Transition metal compounds containing alkynylsilyl groups - Complexes with a metal-silicon bond

Article abstract of DOI:10.1016/j.jorganchem.2012.01.019

Two transition metal complexes containing alkynylsilyl groups and a metal-silicon bond (CpFe(CO)₂SiMe₂C≡CPh (1), Co(CO)₄SiMe₂C≡CPh (2)) have been synthesized by nucleophilic substitution (salt elimination) using both strongly and weakly nucleophilic metallates. No disturbing interactions of the metallate with the CC bond were observed. The synthesis of a third complex ((Ph₃P) ₂RhClHSiMe₂C≡CPh (3)) by oxidative addition was hampered by transition metal catalyzed reactions of the Si-H with the CC triple bond. The reactivity of 1 toward complexation and hydrosilylation of the CC triple bond was studied, leading to the trinuclear dicobaltatetrahedrane compound 1 Co₂(CO)₆ (4) and the vinylsilyl complex CpFe(CO)₂SiMe₂CH=CPh(SiEt₃) (5), respectively. The complexes were characterized by NMR (1-5), IR (1-5), and UV/VIS spectroscopy (1, 3, 4) as well as X-ray crystallography (1-4).

Full text of DOI:10.1016/j.jorganchem.2012.01.019

Journal of Organometallic Chemistry 705 (2012) 59e69
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Transition metal compounds containing alkynylsilyl groups ꢀ complexes with
a metal-silicon bond
*
Florian Hoffmann, Jörg Wagler, Uwe Böhme, Gerhard Roewer
Institut für Anorganische Chemie, Technische Universität Bergakademie Freiberg, Leipziger Str. 29, 09596 Freiberg, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 8 December 2011
Accepted 25 January 2012
Two transition metal complexes containing alkynylsilyl groups and a metalꢀsilicon bond (CpFe(CO)2-
SiMe2C^CPh (1), Co(CO)4SiMe2C^CPh (2)) have been synthesized by nucleophilic substitution (salt
elimination) using both strongly and weakly nucleophilic metallates. No disturbing interactions of the
metallate with the C^C bond were observed. The synthesis of a third complex ((Ph3P)2RhClHSi-
Me2C^CPh (3)) by oxidative addition was hampered by transition metal catalyzed reactions of the SiꢀH
with the C^C triple bond. The reactivity of 1 toward complexation and hydrosilylation of the C^C triple
bond was studied, leading to the trinuclear dicobaltatetrahedrane compound 1 * Co2(CO)6 (4) and the
vinylsilyl complex CpFe(CO)2SiMe2CH¼CPh(SiEt3) (5), respectively. The complexes were characterized by
NMR (1e5), IR (1e5), and UV/VIS spectroscopy (1, 3, 4) as well as X-ray crystallography (1e4).
Ó 2012 Elsevier B.V. All rights reserved.
Keywords:
Iron
Cobalt
Rhodium
Alkynylsilyl complexes
Nucleophilic substitution
Oxidative addition
1. Introduction
Most of the known alkynylsilyl complexes were synthesized by
oxidative addition of SiꢀH bonds to transition metal compounds
Since their first synthesis over 50 years ago transition metal silyl
complexes have acquired considerable importance both in bonding
theory and catalysis [1]. However, subsequent chemistry is often
hampered by the sensitivity of the metal-silicon bond. In this
regard, silyl complexes bearing alkenyl or alkynyl groups at the
silicon are of particular interest, as their unsaturated hydrocarbon
residues may effect an enhanced reactivity in, e.g., complexation,
hydrosilylation, or carbonecarbon bond coupling reactions under
mild conditions, thus preserving the metal-silicon bond. While
there is a lot of research on alkenylsilyl complexes reported in the
literature [2] (including the syntheses of vinylsilylene [2cee] and
(Pt [3], Co [4aeh], Rh [5], W [6a,e], Mo [6c], Ti [7a,b,d], Zr [7b,c]). In
the particular case of reactions with dicobaltoctacarbonyl Co2(CO)8
the alkynyl group reacts much faster with Co2(CO)8 than the SiꢀH
bond, thus furnishing at first hydrosilyl substituted and subse-
quently trinuclear cobalt-silyl substituted alkyne cobalt complexes
[4aeh]. Hence, cobalt alkynylsilyl compounds require an alterna-
tive synthetic route. Nucleophilic substitution, the second preem-
inent synthetic method for silyl complexes, has been reported so far
only for a dinuclear iron complex (normal salt elimination: anionic
metallate þ silyl halide) [8] and a zirconium oligosilyl compound
(inverse salt elimination: metal halide þ silyl anion) [9]. In both
syntheses strong nucleophiles (Fpꢀ 1 or oligosilyl anion, resp.) were
employed. Further preparation methods toward alkynylsilyl
complexes are: silicon-carbon bond formation in a chromium silyl
complex [10], oxidative SiꢀH addition of diphenylsilane Ph2SiH2 to
an IrꢀC^C complex and rearrangement [11], oxidative addition of
a SiꢀC bond to a platinum complex [12], and rearrangement of an
oligosilylalkyne cobalt complex [13].
h
3-silaallyl complexes [2f,g]), we were surprised to find that the
work on alkynylsilyl complexes is rather limited [3e13], though
culminating in the
3-silapropargyl complexes of Sakaba et al. (Mo,
h
W) [6] and Rosenthal et al. (Ti, Zr) [7aed].
Abbreviations: AIM, atoms in molecules; as, asymmetric; br, broad; comb,
combination; Cp, cyclopentadienyl C5H5; dec., decomposition; d, doublet;
bending vibration (IR), chemical shift (NMR); Et, ethyl C2H5; , wagging vibration;
Fp, CpFe(CO)2; m, medium (IR), multiplet (NMR); Me, methyl CH3; , stretching
vibration;
w, wave number; Ph, phenyl C6H5; q, quartet; “qn”, apparent quintet;
d,
To our knowledge no comparative assessment of nucleophilic
substitution with strong and weak nucleophiles and oxidative
addition for the synthesis of alkynylsilyl complexes has been made.
Herein we present such a comparison as well as three new tran-
sition metal alkynylsilyl complexes, among them the first alky-
nylsilyl cobalt compound with a non-complexed C^C triple
bond [14].
g
n
n
r,
rocking vibration; s, singlet (NMR), strong (IR), symmetric (IR); sh, shoulder; t,
triplet; “t”, apparent triplet; TMS, tetramethylsilane; vbr, very broad; vs, very
strong; vw, very weak; w, weak.
* Corresponding author. Tel.: þ49 3731 39 4345; fax: þ49 3731 39 4058.
E-mail address: Gerhard.Roewer@chemie.tu-freiberg.de (G. Roewer).
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2012.01.019

60
F. Hoffmann et al. / Journal of Organometallic Chemistry 705 (2012) 59e69
Scheme 1. Synthesis of compounds 1e3.
2. Results and discussion
[1a,2a,16]. In contrast, a suspension of solid NaCo(CO)4 in hexane
afforded 2 as the main product (as judged by 29Si NMR). Byproducts
(including (PhC^CMe2Si)2O) were formed only in minor amounts.
Work-up gave 2 as colourless low-melting crystals in 82% yield. The
complex is very sensitive to oxidation and hydrolysis. The resulting
dark brown oil can be removed by recrystallization.
2.1. Nucleophilic substitution
Regarding nucleophilic substitution in silyl halides (normal salt
elimination), dicarbonyl(h
5-cyclopentadienyl)ferrate(0) Fpꢀ and
tetracarbonylcobaltate(ꢀI) CoðCOÞ4 were reported as the strongest
and the weakest known nucleophilic metallate, respectively [15].
Thus, these two metallates were chosen for investigating the salt
elimination reaction with an alkynylhalosilane.1
The 1H, 13C, and 29Si NMR data were consistent with the struc-
ture of 2. The 59Co NMR spectrum showed a broad signal
at ꢀ2975 ppm which is comparable to other tetracarbonylcobalt
silyl complexes [18]. The IR spectrum featured four bands in the CO
region, thus indicating a trigonal-bipyramidal coordination of the
cobalt atom with the silyl ligand in axial position and CS symmetry
of the molecule [19].
This conclusion was corroborated by the X-ray crystal structure
determination of 2 (Fig. 2 and Table 1): apart from the orientation of
the phenyl ring the molecule has approximately CS symmetry. The
cobalt is trigonal-bipyramidally coordinated with the silyl ligand in
axial position. The three equatorial carbonyl ligands are not
coplanar with the cobalt atom but bent toward the silyl ligand by
about 10ꢁ. This feature has previously been attributed to packing
effects [19]. However, ab-initio calculations indicate that it is indeed
an electronic effect [20]. Owing to the strong trans-effect of the silyl
ligand the CoꢀC bond of the axial carbonyl ligand is markedly longer
(183.8 pm) than those of the equatorial carbonyl ligands
(178.5e179.2 pm). In accordance with the observed high reactivity
of 2 the CoꢀSi bond (236.8 pm) is distinctly longer than the average
of all known CoꢀSi bond lengths (230 pm) but is comparable to
other tetracarbonylcobalt silyl complexes (234e238 pm).2
For the synthesis of dicarbonyl(
thyl(phenylethynyl)silyl]iron(II) FpSiMe2C^CPh (1) the corre-
sponding chlorosilane chlorodimethyl(phenylethynyl)silane
PhC^CMe2SiCl was reacted with sodium dicarbonyl(
5-cyclo-
h
5-cyclopentadienyl)[dime-
h
pentadienyl)ferrate NaFp in different solvents (THF/hexane, THF/
pentane, cyclohexane) (Scheme 1). In all cases mixtures of 70e85%
1
and 15e30% of the by-product 1,1,3,3-tetramethyl-1,3-
bis(phenylethynyl)-disiloxane (PhC^CMe2Si)2O were obtained as
judged by 29Si NMR, with THF/pentane giving the best results. The
oxygen source for the disiloxane is a CO ligand [16a], further by-
products are tetracarbonyl-di(h
5-cyclopentadienyl)-diiron Fp2 and
an unidentified second compound. The use of solid NaFp in cyclo-
hexane [16] had no advantages. In the work-up of the reaction
mixture a chromatography on silica gel proved to be essential for
the isolation of solid crystalline 1 although the disiloxane could not
be removed completely this way. Nevertheless, subsequent
recrystallization gave 1 as a yellow-brown low-melting solid in 53%
yield. The solid compound is quite stable showing no signs of
decomposition even after one week exposure to air. The NMR, IR,
and X-ray diffraction data were consistent with the structure of 1.
