec). Anal. Calcd for C39H50ClGeN2P2-
RhSi4‚THF: C, 54.48; H, 6.17; N, 2.95. Found: C, 54.13; H, 6.17;
N, 2.55. 1H NMR (THF-d8): δ -0.31 (s, 9H, SiMe3), 0.05 (s, 9H,
SiMe3), 1.85-2.27 (m, 8H, cod-CH2), 3.95 (br, 2H, cod-CH), 5.14
(br, 2H, cod-CH), 6.90 (m, 2H, Ph), 7.11-7.14 (m, 3H, Ph), 7.28-
7.46 (m, 9H, Ph), 7.67-7.70 (m, 2H, Ph), 7.84-7.87 (m, 2H, Ph),
7.84-7.87 (m, 2H, Ph) 8.13-8.14 (m, 2H, Ph). 13C{1H} NMR (THF-
d8): δ 3.39 (SiMe3), 4.74 (SiMe3), 29.59, 30.31, 31.03, 31.74, 34.18,
34.72 (cod-H2Callyl), 75, 77, 77.92, 83.22, 85.43 (cod-HCvinyl), 128.65,
128.81, 128.99, 129.14, 131.75, 132.08, 132.28, 132.44, 133.58,
135.67, 133.73, 133.81, 134.62, 134.77, 135.34, 135.43, 140.01 (Ph).
31P{1H} NMR (THF-d8): δ 45.53, 58.43.
(13) Agustin, D.; Rima, G.; Gornitzka, H.; Barrau, J. Inorg. Chem. 2000,
39, 5492.
(14) A solution of 1 (0.47 g, 0.37 mmol) in THF (30 mL) was added
dropwise to (cod)RhCl (0.18 g, 0.75 mmol) in THF (30 mL) at 0 °C.
The reaction mixture was stirred at room temperature for 40 h.
Volatiles in the mixture were removed under reduced pressure, and
the residue was extracted with Et2O. After filtration and concentration
of the filtrate, 2 was obtained as yellow crystals. Yield: 0.54 g (78%).
(15) Kamalesh Babu, R. P.; McDonald, R.; Cavell, R. G. Organometallics
2000, 19, 3462.
(16) Veith, M.; Mu¨ller, A.; Stahl, L.; No¨tzel, M.; Jarczyk, M.; Huch, V.
Inorg. Chem. 1996, 35, 3848.
(17) Cavell, R. G.; Kamalesh Babu, R. P.; Kasani, A.; McDonald, R. J. J.
Am. Chem. Soc. 1999, 121, 5805.
(18) Aparna, K.; McDonald, R.; Ferguson, M.; Cavell, R. G. Organo-
metallics 1998, 18, 4241.
(19) Aparna, K.; McDonald, R.; Cavell, R. G. Chem. Commun. 1999, 1993.
Inorganic Chemistry, Vol. 44, No. 21, 2005 7287

COMMUNICATION
bonded to the Mn center. One of the imino groups of the
ligand coordinates to the germanium center, while the others
remain uncoordinated. Thus, the geometry around the
germanium center is trigonal planar. The differences in the
P-N bond distances of 1.549(3) and 1.653(2) Å suggest that
the delocalization of π electrons resulted from the conjuga-
tion of PdN and CdGe double bonds in germavinylidene.
Therefore, the Ge1-C1 distance of 1.885(3) Å in 2 is longer
than the calculated value of 1.784-1.815 Å in H2CdGe:.23
The Ge1-C1 distance is comparable with those of 1.905(8)
and 1.908(7) Å in 1.5 The Ge1-Mn1 distance of 2.236(1)
Å is similar to that of 2.250(1) Å in [{(η5-C5H5)Mn(CO)2}3-
Ge]24 and that of 2.180(2) Å in [µ-Ge{(η5-C5Me5)Mn-
(CO)2}2].25
The molecular structure of 3 is shown in Figure 2.26 It
showed that (cod)RhCl was added to the CdGe bond in the
anti position. The imino groups of the ligand coordinate to
the germanium and rhodium centers, respectively. The Ge1-
C4 distance of 2.076(3) Å in 3 is elongated in comparison
to the C-Ge distances in 1. The Ge1-C4 distance is similar
to the Ge-C single-bond distances of 2.067 and 2.012 Å in
[Ge{CH(SiMe3)2}{C(SiMe3)3}]27 and 2.116 Å in [Ge{CPh-
(SiMe3)C5H4N-2}2].28 The Ge1-Cl1 bond distance of 2.350(1)
Å in 3 is slightly longer than that of 2.203(10) Å in
[Ge(C6H3-2,6-Trip2)Cl]29 and that of 2.295(12) Å in
[{HC(CMeNAr)2}GeCl].30 The bond distances of Rh1-C4
[2.204(3) Å] and Rh1-N2 [2.181(3) Å] in 3 are similar to
those in [Rh(CH2PPh2dN-C6H4-CH3-4)(cod)] [Rh-C,
Figure 2. Molecular structure of 3 (30% probability ellipsoids). Selected
bond distances [Å] and angles [deg]: C4-Ge1, 2.076(3); Ge1-Cl1,
2.350(1); Ge1-N1, 2.037(3); P1-N1, 1.612(3); P1-C4, 1.755(3); C4-
Rh1, 2.204(3); Rh1-N2, 2.181(3); P2-N2, 1.607(3); P2-C4, 1.737(3);
Rh1-C51, 2.116(4); Rh1-C58, 2.102(4); Rh1-C54, 2.146(4); Rh1-C55,
2.157(4); C4-Ge1-Cl1, 101.1(9); N1-Ge1-Cl1, 101.9(1); Ge1-N1-
P1, 95.4(1); N1-P1-C4, 97.6(1); P1-C4-P2, 127.3(2); Ge1-C4-Rh1,
112.7(1); Ge1-C4-P1, 89.8(1); Rh1-C4-P2, 86.0(1); C4-P2-N2,
103.7(2); P2-N2-Rh1, 90.1(1).
