Synthesis, characterization, and reactivity of isocyanidephosphidoniobocene derivatives: X-ray diffraction structures of new isocyanideniobocene complexes, [Nb(η5-C5H 4SiMe3)2(CNR)(PMePh2)]I, R = Xylyl, Cy

Article abstract of DOI:10.1021/om060283p

The reaction of the hydride niobocene complexes [Nb(η ⁵-C₅H₄SiMe₃)₂H(L)] [L = CNBuⁿ (1), CNCy (2), and CNXylyl (3)] with ClPPh₂ yielded the cationic niobocene complexes [Nb(η⁵-C₅H ₄SiMe₃)₂(PHPh₂)-(L)]Cl [L = CNBuⁿ (4), CNCy (5), and CNXylyl (6)]. Treatment of these complexes with NaOH yielded a new family of phosphidoniobocene derivatives [Nb(η ⁵-C₅H₄SiMe₃)₂(PPh ₂)(L)] [L = CNBuⁿ (7), CNCy (8), and CNXylyl (9)] by elimination of the hydrogen atom directly bonded to the phosphorus. The cationic d² species [Nb(η⁵-C₅H ₄SiMe₃)₂(PRPh₂)(L)]X [R = Me, X = I, L = CNBuⁿ (10), CNCy (11), and CNXylyl (12); R = CH₂Ph, X = Br, CNBuⁿ (13), CNCy (14), and CNXylyl (15); R = CH ₂CH₂Ph, X = Br, CNBuⁿ (16), CNCy (17), and CNXylyl (18)] were prepared by the reaction of alkyl halides RX (R = Me, X = I; CH₂Ph, X = Br; CH₂CH₂Ph, X = Br) with 7, 8, or 9 by electrophilic attack on the phosphorus atom present in the phosphide terminal ligand. In the same way, the reaction of 9 with ICH₂CH ₂I or iodine yielded the complex [Nb(η⁵-C ₅H₄SiMe₃)₂(P(I)Ph ₂)(CNXylyl)]I₃ (19). The insertion reaction of carbon disulfide into the Nb-P bond of 7, 8, or 9 yielded a new family of diphenylphosphidodithioformato complexes with the niobocene system [Nb(η⁵-C₅H₄SiMe₃) ₂(κ¹-S-SC(S)(PPh₂))(L)] [L = CNBu ⁿ (20), CNCy (21), and CNXylyl (22)]. The molecular structures of 11 and 12 were determined by single-crystal X-ray diffraction studies.

Full text of DOI:10.1021/om060283p

3670
Organometallics 2006, 25, 3670-3677
Synthesis, Characterization, and Reactivity of
Isocyanidephosphidoniobocene Derivatives: X-ray Diffraction
Structures of New Isocyanideniobocene Complexes,
[Nb(η5-C5H4SiMe3)2(CNR)(PMePh2)]I, R ) Xylyl, Cy
Antonio Antin˜olo,* David Evrard, Santiago Garc´ıa-Yuste, Antonio Otero,*
Juan C. Pe´rez-Flores, Rebeca Reguillo-Carmona, Ana M. Rodr´ıguez, and Elena Villasen˜or
Departamento de Qu´ımica Inorga´nica, Orga´nica y Bioqu´ımica, Facultad de Qu´ımica,
UniVersidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
ReceiVed March 30, 2006
The reaction of the hydride niobocene complexes [Nb(η5-C5H4SiMe3)2H(L)] [L ) CNBun (1), CNCy
(2), and CNXylyl (3)] with ClPPh2 yielded the cationic niobocene complexes [Nb(η5-C5H4SiMe3)2(PHPh2)-
(L)]Cl [L ) CNBun (4), CNCy (5), and CNXylyl (6)]. Treatment of these complexes with NaOH yielded
a new family of phosphidoniobocene derivatives [Nb(η5-C5H4SiMe3)2(PPh2)(L)] [L ) CNBun (7), CNCy
(8), and CNXylyl (9)] by elimination of the hydrogen atom directly bonded to the phosphorus. The
cationic d2 species [Nb(η5-C5H4SiMe3)2(PRPh2)(L)]X [R ) Me, X ) I, L ) CNBun (10), CNCy (11),
and CNXylyl (12); R ) CH2Ph, X ) Br, CNBun (13), CNCy (14), and CNXylyl (15); R ) CH2CH2Ph,
X ) Br, CNBun (16), CNCy (17), and CNXylyl (18)] were prepared by the reaction of alkyl halides
RX (R ) Me, X ) I; CH2Ph, X ) Br; CH2CH2Ph, X ) Br) with 7, 8, or 9 by electrophilic attack on
the phosphorus atom present in the phosphido terminal ligand. In the same way, the reaction of 9 with
ICH2CH2I or iodine yielded the complex [Nb(η5-C5H4SiMe3)2(P(I)Ph2)(CNXylyl)]I3 (19). The insertion
reaction of carbon disulfide into the Nb-P bond of 7, 8, or 9 yielded a new family of diphenylphos-
phidodithioformato complexes with the niobocene system [Nb(η5-C5H4SiMe3)2(κ1-S-SC(S)(PPh2))(L)]
[L ) CNBun (20), CNCy (21), and CNXylyl (22)]. The molecular structures of 11 and 12 were determined
by single-crystal X-ray diffraction studies.
and relevance, of the scientific publications related to com-
pounds containing this element.8 Of all the phosphorus ligands
known in organometallic chemistry, the newest typescalled the
phosphido ligandshas not been widely studied in transition
metal chemistry, particularly with respect to group 5 transition
metal complexes.9
Introduction
Hydride complexes of transition metals represent one of the
most important classes of compounds due to their chemical
reactivity and applications in catalysis.1 In recent years our
research group has published several papers concerning the
synthesis, structural characterization, and reactivity of new
niobocene hydrides. Our interest has been focused in important
fields of inorganic and organometallic chemistry such as
hydrogen exchange coupling in metallocene trihydride com-
plexes,2 σ-bond activation by niobocene hydrides,3 insertion
processes with heterocumulene molecules,4 insertion processes
with alkynes,5 the synthesis of dihydrogen complexes in
protonation processes,6 and the synthesis of hydride-olefin
niobocene complexes.7
The number of isocyanideniobocene complexes that have
been characterized by X-ray diffraction methods is very small.10
(7) Antin˜olo, A.; Carrillo, F.; Garc´ıa-Yuste, S.; Otero, A. Organometallics
1994, 13, 2761.
(8) Selected references: (a) Dick, D. G.; Stephan, D. W. Can. J. Chem.
1991, 69. (b) Ho, J. W.; Drake, R. J.; Stephan, D. W. J. Am. Chem. Soc.
1993, 115, 3792. (c) Ho, J. W.; Rousseau, R.; Stephan, D. W. Organome-
tallics 1995, 14, 4030. (d) Baker, R. T.; Calabrese, J. C.; Harlow, R. L.;
Williams, I. D. Organometallics 1993, 12, 830. (e) Hey-Hawkins, E.;
Lappert, M. F.; Atwood, J. L.; Bott, S. G. J. Chem. Soc., Dalton Trans.
1991, 939. (f) Hey-Hawkins, E.; Kurtz, S.; Sieger, J.; Baum, G. J.
Organomet. Chem. 1995, 486, 229. (g) Leblanc, J. C.; Moise, C. J.
Organomet. Chem. 1989, 364, C3. (h) Chang, M. Y.; Gambarotta, S.;
Bolhuis, F. V. Organometallics 1988, 7, 1864. (i) Roddick, D.; Santarsiero,
B. D.; Bercaw, J. E. J. Am. Chem. Soc. 1985, 107, 4670. (j) Rigni, S.;
Leblanc, J. C.; Moise, C.; Nuber, B. J. Chem. Soc., Chem. Commun. 1995,
45. (k) Bonnet, G.; Lavastre, O.; Leblanc, J. C.; Moise, C. New J. Chem.
1988, 12, 551. (l) Bonnet, G.; Kubicki, M. M.; Moise, C.; Lazzaroni, R.;
Salvador, P.; Vitulli, G. Organometallics 1992, 1, 964. (m) Nikonov, G. I.;
Grishin, Y. K.; Lemenovskii, D. A.; Kazennova, N. B.; Kuzmina, L. G.;
Howard, J. A. K. J. Organomet. Chem. 1997, 547, 183. (n) Barre´, C.;
Kubicki, M. M.; Leblanc, J. C.; Moise, C. Inorg. Chem. 1990, 29, 5244.
(o) Barre´, C.; Boudot, P.; Kubicki, M. M.; Moise, C. Inorg. Chem. 1995,
34, 284. (p) Lavastre, O.; Bonnet, G.; Boni, G.; Kubicki, M. M.; Moise, C.
J. Organomet. Chem. 1997, 547, 141.
Furthermore, phosphorus plays an important role in organo-
metallic chemistry, a fact demonstrated by the huge number,
* To whom correspondence should be addressed. E-mail:
antonio.antinolo@uclm.es; antonio.otero@uclm.es. Fax: +34926295318.
(1) Hlatky, G. G.; Crabtree, R. H. Coord. Chem. ReV. 1985, 65, 1.
(2) Antin˜olo, A.; Chaudret, B.; Commenges, G.; Fajardo M.; Jalo´n, F.;
Morris, R. H.; Otero, A.; Schweitzer. C. T. J. Chem. Soc., Chem. Commun.
1988, 1210.
(3) Antin˜olo, A.; Carrillo, F.; Fajardo, M.; Otero, A.; Lanfranchi, M.;
Pellinghelli, M. A. Organometallics 1995, 14, 4, 1518.
(4) Antin˜olo, A.; Carrillo, F.; Fajardo, M.; Garc´ıa-Yuste, S.; Otero, A.