The 1JSiFe coupling constant (15 Hz) is in accord with a direct FeꢀSi
bond [17], and the FeꢀSi bond length (231.0 pm) is equal to the
average value of all known FeꢀSi bond lengths (Fig. 1 and Table 1).2
In contrast to the preparation of 1 the synthesis of tetracarbonyl
[dimethyl(phenylethynyl)silyl]cobalt(I) Co(CO)4SiMe2C^CPh (2) by
reaction of PhC^CMe2SiCl with sodium tetracarbonylcobaltate
NaCo(CO)4 (Scheme 1) was very sensitive to the reaction condi-
tions. Upon using a solution of NaCo(CO)4 in THF, the IR and NMR
spectra of the reaction mixture suggested the disiloxane
(PhC^CMe2Si)2O and alkyne cobalt complexes PhC^CMe2SiX *
Co2(CO)6 [X ¼ Cl,O1/2] to be the main products. These were most
likely formed by THF-catalyzed decomposition of 2 which is
a known limiting factor in preparing and handling silyl complexes
Efforts to react PhC^CMe2SiCl with sodium tetracarbonylfer-
rate Na2Fe(CO)4 did not result in anionic silyl or neutral bis(silyl)
Fig. 1. Molecular structure of 1 (hydrogens omitted). Selected bond lengths [pm] and
angles [ꢁ]: Fe1ꢀSi1 231.01(7), Fe1ꢀCp1 172.27(11), Fe1ꢀC6 173.9(3), Fe1ꢀC7 175.4(3),
Si1ꢀC8 187.6(2), Si1ꢀC9 188.1(2), Si1ꢀC10 184.8(3), C10ꢀC11 120.7(3), C6ꢀFe1ꢀC7
95.42(12), C6ꢀFe1ꢀSi1 84.88(7), C7ꢀFe1ꢀSi1 84.97(8), Fe1ꢀSi1ꢀC8 112.14(8),
Fe1ꢀSi1ꢀC9 114.01(8), Fe1ꢀSi1ꢀC10 111.38(8), C8ꢀSi1ꢀC9 107.57(11), C8ꢀSi1ꢀC10
105.93(11), C9ꢀSi1ꢀC10 105.26(10), Si1ꢀC10ꢀC11 176.7(2), C6ꢀFe1ꢀSi1ꢀC8
162.05(12), C7ꢀFe1ꢀSi1ꢀC10 e175.34(11).
1
The associated inverse reaction (inverse salt elimination) is a less common
entry to silyl complexes as there is no generally applicable synthetic procedure for
the required silyl anions (which are strong nucleophiles). Nevertheless, this route
has been used for the synthesis of a zirconium alkynylsilyl complex [9].
2
All average values are search results from the Cambridge Structural Database
(CSD) of the CCDC.

F. Hoffmann et al. / Journal of Organometallic Chemistry 705 (2012) 59e69
61
Table 1
Crystal structure data for complexes 1e4.
Compound
1
2
3
4
Mol. formula
M (g/mol)
T (K)
C17H16FeO2Si
336.24
93(2)
C14H11CoO4Si
330.25
123(2)
C46H42ClP2RhSi
823.19
93(2)
C23H16Co2FeO8Si
622.16
93(2)
l
(pm)
71.073
71.073
71.073
71.073
Crystal system
Space group
a (pm)
orthorhombic
Pbca
1015.89(6)
1708.65(11)
1881.31(11)
90
90
90
3265.6(3)
8
1.368
monoclinic
P21/c
642.89(3)
750.96(4)
3068.76(16)
90
92.125(2)
90
1480.53(13)
4
triclinic
P1
triclinic
P1
1006.77(10)
1252.57(12)
1625.50(17)
76.107(6)
74.553(5)
87.354(5)
1917.6(3)
2
844.09(7)
1157.68(9)
2555.77(19)
90.243(4)
94.184(4)
93.597(4)
2485.8(3)
4
b (pm)
c (pm)
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
V (106 pm3 ¼ Å3)
Z
rcalc (g/cm3)
1.482
1.248
1.426
0.663
1.662
1.988
m
(mmꢀ1
)
0.997
F(000)
Crystal size (mm)
range (ꢁ)
1392
672
848
1248
0.28 ꢂ 0.25 ꢂ 0.05
2.17e25.20
ꢀ11 ꢃ h ꢃ 11
ꢀ20 ꢃ k ꢃ 20
ꢀ22 ꢃ l ꢃ 22
18600/2928
0.0560
0.36 ꢂ 0.25 ꢂ 0.14
2.66e27.50
ꢀ8 ꢃ h ꢃ 8
0 ꢃ k ꢃ 9
0 ꢃ l ꢃ 39
62741/3371
0.0456
0.18 ꢂ 0.15 ꢂ 0.05
2.10e25.00
ꢀ11 ꢃ h ꢃ 11
ꢀ14 ꢃ k ꢃ 14
ꢀ19 ꢃ l ꢃ 16
20946/6746
0.0288
0.35 ꢂ 0.11 ꢂ 0.02
0.80e25.00
ꢀ10 ꢃ h ꢃ 9
ꢀ13 ꢃ k ꢃ 13
0 ꢃ l ꢃ 30
16139/8674
0.0355
q
hkl ranges
Refl. coll./unique
Rint
Completeness (%)
Absorption corr.
Max./min. transm.
Refinem. method
99.4
98.9
99.9
99.0
semi-emp. from equiv.
0.9518/0.7901
full-matrix least
squares on F2
2928/0/190
1.042
semi-emp. from equiv.
0.8447/0.6784
full-matrix least
squares on F2
3371/0/184
1.230
semi-emp. from equiv.
0.9676/0.8414
full-matrix least
squares on F2
6746/0/463
1.049
semi-emp. from equiv.
0.9708/0.5189
full-matrix least
squares on F2
8674/0/632
Data/restr./param.
GoF (F2)
1.085
R1/wR2 [I ꢄ 2
s
(I)]
0.0306/0.0613
0.0524/0.0660
0.390/ꢀ0.324
0.0542/0.1283
0.0564/0.1290
0.888/ꢀ0.896
0.0262/0.0648
0.0331/0.0670
0.423/ꢀ0.405
0.0481/0.1348
0.0798/0.1444
0.676/ꢀ0.575
R1/wR2 (all data)
rres (max./min.)
(10ꢀ6 e/pm3 ¼ e/Å3)
complexes. Instead, in hydrocarbons no reaction occured while in
diethyl ether or THF the disiloxane (PhC^CMe2Si)2O was formed.
We attempted the synthesis of alkynylsilyl complexes from
dimethyl(phenylethynyl)silane PhC^CMe2SiH and platinum- or
rhodium- phosphane complexes, respectively [3,5]. As to the first,
the reaction starting from tris(triphenylphosphane)platinum(0)
Pt(PPh3)3 [21a,b] proved our expectations true: the 29Si NMR
spectra of the reaction mixtures indicated (by several signals
between ꢀ15 ppm and ꢀ30 ppm without coupling to 31P or 195Pt;
an intense signal at ꢀ23 ppm can be ascribed to 2,5-diphenyl-1,4-
disila-cyclohexa-2,5-diene [22]) that no silyl complexes had
formed but catalytic reactions between the SiꢀH and the C^C
triple bond had occurred. The same result was obtained when
bis(triphenylphosphane)platinum(II)-chloride (Ph3P)2PtCl2 (with
or without zinc powder [21c]) or ethylenebis(triphenylphosphane)
platinum(0) (Ph3P)2Pt(C2H4) [3c,21d] were used.
2.2. Oxidative addition
Oxidative addition of alkynylhydrosilanes to coordinatively
unsaturated compounds has been used for the synthesis of several
alkynylsilyl complexes [3,4aeh,5,6a,c,e,7aed] although interfer-
ences by metal-catalyzed side reactions between the SiꢀH bond
and the C^C triple bond, e.g. hydrosilylation, should have to be
expected, especially in the case of platinum metal compounds.
Eventually, the synthetic attempts had more success using
tris(triphenylphosphane)rhodium(I)-chloride (Ph3P)3RhCl [23],
mainly because of the low solubility of the resulting complex
chlorohydrido[dimethyl(phenylethynyl)silyl]bis(triphenylphosphane)-
rhodium(III) (Ph3P)2RhClHSiMe2C^CPh (3) in organic solvents
which shifts the equilibrium of 3 with the starting materials [23aec]
to the product side (Scheme 1). Nevertheless, this reaction was still
complicated duetointeractionsof the SiꢀHand C^C functionalities.
Failure to isolate 3 immediately after synthesis results in its slow
decomposition as (Ph3P)3RhCl catalyzes irreversible reactions of
PhC^CMe2SiH with itself, thus shifting the equilibrium back to the
left side. Upon addition of further PhC^CMe2SiH the equilibrium
can be re-shifted to 3.
Fig. 2. Molecular structure of 2 (hydrogens omitted). Selected bond lengths [pm] and
angles [ꢁ]: Co1ꢀSi1 236.81(12), Co1ꢀC1 183.8(5), Co1ꢀC2 178.5(4), Co1ꢀC3 179.2(4),
Co1ꢀC4 179.1(4), Si1ꢀC5 187.2(4), Si1ꢀC6 186.1(4), Si1ꢀC7 183.1(4), C7ꢀC8 121.2(6),
C1ꢀCo1ꢀSi1 177.51(13), C1ꢀCo1ꢀC2 95.77(18), C1ꢀCo1ꢀC3 98.78(18), C1ꢀCo1ꢀC4
98.44(18), Co1ꢀSi1ꢀC5 109.47(14), Co1ꢀSi1ꢀC6 111.64(15), Co1ꢀSi1ꢀC7 108.38(13),
C5ꢀSi1ꢀC6111.05(19),C5ꢀSi1ꢀC7108.19(19), C6ꢀSi1ꢀC7108.00(19),Si1ꢀC7ꢀC8177.0(4),
C2ꢀCo1ꢀSi1ꢀC7 ꢀ172.5(2), C3ꢀCo1ꢀSi1ꢀC5 ꢀ174.5(2), C4ꢀCo1ꢀSi1ꢀC6 ꢀ168.8(2).
The synthesis was favourably carried out in methylene chloride,
which supports the formation of 3 under the circumstances out-
lined above. Upon addition of PhC^CMe2SiH the deep red solution
of (Ph3P)3RhCl turned yellow-brown within minutes, and

62
F. Hoffmann et al. / Journal of Organometallic Chemistry 705 (2012) 59e69
immediate reduction of the solvent volume under reduced pressure
followed by cooling furnished 3 in 73% yield as bright yellow
crystals which are air-stable for at least some days. Nevertheless,
elemental analyses were only correct if the samples were prepared
under argon.
Because of its low solubility and decomposition in solution,
NMR spectra of 3 were obtained from a crude reaction mixture in
deuterated methylene chloride, which was sufficiently pure for this
purpose. The 1H NMR showed a complex multiplet at þ7.þ8 ppm
for the aromatic protons, a slightly broadened singlet at þ0.07 ppm
for the methyl groups (doublet splitting intimated), and a doublet
of triplets at ꢀ14.97 ppm for the hydride which suggests chemical
equivalence of the two phosphane ligands. The position of the
methyl signal appears unusual for a silyl complex as a down-field
shifted signal at þ0.5.þ1 ppm would have been expected
[1b,17b]. This feature is explained by the steric demand of both the
silyl group and the phosphane ligands: The location of the methyl
Fig. 4. Molecular structure of 3 (hydrogens except hydride omitted). Selected bond
lengths [pm] and angles [ꢁ]: Rh1ꢀSi1 229.23(7), Rh1ꢀH1 153(2), Rh1ꢀCl1 239.05(6),
Rh1ꢀP1 232.40(6), Rh1ꢀP2 230.52(6), Si1ꢀC37 187.6(2), Si1ꢀC38 186.7(2), Si1ꢀC39
185.2(3), C39ꢀC40 120.9(4), H1ꢀRh1ꢀCl1 176.1(9), H1ꢀRh1ꢀP1 91.5(8), H1ꢀRh1ꢀP2
89.8(9), H1ꢀRh1ꢀSi1 66.7(8), Cl1ꢀRh1ꢀP1 89.07(2), Cl1ꢀRh1ꢀP2 88.53(2),
Cl1ꢀRh1ꢀSi1 117.03(2), P1ꢀRh1ꢀP2 161.67(2), P1ꢀRh1ꢀSi1 99.50(2), P2ꢀRh1ꢀSi1
97.78(2), Rh1ꢀSi1ꢀC37 119.67(8), Rh1ꢀSi1ꢀC38 118.50(8), Rh1ꢀSi1ꢀC39 103.90(7),
C37ꢀSi1ꢀC38 104.58(11), C37ꢀSi1ꢀC39 104.71(11), C38ꢀSi1ꢀC39 103.48(12),
Si1ꢀC39ꢀC40 175.0(2), Cl1ꢀRh1ꢀSi1ꢀC39 3.21(8).
groups in the closer proximity of the phosphane aryl groups
renders the aromatic ring current of the phosphane phenyl rings
(favourably facing the methyl groups with the C6-plane for steric
reasons) a notable shielding influence. This interpretation is sup-
ported by the molecular structure of 3 (see below). The 13C NMR
spectrum was consistent with the structure of 3. The 29Si NMR
spectrum showed a doublet of triplets at þ17.1 ppm while the 31P
NMR spectrum featured one doublet at þ40.9 ppm. The coupling
constants were comparable to similar complexes [1c,23e]. These
findings confirm the assumption of chemically equivalent phos-
phane ligands.
