Preparation and reactivity of nickel(0) complexes with η2-coordinated alkynylphosphines

Article abstract of DOI:10.1021/om000895o

The η²-alkynylphosphine complexes [Ni(η²-Ph₂PC≡CR)(dcpe)] (R = Me (1a), CO₂Me (1b), Ph (1c)), which are formed by displacement of ethylene from [Ni(C₂H₄)(dcpe)] by the corresponding alkynylphosphine, react with HCl (1 equiv) to give five-coordinate nickel(II) complexes, [NiCl{C(=CHR)PPh₂-κP,C¹}(dcpe)] (R = Me (2a), CO₂Me (2b), Ph (2c)), which contain a coordinated methylenephosphanickelacyclopropane fragment. In the case of 1a, the proton adds regiospecifically at the carbon atom bearing the methyl group. This mode of addition is favored for 1b,c, but small amounts of the addition products [NiCl{η¹-C(R)=CH(PPh₂)}(dcpe)] (R = CO₂Me (3b), Ph (3c)), arising from addition at the PPh₂-bearing carbon atoms, are also formed. Unsaturated molecules such as CS₂ and CO₂ insert into the Ni-P bonds of complexes 2a,c to give five-membered nickelacycles. Complexes 1a, 2a,c, and 3c have been structurally characterized by X-ray diffraction analysis.

Full text of DOI:10.1021/om000895o

980
Organometallics 2001, 20, 980-989
P r ep a r a tion a n d Rea ctivity of Nick el(0) Com p lexes w ith
η2-Coor d in a ted Alk yn ylp h osp h in es
Martin A. Bennett,* J effrey Castro, Alison J . Edwards, Mike R. Kopp,
Eric Wenger, and Anthony C. Willis
Research School of Chemistry, Australian National University,
Canberra, Australian Central Territory 0200, Australia
Received October 18, 2000
The η2-alkynylphosphine complexes [Ni(η2-Ph2PCtCR)(dcpe)] (R ) Me (1a ), CO2Me (1b),
Ph (1c)), which are formed by displacement of ethylene from [Ni(C2H4)(dcpe)] by the
corresponding alkynylphosphine, react with HCl (1 equiv) to give five-coordinate nickel(II)
complexes, [NiCl{C(dCHR)PPh2-κP,C1}(dcpe)] (R ) Me (2a ), CO2Me (2b), Ph (2c)), which
contain a coordinated methylenephosphanickelacyclopropane fragment. In the case of 1a ,
the proton adds regiospecifically at the carbon atom bearing the methyl group. This mode
of addition is favored for 1b,c, but small amounts of the addition products [NiCl{η1-C(R)d
CH(PPh2)}(dcpe)] (R ) CO2Me (3b), Ph (3c)), arising from addition at the PPh2-bearing carbon
atoms, are also formed. Unsaturated molecules such as CS2 and CO2 insert into the Ni-P
bonds of complexes 2a ,c to give five-membered nickelacycles. Complexes 1a , 2a ,c, and 3c
have been structurally characterized by X-ray diffraction analysis.
In tr od u ction
Only a few compounds are known in which alkyne
coordination is favored over P-donor coordination, e.g.
[Co2(CO)6{µ-η2-(C6F5)2PCtCR}] (R ) Me, Ph),1a [(CpNi)2-
(µ-η2-Ph2PCtC-tBu)],1b and [W(CO)(η2-Ph2PCtCPPh2)-
(S2CNEt2)2];5 more commonly the Ph2PCtCR ligands
bridge a pair of metal atoms via phosphorus and the
triple bond, as in [Ni2(CO)2(µ-η1:η2-Ph2PCtC-tBu)].6
Recently, however, complexes having Ph2PCtCPh η2-
coordinated to a NiP2 fragment were identified as
byproducts of the double-insertion reactions of this
alkynylphosphine with benzyne- and 4,5-difluoroben-
zyne-nickel(0) complexes.7
It was therefore of interest to investigate nickel(0)
complexes containing η2-coordinated alkynylphosphines
in more detail. In this paper we report the preparation,
characterization, and some reactions of several com-
plexes of this type.
As potentially bifunctional ligands, (alkynyl)diphen-
ylphosphines of general formula Ph2PCtCR have been
used extensively in organometallic and coordination
chemistry, especially for the formation of polynuclear
metal complexes.1 In general, P-donor coordination of
(alkynyl)diphenylphosphines is favored kinetically. In
the case of bis(diphenylphosphino)acetylene (dppa),2 this
property has been used to prepare numerous complexes
or clusters in which dppa acts as a bridging ligand
through its phosphorus atoms.3 Alkynylphosphines are
also known to react with polymetallic species by cleav-
age of the phosphorus-carbon bond.4
(1) Selected references: (a) Patel, H. A.; Carty, A. J .; Hota, N. K. J .
Organomet. Chem. 1973, 50, 247. (b) Carty, A. J .; Paik, H. N.; Ng, T.
W. J . Organomet. Chem. 1974, 74, 279. (c) Carty, A. J .; J acobson, S.
E.; Simpson, R. J .; Taylor, N. J . J . Am. Chem. Soc. 1975, 97, 7254. (d)
Taylor, N. J .; Carty, A. J . J . Chem. Soc., Dalton Trans. 1976, 799. (e)
Carty, A. J . Pure Appl. Chem. 1982, 54, 113. (f) Sappa, E.; Predieri,
G.; Tiripicchio, A.; Camellini, M. T. J . Organomet. Chem. 1985, 297,
103. (g) Nucciarone, D.; MacLaughlin, S. A.; Taylor, N. J .; Carty, A. J .