J. Organomet. Chem. 1994, 482, 93.
(5) Antin˜olo, A.; Carrillo-Hermosilla, F.; Fajardo, M.; Garc´ıa-Yuste, S.;
Lafranchi, M.; Otero, A.; Pellinghelli, M. A.; Prashar, S.; Villasen˜or, E.
Organometallics 1996, 15, 5507.
(6) Antin˜olo, A.; Carrillo-Hermosilla, F.; Fajardo, M.; Garc´ıa-Yuste, S.;
Otero, A.; Camanyes, S.; Maseras, F.; Moreno, M.; Lledo´s, A.; Lluch, J.
M. J. Am. Chem. Soc. 1997, 119, 6107.
(9) Selected references: (a) Bonnet, G.; Leblanc, J. C.; Moise, C. New
J. Chem. 1988, 12, 551. (b) Nikonov, G. I.; Kuzmina, L. G.; Mountford,
P.; Lemenovskii, D. A. Organometallics 1995, 14, 3588. (c) Nikonov, G.
I.; Lemenovskii, D. A.; Lorberth, J. Organometallics 1994, 13, 3127.
10.1021/om060283p CCC: $33.50 © 2006 American Chemical Society
Publication on Web 06/13/2006

Isocyanidephosphidoniobocene DeriVatiVes
Organometallics, Vol. 25, No. 15, 2006 3671
These compounds were synthesized by heating [Nb(η5-C5H4-
SiMe3)2(H)3]2 in the presence of the corresponding isocyanide7
(see Scheme 2).
Scheme 1
ClPPh2 was very smoothly inserted into the Nb-H bond of
complexes 1-3 to give the ionic phosphine complexes [Nb-
(η5-C5H4SiMe3)2(PHPh2)(L)]Cl [L ) CNBun (4), CNCy (5), and
CNXylyl (6)]. Complexes 4-6 were isolated as air-sensitive
red-orange crystalline solids in high yield (∼85%) and as red
The well-known equilibrium between the two extreme pos-
sibilities, isocyanide or carbene coordination mode for the
metal-isocyanide bond,11 has usually been studied by IR spec-
troscopy techniques, while X-ray diffraction methods provide
unambiguous evidence concerning the coordination mode
(Scheme 1).
With the aim of combining aspects of isocyanide and
phosphidoniobocene chemistry, we decided to prepare new
isocyanidephosphidoniobocene complexes starting from new
hydridoisocyanideniobocene complexes in order to investigate
both their reactivity and chemical similarity with the carbon-
ylphosphidoniobocene derivatives in insertion and alkylation
processes.12 We also aimed to prepare a significant number of
different isocyanide complexes in order to increase the number
of structures of this kind of complexes resolved by X-ray
diffraction studies.
1
solids after precipitation from Et2O. The H NMR spectra of
4-6 reveal the equivalence of the two cyclopentadienyl rings,
with an asymmetrical environment for the niobium center; four
multiplets between δ ) 5-7 ppm are observed for the protons
of the Cp rings. In addition, the 1H NMR spectra of 4-6 show
a doublet for the P-H moiety (1JPH ≈ 370 Hz). The IR spectra
of 4-6 reveal the absence of a ν(Nb-H) band and the existence
of ν(P-H) at ca. 2280 cm-1. The 13C{1H}, 31P{1H}, and 31P
NMR spectra are consistent with the observations outlined above
(see Experimental Section).
In the study described here it was envisaged that [Nb(η5-
C5H4SiMe3)2(PPh2)(L)] [L ) CNBun (7), CNCy (8), and
CNXylyl (9)] would be obtained by deprotonation13 of the P-H
bond of 4, 5, and 6. Indeed, the preparation of the phosphi-
doniobiocene complexes 7, 8, and 9 was achieved by deproto-
nation of the PHPh2 ligand present in these complexes (eq 1).
Starting from a well-known methodology13,14 to prepare
phosphidoniobocene complexes [Nb(η5-C5H4R)2(PPh2)(L)], herein
we report new isocyanide-containing niobocene derivatives,
namely, [Nb(η5-C5H4SiMe3)2(PPh2)(CNR)], as well as their
reactivity in alkylation and insertion15-17 processes with elec-
trophilic reagents RX and CS2 to give cationic d2 18-electron
species [Nb(η5-C5H4SiMe3)2(PRPh2)(L)]X and phosphinodithio-
formato-containing complexes [Nb(η5-C5H4SiMe3)2(κ1-S-SC-
(S)(PPh2))(L), respectively.
Complexes 7-9 were isolated as air-sensitive yellow-brown
oils, and they are soluble in most organic solvents such as thf,
hexane, pentane, and toluene. Complexes 7-9 were character-
Results and Discussion
We report the synthesis of new phosphorus-containing
niobocene complexes using a new family of hydride isocyanide
niobiocene complexes as starting materials, [Nb(η5-C5H4-
SiMe3)2H(L)] [L ) CNBun (1), CNCy (2), and CNXylyl (3)].
1
ized by IR and H, 13C{1H}, and 31P NMR spectroscopy. The
IR spectra of 7-9 contain one band between 1990 and 2111
cm-1, and this corresponds to ν(CtN), in agreement with the
linear disposition of the isocyanide ligands. A band correspond-
ing to ν(P-H) of the P-H bond was not observed in the IR
spectra, which is consistent with the conversion of the coordi-
nated diphenylphosphine ligand to a new phosphido ligand.
Further evidence for this transformation was provided by the
1H NMR spectra, which did not contain the doublet correspond-
ing to the P-H bond at ca. 7 ppm that is present in the parent
complexes 4-6.13 Evidence for the presence of a new phosphido
ligand was provided by the 31P NMR spectra, which contain a
singlet at ca. δ -10.8 ppm due to the PPh2 ligand.12 This
latter signal is at higher field than that in the corresponding
PHPh2 ligand in complexes 4-6, which shows the higher
electron density on the P atom in the neutral phosphido ligand.
At low field the 13C{1H} NMR spectra exhibit one signal
between δ 212 and 217 ppm for the carbon atoms of the
CNR ligands. The spectroscopic data are in agreement with an
18-electron d2 niobocene species in which the phosphido
terminal ligand is coordinated as a monoanionic donor ligand.
Thus, the phosphorus atom of the phosphido ligand retains one
electron pair, and this makes it susceptible to further electrophilic
attack. The niobium atom must adopt a pseudo-tetrahedral
structure with both cyclopentadienyl rings bonded in a η5-
coordination mode to give the typical bent metallocene con-
formation.
(10) (a) Alcalde, M. I.; Mata, J.; Go´mez, M.; Royo. P. Organometallics
1994, 13, 462. (b) Carrondo, M. A. A. F. de C. T.; Morais, J.; Romao, C.
C.; Romao. M. J. Polyhedron 1993, 7, 765. (c) Rehder. D.; Bo¨ttcher, C.;
Collazo, C.; Hedelt, R.; Schmidt, H. J. Organomet. Chem. 1999, 585, 294.
(d) Aspinall, H. C.; Roberts, M. M.; Lippard. S. J. Inorg. Chem. 1984, 23,
1782. (e) Yu, J. S.; Felter, L.; Potyen, M. C.; Clark, J. R.; Visciglio, V. M.;
Fanwick, P. E.; Rothwell, I. P. Organometallics 1996, 15, 4443.
(11) Cotton, F. A.; Wilkinson, G.; Murillo, C. A.; Bochmann, M.
AdVanced Inorganic Chemistry, 6th ed.; J. Wiley & Sons: New York, 1999;
p 247.
(12) Antin˜olo, A.; Garc´ıa-Yuste, S.; Otero, A.; Perez-Flores, J. C.;
Reguillo-Carmona, R.; Rodriguez, A. M.; Villasen˜or, E. Organometallics
2006, 25, 1310.
(13) Antin˜olo, A.; Carrillo-Hermosilla, F.; Fernandez-Baeza, J.; Garc´ıa-
Yuste, S.; Otero, A.; Sa´nchez-Prada, J.; Villasen˜or, E. Eur. J. Inorg. Chem.
2000, 1437.
(14) Selected references: (a) Oudet, P.; Kubicki, M. M.; Moise, C.
Organometallics 1994, 13, 4278. (b) Oudet, P.; Perrey, D.; Bonnet, G.;
Moise, C.; Kubicki, M. M. Inorg. Chim. Acta 1995, 273, 79. (c) Challet,
S.; Leblanc, J. C.; Moise, C. New J. Chem. 1993, 17, 251.
(15) (a) Antin˜olo, A.; Fajardo, M.; Lo´pez-Mardomingo, C.; Otero, A.;
Mourad, Y.; Mugnier, Y.; Sanz-Aparicio, J.; Fonseca, I.; Florencio, F.
Organometallics 1990, 9, 164. (b) Antin˜olo, A.; Otero, A.; Fajardo, M.;
Lo´pez-Mardomingo, C.; Lucas, D.; Mugnier, Y.; Lanfranchi, M.; Pelling-
helli, M. A. J. Organomet. Chem. 1992, 435, 55. (c) Antin˜olo, A.; Fajardo,
M.; Gil-Sanz, R.; Lo´pez-Mardomingo, C.; Martin-Villa, P.; Otero, A.;
Kubicki, M. M.; Mugnier, Y.; El Krami, S.; Mourad, Y. Organometallics
1993, 12, 381. (d) Antin˜olo, A.; Carrillo-Hermosilla, F.; Garc´ıa-Yuste, S.;
Freitas, M.; Otero, A.; Prashar, S.; Villasen˜or, E.; Fajardo, M. Inorg. Chim.
Acta 1997, 259, 101.
Complexes 7-9 are excellent starting materials for the
synthesis of a new family of 18 e- cationic niobocene
complexes. In the second part of this article we describe the
reactivity of complexes 7-9 toward alkylation processes with
several RX reagents as electrophilic species. The reaction of
(16) Antin˜olo, A.; del Hierro, I.; Fajardo, M.; Garc´ıa-Yuste, S.; Otero,
A.; Blacque, O.; Kubicki, M. M.; Amaudrut, J. Organometallics 1996, 15,
1966.