The solid-state IR spectrum (KBr pellet) contained three char-
acteristic bands of medium intensity at 2143 cmꢀ1, 2028 cmꢀ1, and
1974 cmꢀ1. The first one was assigned to the C^C vibration by
comparison with other alkynylsilyl compounds. To start with, the
other two bands were both assigned to the RhꢀH vibration. Actually,
there is only one band to be expected [23b,e], but occasionally also
two bands are reported and attributed to the presence of a second
isomer [23a,d]. Other explanations would be coupling with other
vibrations, decomposition of 3, chlorine-bromine exchange with
KBr, or an incompletely divided SiꢀH bond (RheSieH three-centre
bond). The latter seems unlikely since MꢀSiꢀH bands are rather
broad [24] while the two bands in question are not. Unfortunately,
the 1JHSi coupling constant (NMR), which would give further insight,
could not be measured because of decomposition (see above). To
clarify the origin of the IR bands and to elucidate the bonding
situation, 3 was computationally investigated by quantum chemical
(DFT) and topological (AIM) analysis (for details see experimental
section). The calculations clearly indicated the absence of a bond-
critical point between silicon and hydrogen and the presence of
bond-critical points between rhodium and silicon and rhodium and
hydrogen, thus ruling out the three-centre bond (Fig. 3). Further
results (Laplacian analysis) are that the RhꢀSi bond is mainly
covalent while the RhꢀCl bond is mainly ionic. The Rh-bound
Fig. 3. Topological (AIM) analysis of 3: Representation of topological properties in the
ClHRhSi plane. a: electron density
r with bond paths and bond-critical points; b:
Laplacian of electron density V2r. Positive values of V2r are drawn with dashed lines
and represent regions of charge depletion; negative values of V2r are drawn with solid
lines and represent regions of charge concentration. Contour values for both repre-
sentations in atomic units are: 0.001, 0.002, 0.004, 0.008, 0.02, 0.04, 0.08, 0.2, 0.4, 0.8,
2, 4, 8, 20, 40, 80, 200, 400, 800.

F. Hoffmann et al. / Journal of Organometallic Chemistry 705 (2012) 59e69
63
electron density map. The RhꢀH distance (153 pm) is in the re-
ported range for RhꢀH bonds (X-ray 100e224 pm; neutron
diffraction 131e205 pm).2 The SiꢀH distance (219 pm) is much
longer than SiꢀH bonds in silanes (average value: X-ray 141 pm;
neutron diffraction 150 pm)2 but markedly shorter than the sum of
the van der Waals-radii (340 pm) [25]. This hints at an interaction
between hydrogen and silicon, although there is no spectroscopic
or computational support to this deduction. The coordination
polyhedron of the metal atom is very similar to those of related
rhodium silyl complexes [1a,c,d,5c,23e] and can be regarded as an
intermediate state between a square pyramid and a trigonal
bipyramid. The trigonality index
s is 0.23, which means that the
polyhedron is far more a distorted square pyramid than a distorted
trigonal bipyramid [26]. The “square” is made up of the chlorine,
the hydrogen and the two phosphorus atoms while the silicon atom
forms the apex of the pyramid (Fig. 5a). The “trigonal bipyramid”
has the two phosphorus atoms in its axial positions and a bisecting
plane made up of the chlorine, the hydrogen, and the silicon atom.
Although the hydride hydrogen’s bond lengths and angles suffer
from the usual uncertainties encountered with H-atom positions
near a heavy atom (which thwarts a more detailed discussion of the
Rh coordination polyhedron), its position in the rhodium coordi-
nation sphere appears reasonable as similar coordination poly-
hedra are reported for related rhodium silyl [1a,c,d,5c,23e] and
even ruthenium silylene [27] complexes (R3P)2[M(d6)](Si, Cl, H).
The 1H NMR spectrum had indicated an interaction between the
methyl hydrogens and the phenyl rings. Corresponding CH∙∙∙
p
contacts were found in the solid state (Fig. 5b). The minimum
C∙∙∙H distances (C∙∙∙H 270e315 pm, C∙∙∙C 323e360 pm) are
smaller than the sum of the van-der-Waals radii (C∙∙∙H 300 pm,
C∙∙∙C 370 pm) [25b]. Obviously these contacts are enforced by the
steric demand of both the silyl and the phosphane ligands.
Fig. 5. Structural features of 3. a: Coordination polyhedron of the rhodium atom;
b: CH∙∙∙ contacts between methyl protons and phenyl rings (Cp∙∙∙H distances
p
(Cp∙∙∙CMe distances) [pm]: a ¼ 277(333), b ¼ 307(328), c ¼ 315(333), d ¼ 270(328),
e ¼ 281(348), f ¼ 291(323), g ¼ 280(323), h ¼ 292(360)).
hydrogen has a hydridic character. The phosphine ligands are bound
by donoreacceptor interactions. The quantum chemical simulation
of the IR spectra of the model compounds chlorohydridobis-
(trimethylphosphane)(trimethylsilyl)rhodium(III) (Me3P)2RhClH-
SiMe3 and bromohydridobis(trimethylphosphane)(trimethylsilyl)-
rhodium(III) (Me3P)2RhBrHSiMe3 furnished wavenumbers for the
RhꢀH vibration of 2034.7 cmꢀ1 and 2022.6 cmꢀ1, respectively.
There are no other bands in the characteristic region between
1500 cmꢀ1 and 3000 cmꢀ1. Thus, the 2028 cmꢀ1 band was assigned
to the RhꢀH vibration of 3. The 1974 cmꢀ1 band may be ascribed to
the complex formed upon chlorine-bromine exchange. However,
we cannot exclude a second isomer or a decomposition product
formed in the IR sample preparation as origin of the third band.
The X-ray single crystal structure analysis confirmed the
conclusions drawn from the NMR spectra. Apart from the orienta-
tion of the phenyl groups, the molecule has an idealized bisecting
mirror plane made up of the rhodium, the chlorine, the silicon, the
hydride, and the alkyne carbon atoms (Fig. 4 and Table 1). The
RhꢀSi bond is 229.2 pm in length (average value: 234 pm),2 which
is comparable to similar complexes [1a,c,d,5c,23e]. The hydride
hydrogen atom was found directly by analysis of the residual
2.3. Reactivity of the triple bond
In order to examine the synthetic potential of the alkynylsilyl
complexes in further reactions, we explored their reactivity toward
complexation and hydrosilylation of the C^C triple bond.
Reaction of 1 with dicobaltoctacarbonyl Co2(CO)8 afforded the
trinuclear complex octacarbonyl-1
k
2C,2
k
k
3C,3
k
3C-cyclopentadienyl-
2C,C’)silyl-1
Si]-1-
1(
h
5)-[m3-dimethyl(phenylethynyl-2
2C,C’:3
k
k
iron(II)-2,3-bis[cobalt(0)](CoeCo) FpSiMe2CCPh * Co2(CO)6 (4) in
57% yield as a dark brown solid, which is air-stable for at least one
week (Scheme 2). The NMR and IR data were consistent with the
1
anticipated structure. Compared to 1 the JSiFe coupling constant
(15 Hz) and the FeꢀSi bond lengths (232.5 and 232.8 pm; the
asymmetric unit contains two independent molecules with only
slightly different bond parameters and conformations) (Fig. 6 and
Table 1) are nearly unchanged while the 29Si NMR signal is shifted
down-field by about 20 ppm. The 59Co NMR spectrum featured
a very broad signal at ꢀ2300 ppm [28]. Noteworthy, in comparison
to 1 the 13C NMR signals of the alkyne carbon atoms are only
slightly shifted although the C^C triple bond was transformed into
a formal single bond within the dicobaltatetrahedrane cage. This
Scheme 2. Synthesis of compounds 4 and 5.

64
F. Hoffmann et al. / Journal of Organometallic Chemistry 705 (2012) 59e69
Table 2
29Si NMR data of compounds 1e5.a
2
Compound
d/ppm
1JSiꢀC^C/Hz JSiꢀC^C/Hz JSiꢀE/Hz
PhC^CMe2SiꢀFp (1)
þ18.4
þ13.8
68
87
ꢀ
12
16
ꢀ
Fe: 15b
e
PhC^CMe2SiꢀCo(CO)4 (2)
c
c
PhC^CMe2SiꢀRhClH(PPh3)2 (3) þ17.1
P: 9.6
Rh: 31
Fe: 15b
c
PhC^CMe2SiꢀFp * Co2(CO)6 (4) þ39.7
45
ꢀ
c
c
c
FpꢀSiMe2CH¼CPh(SiEt3) (5)
þ32.2/þ1.8
ꢀ
ꢀ
ꢀ
a
29Si NMR data of PhC^CMe2SiH/Cl: [29].
b
c
1
FpSiMe3: JSiFe ¼ 15 Hz [17b].
Satellites too weak or hidden.
The reaction of 2 with (Ph3P)2Pt(C2H4) did not yield a platinum
alkyne complex. Instead, the NMR spectra of the reaction mixture
indicated the formation of trans-(tricarbonyl)[dimethyl(phenyl-
ethynyl)silyl](triphenylphosphane)cobalt(I) (Ph3P)Co(CO)3SiMe2C^
CPh by transfer of a phosphane ligand from platinum to cobalt
with carbonyl substitution (1H NMR (C6D6):
d
¼
þ1.10 (d,
4JHP ¼ 1.5 Hz, SiMe2) ppm; 29Si NMR (C6D6):
d
¼ þ14.3 (d,
2JSiP ¼ 34.0 Hz) ppm; 31P NMR (C6D6):
d
¼ þ57.5 (s) ppm), thus
providing evidence that the cobalt-silicon bond was retained.
Unfortunately, isolation of this compound was not successful.