Organometallics 1988, 7, 106. (h) Charkas, A. A.; Randall, L. H.;
MacLaughlin, S. A.; Mott, G. N.; Taylor, N. J .; Carty, A. J . Organo-
metallics 1988, 7, 969. (i) Sappa, E.; Pasquinelli, G.; Tiripicchio, A.;
Camellini, M. T. J . Chem. Soc., Dalton Trans. 1989, 601. (j) Braga,
D.; Benvenutti, M. H. A.; Grepioni, F.; Vargas, M. D. J . Chem. Soc.,
Chem. Commun. 1990, 730. (k) Lang, H.; Zsolnai, L. Chem. Ber. 1991,
124, 259. (l) Fornie´s, J .; Lalinde, E.; Mart´ın, A.; Moreno, M. T.; Welch,
A. J . J . Chem. Soc., Dalton Trans. 1995, 1333. (m) Moldes, I.; Ros, J .
Inorg. Chim. Acta 1995, 232, 75. (n) Louattani, E.; Suades, J .; Alvarez-
Larena, A.; Piniella, J . F.; Germain, G. J . Organomet. Chem. 1996,
506, 121. (o) Dickson, R. S.; de Simone, T.; Parker, R. J .; Fallon, G. D.
Organometallics 1997, 16, 1531. (p) Ara, I.; Falvello, L. R.; Ferna´ndez,
S.; Fornie´s, J .; Lalinde, E.; Mart´ın, A.; Moreno, M. T. Organometallics
1997, 16, 5923.
Resu lts
Treatment of [Ni(C2H4)(dcpe)] with 1 equiv of Ph2PCt
CR (R ) Me, CO2Me) at 0 °C in diethyl ether gives
initially orange solutions, which are believed to contain
P-coordinated NiL3 species. When the reaction of [Ni-
(C2H4)(dcpe)] with Ph2PCtCMe is monitored by 31P
NMR spectroscopy at 0 °C, a broad triplet at δ 1.4
(4) (a) Bruce, M. I.; Williams, M. L.; Patrick, J . M.; White, A. H. J .
Chem. Soc., Dalton Trans. 1985, 1229. (b) Daran, J .-C.; Cabrera, E.;
Bruce, M. I.; Williams, M. L. J . Organomet. Chem. 1987, 319, 239. (c)
Bruce, M. I.; Liddell, M. J .; Tiekink, E. R. T. J . Organomet. Chem.
1990, 391, 81.
(5) (a) Ward, B. C.; Templeton, J . L. J . Am. Chem. Soc. 1980, 102,
1532. (b) Nickel, T. M.; Wau, S. Y. W.; Went, M. J . J . Chem. Soc., Chem.
Commun. 1989, 775. (c) Powell, A. K.; Went, M. J . J . Chem. Soc.,
Dalton Trans. 1992, 439.
(6) Paik, H. N.; Carty, A. J .; Dymock, K.; Palenik, G. J . J . Orga-
nomet. Chem. 1974, 70, C17.
(7) Bennett, M. A.; Cobley, C. J .; Rae, A. D.; Wenger, E.; Willis, A.
C. Organometallics 2000, 19, 1522.
(2) Abbreviations: dcpe ) bis(dicyclohexylphosphino)ethane, Cy2-
PCH2CH2PCy2; dppm ) bis(diphenylphosphino)methane, Ph2PCH2-
PPh2; dppa ) bis(diphenylphosphino)acetylene, Ph2PC2PPh2.
(3) (a) Orama, O. J . Organomet. Chem. 1986, 314, 273 and refer-
ences therein. (b) Hogarth, G.; Norman, T. Polyhedron 1996, 15, 2859
and references therein. (c) Sappa, E. J . Organomet. Chem. 1988, 352,
327.
10.1021/om000895o CCC: $20.00 © 2001 American Chemical Society
Publication on Web 01/27/2001

Ni(0) Complexes with η2-Alkynylphosphines
Organometallics, Vol. 20, No. 5, 2001 981
Sch em e 1
Sch em e 2
toring by 31P NMR spectroscopy indicates the presence
of other unidentified phosphorus-containing species.
The main product from the reaction of [Ni(η2-Ph2PCt
CMe)(dcpe)] (1a ) with 1 equiv of HCl in diethyl ether is
a thermally sensitive red solid whose 31P NMR spectrum
shows a highly shielded doublet of doublets at δP -100.2
ppm in addition to two doublets of doublets in the region
of δ 73.0-77.0 due to coordinated dcpe. Some [NiCl2-
(dcpe)], identified by its 31P NMR singlet at ca. δ 82.2,
is also formed; this is the main nickel-containing product
if an excess of HCl is used. The signals of the red solid
are broad in benzene, diethyl ether, or thf but sharp in
CD2Cl2. The associated P-P coupling constants of 181.9
assigned to the P-coordinated alkynylphosphine of [Ni-
(η1-Ph2PCtCMe)(dcpe)] and a multiplet at δP 40.0-40.9
due to coordinated dcpe are observed initially. After 30
min at room temperature, these signals disappear and
the reaction mixtures turn yellow, owing to the quan-
titative formation of the corresponding [Ni(η2-Ph2PCt
CR)(dcpe)] complexes (R ) Me (1a ), CO2Me (1b))
(Scheme 1). Although 1a is stable in solution in the
absence of air, the isolated solid decomposes on storage,
even at -20 °C in the absence of light. The carboxylate
analogue 1b is more stable and can be stored at room
temperature under N2 for several weeks. The 31P NMR
spectrum of 1a resembles closely that of the similarly
prepared phenyl analogue [Ni(η2-Ph2PCtCPh)(dcpe)]
(1c),7 consisting of three doublets of doublets, at ca. δ
72 for the phosphorus atom of the dcpe ligand trans to
the alkyne carbon atom bearing the PPh2 group (C1),
at ca. δ 68 for the other phosphorus atom of dcpe, and
at ca. δ -15 for the diphenylphosphino group; the
shielding of the last signal shows clearly that the PPh2
moiety is not coordinated. In 1b, the phosphorus atoms
of dcpe are slightly less shielded and the coupling
constants are slightly smaller than in 1a .