(17) Antin˜olo, A.; Fajardo, M.; Garc´ıa-Yuste, S.; del Hierro, I.; Otero,
A.; El Krami, S.; Mourad, Y.; Mugnier, Y. J. Chem. Soc., Dalton Trans.
1995, 3409.

3672 Organometallics, Vol. 25, No. 15, 2006
Antin˜olo et al.
Scheme 2
complexes 7-9 with excess alkyl halide, such as methyl
iodide (MeI), benzyl bromide (BzBr), and phenethyl bromide
(PhCH2CH2Br), gives d2 18 e- cationic phosphinoniobocene
complexes [Nb(η5-C5H4SiMe3)2(PRPh2)(L)]X [R ) Me, X )
I, L ) CNBun (10), CNCy (11), and CNXylyl (12); R )
CH2Ph, X ) Br, CNBun (13), CNCy (14), and CNXylyl (15);
R ) CH2CH2Ph, X ) Br, CNBun (16), CNCy (17), and
CNXylyl (18)] in high yield (see eq 2):
(19) rather than the expected dicationic derivative [{Nb(η5-
C5H4SiMe3)2(CNXylyl)}2(Ph2P(CH2CH2)PPh2)]I2 (see eq 3).
The reaction of complex 9 with I2/Et2O was successful as an
alternative method to obtain 19. The new iododiphenylphosphine
complex was isolated as a deep red air-sensitive solid. The ionic
nature of complex 19 was confirmed by measurement of the
molar conductivity (ΛM ) 105.6 Ω-1 cm2 mol-1), which is
consistent with a 1:1 electrolyte.18 The structural characterization
was carried out by both spectroscopic and X-ray diffraction
studies (see Experimental Section).
The IR spectrum shows one band at 2078 cm-1, and this
corresponds to ν(CtN) of the CtNXylyl ligand. In the NMR
spectra (1H and 13C) the absence of a resonance in the typical
region for the Ph2P(CH2CH2)PPh2 ligand, corresponding to the
ethylene bridge of the P(CH2CH2)P moiety, confirms that this
ligand is not present. The 13C{1H} NMR spectrum shows the
resonance of the carbon atom of the CNXylyl ligand at δ 190.3
ppm. The 31P NMR spectrum contains a signal at δ 85.2 ppm
due to the iodophosphine ligand (see Experimental Section).
These chemical shift values show the effect of the presence of
the iodine atom by comparison with the data for complex 9.
This comparison is consistent with the decreasing electronic
density in the phosphorus atom.12
X-ray Diffraction Study of [Nb(η5-C5H4SiMe3)2(PMePh2)-
(CNCy)]I (11) and [Nb(η5-C5H4SiMe3)2(PMePh2)(CNXylyl)]I
(12). Crystallographic analyses were carried out on suitable
single crystals of 11 and 12. The aim of this crystallographic
study was to establish the structures of 11 and 12 unambiguously
and to ascertain the effect of steric hindrance of the isocyanide
alkyl or aryl substitutes on the NbC-N-C bond angle of the
isocyanide ligand. To the best of our knowledge, these molecular
structures represent two of the few examples described for
niobocene complexes containing an isocyanide moiety.
Single crystals of 11 and 12 suitable for X-ray analysis were
obtained by slow diffusion of diethyl ether into dichloromethane
solutions of the complexes. ORTEP views of the molecular
structures of complexes 11 and 12 are shown in Figures 1 and
2, respectively, and selected bond distances and angles are given
in Table 1.
The formation of these complexes must be considered in
terms of an alkylation process resulting from electrophilic attack
of the alkyl halide on the nucleophilic P atom of the phosphido
terminal ligand.9a,12
Complexes 10-18 were isolated as deep red air-sensitive
crystalline solids. The low solubility of the complexes in
hydrocarbons, ethers, and aromatic solvents enabled us to isolate
the products very easily in analytically pure form.
Fortunately, all of the complexes are sufficiently soluble in
acetone to allow their NMR spectra to be recorded. The ionic
nature of complexes 10-18 was confirmed by measuring the
molar conductivity (see Experimental Section), and the values
are consistent with 1:1 electrolytes.18
Compounds 10-18 were characterized spectroscopically (see
Experimental Section). The most significant bands in the IR
spectra appear at ca. 2000 cm-1, and these correspond to
ν(CtN) (see Experimental Section), in agreement with a linear
disposition of the isocyanide ligands. The 31P NMR spectra each
contain a broad resonance, and these appear at ca. δ 50 ppm
(see Experimental Section). These chemical shift values show
the effect that alkylation has on the phosphorus by comparison
with the 31P NMR chemical shift of the phosphido terminal
ligand in complexes 7-9. This comparison shows the differ-
ences in electron density on the P atom. In agreement with the
IR spectra, the 13C{1H} NMR spectra of 10-18 show low-field
resonances for the carbon atom of the isocyanide ligand (ca. δ
200 ppm) as broad signals, probably due to the quadrupolar
moment of the niobium atom.
The use of 1,2-diiodoethane (ICH2CH2I) as the alkylating
reagent with 9 gave the cationic iodophosphinoniobocene
triiodide complex [Nb(η5-C5H4SiMe3)2(P(I)Ph2)(CNXylyl)]I3
The molecular structures of 11 and 12 are typical of bent
metallocenes. The niobium geometry is distorted tetrahedral in
which the centroids of the cyclopentadienyl rings are considered
as occupying one unique coordination site and the phosphine
and the isocyanide ligands occupy the other two sites. The
(18) Geary, W. J. Coord. Chem. ReV. 1971, 7, 81.

Isocyanidephosphidoniobocene DeriVatiVes
Organometallics, Vol. 25, No. 15, 2006 3673
Table 1. Bond Lengths [Å] and Angles [deg] for 11 and 12
Bond Lengths
11
12
Nb(1)-C(1)
Nb(1)-C(25)
Nb(1)-C(21)
Nb(1)-C(22)
Nb(1)-C(32)
Nb(1)-C(31)
Nb(1)-C(30)
Nb(1)-C(33)
Nb(1)-C(24)
Nb(1)-C(23)
Nb(1)-C(29)
Nb(1)-P(1)
P(1)-C(8)
2.099(5)
2.353(5)
2.356(5)
2.356(5)
2.361(5)
2.367(5)
2.393(5)
2.414(5)
2.421(5)
2.433(5)
2.446(5)
2.574(1)
1.824(6)
1.829(6)
1.840(6)
1.177(7)
1.46(1)
Nb(1)-C(1)
Nb(1)-C(31)
Nb(1)-C(25)
Nb(1)-C(26)
Nb(1)-C(32)
Nb(1)-C(27)
Nb(1)-C(35)
Nb(1)-C(33)
Nb(1)-C(34)
Nb(1)-C(24)
Nb(1)-C(23)
Nb(1)-P(1)
P(1)-C(11)
P(1)-C(17)
P(1)-C(10)
N(1)-C(1)
2.09(1)
2.35(1)
2.335(9)
2.35(1)
2.36(1)
2.39(1)
2.413(9)
2.41(1)
2.44(1)
2.44(1)
2.511(8)
2.59(3)
1.81(1)
1.84(1)
1.84(1)
1.16(1)
1.39(1)
P(1)-C(9)
P(1)-C(15)
N(1)-C(1)
N(1)-C(2)
N(1)-C(2)
Bond Angles
Figure 1. ORTEP view of the molecular structure of 11 with 30%
probability ellipsoids. Hydrogen atoms have been omitted.
11
12
C(1)-Nb(1)-P(1)
C(8)-P(1)-C(9)
C(8)-P(1)-C(15)
C(9)-P(1)-C(15)
C(8)-P(1)-Nb(1)
C(9)-P(1)-Nb(1)
C(15)-P(1)-Nb(1)
C(1)-N(1)-C(2)
N(1)-C(1)-Nb(1)
83.2(2)
101.8(3)
101.0(3)
102.5(3)
114.0(2)
120.9(2)
114.0(2)
162.2(8)
173.1(5)
C(1)-Nb(1)-P(1)
C(11)-P(1)-C(17)
C(11)-P(1)-C(10)
C(17)-P(1)-C(10)
C(11)-P(1)-Nb(1)
C(17)-P(1)-Nb(1)
C(10)-P(1)-Nb(1)
C(1)-N(1)-C(2)
N(1)-C(1)-Nb(1)
83.6(3)
102.6(5)
98.3(6)
103.6(6)
116.0(3)
119.8(3)
113.8(4)
164(1)
173.5(9)
Table 2. Crystal Data and Structure Refinement for
11 and 12
11
12
empirical formula
fw
C36H50INNbPSi2 C38H48INNbPSi2
803.73
825.73
temperature (K)
wavelength (Å)
cryst syst, space group
293(2)
0.71073
monoclinic,
P21/c
293(2)
0.71073
orthorhombic,
P212121
a (Å)
b (Å)
c (Å)
â (deg)
11.143(5)
14.322(1)
24.444(3)
97.40(1)
3868(2)
4, 1.380
10.992(5)
14.390(2)
24.683(2)
Figure 2. ORTEP view of the molecular structure of 12 with 30%
probability ellipsoids. Hydrogen atoms have been omitted.