Fig. 6. Molecular structure of 4 (hydrogens omitted). Only one of the two molecules in
the asymmetric unit is shown. Selected bond lengths [pm] and angles [ꢁ]: Fe1ꢀSi1
232.49(15), Fe1ꢀCp1 172.53(22), Fe1ꢀC6 174.6(6), Fe1ꢀC7 174.3(6), Si1ꢀC8 187.7(5),
Si1ꢀC9 188.1(4), Si1ꢀC10 187.4(5), C10ꢀC11 132.5(6), C10ꢀCo1 201.1(4), C10ꢀCo2
200.5(4), C11ꢀCo1 199.4(4), C11ꢀCo2 194.9(4), Co1ꢀCo2 246.52(9), C6ꢀFe1ꢀC7
94.9(2), C6ꢀFe1ꢀSi1 85.63(18), C7ꢀFe1ꢀSi1 83.53(16), Fe1ꢀSi1ꢀC8 111.76(18),
Fe1ꢀSi1ꢀC9 111.68(16), Fe1ꢀSi1ꢀC10 111.62(15), C8ꢀSi1ꢀC9 107.5(2), C8ꢀSi1ꢀC10
106.0(2), C9ꢀSi1ꢀC10 107.9(2), Si1ꢀC10ꢀC11 148.6(4), Si1ꢀC10ꢀCo1 131.8(2),
Si1ꢀC10ꢀCo2 132.6(2), C6ꢀFe1ꢀSi1ꢀC10 e167.9(2), C9ꢀSi1ꢀC10ꢀC11 e177.1(7).
Complexation of
solubility.
3 was not attempted because of its low
2.4. Spectroscopic properties
The 29Si NMR spectroscopic parameters of the synthesized
complexes are listed in Table 2. The 29Si NMR signals of the alky-
nylsilyl complexes 1, 2, and 3 appeared at þ13.þ19 ppm.
Regarding the different complex fragments bound to the silyl group
this range is surprisingly narrow. Unsaturated organic groups
(especially alkynyl groups) increase the shielding of the 29Si
nucleus in silanes, while transition metal complex fragments are
known to cause a down-field shift of the 29Si resonance (e.g.
phenomenon has been reported several times in the literature [29].
Considering the correlation between 13C NMR chemical shift and
hybridization (alkanes (sp3): 0 to þ70 ppm; alkenes (sp2): þ100
to þ165 ppm; alkynes (sp): þ60 to þ100 ppm [30]), it indicates an
intermediate state between sp2 and sp3 hybridization corre-
sponding to a CꢀC bond order between two and one. This is sup-
ported by the lowered silicon-alkyne carbon NMR coupling
MeꢀSiMe3:
d
¼ 0 ppm, FpꢀSiMe3: ¼ þ41.5 ppm, PhꢀSiMe3:
d
d
d
¼
ꢀ4.8 ppm, ViꢀSiMe3: ¼ ꢀ7.0 ppm, HC^CꢀSiMe3:
d
¼ ꢀ17.5 ppm) [1aec,17b,35]. Apparently, the opposite trends of
transition metal and alkynyl group superimpose, thus resulting in
an intermediate position of the 29Si NMR signals. “Removal” or
“diminution” of the alkynyl triple bond character by complexation
(4) or hydrosilylation (5) also removes or diminishes the shielding
influence. Thus, the 29Si NMR shifts of 4 and 5 resemble that of
dicarbonyl(cyclopentadienyl)trimethylsilyliron(II) FpSiMe3.
1
1
constant (1JSiC ¼ 45 Hz; JSiC(sp) w 75 Hz, JSiC(sp2) w 65 Hz,
1JSiC(sp3) w 50 Hz [1b,e,31]). The nCC band of the former triple bond
appeared in the IR spectrum of 4 at 1574 cmꢀ1, which is in the
characteristic region of bands for alkenes and aromatic double
bonds. Finally, the former alkyne triple bonds are 132.5 pm and
133.3 pm long, corresponding to a double bond character in this
complex. In conclusion, these data suggest retention of at least
partial C]C double bond character in this complex.
The 1H and 13C NMR signals appeared in the expected ranges.
The alkyne carbon atoms featured signals in the
Table 3
Compound 1 undergoes hydrosilylation with triethylsilane
Et3SiH in the presence of Speier’s catalyst (H2PtCl6 in isopropanol)
IR data of compounds 1e5.a
[32a,b] to yield the complex dicarbonyl(
h
5-cyclopentadienyl)
Compound
n
w(C^C)/cmꢀ1
n
w(C^O)/cmꢀ1
PhC^CMe2SiꢀFp (1)
2148b; 2145c
2157b; 2153d
2001, 1950b; 1994, 1937c
2094, 2033, 2008, 1998b;
2092, 2029, 1994d
e
{dimethyl[(E)-2-phenyl-2-triethylsilyl-ethen-1-yl]silyl}iron(II)
FpSiMe2CH¼CPh(SiEt3) (5) in quantitative yield as a brown oil
(Scheme 2). Wilkinson’s catalyst ((Ph3P)3RhCl) [32c] and aluminium
chloride AlCl3 [32d,e] were also probed, but had no effect or led to
reactions other than hydrosilylation, respectively. The spectral data
of 5 are in accord with the anticipated structure and confirm that the
E-isomer (Scheme 2) had formed selectively. Unfortunately, crystals
of 5 could not be obtained to date.
Irradiation induced ligand substitutions are quite common, also
for silyl [33] and stannyl [34] complexes with unsaturated hydro-
carbons. Consequently, a solution of 1 was UV-irradiated with IR
and NMR monitoring (0.017 M in benzene, 12 h [34aec]), but only
decomposition occurred and Fp2 was the only product identified.
PhC^CMe2SiꢀCo(CO)4 (2)
PhC^CMe2SiꢀRhClH(PPh3)2
2143c
1574c
(3)
PhC^CMe2SiꢀFp * Co2(CO)6
2085, 2047, 2026, 2015,
2001, 1949b;
(4)
2083, 2046, 2020, 2012,
1993, 1933c
e
FpꢀSiMe2CH¼CPh(SiEt3) (5)
ꢀ
1996, 1943b
a
IR data of PhC^CMe2SiH/Cl: [29].
Solution in hexane.
KBr pellet.
Neat liquid.
Not assigned.
b
c
d
e

F. Hoffmann et al. / Journal of Organometallic Chemistry 705 (2012) 59e69
65
range þ95.þ111 ppm with the one of the silicon-bound carbon at
4.3. Crystal structure analyses
higher field (assignment by 29Si satellites). The IR spectroscopic
data of the synthesized compounds are summarized in Table 3. The
bands of the C^C triple bonds appear in the narrow range of
The X-ray single crystal structure analyses were performed on
Bruker-Nonius X8 diffractometer using MoKa radiation
¼ 71.073 pm) and an APEX2-CCD area detector. For solving,
a
(l
2143e2157 cmꢀ1
.
refining, and visualization of the structures the programmes Bruker
SMART [38a], Bruker SAINT [38a], Bruker SHELXTL [38b], SHELXS-
97 [38c], SHELXL-97 [38d], WinGX [38e], and ORTEP32 [38f] were
used. The thermal ellipsoids are drawn at the 50% probability level.
The diffraction pattern of the crystal of compound 2 exhibited
features of both twinning and high mosaic spread of the reflections.
Upon absorption correction with Xabs2 (as implemented in
WinGX) the final refinement was carried out using the corrected
HKLF4 format data set and the twin law (ꢀ1 0 0)(0 1 0)(0 0 1). The
twin population parameter BASF refined to 0.0045(5). The data set
of 4 was collected from a twin with two populations in ratio 0.60 :
0.40 (according to the BASF of 0.4026(6) refined from a HKLF5
format data set comprising full data of both populations, which was
generated using SAINTPLUS [38a]).
3. Conclusions
Transition metal alkynylsilyl complexes with a metal-silicon
bond are accessible both by nucleophilic substitution and oxida-
tive addition. In the first synthetic pathway both strongly and
weakly nucleophilic metallates can be used. Disturbing interactions
of the metallates with the C^C triple bond were not observed, but
formation of siloxanes can interfere. Synthesis by oxidative addi-
tion can be hampered by transition metal catalyzed reactions
between the SiꢀH and the C^C triple bond. The metallosilyl
functionalized alkynyl groups were shown to undergo further
complexation or hydrosilylation while the metal-silicon bond is
preserved. Thus, alkynylsilyl complexes may be useful as precursors
to novel compounds, e.g. multinuclear heterometallic complexes,
or metal- and silicon-containing polymers.
4.4. Computational details
The quantum chemical calculations were performed using
GAUSSIAN 03 [39]. For the topological analysis the geometry of the
X-ray structure of 3 was used for a single point calculation at the
density functional theory level (DFT) using Becke’s three-parameter
hybrid exchange functional and the correlation functional of Lee,
Yang and Parr (B3LYP) [40]. All elements were treated with the 3-
21G basis set [41]. The wavefunction files for the AIM analysis were
generated in Cartesian coordinates with a basis set containing 6d
functions. The electron density topology was analysed using the
programs AIM2000 [42a] and Xaim [42b].
For the calculation of the IR data of the model compounds
(Me3P)RhCl(H)SiMe3 and (Me3P)RhBr(H)SiMe3 the molecular
geometries were fully optimized at the B3LYP level [40]. Rhodium
was treated with an effective core potential, a valence double zeta
basis set (Hay/Wadt pseudopotential, LANL2DZ), and an additional
f-type polarization function [43]. The 6e31G(d) basis set was used
for all main group elements [44]. Harmonic vibrational frequencies
were determined by analytic second derivative methods. The
values of the vibrational frequencies were not scaled since
4. Experimental section
4.1. General Remarks
All operations were performed under purified argon using
standard Schlenk line or glovebox techniques. If possible, reactions
were monitored by NMR or IR spectroscopy. Assignments were
made by comparison of the spectra with each other and with
literature data. Missing NMR peaks are hidden by other peaks, often
by those of the solvent. Melting points were determined between
thin glass plates (air) or in sealed capillaries (argon) on a Boëtius
type heating microscope with a heating rate of about 4 K/min.
Elemental analyses were performed in duplicate with a CHN-O-
Rapid (Heraeus) and the values averaged. The NMR spectra were
recorded at 22 ꢁC with a Bruker DPX 400 Avance spectrometer
using tetramethylsilane Me4Si (TMS) as internal standard for 1H
(400.13 MHz), 13C (100.63 MHz), and 29Si (79.49 MHz). The external
standards for 31P (161.98 MHz) and 59Co (94.65 MHz) were 85%
H3PO4 and 0.1 M K3[Co(CN)6] in D2O, respectively [36]. For 29Si
NMR spectra the INEPT pulse sequence was employed. IR spectra
were recorded with a Specord M 82 (VEB Carl Zeiss JENA) or
a Nicolet 510 spectrometer. Liquid samples were prepared between
NaCl plates, whereas solids were examined in KBr disks. UV/Vis
spectra were recorded with a Specord S 100 (Analytik Jena AG) in
the range 190e1000 nm.
a
combination of different basis sets was used for these
calculations.
4.5. Syntheses
4.5.1. Dicarbonyl(h
5-cyclopentadienyl)[dimethyl(phenylethynyl)
silyl]iron(II) (1)
A solution of NaFp in THF (prepared from Na (115 mg,
5.00 mmol), Hg (2.0 mL, 27.1 g,135 mmol), Fp2 (757 mg, 2.14 mmol),
and THF (20 mL) by stirring for 3 h at room temperature) was added
to PhC^CMe2SiCl (810 mg, 4.16 mmol) in pentane (40 mL) at 0 ꢁC.
The brown suspension was warmed to room temperature over-
night and then evaporated in vacuo. The residue was extracted with
hexane (3 ꢂ 5 mL). The extract was concentrated to 2 mL and
chromatographed on silicagel (10 cm ꢂ 2 cm) with hexane/toluene
8:2 as eluent. The product passed the column as a yellow band. The
eluate was evaporated in vacuo (1.31 g, 94% crude yield) and the
residue redissolved in 5 mL hexane. On slow cooling to ꢀ78 ꢁC
a solid deposited which was separated and dried in vacuo (975 mg,
70%). The recrystallization was repeated twice yielding yellow-
brown crystals which were directly suitable for X-ray crystallog-
raphy. The compound is air-stable for several days but should be
stored under argon in a refrigerator.