2
and 29.9 Hz are characteristic of trans and cis J (PP)
couplings, respectively, with dcpe, showing clearly that
the phosphorus atom of PPh2 is now coordinated. The
1H and 13C NMR spectra (see Experimental Section)
show the presence of a vinylic CH group, resulting from
protonation of the alkynyl function, and a quaternary
carbon atom bound to nickel, while the FAB mass
spectrum shows the highest mass peak at m/z 705
similar to that observed in the FAB mass spectrum of
1a . All these data are consistent with a Ni(dcpe)
complex containing a vinylphosphine group that is
formed by protonation of 1a at C2 and is coordinated
via both phosphorus and the carbon atom C1. They do
not, however, establish whether the complex is the
chloride salt of a four-coordinate cation or a five-
coordinate complex with a labile chloride. The formula-
tion of the complex as five-coordinate [NiCl{C(dCHMe)-
PPh2-κP,C1}(dcpe)] (2a ) (Scheme 2) has been confirmed
by single-crystal X-ray analysis (see below).
Complex 2a is fairly air-stable as a solid or in solution
up to 50 °C in dry aprotic solvents. In the presence of
moisture, decomposition occurs more rapidly to form the
(Z)-vinylphosphine Ph2PCHdCHMe. This compound is
also obtained, together with [NiCl2(dcpe)], after addition
of more HCl to 2a , or it can be isolated in 65% overall
yield, based on [Ni(C2H4)(dcpe)], after in situ reaction
of 1a with HCl (2 equiv). The product has been fully
characterized, and the spectroscopic data are identical
with those reported for (Z)-Ph2PCHdCHMe.11,12 The
protonation of the triple bond is apparently irrevers-
ible: complex 2a is inert toward bases such as NHEt2
and CaH2.
The 13C NMR chemical shifts of the quaternary
carbons of the triple bond of Ph2PC1tC2R are deshielded
by ca. 40 ppm compared with those of the free alky-
nylphosphines,7,8 showing that these carbon atoms are
coordinated to the metal center. The signals appear as
doublets of doublets of doublets at δC 120.42 (1a ), 136.43
(1b), and 140.38 (1c)9 for C1 and at δC 146.63 (1a ),
140.62 (1b), and 150.27 (1c) for C2. The assignments of
C1 and C2 are based on the observation that the coupling
observed for J (C1P) (20-45 Hz) is greater than J (C2P)
(18-19 Hz). The coupling constants between the two
alkynyl carbons and the phosphorus atoms of the dcpe
ligand are similar to the values reported for other
unsymmetrical alkynes coordinated to a Ni0P2 frag-
ment.10
Evidence for coordination of the triple bond comes also
from the infrared spectra, which show a band due to
CtC stretching for 1a at 1758 cm-1 and for 1b at 1735
cm-1. The structure of complex 1a has been confirmed
by single-crystal X-ray diffraction (see below).
Unsaturated molecules such as dimethyl acetylene-
dicarboxylate or CO displace the alkynylphosphine from
1a , there being no evidence for insertion into the Ni-C
bond. The reaction of 1b with CO also causes decom-
position to give [Ni(CO)2(dcpe)] and [Ni(dcpe)2], but in
this case no free Ph2PCtCCO2Me was observed. Moni-
The alkynylphosphine complex 1c reacts analogously
with HCl to give [NiCl{C(dCHPh)PPh2-κP,C1}(dcpe)]
(2c) as the main product, which has been isolated as
air-stable red crystals and its structure confirmed by
X-ray crystallography (see below) (Scheme 3). The NMR
data are similar to those of 2a , but the 31P NMR signals
are broad at room temperature. Cooling to -20 °C was
required to obtain a well-resolved spectrum (see Ex-
(8) Louattani, E.; Lledo´s, A.; Suades, J .; Alvarez-Larena, A.; Piniella,
J . F. Organometallics 1995, 14, 1053.
(9) The previously reported 13C chemical shift for C1 of 1b7 was
misassigned. The correct 13C NMR data are given in the Experimental
Section.
(10) Bartik, T.; Happ, B.; Iglewsky, M.; Bandmann, H.; Boese, R.;
Heimbach, P.; Hoffmann, T.; Wenschuh, E. Organometallics 1992, 11,
1235.
(11) Grim, S. O.; Molenda, R. P.; Mitchell, J . D. J . Org. Chem. 1980,
45, 250.
(12) Duncan, M.; Gallagher, M. J . Org. Magn. Reson. 1981, 15, 37.

982 Organometallics, Vol. 20, No. 5, 2001
Bennett et al.