volume (Å3)
Z, calcd density (g/cm3)
3904(2)
4, 1.405
12.27
1680
structural parameters for the (Cp′)2Nb unit are very similar in
both complexes (Table 2), and the mutual orientation of the
two Cp′ rings is intermediate between eclipsed and staggered
in both compounds. The Si(1)-Cent(1)-Cent(2)-Si(2) angles
are 131.2° for 11 and 126.5° for 12. The distances between the
metal atom and the centroids of the Cp rings fall between
2.057(1) and 2.090(1) Å, and the value of the angle Cent(1)-
Nb(1)-Cent(2) is between 139.39(3)° and 132.71(4)° [Cent(1)
is the centroid of C(21)-C(25) for 11 and C(23)-C(27) for
12; Cent(2) is the centroid of C(29)-C(33) for 11 and
C(31)-C(35) for 12]. These values are typical of bent niobocene
derivatives. The Nb(1)-P(1) bond distances of 2.574(1) and
2.59(3) Å, respectively, are very close to the expected values
for phosphinoniobocene derivatives.19 The P(1) atom is pseudo-
tetrahedral. The CH3-P bond lengths of 1.824(6) Å for 11 and
abs coeff (cm-1
F(000)
)
12.36
1640
cryst size (mm)
limiting indices
0.3 × 0.1 × 0.1
0 e h e 14
0 e k e 18
-32 e l e 31
9299 [R(int) )
0.0276]
9299/78/495
1.063
R1 ) 0.0491,
wR2 ) 0.1403
0.4 × 0.4 × 0.2
0 e h e 14
0 e k e 18
-32 e l e 32
9411 [R(int) )
0.0314]
9411/0/406
0.967
R1 ) 0.0592,
wR2 ) 0.1280
no. of reflns collected/unique
no. of data/restraints/params
goodness-of-fit on F2
final R indices [I > 2σ(I)]
largest diff peak and hole (e‚A-3
) 0.924 and -0.806 0.729 and -0.709
1.84(1) Å for 12 fall into the expected range for other methyl-
phosphorus bonds.20 The C(1)-N(1) bond lengths of 1.177(7)
and 1.16(1) Å are consistent with the presence of a carbon-
nitrogen triple bond,21 and the C(1)-N(1)-C(2) angles are
162.2(8)° and 164(1)°; that is, they clearly deviate from linearity.
This confirms the back-donation of the niobium(III) d2 center
to the isocyanide ligand, with a triple bond remaining between
(19) (a) Challet, S.; Kubicki, M. M.; Leblanc, J.-C.; Moise, C.; Nuber,
B. J. Organomet. Chem. 1994, 483, 47. (b) Thiygarajan, B.; Michalczyk,
L.; Bollinger, J. C.; Bruno, J. W. Organometallics 1996, 15, 2588. (c) Bailey,
N. J.; Green, M. L. H.; Leech, M. A.; Saunders, J. F.; Tidswell, H. M. J.
Organomet. Chem. 1997, 538, 111. (d) Humphries, M. J.; Douthwaite, R.
E.; Green, M. L. H. J. Chem. Soc., Dalton Trans. 2000, 2952. (e) Nikonov,
G. I.; Crishin, Y. K.; Lemenovskii, D. A.; Kazennova, N. B.; Kumina, L.
G.; Howard, S. A. K. J. Organomet. Chem. 1997, 547, 183. (f) Nikonov,
G. I.; Lemenovskii, Yudorogar, K.; Churakov, A. V. Polyhedron 1999, 18,
1159.
(20) Fettinger, J. C.; Keogh, D. W.; Poli, R. Inorg. Chem. 1995, 34,
2343.
(21) Collazo, C.; Rodewald; D.; Schmidt H.; Rehder, D. Organometallics
1996, 15, 4884.

3674 Organometallics, Vol. 25, No. 15, 2006
Antin˜olo et al.
Scheme 3
C(1)-N(1), but in these cases, the contribution of the carbene
form in the interaction with the niobium center is small (see
Scheme 1). The results of this analysis are in agreement with
the IR data in solution (see Experimental Section).
The cyclohexylisocyanido and the xylylisocyanido ligands
are bonded to niobium at a lateral position in the major
coordination plane at the front sector of the bent-metallocene
wedge [C(1)-Nb-C(11) ) 107.3(3)°]. In both complexes the
-CtN substituent is oriented in an equatorial position in order
to decrease steric repulsive interactions between the phenyl rings
of the phosphine.
In the last part of this article we will describe the insertion
reaction of CS2 into the Nb-P bond of complexes 7-9 to yield
the products in which the diphenylphosphinodithioformato
ligand, Ph2P(S)CS-, is coordinated to the niobium center.12 Of
all the possible coordination modes to a metal center, the one
expected for the diphenylphosphinodithioformato ligand22 (see
Scheme 3) is the S-monodentate coordination mode c that exists
in the new diphenylphosphinodithioformatoniobocene [Nb(η5-
C5H4SiMe3)2(κ1-SC(S)(PPh2))(CNR)] [R ) Bun (20), Cy (21),
and Xylyl (22)].
The complexes were prepared by stirring of a mixture of 7
and 8 with carbon disulfide for few days. In this way, we were
able to isolate complexes 20-22 as air-sensitive red solids after
the appropriate workup. When the reaction mixture in thf was
stirred over a longer period of time, the solution became green
and the solvent was removed to give complex [Nb(η5-C5H4-
SiMe3)2(κ2-S,S-SC(S)(PPh2))], 23.
1H NMR and13C NMR have demonstrated to be a useful tool
to distinguish between the coordination modes of the dithio-
formate ligand in 20 and 21 versus 23. The most significant
difference between 20/21 and 23 in the spectra is the number
of signals corresponding to the cyclopentadienyl ligands. In fact,
1
the H NMR spectra show four multiplet resonances for 20-
22, for the mentioned ligand, whereas only two are present for
23; this observation is consistent with the absence or presence
of a symmetry plane (σv) respectively through the niobium
center. Similarly there are five and three signals for 20-22 and
23, respectively, in the 13C NMR spectra of the cyclopentadienyl
ligand of the niobocene system. Both the 1H NMR and 13C NMR
spectra are consistent with the formulas [Nb]-(κ1-S-SC(S)(PPh2))
for 20-22 and [Nb]-(κ2-S,S-SC(S)(PPh2)) for 23.12
Two possibilities can explain the formation of the diphe-
nylphosphinodithioformato ligand. (i) The insertion reaction
goes via a four-centered transition state to give the corresponding
new ligand. (ii) The transition state is formed by nucleophilic
attack by the lone electron pair of the phosphorus atom at the
carbon atom of the carbon disulfide, followed by the interaction
of one of the noncoordinated sulfur atoms with the niobium
metal center with simultaneous cleavage of the Nb-P bond.
As far as the mechanism for the formation of complex 23 is
concerned, this could occur by attack of the noncoordinated S
atom of the κ1-S-diphenylphosphinodithioformato ligand in 20
and 21 to the Nb center and the simultaneous elimination of
the CNR ligand to give the κ2-S,S-diphenylphosphinodithiofor-
mato coordination mode in milder conditions as reported for
other related compounds.4,12,13
Conclusions
We have prepared new phosphidoniobocenes 7 and 8, which
contain isocyanide as an ancillary ligand, starting from hydride
niobocenes (1, 2, or 3) and ClPPh2 through the formation of 4,
5, or 6 and subsequent reaction with sodium hydroxide. The
electrophilic attack of alkyl halides on the phosphorus atom of
the phosphido ligand in 7, 8, or 9 allowed the isolation of a
new family of d2 cationic niobocene species 10-19. The X-ray
molecular structures of 11 and 12 were determined, and they
are members of a small family of metallocenes of early transition
metals with isocyanide ligands. Finally, we studied the reactivity
of phosphido-containing niobocene complexes 7, 8, and 9
toward CS2. It was found that an insertion process into the Nb-P
bond occurs to give complexes 20, 21, and 22, in which a
phosphinodithioformato ligand is present.
The new diphenylphosphinodithioformatoniobocene deriva-
tives 20-23 were isolated as air-sensitive solids and were
characterized by IR and NMR spectroscopy (see Experimental
Section).
The IR spectra of 20-22 display a characteristic band at ca.
1000 cm-1, which corresponds to the ν(CdS),4,13 and another
band at 2040 cm-1 corresponding to the CNR group. The
presence of a Ph2P(S)CS- ligand is confirmed by a resonance
in each of the 31P{1H} NMR spectra at δ 40.3, 27.2, and 18.6
for complexes 20, 21, and 22, respectively (see Experimental
Section).
Compared with the 31P chemical shift for compounds 7-9,
the relatively low-field shift of each resonance for 20-22 is in
agreement with the different chemical environments for the
phosphorus atoms in the complexes.12
Experimental Section
General Procedures. All reactions were carried out using
Schlenk techniques. Oxygen and water were excluded through the
use of vacuum lines supplied with purified N2. Toluene was distilled
from sodium. Hexane was distilled from sodium/potassium alloy.
Diethyl ether and THF were distilled from sodium benzophenone.
All solvents were deoxygenated prior to use. [Nb(η5-C5H4SiMe3)2-
(H)3],2 [Nb(η5-C5H4SiMe3)2H(L)]6 (L ) CNCy (2), CNXylyl (3)),
(22) (a) Hey-Hawkins, E.; Lappert, M. F.; Atwood, J. L.; Boot, S. G. J.
Chem. Soc., Chem. Commun. 1987, 421. (b) Yih, K.-H.; Lin, Y.-C.; Cheng,
M.-C.; Wang, Y. J. Chem. Soc., Dalton Trans. 1995, 1305. (c) Yih, K.-H.;
Lin, Y.-C.; Cheng, M.-C.; Wang, J. Chem. Soc., Chem. Commun. 1993,
1380.