2.128(3) Å; Rh-N, 2.132(3) Å].31 The Rh1-C58 and Rh1-
C51 bond distances of 2.102(4) and 2.116(4) Å are longer
than those of Rh1-C54 [2.146(4) Å] and Rh1-C55 [2.157(4)
Å]. This can be ascribed to the higher trans influence of the
carbon atom compared to the nitrogen atom of the bis-
(iminophosphorano)methanide ligand.31,32 Similar structural
features can also be found in [Rh(CH2PPh2dN-C6H4-CH3-
4)(cod)]31 and [Rh(p-tol-NdPPh2CHPPh2NH-p-tol)(cod)].32
(22) Crystal data for 2 (C38H43GeMnN2O2P2Si2): formula weight 805.39;
a ) 19.929(9) Å, b ) 10.072(5) Å, c ) 22.510(10) Å; R ) 90°, â )
116.226(7)°, γ ) 90°; V ) 4053(3) Å3; Z ) 4; space group Cc
(monoclinic); T ) 293(2) K; λ ) 0.710 73 Å; µ ) 1.225 mm-1; Dcalc
) 1.320 g cm-3; R1 ) 0.0291, wR2 ) 0.0650.
(23) Stogner, S. M.; Grev, R. S. J. Chem. Phys. 1998, 108, 5458.
(24) Melzer, D.; Weiss, E. J. Organomet. Chem. 1984, 263, 67.
(25) Korp, J. D.; Bernal, I.; Ho¨rlein, R.; Serrano, R.; Herrmann, W. A.
Chem. Ber. 1985, 118, 340.
(26) Crystal data for 3 (C39H50ClGeN2P2RhSi4‚THF): formula weight
947.98; a ) 9.728(2) Å, b ) 10.947(2) Å, c ) 23.382(4) Å; R )
83.703(4)°, â ) 78.379(4)°, γ ) 69.488(4)°; V ) 2282.3(7) Å3; Z )
2; space group Ph1 (triclinic); T ) 293(2) K; λ ) 0.710 73 Å; µ )
1.235 mm-1; Dcalc ) 1.379 g cm-3; R1 ) 0.0403, wR2 ) 0.0936.
(27) Jutzi, P.; Becker, A.; Stammler, H. G.; Neumann, B. Organometallics
1991, 10,1647.
Acknowledgment. This work was supported by the Hong
Kong Research Grants Council (Project CUHK 401404).
Supporting Information Available: Details in CIF format
about the X-ray crystal structures, including ORTEP diagrams and
tables of crystal data and structure refinement, atomic coordinates,
bond lengths and angles, and anisotropic displacement parameters
for 2 and 3. This material is available free of charge via the Internet
at http://pubs.acs.org.
(28) Leung, W.-P.; Kwok, W.-H.; Weng, L.-H.; Law, L. T. C.; Zhou, Z.-
Y.; Mak, T. C. W. J. Chem. Soc., Dalton Trans. 1997, 22, 4301.
(29) Pu, L.; Olmstead, M. M.; Power, P. P.; Berthold, S. Organometallics
1998, 17, 5602.
(30) Ding, Y.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G. Organo-
metallics 2001, 20, 1190.
IC050969U
(31) Imhoff, P.; Nefkens, S. C. A.; Elsevier, C. J.; Goubitz, K.; Stam, C.
H. Organometallics 1991, 10, 1421.
(32) Imhoff, P.; Elsevier, C. J. J. Organomet. Chem. 1989, 361, C61.
7288 Inorganic Chemistry, Vol. 44, No. 21, 2005