Sch em e 3
Sch em e 4
perimental Section). However, the protonation is not as
regiospecific as for 2a . A second product (3c) is formed
in ca. 5% yield whose 31P NMR spectrum shows doublets
of doublets at δP 62.0 and 66.5 for the dcpe ligand and
a doublet of doublets at δP -28.8 for the remaining
phosphorus atom. The chemical shift of the latter signal
is in the range expected for an uncoordinated vinyl-
diphenylphosphine,11,12 which could result from proto-
nation at C1. Unfortunately, the 1H and 13C NMR
spectra are very broad and uninformative, although
the resonance due to P1 at δP -100.2 by a doublet of
doublets at δP 30.3 and a small shift for the dcpe
resonances. The small coupling constants observed
between P1 and the dcpe phosphorus atoms (5.7 and 2.2
Hz) suggest that P1 is no longer coordinated; moreover,
its chemical shift is outside the range of δP 45.0-50.0
that is characteristic of five-membered phosphanickel-
acycles13-15 but is similar to the values reported for
cationic phosphinodithiocarboxylato complexes that arise
from insertion of CS2 into nickel-, palladium-, or
platinum-phosphine bonds.16-18 These data suggest
that CS2 has inserted into the Ni-P rather than the
Ni-C bond of the three-membered nickelacycle, leading
to the zwitterionic species 4a (Scheme 4).19 The 13C
resonance of the inserted CS2 group appears as a
doublet of doublets at δC 236.45, with a coupling
constant of 71.4 Hz to the adjacent phosphorus atom of
PPh2. The 13C and 2J (PC) values are almost identical
with those of the zwitterionic five-membered zircona-
cycle obtained by reaction of CS2 with the zirconaindene
1
there is a doublet of doublets at δH 6.36 in the H NMR
spectrum corresponding to a vinylic proton. An X-ray
crystallographic study has shown that 3c is indeed
[NiCl{η1-C(Ph)dCH(PPh2)}(dcpe)] (see below).
Similar reaction of 1b with HCl yields a mixture of
two species in a 3:2 ratio, which are believed to be [NiCl-
{C(dCHCO2Me)PPh2-κP,C1}(dcpe)] (2b) and [NiCl{η1-
C(CO2Me)dCH(PPh2)}(dcpe)] (3b), respectively. The
structural assignments are based on the 31P NMR
spectrum of the mixture, as the compounds could not
be separated. The signals of 3b are sharp and well-
defined and are similar to those of 3c, whereas those of
2b are very broad: one at δP -97.1 for P1 and two at δP
68.0-69.1 for coordinated dcpe in CD2Cl2 at room
temperature. The peaks sharpen on warming to +60 °C,
leading to a well-defined triplet for P1. The signals of
2b split when the solution is cooled to -90 °C, showing
that two distinct species are present. The parameters
for the predominant species are very similar to those of
2c, i.e., a broad doublet at δP -92.5 and broad signals
for the dcpe phosphorus atoms in the region 73.0-78.0
ppm, whereas the 31P NMR chemical shifts for the minor
species are more shielded, e.g. δP -105.0 for P1 and δP
65.0-70.0 for dcpe. This behavior is indicative of a fast
exchange between two isomers, which may arise from
syn and anti arrangements of the CdC and CdO bonds
of the R,â-unsaturated carboxylate group (eq 1).
[Cp2Zr{o-C6H4CHdC(PPh2)}],20 thus providing further
support for the suggested structure.
The reaction of CS2 with the phenyl analogue 2c is
very slow, and after 5 days at 28 °C, the yield of the
corresponding insertion product is only 40%, as esti-
mated by 31P NMR spectroscopy. In addition, the
solution contains starting material, [NiCl2(dcpe)], and
other decomposition products; therefore, the insertion
compound could not be isolated. Complexes 2a ,c also
react slowly with technical grade CO2 at room temper-
ature, but the reactions are not clean and the products
are unstable. For example, a solution of the adduct
prepared from 2c decomposed overnight, releasing CO2,
as shown by 13C NMR spectroscopy. The main products
are believed to be the nickelacycles [NiCl{C(dCHR)-
PPh2C(O)O}(dcpe)] (R ) Me (5a ), Ph (5c)) (Scheme 4),
since their 31P NMR spectra are similar to those of 4a ,c:
i.e., one doublet of doublets at ca. δP 32.0 for P1 and two
others in the region δP 62.0-69.5 for dcpe. Surprisingly,
similar reactions attempted with dry 13CO2 did not give
any insertion products, which suggests that water or
The reactions of complexes 2a ,c with small molecules
have been investigated briefly. Complex 2a reacts
rapidly with CO and with dimethyl acetylenedicarboxy-
late at room temperature to give uncharacterizable
mixtures of products but is unreactive toward diphen-
ylacetylene, methyl 2-butynoate, and 3-(diphenylphos-
phino)-2-propyne under the same conditions. The reac-
tions of 2a and 2c with CO2 and CS2 give insertion
products, as shown by 31P NMR spectroscopy, but are
accompanied by considerable decomposition. Thus, ad-
dition of CS2 to a solution of 2a causes replacement of
(13) Carty, A. J .; J ohnson, D. K.; J acobson, S. E. J . Am. Chem. Soc.
1979, 101, 5612.
(14) Garrou, P. E. Chem. Rev. 1981, 81, 229.
(15) Muller, G.; Panyella, D.; Rocamora, M.; Sales, J .; Font-Bardia,
M.; Solans, X. J . Chem. Soc., Dalton Trans. 1993, 2959.