Isocyanidephosphidoniobocene DeriVatiVes
Organometallics, Vol. 25, No. 15, 2006 3675
[Nb(η5-C5H4SiMe3)2(PHPh2)(L)]Cl13 (L ) CNXylyl (6)), and
[Nb(η5-C5H4SiMe3)2(PPh2)(L)]23 (L ) CNXylyl (9)) were prepared
as described in the literature. Deuterated solvents were dried over
4 Å molecular sieves and degassed prior to use. ClPPh2, CNBun,
CS2, MeI, (C6H5)CH2Br, (C6H5)CH2CH2Br, and I2 were used as
supplied by Aldrich. 1H, 13C, and 31P NMR spectra were recorded
on a Varian Innova 500 MHz spectrometer at ambient temperature
Preparation of [Nb(η5-C5H4SiMe3)2(PPh2)(L)] [L ) CNBun
(7) and CNCy (8)]. A solution of [Nb(η5-C5H4SiMe3)2(PHPh2)(L)
]Cl [L ) CNBun (4) and CNCy (5)] (0.87 mmol) in toluene (30
mL) was treated with 0.5 M aqueous NaOH (1.72 mL, 10% excess).
The mixture was vigorously stirred. Within 4 h the precipitate had
dissolved and the organic phase had turned dark brown. The toluene
solution was filtered and evaporated to dryness. The product was
obtained as a yellow-brown oil in 80% yield for both 7 and 8.
1
unless stated otherwise. H, 13C, and 31P NMR chemical shifts (δ
values) are given in ppm relative to the solvent signal (1H, 13C) or
standard resonances (31P, external 85% H3PO4). IR spectra were
recorded on a Perkin-Elmer 883 spectrophotometer as Nujol mulls
on CsI windows.
Complex 7. IR (Nujol): ν (cm-1) 2111, 1817 (CtN). 1H NMR
3
(500 MHz, C6D6): δ 0.09 (s, 18 H, SiMe3), 0.65 (t, JHH ) 5 Hz,
3 H, CH3), 1.02, 1.14 (m, 2 H, -CH2-CH2), 3.16 (t, 3JHH ) 5 Hz,
2 H, CN-CH2), 4.46, 4.70, 4.75, 5.31 (2H, each a complex signal,
C5H4SiMe3), 6.99, 7.14, 7.65 (each a complex signal, C6H5).
13C{1H} NMR (125 MHz, C6D6): δ 0.6 (SiMe3), 13.6 (CH3), 20.5,
32.5 (-CH2-CH2-), 51.1 (-CN-CH2-), 87.7, 91.7, 92.1, 94.0
(C2-5, exact assignment not possible, C5H4SiMe3), 89.3 (C1,
Preparation of [Nb(η5-C5H4SiMe3)2(H)(CNBun)] (1). CNBun
(0.091 mL, 0.067 g, 0.800 mmol) was added by syringe to a solution
of [Nb(η5-C5H4SiMe3)2(H)3] (0.80 mmol) in THF (40 mL). The
mixture was stirred at 343 K for 2 h. The resulting red-brown
solution was filtered and evaporated to dryness. Complex 1 was
isolated as a red oily material after maintaining it under vacuum
for a lengthy period (yield: 95%).
1
C5H4SiMe3), 115.0, 123.0 (C6H5), 153.6 (d, JCP ) 30.0 Hz, Cipso
of C6H5), 214.1 (CtN). 31P{1H} NMR (202 MHz, C6D6): δ -4.2
(s, PPh2). Anal. Calcd for C33H45NNbPSi2: C, 62.34; H, 7.13; N
2.20. Found: C, 62.35; H, 7.21; N, 2.21.
Complex 1. IR (Nujol): ν (cm-1) 1715 (Nb-H), 2089, 1811
(CtN). 1H NMR (500 MHz, C6D6): δ -5.85 (s, 1 H, Nb-H), 0.25
Complex 8. IR (Nujol): ν (cm-1) 2098, 1830 (CtN). 1H NMR
(500 MHz, C6D6): δ 0.11 (s, 18 H, SiMe3), 0.80-1.62 (m, 10 H,
C6H11), 3.49 (m, 1H, H1, C6H11), 4.54, 4.82, 4.84, 5.41 (2 H, each
a complex signal, C5H4SiMe3), 6.90, 7.15, 7.65 (m, each a complex
signal, C6H5). 13C{1H} NMR (125 MHz, C6D6): δ 0.6 (SiMe3),
23.9, 25.1, 33.3 (C5H11), 57.2 (C1, C6H11), 91.9, 99.0, 99.3, 102.7
(C2-5, exact assignment not possible, C5H4SiMe3), 95.2 (C1,
C5H4SiMe3), 124.1, 133.8, 134.1 (C6H5), 154.1 (d, 1JCP ) 33.0 Hz,
3
(s, 18 H, SiMe3), 0.75 (t, JHH ) 5 Hz, 3 H, CH3), 1.25, 1.42 (m,
2 H, CH2-CH2), 3.20 (t, 2 H, CN-CH2), 4.38, 4.56, 4.89, 5.13
(2H, each a complex signal, C5H4SiMe3). 13C{1H} NMR (125 MHz,
C6D6): δ 0.7 (SiMe3), 13.6 (CH3), 20.5, 30.5 (CH2-CH2), 51.0
(CN-CH2), 87.7, 91.7, 92.0, 94.0 (C2-5, exact assignment not
possible, C5H4SiMe3), 94.6 (C1, C5H4SiMe3), 264.0 (CNBun). Anal.
Calcd for C21H36NNbSi2: C, 55.85; H, 8.04; N, 3.10. Found: C,
55.76; H, 8.13; N, 3.20.
C
ipso,C6H5), 212.2 (CtN). 31P{1H} NMR (202 MHz, C6D6): δ -3.3
Preparation of [Nb(η5-C5H4SiMe3)2(PHPh2)(L)]Cl [L )
CNBun (4) and CNCy (5)]. To a solution of [Nb(η5-C5H4SiMe3)2-
H(L)] [L ) CNBun (1)] (0.55 mmol) in Et2O (40 mL) was added
ClPPh2 (125 µL, 0.70 mmol) by syringe. A red-orange precipitate
formed immediately. When sedimentation was complete, the
solution was filtered and the residue was washed with Et2O (2 ×
20 mL) and dried in vacuo. Complex 4 was obtained as an orange
solid in 80% yield. Complex 5 was obtained in 80% yield by
following the same process as for 4.
(PPh2). Anal. Calcd for C35H47NNbPSi2: C, 63.52; H, 7.16; N,
2.12. Found: C, 63.45; H, 7.21; N, 2.28.
Preparation of [Nb(η5-C5H4SiMe3)2(PRPh2)(L)]X [R ) Me,
X ) I, L ) CNBun (10), CNCy (11), and CNXylyl (12); R )
CH2Ph, X ) Br, CNBun (13), CNCy (14), and CNXylyl (15); R
) CH2CH2Ph, X ) Br, CNBun (16), CNCy (17), and CNXylyl
(18)]. To a solution of [Nb(η5-C5H4SiMe3)2(PPh2)(L)] [L ) CNBun
(7), CNCy (8), and CNXylyl (9)] (0.83 mmol) in dry toluene (30
mL) was added an excess of the appropriate alkyl halide [5, methyl
iodide (1:10) (1.17 g, 0.51 mL, F ) 2.28 g/mL, 8.30 mmol); 6,
benzyl bromide, (1:10) (1.42 g, 0.98 mL, F ) 1.44 g/mL, 8.30
mmol); and 7, 1-(2-bromoethyl)benzene (1:10) (1.53 g, 1.14 mL,
F ) 1.34 g/mL, 8.30 mmol)]. In each case the reaction mixture
was stirred at room temperature for 2 h. During this time the
solution changed to a deep red color. The solvent was evaporated
under vacuum to dryness. The resulting solid was recrystallized
by dissolving it in dichloromethane and placing a layer of diethyl
ether above it in a Schlenk tube. Deep red crystals began to grow
within a few days. The resulting solid was filtered off to give a
deep red solid in 80-85% yield for 10, 11, 12, 13, 14, 15, 16, 17,
and 18.
Complex 4. ΛM (Ω-1 cm2 mol-1): 92.1. IR (Nujol): ν (cm-1
)
1
2245 (P-H), 2111 (CtN). H NMR (500 MHz, acetone-d6): δ
0.02 (s, 18 H, SiMe3), 0.95 (t, 3JHH ) 5 Hz, 3 H, CH3), 1.45, 1.76
(m, 2 H, CH2-CH2), 4.09 (t, 2 H, CN-CH2), 5.11, 5.14, 5.41,
1
5.70 (2H, each a complex signal, C5H4SiMe3), 7.27 (d, JHP
)
357 Hz, PHPh2), 7.48 (m, 2 H, C6H5), 7.68 (m, 8 H, C6H5).
13C{1H} NMR (125 MHz, acetone-d6): δ 0.0 (SiMe3), 13.6
(CH3), 20.5, 30.5 (CH2-CH2), 47.2 (CN-CH2), 92.5, 99.0, 100.6
(C2-5, exact assignment not possible, C5H4SiMe3), 99.3 (C1,
C5H4SiMe3), 122.7, 125.3, 131.2, 139.4 (C6H5). 31P{1H} NMR
(202 MHz, acetone-d6): δ 32.8 (s, PHPh2). 31P NMR (202 MHz,
1
acetone-d6): δ 32.8 (d, JPH ) 357 Hz, PHPh2). Anal. Calcd for
C33H46ClNNbPSi2: C, 58.97; H, 6.85; N, 2.01. Found: C, 58.56;
H, 6.23; N, 2.30.