4.2. Chemicals
Solvents were dried and deoxygenated by distillation under
argon from sodium-benzophenone (diethyl ether, hexane, THF,
toluene), calcium hydride (CDCl3, methylene chloride), lithium
aluminium hydride (pentane), or sodium-potassium alloy (C6D6)
and stored under argon until use. PhC^CMe2SiCl and
PhC^CMe2SiH were synthesized as previously published [29].
Solid NaCo(CO)4 was prepared by reaction of Co2(CO)8 with NaOH
in THF, evaporation of the filtered solution in vacuo, and heating of
the residue in vacuo up to 100 ꢁC [37]. Chromatography was per-
formed on “Silica gel L5/40” from LACHEMA (Brno)/CHEMAPOL
(Prague). The other chemicals were prepared after common
procedures or purchased from commercial suppliers and were used
as received.

66
F. Hoffmann et al. / Journal of Organometallic Chemistry 705 (2012) 59e69
Yield: 740 mg, 2.20 mmol, 53%. Mp: 31e34 ꢁC (argon), 30e33 ꢁC
(air). Solubility: hexane, pentane, CHCl3 (dec.). Anal. found (calcd.)
for C17H16FeO2Si (336.246 g/mol): C 60.88 (60.73) %, H 4.93 (4.80) %.
r
(SiCH3)), 827 (s,
r
(SiCH3)), 806 (s,
r(SiCH3)), 777 (m, r(SiCH3)), 757
(m, (CHPhC^C)), 690 (m, g
g
(CHPhC^C)), 671 (m), 603 (w) cmꢀ1 [47].
1H NMR (0.75 M in CDCl3):
d
¼ 7.45 (m, 2 H, Phortho), 7.29 (m, 3 H,
4.5.3. Chlorohydrido[dimethyl(phenylethynyl)silyl]
bis(triphenylphosphane)rhodium(III) (3)
Phmeta þ para), 4.81 (s, 1JHC ¼ 180 Hz, 5 H, Cp), 0.58 (s, 1JHC ¼ 121 Hz,
6 H, SiMe2) ppm. 13C NMR (0.75 M in CDCl3):
d
¼ 214.6 (s, 2 C, CO),
(Ph3P)3RhCl (231 mg, 0.25 mmol) was dissolved in CH2Cl2
131.7 (s, 1JCC ¼ 57 Hz, 2 C, Phortho), 128.2 (s, 2 C, Phmeta), 128.1 (s, 1 C,
Phpara), 123.8 (s, 1 C, Phipso), 107.5 (s, 2JCSi ¼ 12 Hz, 1 C, C^CꢀSi), 99.1
(s, 1JCSi ¼ 68 Hz, 1 C, C^CꢀSi), 84.4 (s, 5 C, Cp), 6.7 (s, 1JCSi ¼ 50 Hz,
(5 mL). PhC^CMe2SiH (75 mL, 70 mg, 0.44 mmol) was then added
to the deep red brown solution at room temperature with stirring.
The mixture changed its colour to amber within minutes. The
solution was then evaporated to half its volume in vacuo and slowly
cooled to ꢀ78 ꢁC. Without removal of the precipitated crystals the
solution was again evaporated to half its volume in vacuo and
cooled to ꢀ78 ꢁC. The solid was separated, washed with ether
(4 ꢂ 1 mL), and dried in vacuo yielding bright yellow crystals which
were directly suitable for X-ray crystallography. The compound is
air-stable for some time but should be stored under argon.
2 C, SiMe2) ppm. 29Si NMR (0.75 M in CDCl3):
d
¼ þ18.4 (s (1H
2
1
coupled: septet, JSiH
¼
6.8 Hz), JSiC(Me)
¼
50 Hz (2 C),
1JSiC(C^C) ¼ 68 Hz (1 C), 2JSiC(C^C) ¼ 12 Hz (1 C), 1JSiFe ¼ 15 Hz) ppm.
IR (hexane): nw ¼ 2148 (w,
n(C^C)), 2002 (vs, n(C^O)), 1951 (vs,
n
(C^O)) cmꢀ1. IR (KBr): nw ¼ 3095 (vw,
n
(CHCp/Ph)), 3073 (w,
(CH)), 2922 (vw, (CH)),
(C^C)), 1994 (vs,
(C¼CPhC^C)), 1571 (vw,
(C¼CPhC^C)), 1440 (w, (C¼CPhC^C)), 1431
(C¼CCp) þ das(SiCH3)), 1359 (vw), 1244 (m, ds(SiCH3)),
(CHPhC^C)), 1111 (vw, (CHPhC^C)),
(C¼CCp)), 1068 (w,
(CHPhC^C)), 1015 (w, (CHCp)), 1000 (w), 916 (w,
(CHCp (SiCH3)), 827 (s,
(SiCH3)), 759 (s, (CHPhC^C)), 690 (m,
(CHPhC^C)), 663 (m), 645 (m, (FeCO)), 593 (s, (FeCO)), 534 (m,
(FeCCO)), 465 (vw); 405 (m), 376 (vw), 357 (w)
cmꢀ1 [45a,b,46]. UV/VIS (hexane):
n
(CHCp/Ph)), 2955 (m, nas(CH3)), 2930 (vw,
n
n
2890 (w, ns(CH3)), 2858 (vw,
n
(CH)), 2145 (m,
(C^O)), 1592 (w,
(C¼CPhC^C)), 1486 (m,
n
n
(C^O)), 1937 (vs,
n
n
Yield: 150 mg, 0.18 mmol, 73%. Mp: 235 ꢁC (dec., argon), 145 ꢁC
(dec., air). Solubility: CH2Cl2 (dec.), CHCl3 (dec.); insoluble in
hexane, toluene, diethyl ether. Anal. found (calcd.) for
C46H42ClP2RhSi (823.239 g/mol): C 67.19 (67.11) %, H 5.17 (5.14) %. 1H
n
n
n
(w), 1413 (m,
n
1219 (m,
1024 (w,
d
n
d
d
d
NMR (0.1 M in CD2Cl2):
d
¼ 7.8.7.7 (m, 14 H, Phortho), 7.4.7.3 (m,
d
(CHPhC^C)), 834 (s,
g
)
þ
r
21 H, Phmeta þ para), 0.07 (s,4 6 H, SiMe2), ꢀ14.97 (dt, 1JHRh ¼ 22.5 Hz,
g
g
(CHCp) þ
r
(SiCH3)), 801 (s,
r
g
2JHP ¼ 14.2 Hz, 1 H, RhH) ppm. 13C NMR (0.1 M in CD2Cl2):
¼ 135.4
d
d
d
(s,4 6 C, PhPipso), 135.2 (“t”, JCP/Rh ¼ 6.2 Hz, 12 C, PhPortho),
132.5.131.5 (ꢀ,5 PhC^Cortho), 130.5 (s, 6 C, PhPpara), 129.127 (ꢀ,5
PhC^Cmeta þ para), 128.5 (“t”, JCP/Rh ¼ 4.6 Hz, 12 C, PhPmeta), 123.9 (s,
1 C, PhC^Cipso), 106.4 (s, 1 C, C^CꢀSi), 100.8 (s,4 1 C, C^CꢀSi), 9.8
(s,4 1JCSi ¼ 53 Hz, 2 C, SiMe2) ppm. 29Si NMR (0.1 M in CD2Cl2):
n
(FeCCO)), 522 (w, n
l
(ε) ¼ 215 (12,000), 250
(12,000), 259 (12,000), 278 (sh, 8000), 285 (sh, 7000), 330 (br/sh,
1300) nm (L/mol*cm) [45c].
d
¼ þ17.1 (dt, 1JSiRh ¼ 30.9 Hz, 2JSiP ¼ 9.6 Hz) ppm. 31P NMR (0.1 M in
4.5.2. Tetracarbonyl[dimethyl(phenylethynyl)silyl]cobalt(I) (2)
NaCo(CO)4 (1000 mg, 5.16 mmol) was suspended in hexane
(25 mL) and mixed with PhC^CMe2SiCl (1145 mg, 5.88 mmol). The
solution was stirred at room temperature for 2 d. The brown
mixture was then filtered and evaporated in vacuo. The residue was
redissolved in hexane (2 mL) and the solution slowly cooled
to ꢀ78 ꢁC. A colourless solid deposited which was separated and
dried in vacuo (1400 mg, 82%). An adhering dark brown oil could be
removed to a large extent by five further recrystallizations resulting
in almost colourless crystals which were directly suitable for X-ray
crystallography. The product is very air-sensitive and should be
stored under argon in a refrigerator.
CD2Cl2):
(vw,
(CHPh)), 3005 (w,
2951 (w, (CH3)), 2889 (vw,
(RhH)), 1974 (m), 1891 (vw, gcomb(CHPh)), 1817 (vw, gcomb(CHPh)),
1775 (vw, gcomb(CHPh)), 1587 (w,
(C¼CPhC^C)), 1572 (w,
(C¼CPhC^C)), 1435 (s,
(C¼CPhC^C)), 1399 (vw, das(SiCH3)), 1332 (vw), 1311
(CHPhC^C)), 1187 (w), 1157
(CHPhP)), 1071 (vw, (CHPhC^C)), 1027 (w,
(CHPhC^C)), 999 (w), 910 (vw, (CHPhC^C)), 842 (m, (SiCH3)), 823
(s, (SiCH3)), 803 (m, (SiCH3)), 764 (m, (CHPhC^C)), 753 (s,
(CHPhP)), 749 (s, (CHPhP)), 693 (s, (CHPh)), 670 (w), 618 (vw), 600
(vw), 535 (w, RhPPh3), 517 (s, RhPPh3), 457 (w), 431 (vw), 420 (vw),
405 (vw), 369 (vw) cmꢀ1 [48]. UV/VIS (CH2Cl2):
d
¼ þ40.9 (d, 1JPRh ¼ 123.9 Hz) ppm. IR (KBr): nw ¼ 3143
n
(CHPh)), 3074 (w, n(CHPh)), 3053 (m, n(CHPh)), 3026 (w,
n
n(CHPh)), 2983 (vw,
n
(CH)), 2972 (w,
n(CH3)),
n
n
(CH3)), 2143 (m, n
(C^C)), 2028 (m,
n
n
n
(C¼CPhC^C)), 1482 (s,
(C¼CPhP) þ
n(C¼CPhP
)
þ
n
n
n
(vw), 1243 (w, ds(SiCH3)), 1219 (vw,
(vw), 1119 (vw), 1098 (s,
d
d
d
d
d
r
r
r
g
Yield: 685 mg, 2.07 mmol, 40%. Mp: 22e26 ꢁC (argon). Solu-
bility: hexane, pentane, benzene. Anal. found (calcd.) for
C14H11CoO4Si (330.257 g/mol): C 51.16 (50.92) %, H 3.52 (3.36) %. 1H
g
g
g
l
(ε) ¼ 235 (27,000),
NMR (0.12 M in C6D6):
d
¼ 7.43 (m, 2 H, Phortho), 6.91 (m, 3 H,
248 (26,000), 261 (20,000), 275 (sh, 8500), 282 (sh, 8500), 300 (br/
sh, 8500), 339 (br, 8500), 374 (br/sh, 4300) nm (L/mol*cm).