(16) Werner, H.; Bertleff, W. Chem. Ber. 1980, 113, 267.
(17) Bertleff, W.; Werner, H. Z. Naturforsch. 1982, 37B, 1294.
(18) Uso´n, R.; Fornie´s, J .; Navarro, R.; Uso´n, M. A.; Garcia, M. P.;
Welch, A. J . J . Chem. Soc., Dalton Trans. 1984, 345.
(19) For a review on the reactions of CS2 and CO2 with organome-
tallic complexes, see: Pandey, K. K. Coord. Chem. Rev. 1995, 140, 37.
(20) Cadierno, V.; Zablocka, M.; Donnadieu, B.; Igau, A.; Majoral,
J .-P. Organometallics 1999, 18, 1882.

Ni(0) Complexes with η2-Alkynylphosphines
Organometallics, Vol. 20, No. 5, 2001 983
F igu r e 3. Molecular structure of 2c with selected atom
labeling. Thermal ellipsoids show 30% probability levels;
hydrogen atoms have been omitted for clarity.
F igu r e 1. Molecular structure of 1a with selected atom
labeling. Thermal ellipsoids show 30% probability levels;
hydrogen atoms have been omitted for clarity.
F igu r e 4. Molecular structure of 3c with selected atom
labeling. Thermal ellipsoids show 30% probability levels;
hydrogen atoms have been omitted for clarity.
Ta ble 1. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 1a
Ni(1)-P(1)
Ni(1)-C(2)
C(1)-C(2)
P(3)-C(3)
2.1478(8)
1.869(3)
1.489(5)
1.763(3)
Ni(1)-P(2)
Ni(1)-C(3)
C(2)-C(3)
2.1613(9)
1.913(3)
1.280(4)
F igu r e 2. Molecular structure of 2a with selected atom
labeling. Thermal ellipsoids show 50% probability levels;
hydrogen atoms have been omitted for clarity.
P(1)-Ni(1)-P(2)
P(2)-Ni(1)-C(3)
P(3)-C(3)-C(2)
91.46(3)
118.8(1)
154.9(3)
P(1)-Ni(1)-C(2)
C(1)-C(2)-C(3)
Ni(1)-C(3)-C(2)
110.2(1)
147.6(3)
68.4(2)
oxygen, both present in technical grade CO2, may
catalyze the insertion.
Molecu la r Str u ctu r es of [Ni(η2-P h 2P CtCMe)-
(d cp e)] (1a ), [NiCl{C(dCHMe)P P h 2-KP ,C1}(d cp e)]
(2a ), [NiCl{C(dCHP h )P P h 2-KP ,C1}(d cp e)] (2c), a n d
[NiCl{η1-C(P h )dCH(P P h 2)}(d cp e)] (3c). The molec-
ular geometries of 1a , 2a ,c, and 3c are shown, together
with the atom labeling, in Figures 1-4, respectively;
corresponding selected interatomic distances and angles
are listed in Tables 1-4. The coordination of complex
1a is trigonal planar with the CtC bond and its two
substituents laying in the NiP2 plane, as expected for
nickel(0)-alkyne complexes bearing chelating diphos-
phine ligands.10,21,22 The deviations from the coordina-
tion plane of the alkynyl carbon atoms C(2) and C(3)
are only -0.016 and -0.076 Å, respectively. The Ni-C
distances, 1.869(3) and 1.913(3) Å, the slightly elongated
bond length for the coordinated triple bond with respect
to that of a free alkyne, and the angles of the alkynyl
substituents, 147.6° for C(1)-C(2)-C(3) and 154.9° for
(21) Bonrath, W.; Po¨rschke, K. R.; Wilke, G.; Angermund, K.;
Kru¨ger, C. Angew. Chem., Int. Ed. Engl. 1988, 27, 833.
(22) Edelbach, B. L.; Lachicotte, R. J .; J ones, W. D. Organometallics
1999, 18, 4660.

984 Organometallics, Vol. 20, No. 5, 2001
Bennett et al.
Ta ble 2. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 2a
dimer [PdCl{CH(µ-C6H4C6H4N)PMe(C6H2 Bu3)}]2.24 The
angles in the metallacycles of the latter complexes are,
however, quite different from those in 2a , due to the
absence of an sp2 carbon atom (see Discussion).