Complex 10. ΛM (Ω-1 cm2 mol-1): 95.2. IR (Nujol): ν (cm-1
)
1
2053 (CtN). H NMR (500 MHz, acetone-d6): δ 0.25 (s, 18 H,
Complex 5. ΛM (Ω-1 cm2 mol-1): 108.1. IR (Nujol): ν (cm-1
)
3
SiMe3), 1.01 (t, JHH ) 5.5 Hz, 3 H, -CH3), 1.53, 1.92 (m, 2 H,
2250 (P-H), 2108 (CtN). 1H NMR (500 MHz, CDCl3):
δ
3
-CH2-CH2-), 4.27 (t, JHH ) 5.5 Hz, 2 H, CN-CH2), 2.25 (d,
0.15 (s, 18 H, SiMe3), 0.80-2.06 (m, 10 H, C6H11), 4.10 (m,
1H, H1, C6H11), 4.88, 4.95, 5.11, 5.48 (2H, each a complex signal,
C5H4SiMe3), 7.50 (d, 1JHP ) 325 Hz, PHPh2), 7.40-7.68 (m, C6H5).
13C{1H} NMR (125 MHz, acetone-d6): δ 0.1 (SiMe3), 23.6, 24.6,
32.8 (C5H11), 56.9 (C1, C5H11), 90.8, 98.5, 98.6, 100.2 (C2-5, exact
assignment not possible, C5H4SiMe3), 99.1 (C1, C5H4SiMe3), 128.9,
129.1, 130.4, 132.4 (C6H5). 31P{1H} NMR (202 MHz, CDCl3): δ
32.2 (s, PHPh2). 31P NMR (202 MHz, acetone-d6): δ 32.2 (d, 1JPH
) 325 Hz, PHPh2). Anal. Calcd for C35H48ClNNbPSi2: C, 60.20;
H, 6.93; N, 2.01. Found: C, 59.96; H, 6.73; N, 2.10.
2JHP ) 7.8 Hz, 3 H, Me), 4.37, 4.73, 5.02, 5.35 (2H, each a com-
plex signal, C5H4SiMe3), 7.53 (m, 10 H, C6H5). 13C{1H} NMR
(125 MHz, acetone-d6): δ 0.2 (SiMe3), 15.2 (-CH3), 22.6
(-CH2-CH2-CH3), 24.5 (-CH2-CH2-CH2), 48.1 (CN-CH2-),
18.2 (d, 1JCP ) 27 Hz, Me), 89.6 (C1, C5H4SiMe3), 90.8, 95.2, 96.3,
99.3 (C2-5, exact assignment not possible, C5H4SiMe3), 116-129
1
(C6H5), 133.8 (d, JCP ) 33 Hz, Cipso C6H5), 203.2 (CtN).
31P{1H} NMR (202 MHz, acetone-d6): δ 41.4 (PMePh2). Anal.
Calcd for C34H48INNbPSi2: C, 52.51; H, 6.22; N, 1.80. Found: C,
52.79; H, 6.32; N, 1.70.
Complex 11. ΛM (Ω-1 cm2 mol-1): 90.3. IR (Nujol): ν (cm-1
)
(23) Antin˜olo, A.; Garc´ıa-Yuste, S.; Lopez-Solera, M. I.; Otero, A.; Pe´rez-
Flores, J. C.; Reguillo-Carmona, R.; Villasen˜or, E. J. Chem. Soc., Dalton
Trans. 2006, 1495.
1
2074 (CtN). H NMR (500 MHz, acetone-d6): δ 0.25 (s, 18 H,
SiMe3), 1.30-1.95 (m, 10 H, C6H11), 2.65 (d, 2JHP ) 7.3 Hz, 3 H,

3676 Organometallics, Vol. 25, No. 15, 2006
Antin˜olo et al.
3
Me), 4.5 (m, 1 H, H1 C6H11), 4.75, 5.09, 5.35, 5.67 (2H, each a
complex signal, C5H4SiMe3), 7.03, 7.34, 7.76 (m, C6H5). 13C{1H}
0.93 (t, JHH ) 5.3 Hz, 3 H, -CH3), 1.22, 1.42 (m, 2 H,
3
-CH2-CH2-), 4.20 (t, JHH ) 5.0 Hz, 2 H, CN-CH2), 3.6 (d,
1
NMR (125 MHz, acetone-d6): δ 0.0 (SiMe3), 15.8 (d, JCP ) 30
2JHP ) 7.4 Hz, 4 H, -CH2-CH2-Ph), 4.83 (4H, a complex
signal, C5H4SiMe3), 5.01, 5.58 (2H, each a complex signal,
C5H4SiMe3), 6.55-7.70 (m, C6H5). 13C{1H} NMR (125 MHz,
CDCl3): δ 0.2 (SiMe3), 13.6 (-CH3), 20.4, 25.5 (-CH2-CH2-),
47.6 (-CN-CH2-), 34.0 (d, 1JCP ) 28 Hz, -CH2-CH2-Ph), 93.5
(C1, C5H4SiMe3), 90.5, 99.1, 99.7, 99.9 (C2-5, exact assign-
ment not possible, C5H4SiMe3), 126.0-134.0 (C6H5), 140.0 (d,
1JCP ) 35.0 Hz, Cipso C6H5), 181.7 (CtN). 31P{1H} NMR (202
MHz, CDCl3): δ 50.6 (s, P(CH2Ph)Ph2). Anal. Calcd for
C43H56BrNNbPSi2: C, 60.98; H, 6.67; N, 1.65. Found: C, 60.81;
H, 6.71; N, 1.72.
Hz, Me), 13.8, 20.4, 47.1 (exact assignment not possible, C6H11),
68.8 (C1, C6H11), 98.8, 99.2, 100.5 (C2-5, exact assignment not
3
possible, C5H4SiMe3), 92.5 (C1, C5H4SiMe3), 129.4 (d, JCP ) 9
Hz, Cmeta of C6H5), 131.2 (C6H5), 133.3 (d, 2JCP ) 16 Hz, Cortho of
1
C6H5), 134.5 (d, JCP ) 34 Hz, Cipso of C6H5), 205.2 (CtN).
31P{1H} NMR (202 MHz, acetone-d6): δ 40.5 (PMePh2). Anal.
Calcd for C36H50INNbPSi2: C, 53.80; H, 6.27; N, 1.74. Found: C,
53.70; H, 6.30; N, 1.72.
Complex 12. ΛM (Ω-1 cm2 mol-1): 99.0. IR (Nujol): ν (cm-1
)
2031 (CtN). 1H NMR (500 MHz, CDCl3): δ 0.18 (s, 18 H, SiMe3),
2
Complex 17. ΛM (Ω-1 cm2 mol-1): 103.2. IR (Nujol): ν (cm-1
)
2.16 (d, JHP ) 8.0 Hz, 3 H, Me), 2.39 (s, 6 H, CH3 of Xylyl),
1
4.58, 5.05, 5.15, 5.56 (2H, each a complex signal, C5H4SiMe3),
7.18, 7.24, 7.39, 7.41 (m, each a complex signal C6H5). 13C{1H}
NMR (125 MHz, CDCl3): δ 0.2 (SiMe3), 19.3 (CH3 Xylyl), 19.3
2047 (CtN). H NMR (500 MHz, acetone-d6): δ 0.14 (s, 18 H,
SiMe3), 1.41-2.70 (m, 10 H, C6H11), 2.50 (s, 4 H, -CH2-CH2-
Ph), 3.79 (m, 1 H, H1 C6H11), 4.01 (d, 2JHP ) 6.5 Hz, 2 H, -CH2-
CH2-Ph), 4.72, 5.10, 5.53, 5.85 (2H, each a complex signal,
C5H4SiMe3), 6.90-7.90 (m, 15 H, C6H5). 13C{1H} NMR (125 MHz,
C6D6): δ 0.2 (SiMe3), 16.8, 22.4, 41.0 (C6H11), 66.1 (C1, C6H11),
1
(d, JCP ) 29 Hz, Me), 91.8, 98.9, 100.2, 100.6 (C2-5, exact
assignment not possible, C5H4SiMe3), 101.9 (C1, C5H4SiMe3),
127.5, 128.7, 128.8, 128.9, 130.9, 131.1, 131.3 (exact assignment
1
1
not possible, C6H5), 135.5 (d, JCP ) 37.5 Hz, Cipso C6H5), 198.1
33.5 (-CH2-CH2-Ph), 44.3 (d, JCP ) 25 Hz, -CH2-CH2-Ph),
(CtN). 31P{1H} NMR (202 MHz, CDCl3): δ 38.3 (s, PMePh2).
Anal. Calcd for C38H48INNbPSi2: C, 55.27; H, 5.86; N, 1.70.
Found: C, 55.08; H, 5.72; N, 1.82.
92.4, 93.6, 102.4, 104.5 (C2-5, exact assignment not possible,
C5H4SiMe3), 97.8 (C1, C5H4SiMe3), 128.0-131.1 (C6H5), 134.2
(d, JCP ) 35 Hz, Cipso C6H5), 201.4 (CtN). 31P{1H} NMR (202
1
Complex 13. ΛM (Ω-1 cm2 mol-1): 92.0. IR (Nujol): ν (cm-1
)
MHz, C6D6): δ 53.2 (s, P(CH2CH2Ph)Ph2). Anal. Calcd for
C43H56BrNbPSi2: C, 60.98; H, 6.67; N, 1.65. Found: C, 61.15; H,
6.54 3.21; N, 1.44.