1
Phmeta para), 0.72 (s, JHC ¼ 122 Hz, 6 H, SiMe2) ppm. 13C NMR
þ
(0.12 M in C6D6):
d
¼ 199.0 (br,3 Dn1/2 ¼ 60 Hz, CO), 132.1 (s, 2 C,
Phortho), 129.1 (s, 1 C, Phpara), 128.6 (s, 2 C, Phmeta), 123.2 (s, 1 C,
4.5.4. Octacarbonyl-1
k
2C,2
k
3C,3
k
3C-cyclopentadienyl-1(
h
5)-[m3
-
Phipso), 110.5 (s, 1 C, C^CꢀSi), 95.1 (s, 1 C, C^CꢀSi), 7.6 (s,
dimethyl(phenylethynyl-2k2C,C0:3k2C,C0)silyl-1
bis[cobalt(0)](CoeCo) (4)
kSi]-1-iron(II)-2,3-
1JCSi ¼ 54 Hz, 2 C, SiMe2) ppm. 29Si NMR (0.12 M in C6D6):
¼ þ13.8
d
2
1
(s (1H coupled: septet, JSiH ¼ 7.3 Hz), JSiC(Me) ¼ 54 Hz (2 C),
Co2(CO)8 (650 mg, 1.90 mmol) in hexane (20 mL) was added at
room temperature with stirring to a solution of 1 (650 mg,
1.93 mmol) in hexane (20 mL) whereupon a weak effervescence
commenced. After 1 d the dark brown solution was filtered, slowly
evaporated in vacuo to a volume of 5 mL, and cooled to ꢀ20 ꢁC. The
precipitated solid was isolated and dried in vacuo (770 mg, 65%
crude yield). From the mother liquor additional solid (110 mg, 9%
crude yield) could be obtained by evaporation and cooling. The
crude product was recrystallized from hexane (25 mL, evaporation
in vacuo to 5 mL, cooling to ꢀ20 ꢁC, isolation, washing with 3 x
0.5 mL hexane, drying in vacuo) yielding dark brown crystals which
1JSiC(C^C) ¼ 87 Hz (1 C), JSiC(C^C) ¼ 16 Hz (1 C)) ppm. 59Co NMR
2
(0.12 M in C6D6):
d
¼ ꢀ2975 (Dn1/2 ¼ 8 kHz) ppm. IR (hexane):
nw ¼ 2157 (w,
n(C^C)), 2094 (s, n(C^O)), 2033 (s, n(C^O)), 2008
(vs,
(w,
n
(C^O)), 1998 (vs,
n
(C^O)) cmꢀ1. IR (neat liquid): nw ¼ 3082
n
(CHPh)), 3052 (w, n(CHPh)), 3033 (w, n(CHPh)), 2961 (w,
nas(CH3)), 2897 (vw, ns(CH3)), 2153 (s,
2029 (vs, (C^O)), 1994 (vs, (C^O)), 1595 (w,
(vw, (C¼CPhC^C)), 1443 (w,
(C¼CPhC^C)), 1487 (w,
1406 (w, das(SiCH3)),1251 (m, ds(SiCH3)),1223 (w, (CHPhC^C)),1069
(CHPhC^C)), 851 (s,
n
(C^C)), 2092 (s,
(C¼CPhC^C)), 1572
(C¼CPhC^C)),
n(C^O)),
n
n
n
n
n
n
d
(w, d(CHPhC^C)), 1028 (w, d(CHPhC^C)), 915 (w, d
4
Multiplett intimated.
Overlap with signals of by-products and impurities.
3
5
A splitting into two signals (axial/equatorial) was intimated.

F. Hoffmann et al. / Journal of Organometallic Chemistry 705 (2012) 59e69
67
were directly suitable for X-ray crystallography. They were air-
Acknowledgement
stable for at least 1 week but should be stored under argon.
Yield: 670 mg, 1.08 mmol, 57%. Mp: 86e87 ꢁC (argon), 83e84 ꢁC
(dec., air). Solubility: hexane, benzene. Anal. found (calcd.) for
C23H16Co2FeO8Si (622.172 g/mol): C 44.39 (44.40) %, H 2.74 (2.59) %.
The authors thank the Deutsche Forschungsgemeinschaft and
the Fonds der chemischen Industrie for financial support.
1H NMR (0.05 M in C6D6):
d
¼ 7.56 (d, 3JHH ¼ 7.6 Hz, 2 H, Phortho), 7.02
Appendix A. Supplementary material
(“t”, 3JHH ¼ 7.4 Hz, 2 H, Phmeta), 6.93 (t, 3JHH ¼ 7.2 Hz,1 H, Phpara), 4.05
(s, 1JHC ¼ 178 Hz, 5 H, Cp), 0.87 (s, 1JHC ¼ 120 Hz, 6 H, SiMe2) ppm. 13
C
642194(1), 299782(2), 642198(3), and 642195(4) contain the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
NMR (0.05 M in C6D6):
d
¼ 215.6 (s, Dn1/2 ¼ 4 Hz, FeCO), 200.9 (br,
Dn1/2 ¼ 40 Hz, CoCO), 139.7 (s, Dn1/2 ¼ 3 Hz, 1 C, Phipso), 129.7 (s, Dn1/
¼ 4 Hz, 2 C, Phortho), 129.2 (s, Dn1/2 ¼ 4 Hz, 2 C, Phmeta), 127.9 (s, 1 C,
2
Phpara),108.2 (s, Dn1/2 ¼ 7 Hz,1 C, C^CꢀSi*Co2), 91.3 (s, Dn1/2 ¼ 6 Hz,
1 C, C^CꢀSi*Co2), 83.8 (s, Dn1/2 ¼ 4 Hz, 5 C, Cp), 9.8 (s, Dn1/2 ¼ 3 Hz,
1JCSi ¼ 47 Hz, 2 C, SiMe2) ppm. 29Si NMR (0.05 M in C6D6):
¼ þ39.7
d
Appendix B. Supplementary material
2
1
(s (1H coupled: septet), JSiH ¼ 6.3 Hz, JSiC(Me) ¼ 47 Hz (2 C),
1JSiC(C^C Co2)
*
¼ 45 Hz (1 C), 1JSiFe ¼ 15 Hz) ppm. 59Co NMR (0.05 M in
Supplementary data related to this article can be found online at
doi:10.1016/j.jorganchem.2012.01.019.
C6D6):
d
¼ ꢀ2300 ꢅ 100 (vbr, Dn1/2 ¼ 37 kHz) ppm. IR (hexane):
nw ¼ 2085 (m,
n
(CoC^O)), 2047 (s,
n
(CoC^O)), 2026 (s,
(FeC^O)), 1949 (m,
(CHCp/Ph)), 3068 (vw,
n(CoC^O)),
(FeC^O))
(CHCp/Ph)),
2015 (m/sh,
n
(CoC^O), 2001 (m,
n
n
References
cmꢀ1. IR (KBr): nw ¼ 3130 (vw,
n
n
[1] S. Patai, Z. Rappoport (Eds.), The Chemistry of Functional Groups ꢀ The
Chemistry of Organosilicon Compounds, vol. 1, John Wiley & Sons, Chichester,
1989;
2959 (w, nas(CH3)), 2899 (vw, ns(CH3)), 2083 (s,
n
(CoC^O)), 2046 (vs,
(CoC^O)), 1993 (vs,
(C¼CPh)), 1574 (w,
(C¼CPh)), 1439 (w,
(C¼CCp)), 1407 (w, das(SiCH3)), 1360 (vw); 1249
n
n
n
n
(CoC^O)), 2020 (vs,
(FeC^O)), 1933 (s,
n
(CoC^O)), 2012 (vs,
(FeC^O)), 1596 (w,
(C^C)), 1560 (vw/sh), 1522 (vw), 1476 (w,
(C¼CPh)), 1413 (w,
n
n
n
Z. Rappoport, Y. Apeloig (Eds.), The Chemistry of Functional Groups ꢀ The
Chemistry of Organosilicon Compounds, vol. 2, John Wiley & Sons, Chichester,
1998;
Z. Rappoport, Y. Apeloig (Eds.), The Chemistry of Functional Groups ꢀ The
Chemistry of Organosilicon Compounds, vol. 3, John Wiley & Sons, Chichester,
2001;
n
n
(w, ds(SiCH3)), 1241 (w, ds(SiCH3)), 1178 (vw), 1165 (vw/sh), 1075
(vw/sh), 1065 (vw), 1015 (vw, (CHCp)), 1001 (vw), 861 (w), 845 (sh,
(CHCp) þ (SiCH3)), 828 (m, (SiCH3)), 800 (m, (SiCH3)),
758 (m, (CHPh)), 693 (w, (CHPh)), 680 (vw/sh), 645 (m,
635 (w/sh), 605 (m/sh), 594 (s, (FeCO)), 567 (w), 516 (s,
495 (s, (CoCO)), 475 (w/sh), 465 (m), 457 (m,
(w), 393 (w) cmꢀ1 [45a,b,d,46,49,50]. UV/VIS (hexane):
d
(a) T. D. Tilley, vol. 1, part 2, ch. 24, p. 1415e1477;
(b) E. A. Williams, vol. 1, part 1, ch. 8, pp. 511e554;
(c) M. S. Eisen, vol. 2, part 3, ch. 35, pp. 2037e2128;
(d) W. S. Sheldrick, vol. 1, part 1, ch. 3, pp. 227e303;
(e) Y. Takeuchi, T. Takayama, vol. 2, part 1, ch. 6, pp. 267e354.
[2] Selected references: (a) W. Malisch, P. Panster, Chem. Ber. 108 (1975)
2554e2573;
g
r
g(CHCp) þ
r
r
g
g
d
(FeCO)),
d
d(CoCO)),
d
d(CoCO)), 431 (w), 416
l
(ε) ¼ 216
(50,000), 290 (br/sh, 20,000), 330 (br/sh,13,000), 375 (br/sh, 3000),
(b) G.P. Mitchell, T.D. Tilley, Organometallics 15 (1996) 3477e3479;
(c) H. Lang, M. Weinmann, W. Frosch, M. Büchner, B. Schiemenz, Chem.
Commun. (1996) 1299e1300;
450 (br/sh, 700), 575 (br/sh, 300) nm (L/mol*cm) [45c,d,51].
(d) M. Weinmann, H. Lang, O. Walter, M. Büchner, in: N. Auner, J. Weis (Eds.),
Organosilicon Chemistry II ꢀ From Molecules to Materials, VCH, Weinheim,
1996, pp. 569e574;
(e) M. Weinmann, G. Rheinwald, L. Zsolnai, O. Walter, M. Büchner,
B. Schiemenz, G. Huttner, H. Lang, Organometallics 17 (1998) 3299e3307;
(f) H. Sakaba, S. Watanabe, C. Kabuto, K. Kabuto, J. Am. Chem. Soc. 125 (2003)
2842e2843;
4.5.5. Dicarbonyl(h
5-cyclopentadienyl){dimethyl[(E)-2-phenyl-2-
triethylsilyl-ethen-1-yl]silyl}iron(II) (5)
Complex 1 (182 mg, 0.54 mmol) and a few mg H2PtCl6 * 6H2O in
2 drops of isopropanol were dissolved in Et3SiH (2.5 mL, 1.83 g,
15.70 mmol), stirred at room temperature for 6 d, and additionally
refluxed for 2 h. The mixture was then evaporated in vacuo and the
residue extracted with hexane (5 mL). The extract was again
evaporated in vacuo leaving 5 as a brown oil.
(g) M. Ray, Y. Nakao, H. Sato, S. Sakaki, Organometallics 26 (2007) 4413e4423.