t
Ni(1)-P(1)
Ni(1)-P(3)
Ni(1)-C(1)
C(1)-C(2)
2.1862(11)
2.1699(11)
1.903(4)
Ni(1)-P(2)
Ni(1)-Cl(1)
P(1)-C(1)
C(2)-C(3)
2.2272(11)
2.4220(10)
1.747(4)
1.324(5)
1.500(6)
Structural analogies with a nickelaphosphacyclopro-
pane are provided by nickel(0) complexes with η2-
phosphaalkene groups. These species have P-C dis-
tances similar to those of 2a (1.83 Å for [Ni{η2-P(2,6-
Me2C6H3)dCPh2}(bipy)]25,26 and 1.77 Å for [Ni{η2-
P(CH(SiMe3)2)dC(SiMe3)2}(PMe3)2]27,28), values which
are closer to a single rather than a double bond between
the phosphorus and the carbon atoms of the coordinated
phosphaalkenes. These species, however, have Ni-P
and Ni-C distances longer than those of 2a . The bond
lengths of C(1)-C(2) (1.324(5) Å) and C(2)-C(3) (1.500-
(6) Å) are typical of double and single bonds, respec-
tively, and the vinylic character of C(1)-C(2) is con-
firmed by the C(1)-C(2)-C(3) angle of 125.8°. The Ni-
Cl distance of 2.4220(10) Å lies in the middle of the
range known for the limited number of structurally
characterized pentacoordinate chloronickel(II) tertiary
phosphine complexes. They range from 2.169 Å for the
trigonal-bipyramidal [NiCl{(Ph2PCH2CH2)3N}]PF629 to
2.699 Å for the square-pyramidal complex [NiCl-
{CH2(PPhCH2CH2NH2)2}]PF6.30,31
P(1)-Ni(1)-P(2)
P(1)-Ni(1)-P(3)
P(2)-Ni(1)-C(1)
P(1)-C(1)-C(2)
112.63(4)
136.24(5)
158.70(12) C(1)-C(2)-C(3)
137.4(3)
P(1)-Ni(1)-C(1)
P(2)-Ni(1)-P(3)
49.98(11)
88.88(4)
125.8(4)
148.5(3)
95.62(11)
Ni(1)-C(1)-C(2)
Cl(1)-Ni(1)-C(1)
Cl(1)-Ni(1)-P(2) 101.04(4)
Cl(1)-Ni(1)-P(3) 110.19(4)
Cl(1)-Ni(1)-P(1) 102.68(4)
Ni(1)-P(1)-C(1)
56.6(2)
Ni(1)-C(1)-P(1)
73.5(2)
Ta ble 3. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 2c
Ni(1)-P(1)
Ni(1)-P(3)
Ni(1)-C(1)
C(1)-C(2)
2.1734(8)
2.1952(9)
1.903(3)
1.328(5)
Ni(1)-P(2)
Ni(1)-Cl(1)
P(1)-C(1)
C(2)-C(3)
2.2300(9)
2.4119(8)
1.751(3)
1.478(4)
P(1)-Ni(1)-P(2)
P(1)-Ni(1)-P(3)
P(2)-Ni(1)-C(1)
P(1)-C(1)-C(2)
Cl(1)-Ni(1)-P(2)
Cl(1)-Ni(1)-P(3) 108.44(3)
Ni(1)-P(1)-C(1)
112.49(3)
135.96(4)
161.28(9)
142.8(2)
98.07(3)
P(1)-Ni(1)-C(1)
P(2)-Ni(1)-P(3)
C(1)-C(2)-C(3)
Ni(1)-C(1)-C(2)
Cl(1)-Ni(1)-C(1)
50.34(9)
88.62(3)
129.2(3)
144.3(2)
94.78(9)
Cl(1)-Ni(1)-P(1) 106.24(3)
56.79(10) Ni(1)-C(1)-P(1)
72.87(12)
Ta ble 4. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 3c
Apart from the substituent on C(2), the molecular
structure of 2c is practically identical with that of 2a .
The phenyl substituent is cis to the PPh2 group, with
contact distances between the two groups indicative of
steric interactions.
P(1)-C(1)
Ni(1)-P(3)
Ni(1)-C(2)
C(2)-C(3)
1.823(7)
2.148(2)
1.944(7)
1.50(1)
Ni(1)-P(2)
Ni(1)-Cl(1)
C(1)-C(2)
2.212(2)
2.230(2)
1.322(9)
Complex 3c shows a conventional square-planar
environment around the nickel atom, including the η1-
vinyl ligand -C(Ph)dCH(PPh2), in which the PPh2 and
Ph groups are mutually cis. The Ni-P distances to Cy2-
PCH2CH2PCy2 are 2.212(2) Å (trans to the vinyl group)
and 2.148(2) Å (trans to Cl), reflecting the higher trans
influence of the η1-vinyl ligand. The CdC and C-P
distances (1.322(9) and 1.823(9) Å, respectively) are
unexceptional. The phosphorus atom bonded to carbon
C(1) of the vinyl group is completely enclosed by the
P(2)-Ni(1)-P(3)
P(2)-Ni(1)-C(2)
P(1)-C(1)-C(2)
C(1)-C(2)-C(3)
88.73(8)
177.3(2)
126.2(6)
123.3(7)
P(2)-Ni(1)-Cl(1)
Ni(1)-C(2)-C(3)
Ni(1)-C(2)-C(1)
Cl(1)-Ni(1)-C(2)
89.68(8)
116.8(5)
119.5(6)
89.7(2)
C(2)-C(3)-P(3), are in the normal range for such
complexes.
The molecular structure of the five-coordinated com-
plex 2a shows a distorted-trigonal-bipyramidal arrange-
ment around the nickel(II) center, the carbon atom C(1)
being -0.437 Å from the trigonal plane defined by Ni-
(1)-Cl(1)-P(2). The molecule contains a three-mem-
bered phosphametallacycle formed by Ni(1), P(1), and
C(1). The vinylic carbon atom C(2) and its methyl
substituent C(3) are only 0.118 and 0.248 Å, respec-
tively, out of the plane of the three-membered ring. The
Ni-C(1) distance of 1.903(4) Å is slightly shorter than
the range of 1.92-1.95 Å reported for Ni-aryl or Ni-
vinyl bonds in metallacycles, and the P(1)-C(1) distance
(1.747(4) Å) is also short compared to the average P-C
distance of 1.85 Å; these shortenings are probably a
consequence of the strain in the three-membered ring.