2043 (CtN). 1H NMR (500 MHz, CDCl3): δ 0.22 (s, 18 H,
3
SiMe3), 1.23 (t, JHH ) 5.3 Hz, 3 H, -CH3), 1.32, 1.52 (m, 2 H,
3
Complex 18. ΛM (Ω-1 cm2 mol-1): 95.0. IR (Nujol): ν (cm-1
)
-CH2-CH2-), 3.98 (t, JHH ) 5.0 Hz, 2 H, CN-CH2), 3.80 (d,
2JHP ) 7.4 Hz, 2 H, -CH2-Ph), 4.75, 5.19, 5.33, 5.74 (2H, each
a complex signal, C5H4SiMe3), 6.55, 7.35, 6.96, 7.05, 7.20 (m, exact
assignment not possible C6H5). 13C{1H} NMR (125 MHz,
CDCl3): δ 0.2 (SiMe3), 15.5 (-CH3), 23.4, 25.5 (-CH2-CH2-
2034 (CtN). 1H NMR (500 MHz, CDCl3): δ 0.15 (s, 18 H, SiMe3),
2.25 (s, 6 H, CH3 of Xylyl), 2.56 (s, 2 H, -CH2-CH2-Ph), 3.38
2
3
(dt, JHP ) 7.2 Hz, JHH ) 5.8 Hz, -CH2-CH2-Ph), 4.68, 5.07,
3
5.23, 5.76 (2H, each a complex signal, C5H4SiMe3), 6.96 (t, JHH
1
) 7.3 Hz, 2 H, Hpara of C6H5), 7.20 (d, 3JHH ) 7.2 Hz, 4 H, Hortho
CH3), 45.3 (-CN-CH2-), 43.1 (d, JCP ) 28 Hz, -CH2-Ph),
89.3 (C1, C5H4SiMe3), 95.2, 96.6, 98.6, 102.5 (C2-5, exact assign-
ment not possible, C5H4SiMe3), 129.0-133.0 (C6H5), 135.6 (d,
1JCP ) 35.0 Hz, Cipso C6H5), 202.5 (CtN). 31P{1H} NMR (202
MHz, CDCl3): δ 56.4 (s, P(CH2Ph)Ph2). Anal. Calcd for
C40H52BrNNbPSi2: C, 59.55; H, 6.45; N, 1.74. Found: C, 59.80;
H, 6.61; N, 1.72.
3
of C6H5), 7.18 (s, 3 H, Harom of Xylyl), 7.40 (t, JHH ) 7.3 Hz, 4
H, Hmeta of C6H5), 7.42-7.70 (m, 5 H, Ph). 13C{1H} NMR (125
2
MHz, CDCl3): δ 0.1 (SiMe3), 19.0 (CH3 of Xylyl), 30.9 (d, JCP
) 5.8 Hz, -CH2-CH2-Ph), 34.6 (d, JCP ) 19.0 Hz, -CH2-
1
CH2-Ph), 92.1, 98.7, 100.4, 100.9 (C2-5, exact assignment not
possible, C5H4SiMe3), 101.6 (C1, C5H4SiMe3), 126.7, 127.9, 128.9,
133.0, 132, 129.2, 129.6, 130.0, 130.4 (Carom of Xylyl), 132.3 (d,
2JCP ) 15 Hz, Cortho of C6H5), 134.8 (Cipso of Xylyl), 140.3 (d, 1JCP
) 30 Hz, Cipso C6H5), 199.3 (CtN). 31P{1H} NMR (202
MHz, CDCl3): δ 50.5 (s, P(CH2CH2Ph)Ph2). Anal. Calcd for
C45H54BrNNbPSi2: C, 62.20; H, 6.26; N, 1.61. Found: C, 62.32;
H, 5.98; N, 1.54.
Complex 14. ΛM (Ω-1 cm2 mol-1): 103.0. IR (Nujol): ν (cm-1
)
1
2058 (CtN). H NMR (500 MHz, acetone-d6): δ 0.23 (s, 18 H,
SiMe3), 1.30-2.22 (m, 10 H, C6H11), 3.89 (m, 1 H, H1 C6H11),
3.96 (d, 2JHP ) 6.5 Hz, 2 H, -CH2-Ph), 4.82, 5.09, 5.44, 5.70 (2
H, each a complex signal, C5H4SiMe3), 6.71-7.90 (m, 15 H, C6H5).
13C{1H} NMR (125 MHz, acetone-d6): δ 0.3 (SiMe3), 15.8, 22.5,
42.3 (C6H11), 71.2 (C1, C6H11), 41.4 (d, 1JCP ) 25 Hz, -CH2-Ph),
89.2, 93.8, 99.9, 103.5 (C2-5, exact assignment not possible,
C5H4SiMe3), 94.7 (C1, C5H4SiMe3), 129.0-133.0 (C6H5), 135.6 (d,
1JCP ) 35 Hz, Cipso of C6H5). 31P{1H} NMR (202 MHz, C6D6): δ
55.5 (s, P(CH2Ph)Ph2). Anal. Calcd for C42H54BrNNbPSi2: C,
60.57; H, 6.54; N, 1.68. Found: C, 60.62; H, 6.68; N, 1.71.
Preparation of [Nb(η5-C5H4SiMe3)2(P(I)Ph2)(CNXylyl)]I3
(19). Method 1. To a solution of [Nb(η5-C5H4SiMe3)2(PPh2)-
(CNXylyl)](9) (0.45 g, 0.74 mmol) in dry toluene (30 mL) was
added an excess of 1,2-diiodoethane [ICH2CH2I; (1:10) (2.23 g;
1.05 mL; F ) 2.13 g/mL; 7.40 mmol)]. The reaction mixture was
stirred at room temperature for 2 h. During this time the solution
changed to a deep red color. The solvent was evaporated under
vacuum to dryness. The remaining solid was crystallized by
dissolving it in dichloromethane and placing a layer of diethyl ether
above it in a Schlenk tube. Deep red crystals began to grow within
a few days. The resulting product was filtered off to give a deep
red solid in 85% yield.
Method 2. To a solution of [Nb(η5-C5H4SiMe3)2(PPh2)-
(CNXylyl)] (9) (0.50 g, 0.83 mmol) in dry toluene (30 mL) was
added an excess of I2 in diethyl ether (1:2) (0.42 g, 1.66 mmol).
The reaction mixture was stirred at room temperature for 2 h. During
this time the solution changed to a deep red color. The solvent
was evaporated under vacuum to dryness. The resulting solid was
crystallized by dissolving it in dichloromethane and placing a layer
of diethyl ether above it in a Schlenk tube. Deep red crystals began
to grow within a few days. The resulting solid was filtered off to
give a deep red solid in 80% yield.
Complex 15. ΛM (Ω-1 cm2 mol-1): 95.5. IR (Nujol): ν (cm-1
)
2038 (CtN). 1H NMR (500 MHz, CDCl3): δ 0.17 (s, 18 H, SiMe3),
2.42 (s, 6 H, CH3 Xylyl), 3.74 (d, 2JHP ) 6.4 Hz, 2 H, -CH2-Ph),
4.67, 5.13, 5.26, 5.72 (2H, each a complex signal, C5H4SiMe3),
6.52, 6.91, 7.03, 7.39, 7.19, 7.17, 7.45, 7.32 (m, each a complex
signal C6H5). 13C{1H} NMR (125 MHz, CDCl3): δ 0.7 (SiMe3),
19.8 (CH3 lyl), 39.9 (d, 1JCP ) 29.0 Hz, -CH2-Ph), 93.36, 98.95,
100.96, 101.59 (C2-5, exact assignment not possible, C5H4SiMe3),
102.14 (C1, C5H4SiMe3), 127.81 (Cipso of Xylyl), 128.27, 128.65,
128.78 (Carom of Xylyl), 130.63, 131.69, 133.70 (Cortho, Cmeta, and
1
Cpara of C6H5), 132.7 (d, JCP ) 37.5 Hz, Cipso of C6H5), 201.1
(CtN). 31P{1H} NMR (202 MHz, CDCl3): δ 53.3 (s, P(CH2Ph)-
Ph2). Anal. Calcd for C44H52BrNNbPSi2: C, 61.82; H, 6.13; N,
1.64. Found: C, 61.85; H, 5.99; N, 1.63.
Complex 16. ΛM (Ω-1 cm2 mol-1): 96.7. IR (Nujol): ν (cm-1
)
2106 (CtN). 1H NMR (500 MHz, CDCl3): δ 0.13 (s, 18 H, SiMe3),

Isocyanidephosphidoniobocene DeriVatiVes
Organometallics, Vol. 25, No. 15, 2006 3677
Complex 19. ΛM (Ω-1 cm2 mol-1): 105.6. IR (Nujol): ν (cm-1
)
C38H45NNbPS2Si2: C, 60.06; H, 5.97; N, 1.84. Found: C, 60.17;
H, 6.11; N, 1.89.
2078 (CtN). 1H NMR (500 MHz, CDCl3): δ 0.33 (s, 18 H, SiMe3),
2.56 (s, 6 H, CH3 of Xylyl), 4.62, 5.91 (2H, each a complex signal,
C5H4SiMe3), 5.34 (4H, a complex signal, C5H4SiMe3), 7.53 (m,
13 H, Harom of C6H5 and Xylyl). 13C{1H} NMR (125 MHz, C6D6):
δ 1.0 (SiMe3), 20.3 (CH3 of Xylyl), 94.5, 101.8, 103.7 (C2-5, exact
assignment not possible, C5H4SiMe3), 104.6 (C1, C5H4SiMe3),
128.6, 129.1, 133.6 (Carom of Xylyl), 133.4 (C1 of Xylyl), 129.3
Preparation of [Nb(η5-C5H4SiMe3)2(K2-S,S-SC(S)(PPh2))] (23).
A mixture of [Nb(η5-C5H4SiMe3)2(κ1-S-SC(S)(PPh2))(L)] [L )
CNBun (20), CNCy (21), and CNXylyl (22)] (0.56 g, 0.82 mmol)
and dry THF (20 mL) was stirred at room temperature for 15 days.
During this time the solution changed color from dark red to dark
green. The solvent was evaporated under vacuum to dryness. The
dark green oily residue was extracted with hexane (5 mL). The
solid was filtered off to give 90% yield of 23.
2
(Cpara Cmeta of C6H5), 136.0 (d, JCP ) 12 Hz, Cortho of C6H5),
and
138.0 (d, JCP ) 24 Hz, Cipso of C6H5), 190.3 (CtN). 31P{1H}
1
Complex 23. IR (Nujol): ν (cm-1) 1000 (CdS). 1H NMR (500
MHz, C6D6): δ 0.23 (s, 18 H, SiMe3), 4.94, 5.09 (m, 4 H each a
NMR (202 MHz, C6D6): δ 85.2 (s, P(I)Ph2). Anal. Calcd for
C37H45I4NNbPSi2: C, 37.30; H, 3.81; N, 1.18. Found: C, 37.26;
H, 3.64; N, 1.09.