[3] (a) D.W.W. Anderson, E.A.V. Ebsworth, J.K. Macdougall, D.W.H. Rankin,
J. Inorg. Nucl. Chem. 35 (1973) 2259e2263;
(b) D.W.W. Anderson, E.A.V. Ebsworth, D.W.H. Rankin, J. Chem. Soc. Dalton
Trans. (1973) 2370e2373;
(c) C. Eaborn, T.N. Metham, A. Pidcock, J. Organomet. Chem. 63 (1973)
107e117.
Yield: 245 mg, 0.54 mmol, 99.6%. 1H NMR (0.2 M in C6D6):
d
¼ 7.17 (m, 2 H, Phortho), 7.08 (m, 3 H, Phmeta þ para), 6.72 (s,1 H, HC]
[4] (a) S. Kotani, T. Matsumoto, H. Yamaguchi, K. Shiina, K. Sonogashira, Chem.
Lett. (1989) 293e296;
C), 4.13 (s, 5 H, Cp), 0.99 (t, 3JHH ¼ 7.8 Hz, 9 H, ꢀCH2ꢀCH3), 0.63 (q,
(b) R.J.P. Corriu, J.J.E. Moreau, H. Praet, J. Organomet. Chem. 376 (1989)
C39eC43;
3JHH ¼ 7.8 Hz, 6 H, ꢀCH2ꢀCH3), 0.33 (s, 6 H, SiMe2) ppm. 13C NMR
(0.2 M in C6D6):
d
¼ 216.0 (s, 2 C, CO), 157.2 (s, 1 C, HC]C), 151.8 (s,
(c) R.J.P. Corriu, J.J.E. Moreau, H. Praet, Organometallics 8 (1989) 2779e2786;
(d) R.J.P. Corriu, J.J.E. Moreau, H. Praet, Organometallics 9 (1990) 2086e2091;
(e) H. Lang, U. Lay, J. Organomet. Chem. 388 (1990) C1eC4;
(f) H. Lang, U. Lay, L. Zsolnai, J. Organomet. Chem. 417 (1991) 377e387;
(g) U. Lay, H. Lang, J. Organomet. Chem. 418 (1991) 79e89;
(h) H. Lang, U. Lay, M. Weinmann, J. Organomet. Chem. 436 (1992) 265e276;
(i) R. Ruffolo, A. Decken, L. Girard, H.K. Gupta, M.A. Brook, M.J. McGlinchey,
Organometallics 13 (1994) 4328e4335.
1 C, HC]C),145.8 (s,1 C, Phipso),125.9 (s,1 C, Phpara), 83.8 (s, 5 C, Cp),
1
7.7 (s, 3 C, ꢀCH2ꢀCH3), 6.8 (s, JCSi ¼ 45 Hz, 2 C, SiMe2), 3.3 (s,
1JCSi ¼ 52 Hz, 3 C, ꢀCH2ꢀCH3) ppm. 13C NMR (0.2 M in hexane):
d
¼ 215.3 (s, 2 C, CO), 157.1 (s (1H coupled: s/br), 1 C, HC]C), 152.3 (s
(1H coupled: d, 1JCH ¼ 132 Hz), 1 C, HC]C), 146.0 (s (1H coupled: dt,
2/3
J
¼ 15 Hz, 2/3JCH ¼ 7.5 Hz), 1 C, Phipso), 128.1 (s (1H coupled: dd,
CH
[5] (a) D. Schneider, H. Werner, Angew. Chem. 103 (1991) 710e712;
Angew. Chem., Int. Ed. Engl. 30 (1991) 700e702;
1JCH ¼ 161 Hz, JCH ¼ 7 Hz), 2 C, Phmeta), 128.0 (s (1H coupled: dt,
3
1JCH ¼ 159 Hz, JCH ¼ 6 Hz), 2 C, Phortho), 126.0 (s (1H coupled: dt,
3
(b) H. Werner, M. Baum, D. Schneider, B. Windmüller, Organometallics 13
(1994) 1089e1097;
(c) K. Osakada, T. Koizumi, T. Yamamoto, Organometallics 16 (1997)
2063e2069.
1JCH ¼ 159 Hz, 3JCH ¼ 7 Hz), 1 C, Phpara), 83.7 (s (1H coupled: d“qn”,
1JCH ¼ 179 Hz,
J
¼ 6.5 Hz), 5 C, Cp), 7.6 (s (1H coupled: qt,
2/3
CH
1JCH ¼ 126 Hz, 2JCH ¼ 5 Hz), 3 C, ꢀCH2ꢀCH3), 6.5 (s (1H coupled: q,
1JCH ¼ 119 Hz), 2 C, SiMe2), 3.5 (s (1H coupled: t/br, 1JCH ¼ 118 Hz),
[6] (a) H. Sakaba, M. Yoshida, C. Kabuto, K. Kabuto, J. Am. Chem. Soc. 127 (2005)
7276e7277;
(b) M. Ray, Y. Nakao, H. Sato, H. Sakaba, S. Sakaki, J. Am. Chem. Soc. 128 (2006)
11927e11939;
(c) M. Yabe-Yoshida, C. Kabuto, K. Kabuto, E. Kwon, H. Sakaba, J. Am. Chem.
Soc. 131 (2009) 9138e9139;
(d) M. Ray, Y. Nakao, H. Sato, H. Sakaba, S. Sakaki, Organometallics 28 (2009)
65e73;
3 C, ꢀCH2ꢀCH3) ppm. 29Si NMR (0.2 M in C6D6):
d
¼ þ32.2 (s (1H
coupled: octet), 2JSiH ¼ 6.5 Hz, 1JSiC(Me) ¼ 45 Hz, 1 Si, FpSiMe2), þ1.8
(s, JSiC(Me) ¼ 54 Hz, 1 Si, SiEt3) ppm. IR (hexane): nw ¼ 1996 (s,
1
n
(C^O)), 1943 (s, n .
(C^O)) cmꢀ1

68
F. Hoffmann et al. / Journal of Organometallic Chemistry 705 (2012) 59e69
(e) H. Sakaba, M. Yabe-Yoshida, H. Oike, C. Kabuto, Organometallics 29 (2010)
4115e4119.
(d) K. Oertle, H. Wetter, Tetrahedron Lett. 26 (1985) 5511e5514;
(e) N. Asao, T. Sudo, Y. Yamamoto, J. Org. Chem. 61 (1996) 7654e7655.
[33] (a) C.L. Randolph, M.S. Wrighton, J. Am. Chem. Soc. 108 (1986) 3366e3374;
(b) K.H. Pannell, S.-H. Lin, R.N. Kapoor, F. Cervantes-Lee, M. Pinon, L. Parkanyi,
Organometallics 9 (1990) 2454e2462;
[7] (a) A. Ohff, P. Kosse, W. Baumann, A. Tillack, R. Kempe, H. Goerls,
V.V. Burlakov, U. Rosenthal, J. Am. Chem. Soc. 117 (1995) 10399e10400;
(b) N. Peulecke, A. Ohff, P. Kosse, A. Tillack, A. Spannenberg, R. Kempe,
W. Baumann, V.V. Burlakov, U. Rosenthal, Chem. Eur. J. 4 (1998) 1852e1861;
(c) A. Haynes, M.W. George, M.T. Haward, M. Poliakoff, J.J. Turner, N.M. Boag,
M. Green, J. Am. Chem. Soc. 113 (1991) 2011e2020.
ꢀ
(c) M. Lamac, A. Spannenberg, H.-J. Jiao, S. Hansen, W. Baumann, P. Arndt,
U. Rosenthal, Angew. Chem. 122 (2010) 2999e3002;
Angew. Chem., Int. Ed. Engl. 49 (2010) 2937e2940;
(d) M. Lamac, A. Spannenberg, W. Baumann, H.-J. Jiao, C. Fischer, S. Hansen,
[34] (a) A.N. Nesmeyanov, N.E. Kolobova, V.V. Skripkin, K.N. Anisimov,
L.A. Fedorov, Dokl. Akad. Nauk SSSR 195 (1970) 368e371;
(b) N.E. Kolobova, V.V. Skripkin, K.N. Anisimov, Izv. Akad. Nauk SSSR, Ser.
Khim (1970) 2225e2228;
ꢀ
P. Arndt, U. Rosenthal, J. Am. Chem. Soc. 132 (2010) 4369e4380;
(e) M.-F. Fan, Z.-Y. Lin, Organometallics 16 (1997) 494e496.
[8] E. Ramirez-Oliva, J. Cervantes, F. Cervantes-Lee, R.N. Kapoor, K.H. Pannell,
J. Organomet. Chem. 510 (1996) 57e62.
[9] R. Fischer, D. Frank, W. Gaderbauer, C. Kayser, C. Mechtler, J. Baumgartner,
C. Marschner, Organometallics 22 (2003) 3723e3731.
[10] R.J.P. Corriu, B.P.S. Chauhan, G.F. Lanneau, Organometallics 14 (1995)
4014e4017.
[11] M.A. Esteruelas, M. Olivan, L.A. Oro, Organometallics 15 (1996) 814e822.
[12] W.-Y. Chan, A. Berenbaum, S.B. Clendenning, A.J. Lough, I. Manners, Organo-
metallics 22 (2003) 3796e3808.
[13] M. Zirngast, C. Marschner, J. Baumgartner, Organometallics 25 (2006)
4897e4908.
(c) A.N. Nesmeyanov, N.E. Kolobova, V.V. Skripkin, K.N. Anisimov, Dokl. Akad.
Nauk SSSR 196 (1971) 606e608;
(d) V.E. Shklover, V.V. Skripkin, A.I. Gusev, Y.T. Struchkov, Zh. Strukt. Khim 13
(1972) 744e745.
[35] (a) S. Li, D.L. Johnson, J.A. Gladysz, K.L. Servis, J. Organomet. Chem. 166 (1979)
317e321;
(b) H. Sakurai, Y. Kamiyama, A. Mikoda, T. Kobayashi, K. Sasaki, Y. Nakadaira,
J. Organomet. Chem. 201 (1980) C14eC18;
(c) K.H. Pannell, A.R. Bassindale, J. Organomet. Chem. 229 (1982) 1e9;
(d) M.I. Al-Hassan, I.M. Al-Najjar, I.M. Al-Oraify, Magn. Res. Chem. 27 (1989)
1112e1116;
(e) F. Hoffmann, U. Böhme, G. Roewer, in: N. Auner, J. Weis (Eds.), Organo-
[14] Preliminary Communication: F. Hoffmann, J. Wagler, G. Roewer, Transition
Metal Alkynyl Silyl Complexes, Poster P033, 14th International Symposium on
Organosilicon Chemistry / 3rd European Organosilicon Days, Würzburg, July
31-August 5, 2005, Book of Abstracts, p. 139.
[15] R.E. Dessy, R.L. Pohl, R.B. King, J. Am. Chem. Soc. 88 (1966) 5121e5124.
[16] (a) W. Malisch, M. Kuhn, Chem. Ber. 107 (1974) 979e995;
(b) W. Malisch, J. Organomet. Chem. 82 (1974) 185e199.
[17] (a) E. Hengge, M. Eibl, F. Schrank, J. Organomet. Chem. 369 (1989) C23eC26;
(b) F. Hoffmann, Diploma Thesis, TU Bergakademie Freiberg, Freiberg, Ger-
many, 2001.
[18] H.W. Spiess, R.K. Sheline, J. Chem. Phys. 53 (1970) 3036e3041.
[19] D.J. Patmore, W.A.G. Graham, Inorg. Chem. 6 (1967) 981e988.