The Ni-P(1) distance (2.1862(11) Å) is similar to that
of the two other Ni-P bonds in the molecule. Several
phosphametallacyclopropane complexes have been struc-
turally characterized (see examples in Table 5). Two
complexes with group 10 metals have been reported, but
none with nickel. They show the P-C bond lengths in
the metallacycle to be quite similar to that measured
(24) van der Sluis, M.; Beverwijk, V.; Termaten, A.; Bickelhaupt,
F.; Kooijman, H.; Spek, A. L. Organometallics 1999, 18, 1402.
(25) van der Knaap, T. A.; J enneskens, L. W.; Meeuwissen, H. J .;
Bickelhaupt, F.; Walther, D.; Dinjus, E.; Uhlig, E.; Spek, A. L. J .
Organomet. Chem. 1983, 254, C33.
(26) Spek, A. L.; Duisenberg, A. J . M. Acta Crystallogr., Sect. C 1987,
43, 1216.
(27) Cowley, A. H.; J ones, R. A.; Stewart, C. A.; Stuart, A. L.;
Atwood, J . L.; Hunter, W. E.; Zhang, H.-M. J . Am. Chem. Soc. 1983,
105, 3737.
(28) Cowley, A. H.; J ones, R. A.; Lasch, J . G.; Norman, N. C.;
Stewart, C. A.; Stuart, A. L.; Atwood, J . L.; Hunter, W. E.; Zhang, H.
M. J . Am. Chem. Soc. 1984, 106, 7015.
(29) Di Vaira, M.; Sacconi, L. J . Chem. Soc., Dalton Trans. 1975,
493.
(30) Scanlon, L. G.; Tsao, Y.-Y.; Toman, K.; Cummings, S. C.; Meek,
D. W. Inorg. Chem. 1982, 21, 2707.
(31) Most of the Ni-Cl bond lengths in five-coordinate tris- or
tetrakis(tertiary phosphine) complexes fall in the range 2.23-2.48 Å;
see for example: (a) Font-Bard´ıa, M.; Gonza´lez-Platas, J .; Muller, G.;
Panyella, D.; Rocamora, M.; Solans, X. J . Chem. Soc., Dalton Trans.
1994, 3075. (b) Manojlovic-Muir, L.; Mirza, H. A.; Sadiq, N.; Pud-
dephatt, R. J . Inorg. Chem. 1993, 32, 117. (c) Kyba, E. P.; Davis, R.
E.; Fox, M. A.; Clubb, C. N.; Liu, S.-T.; Reitz, G. A.; Scheuler, V. J .;
Kashyap, R. P. Inorg. Chem. 1987, 26, 1647. (d) Fox, M. A.; Chandler,
D. A.; Kyba, E. P. J . Coord. Chem. 1992, 25, 1. (e) Powell, H. M.; Chui,
K. M. J . Chem. Soc., Dalton Trans. 1976, 1301. (f) Wartchow, R. Z.
Kristallogr.s New Cryst. Struct. 1998, 213, 191. (g) Airey, A. L.;
Hockless, D. C. R.; Swiegers, G. F.; Wild, S. B. Z. Kristallogr. 1996,
211, 939. (h) Arbuckle, B. W.; Musker, W. K. Polyhedron 1991, 10,
415. (i) Baxley, G. T.; Miller, W. K.; Lyon, D. K.; Miller, B. E.; Nieckarz,
G. F.; Weakley, T. J . R.; Tyler, D. R. Inorg. Chem. 1996, 35, 6688.
in 2a (or in 2c, see below): i.e., 1.76 Å in [Pt(CH(Ph)-
PBz2)(PBz3)(2-Me-1,2-B10C2H10)]23 or 1.754 Å in the
(23) Bresadola, S.; Bresciani-Pahor, N.; Longato, B. J . Organomet.
Chem. 1979, 179, 73.

Ni(0) Complexes with η2-Alkynylphosphines
Organometallics, Vol. 20, No. 5, 2001 985
Ta ble 5. 31P NMR Ch em ica l Sh ifts a n d Cor r esp on d in g M-P -C Bon d An gles for Selected Th r ee-Mem ber ed
P h osp h a m eta lla cycles
entry
complex
[Ni(CH2PMe2)(PMe3)3]+
δP
M-P-C (deg)
ref
1
-27.1
-100.2
-88.6
-17.7
-22.7
13.0
36
2
[NiCl{C(dCHMe)PPh2}(dcpe) (2a )
56.6
56.8
this work
3
[NiCl{C(dCHPh)PPh2}(dcpe) (2c)
this work
4
[Pt{CH2PPh2)(PPh2Me)(2-Ph-1,2-B10C2H10)]
[Pt(CH(Ph)PBz2)(PBz2)(2-Me-1,2-B10C2H10)]
[Mn(CH2PPh2)(CO)4]
37
23
38
39
40
41
42
43
33
44
5
63.9
6
65.2
7
[(CO)2Fe(µ-Ph2PCHPPh2)(µ-H)Fe(CO)3]
[(CO)2Fe(µ-Ph2PCdCH2)(µ-PPh2)Fe(CO)3]
[Mo(CH2PPh2)(CO)2(Cp)]
13.5
63.4/65.5
56.3
8
-44.6
1.3
9
66.5
10
11
12
13
[(Cp)(Cl)Mo(µ-Ph2PCdCHPh)(µ-PPh2)W(Cl)(Cp)]
[(Cp)(Cl)Mo(µ-Ph2PCdCHMe)(µ-PPh2)Mo(Cl)(Cp)]
[W{C(Me)(PMe3)PPh2}(CO)(Cp)(PMe3)]PF6
[W{C(p-C6H4Me)(CO)PPh2}(Cp)(PMe3)(NCMe)]BF4
-233.4
-243.3
-1.6
58.8
66.8
67.8
-27.0
14
15
[W{C(dCH2)PPh2}(CO)2(Cp)]
-124.1
-241.1
33
42
[(Cp)(Cl)W(µ-Ph2PCdCHPh)(µ-PPh2)Mo(Cl)(Cp)]
58.4
surrounding phenyl rings and therefore cannot bind to
the nickel atoms of neighboring molecules in the lattice.