3
complex signal, C5H4SiMe3); 6.55 (t, JHH ) 7.2 Hz, 2 H, C6H5),
3
3
Preparation of [Nb(η5-C5H4SiMe3)2(K1-S-SC(S)(PPh2))(L)] [L
) CNBun (20), CNCy (21), and CNXylyl (22)]. A mixture of
[Nb(η5-C5H4SiMe3)2(PPh2)(L)] [L ) CNBun (7), CNCy (8), and
CNXylyl (9)] (0.93 mmol) was treated with a stoichiometric amount
of CS2 (0.07 g, 0.06 mL, F ) 1.26 g/mL; 0.93 mmol), and the
mixture was stirred in dry THF (30 mL) at room temperature for
4 h. During this time the solution changed color from yellow-brown
to dark red. The solvent was evaporated under vacuum to dryness.
The dark red oily residue was extracted with hexane (5 mL). The
resulting solution was filtered and evaporated to dryness. The deep
red oil was dissolved in hexane (5 mL) and kept at 5 °C for 10 h.
A microcrystalline dark purple-red solid was obtained. The solid
was filtered off to give 82%, 85%, and 80% yield for 20, 21, and
22, respectively.
6.80 (d, JHH ) 7.1 Hz, 4 H, C6H5), 7.53 (t, JHH ) 7.1 Hz, 4 H,
C6H5). 13C{1H} NMR (125 MHz, C6D6): δ 0.4 (SiMe3), 105.9
(C1, C5H4SiMe3), 97.8, 105.3 (C2-3, exact assignment not possible,
1
C5H4SiMe3); 124.3, 125.7, 129.7 (C6H5), 141.8 (d, JCP ) 23.00
Hz, C6H5), 244.0 (d, JCP ) 20.00 Hz, CS2). 31P NMR (C6D6): δ
1
2.03 (PPh2). 31P{1H} NMR (202 MHz, C6D6): δ 2.03 (q, JPH
)
3
7.30 Hz, PPh2). Anal. Calcd for C30H39NbPS2Si2: C, 55.97; H,
6.11. Found: C, 56.00; H, 5.93.
X-ray Crystallographic Structure Determination of 11 and
12. Single crystals of a red block of 11 and red prismatic crystals
of 12 were placed in a NONIUS-MACH3 diffractometer equipped
with graphite-monochromated Mo KR radiation (λ ) 0.71073 Å).
The crystal data, data collection, structural solution, and refinement
parameters for both compounds are given in Table 2. Intensity data
were collected using an ω/2θ scan technique. Examination of two
standard reflections, monitored after 60 min, showed no sign of
crystal deterioration. Data were corrected for Lorentz and polariza-
tion effects, and semiempirical absorption correction (psi-scans)
was made.24 The structures were solved by direct methods using
the SIR92 computer program,25 completed by subsequent difference
Fourier syntheses, and refined by full matrix least-squares proce-
dures (SHELXL97)26 on F2. All non-hydrogen atoms were refined
with anisotropic thermal parameters. The hydrogen atoms were
placed using a “riding model” and included in the refinement at
calculated positions. Compound 11 exhibited a rotational disorder
of the SiMe3 groups with a 50:50 occupancy ratio. Furthermore
the cyclohexylisocyanide ligand appeared disordered over two
distinct sites in 50:50 ratio.
Complex 20. IR (Nujol): ν (cm-1) 2098 (CtN), 1100 (CdS),
630 (C-S). 1H NMR (500 MHz, C6D6): δ 0.10 (s, 18 H, SiMe3),
3
0.93 (t, JHH ) 5.3 Hz, 3 H, -CH3), 1.12, 1.42 (m, 2 H, -CH2-
CH2-), 4.40 (m, 2 H, CN-CH2), 4.63, 4.82, 5.20, 5.48 (2H, each
a complex signal, C5H4SiMe3), 6.90-7.70 (m, C6H5). 13C{1H}
NMR (125 MHz, C6D6): δ 0.2 (SiMe3), 13.6 (-CH3), 20.4, 25.5-
1
(-CH2-CH2-), 47.6 (-CN-CH2-), 34.0 (d, JCP ) 28 Hz,
-CH2-CH2-Ph), 92.6 (C1, C5H4SiMe3), 92.3, 94.0, 96.0, 99.9
(C2-5, exact assignment not possible, C5H4SiMe3), 126.0-134.0
(C6H5), 140.0 (d, 1JCP ) 35.0 Hz, Cipso C6H5), 185.5 (CtN), 260.3
(d, 1JCP ) 45.5 Hz, CS2). 31P{1H} NMR (202 MHz, C6D6): δ 40.3
(s, P(CH2Ph)Ph2). Anal. Calcd for C34H45NNbPS2Si2: C, 60.06;
H, 5.97; N, 1.84. Found: C, 60.11, 33.35; H, 6.11, 3.21; N, 1.72.
Complex 21. IR (Nujol): ν (cm-1) 2050 (CtN), 1089 (CdS),
The single crystals obtained for compound 19 diffracted par-
ticularly poorly and were of rather poor quality. For this reason
only a rough model of the structure could be obtained. Crystal
data: monoclinic, P21/n, a ) 21.397(2) Å, b ) 11.022(2) Å, c )
19.600(3) Å, â ) 107.19(1)°; V ) 4416(1), Z ) 4.
625 (C-S). 1H NMR (500 MHz, C6D6): δ 0.06 (s, 18 H, SiMe3),
3
0.90-1.60 (m, 10 H, C6H11), 3.39 (q, JHH ) 5.0 Hz, 1 H, H1 of
C6H11), 4.79, 4.91, 5.27, 5.29 (2H, each a complex signal,
C5H4SiMe3), 7.00 (d, 3JHH ) 7.0 Hz, 4 H, Hortho of C6H5), 7.77 (t,
3
3JHH ) 7.4 Hz, 4 H, Hmeta of C6H5), 7.93 (t, JHH ) 7.5 Hz, 2 H,
Hpara of C6H5). 13C{1H} NMR (125 MHz, C6D6): δ 0.4 (SiMe3),
23.7, 23.9, 32.8 (C6H11), 58.5 (C1 of C6H11), 92.6 (C1, C5H4SiMe3),
95.9, 100.9, 101.9, 103.7 (C2-5, exact assignment not possible,
C5H4SiMe3), 125.6, 128.3, 129.2 (C6H5), 135.0 (d, 1JCP ) 33.0 Hz,
Acknowledgment. We gratefully acknowledge financial
support from the Direccio´n General de Investigacio´n Cient´ıfica
Spain (MEC Grant. No. BQU2002-04638-CO2-02) and the
Junta de Comunidades de Castilla-La Mancha (Grant Nos. PAC-
02-003, GC-02-010, PBI05-23, and PBI-05-029).
1
Cipso of C6H5), 198.2 (CtN), 261.5 (d, JCP ) 45.5 Hz, CS2).
31P{1H} NMR (202 MHz, C6D6): δ 27.2 (s, PPh2). Anal. Calcd
for C36H47NNbPS2Si2: C, 58.59; H, 6.42; N, 1.90. Found: C, 58.60;
H, 6.45; N, 1.92.
Supporting Information Available: Detailed X-ray crystal-
lographic data of atomic positional parameters, bond distances and
angles, and anisotropic thermal parameters for complexes 11 and
12. Tables of X-ray crystallographic data for complexes 11 and
12. This material is available free of charge via the Internet at
http://pubs.acs.org.
Complex 22. IR (Nujol): ν (cm-1) 2042 (CtN), 1100 (CdS),
630 (C-S). 1H NMR (500 MHz, C6D6): δ -0.03 (s, 18 H, SiMe3),
2.19 (s, 6 H, CH3 of Xylyl), 4.82, 5.09, 5.19, 5.38 (2H, each a
complex signal, C5H4SiMe3), 6.70 (s, 3 H, Harom of Xylyl), 6.99 (t,
3
3JHH ) 7.2 Hz, 2 H, Hpara of C6H5), 7.05 (d, JHH ) 7.0 Hz, 4 H,
3
Hortho of C6H5), 7.75 (t, JHH ) 7.2 Hz, 4 H, Hmeta of C6H5).
OM060283P
13C{1H} NMR (125 MHz, C6D6): δ 0.8 (SiMe3), 19.9 (CH3 of
Xylyl), 97.1, 101.4, 102.9, 105.2 (C2-5, exact assignment not
possible, C5H4SiMe3), 95.8 (C1, C5H4SiMe3), 127.7, 127.9, 129.7
(s, Cpara, Cmeta, and Cortho of C6H5), 133.9, 135.4, 135.8 (s, Carom of
(24) North, A. C. T.; Phillips D. C.; Mathews, F. S. Acta Crystallogr.
Sect. A 1968, 24, 351.
(25) Altomare, A.; Cascarano, G.; Giacovazzo C.; Guagliardi, A. J. Appl.
Crystallogr. 1993, 26, 343.
(26) Sheldrick, G. M. SHELXL97, Programs for the Refinement of Crystal
Structures from the Diffraction Data; University of Go¨ttingen: Go¨ttingen,
Germany, 1997.
1
Xylyl), 141.2 (s, C1 of Xylyl), 141.6 (d, JCP ) 23 Hz, Cipso of
1
C6H5), 214.3 (s, CtN), 262.6 (d, JCP ) 46.5 Hz, CS2). 31P{1H}
NMR (202 MHz, C6D6): δ 18.6 (s, PPh2). Anal. Calcd for