[20] F. Hoffmann, U. Böhme, unpublished results, publication in preparation.
[21] (a) J. Chatt, C. Eaborn, P.N. Kapoor, J. Chem. Soc. A (1970) 881e884;
(b) W. Fink, A. Wenger, Helv. Chim. Acta 54 (1971) 2186e2189;
(c) P. Giannoccaro, A. Sacco, G. Vasapollo, Inorg. Chim. Acta 37 (1979)
L455eL456;
silicon Chemistry VI
Weinheim, 2005, pp. 445e451.
[36] J. Mason (Ed.), Multinuclear NMR, Plenum Press, New York, London, 1987.
[37] N.C. Schroeder, J.W. Richardson, S.L. Wang, R.A. Jacobson, R.J. Angelici,
Organometallics 4 (1985) 1226e1233.
ꢀ
From Molecules to Materials, vol. 1, Wiley-VCH,
[38] (a) Bruker AXS Inc., Madison, Wisconsin, USA, 2003;
(b) G.M. Sheldrick, SHELXTL (version 6), Bruker Analytical X-ray Instruments
Inc, Madison, Wisconsin, USA, 2001;
see also: G.M. Sheldrick Acta Crystallogr. A64 (2008) 112e122;
(c) G.M. Sheldrick, SHELXS-97, University ofGöttingen, Göttingen, Germany, 1997;
see also: G.M. Sheldrick Acta Crystallogr. A46 (1990) 467e473;
(d)G.M. Sheldrick, SHELXL-97, University ofGöttingen, Göttingen, Germany, 1997;
see also: G.M. Sheldrick Acta Crystallogr. A64 (2008) 112e122;
(e) L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837e838;
(f) C.K. Johnson, M.N. Burnett, ORTEP-32 Rep. ORNL-6895, Oak Ridge National
Laboratory, Oak Ridge, Tennessee, USA, 1996, Windows version: L. J. Farrugia,
University of Glasgow, Glasgow, Scotland, United Kingdom, 1999;
see also: L.J. Farrugia J. Appl. Crystallogr. 30 (1997) 565.
(d) L. Abdol-Latif, C. Eaborn, A.P. Pidcock, N.S. Weng, J. Organomet. Chem. 474
(1994) 217e221.
[22] Y. Tanaka, H. Yamashita, M. Tanaka, Organometallics 14 (1995) 530e541.
[23] (a) F. de Charentenay, J.A. Osborn, G. Wilkinson, J. Chem. Soc. A (1968)
787e790;
[39] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb,
J.R. Cheeseman, J.A. Montgomery Jr., T. Vreven, K.N. Kudin, J.C. Burant,
J.M. Millam, S.S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi,
G. Scalmani, N. Rega, G.A. Petersson, H. Nakatsuji, M. Hada, M. Ehara,
K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, M. Klene, X. Li, J.E. Knox, H.P. Hratchian, J.B. Cross, C. Adamo,
J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi,
C. Pomelli, J.W. Ochterski, P.Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador,
J.J. Dannenberg, V.G. Zakrzewski, S. Dapprich, A.D. Daniels, M.C. Strain,
O. Farkas, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J.V. Ortiz,
Q. Cui, A.G. Baboul, S. Clifford, J. Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko,
P. Piskorz, I. Komaromi, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng,
A. Nanayakkara, M. Challacombe, P.M.W. Gill, B. Johnson, W. Chen,
M.W. Wong, C. Gonzalez, J.A. Pople, Gaussian 03, Revision C.02, Gaussian Inc,
Wallingford, Connecticut, 2004.
(b) R.N. Haszeldine, R.V. Parish, D.J. Parry, J. Chem. Soc. A (1969) 683e690;
(c) R.N. Haszeldine, R.V. Parish, R.J. Taylor, J. Chem. Soc. Dalton Trans. (1974)
2311e2315;
(d) I. Ojima, M. Nihonyanagi, T. Kogure, M. Kumagai, S. Horiuchi,
K. Nakatsugawa, Y. Nagai, J. Organomet. Chem. 94 (1975) 449e461;
(e) Y. Nishihara, M. Takemura, K. Osakada, Organometallics 21 (2002)
825e831.
[24] (a) T. Takao, H. Suzuki, M. Tanaka, Organometallics 13 (1994) 2554e2556;
(b) T. Takao, S. Yoshida, H. Suzuki, M. Tanaka, Organometallics 14 (1995)
3855e3868;
(c) F. Delpech, S. Sabo-Etienne, B. Chaudret, J.-C. Daran, J. Am. Chem. Soc. 119
(1997) 3167e3168;
[40] (a) A.D. Becke, J. Chem. Phys. 98 (1993) 5648e5652;
(d) J.M. Dysard, T.D. Tilley, Organometallics 19 (2000) 4726e4732;
(e) J. Braddock-Wilking, Y. Levchinsky, N.P. Rath, Organometallics 19 (2000)
5500e5510;
(f) J. Braddock-Wilking, Y. Levchinsky, N.P. Rath, Inorg. Chim. Acta 330 (2002)
82e88.
(b) P.J. Stephens, F.J. Devlin, C.F. Chabalowski, M.J. Frisch, J. Phys. Chem. 98
(1994) 11623e11627.
[41] (a) J.S. Binkley, J.A. Pople, W.J. Hehre, J. Am. Chem. Soc. 102 (1980) 939e947;
(b) M.S. Gordon, J.S. Binkley, J.A. Pople, W.J. Pietro, W.J. Hehre, J. Am. Chem.
Soc. 104 (1982) 2797e2803;
[25] (a) A.F. Holleman, E. Wiberg, N. Wiberg, Lehrbuch der Anorganischen Chemie,
101st ed. Walter de Gruyter, Berlin, New York, 1995, pp. 1838e1841;
(c) K.D. Dobbs, W.J. Hehre, J. Comput. Chem. 7 (1986) 359e378;
(d) K.D. Dobbs, W.J. Hehre, J. Comput. Chem. 8 (1987) 861e879;
(e) K.D. Dobbs, W.J. Hehre, J. Comput. Chem. 8 (1987) 880e893.
[42] (a) F. Biegler-König, J. Schönbohm, D. Bayles, J. Comput. Chem. 22 (2001)
545e559;
(b) J. C. Ortiz, C.Bo, Xaim, Universidad Rovira i Virgili, Tarragona, Spain.
[43] (a) P.J. Hay, W.R. Wadt, J. Chem. Phys. 82 (1985) 299e310;
(b) A.W. Ehlers, M. Böhme, S. Dapprich, A. Gobbi, A. Höllwarth, V. Jonas,
K.F. Köhler, R. Stegmann, A. Veldkamp, G. Frenking, Chem. Phys. Lett. 208
(1993) 111e114.
(b) M. Nishio, M. Hirota, Y. Umezawa, The CH/
p
Interaction ꢀ Evidence,
Nature, and Consequences, Wiley-VCH, New York, 1998, p. 34/35/81;
(c) C. Steinbrüchel, D.M. Gruen, J. Chem. Phys. 74 (1981) 205e214.
[26] A.W. Addison, T.N. Rao, J. Chem. Soc. Dalton Trans. (1984) 1349e1356.
[27] I.A. Cade, A.F. Hill, A. Kämpfe, J. Wagler, Organometallics 29 (2010)
4012e4017.
[28] P. Galow, A. Sebald, B. Wrackmeyer, J. Organomet. Chem. 259 (1983)
253e268.
[29] F. Hoffmann, J. Wagler, G. Roewer, Eur. J. Inorg. Chem. (2010) 1133e1142 (and
references cited therein).
[44] (a) P.C. Hariharan, J.A. Pople, Theor. Chim. Acta 28 (1973) 213e222;
(b) M.M. Francl, W.J. Pietro, W.J. Hehre, J.S. Binkley, M.S. Gordon, D.J. DeFrees,
J.A. Pople, J. Chem. Phys. 77 (1982) 3654e3665.
[45] (a) Gmelin Institut der Max-Planck-Gesellschaft (Ed.), Gmelin Handbook of
Inorganic Chemistry, eighth ed., vol. 59 / B11. Springer, Berlin, 1983, pp.
263e265;
[30] (a) H.-O. Kalinowski, S. Berger, S. Braun, 13C-NMR-Spektroskopie, Georg
Thieme, Stuttgart, New York, 1984;
(b) E. Breitmaier, W. Voelter, Carbon-13 NMR Spectroscopy, third ed.. VCH,
Weinheim, 1987.
[31] U. Herzog, Ph.D. Thesis, TU Bergakademie Freiberg, Freiberg, Germany,
1997.
[32] (a) J.L. Speier, J.A. Webster, G.H. Barnes, J. Am. Chem. Soc. 79 (1957) 974e979;
(b) R.A. Benkeser, R.F. Cunico, S. Dunny, P.R. Jones, P.G. Nerlekar, J. Org. Chem.
32 (1967) 2634e2636;
(b) Gmelin Institut der Max-Planck-Gesellschaft (Ed.), Gmelin Handbook of
Inorganic Chemistry, eighth ed., vol. 59 / C4. Springer, Berlin, 1981, pp. 54e59;
(c) Gmelin Institut der Max-Planck-Gesellschaft (Ed.), Gmelin Handbook of
Inorganic Chemistry, eighth ed., vol. 59 / B12. Springer, Berlin, 1984, p. 23;
(d) part 2, Gmelin Institut der Max-Planck-Gesellschaft (Ed.), Gmelin Handbook
of Inorganic Chemistry, eighth ed., vol. 58 / E6. Verlag Chemie, Weinheim, 1973,
pp. 87e101.
(c) I. Ojima, N. Clos, R.J. Donovan, P. Ingallina, Organometallics 9 (1990)
3127e3133;

F. Hoffmann et al. / Journal of Organometallic Chemistry 705 (2012) 59e69
69
[46] D. Hartley, M.J. Ware, J. Chem. Soc. A (1969) 138e142.
(Ed.), Comprehensive Organometallic Chemistry II ꢀ A Review of the Litera-
ture 1982-1994, vol. 8, Pergamon Elsevier Science, 1995, pp. 74e75 ch. 1.4.2.
[50] (a) Y. Iwashita, F. Tamura, A. Nakamura, Inorg. Chem. 8 (1969) 1179e1183;
(b) Y. Iwashita, A. Ishikawa, M. Kainosho, Spectrochim. Acta 27A (1971) 271e277;
(c) S.F.A. Kettle, P.L. Stanghellini, Inorg. Chem. 16 (1977) 753e758.
[51] (a) G. Peyronel, A. Ragni, E.F. Trogu, Gazz. Chim. Ital. 97 (1967) 1327e1343;
(b) W.E. Lindsell, P.N. Preston, P.J. Tomb, J. Organomet. Chem. 439 (1992)
201e212.
[47] Y.L. Baay, A.G. MacDiarmid, Inorg. Chem. 8 (1969) 986e994.
[48] D.J. Parker, M.H.B. Stiddard, J. Chem. Soc. A (1970) 1040e1049.
[49] (a) R.D.W. Kemmitt, D.R. Russell, in: G. Wilkinson, F.G.A. Stone, E.W. Abel
(Eds.), Comprehensive Organometallic Chemistry ꢀ The Synthesis, Reactions
and Structures of Organometallic Compounds, vol. 5, Pergamon Press, Oxford,
1982, p. 195 ch. 34.4.2.1;
(b) R.L. Sweany, in: E.W. Abel, F.G.A. Stone, G. Wilkinson (Eds.), in: J.D. Atwood