A notable feature of complexes 2a -c is the shielding
of the phosphorus atom P1 (δ -100.2, -97.1, and -88.6,
respectively), which is in the same region as that
observed in phosphiranes. It is far greater than that
Discu ssion
The reaction of alkynylphosphines with [Ni(η2-C2H4)-
(dcpe)] gives mononuclear, trigonally coordinated η2-
alkyne complexes [Ni(η2-Ph2PCtCR)(dcpe)]. The strong
π-donor ability of the electron-rich Ni(dcpe) fragment
probably is an important factor that favors η2-alkyne
over P-coordination. The reactions of alkynylphosphines
with [Ni(CO)4] generally give P-donor substitution
products32 and, as noted in the Introduction, η2-alkyne
coordination to nickel has been observed previously only
in dinuclear nickel complexes. In our case, P-coordinated
species are observed as the kinetically favored products,
but they rearrange rapidly to the corresponding η2-
coordinated complexes.
found in three-membered metallacycles of the type M-
(CR2PPh2), which usually have values ranging from δP
+15.0 to -60.0, e.g. δP +13.0 and +13.5 for Mn and Fe
species, respectively (Table 5, entries 6 and 7), and δP
-57.4 for [W{C(Me)(SMe)PPh2}(Cp)(PMe3)(CO)]PF6.33
Somewhat higher shieldings occur in analogous di-
methylphosphino complexes of 5d elements; e.g., for [Os-
(CH2PMe2)(H)(PMe3)3] the δ value is -71.0.34 However,
a pronounced shielding occurs when the carbon atom
of the phosphametallacyclopropane is part of a double
bond. This was also observed for the mononuclear
Protonation of 1a -c generates a substituted η2-
methylenenickelaphosphacyclopropane, a ligand system
that, to the best of our knowledge, has never been
structurally characterized in a monometallic complex.
Such a ligand has been observed in the neutral tungsten
complex [W{C(dCH2)PPh2}(CO)2(Cp)], whose 31P reso-
nance is shielded by more than 100 ppm relative to
those of analogous tungsten complexes where C1 is sp3
hybridized (see Table 5, entries 12-14). The effect is
even more marked for dinuclear complexes in which the
ligand bridges the two metal atoms via its double bond.
Shieldings of ca. 50 ppm are observed for iron (entry 8)
and up to 240 ppm for 4d and 5d elements (entries 10,
11, and 15). Although the reasons for this shielding are
not well understood, it seem to correlate with the
M-P-C angle, which decreases from ca. 65 to 57° when
the hybridization of C1 changes from sp3 to sp2 (see
Table 5), thus bending the M-C bond further away from
the ideal tetrahedral geometry. A similar angle depen-
dence of chemical shift tensors, measured by 31P solid-
state NMR spectroscopy, has been reported.35
complex [W{C(dCH2)PPh2}(CO)2(Cp)], which has been
generated by deprotonation of a cationic phosphinocar-
bene complex (entry 14 of Table 5 and eq 2).33
Binuclear complexes containing a methylenemetal-
laphosphacyclopropane unit have been described in
which the ligand is coordinated through its double bond
to the second metal atom (see examples in Table 5,
entries 8, 10, 11, and 15).
The protonation of 1a -c probably occurs by initial
oxidative addition of HCl to the metal atoms and
(32) Hengefeld, A.; Nast, R. J . Organomet. Chem. 1983, 252, 375.
(33) Ostermeier, J .; Hiller, W.; Kreissl, F. R. J . Organomet. Chem.
1995, 491, 283.
(34) Werner, H.; Gotzig, J . Organometallics 1983, 2, 547.
(35) Lindner, E.; Fawzi, R.; Mayer, H. A.; Eichele, K.; Hiller, W.
Organometallics 1992, 11, 1033.

986 Organometallics, Vol. 20, No. 5, 2001
Bennett et al.
subsequent hydride migration to carbon atom C2 to give
a η1-vinyl that is stabilized by coordination of the
adjacent PPh2 group to the metal atom. The first step
is similar to that proposed for the addition of acids to
the platinum(0)-alkyne complexes [Pt(RCtCR)(PPh3)2].45
The second step would give rise to a cis arrangement of
the substituent on C2 and the PPh2 group in the
resulting vinylic double bond, as is observed in 2a ,c. The
reaction of HCl with 1c is not as regiospecific as that
with 1a , as shown by the formation of a small amount
of 3c, which results from addition of the hydrogen atom
to C1. This small decrease in regioselectivity can be
correlated with the difference in chemical shifts of the
acetylenic carbon atoms in 1a ,c. In 1a , C2 is 26 ppm
less shielded than C1, whereas the difference in 1c is
only 10 ppm. Thus, in 1c, the electron deficiency at C2
is less than that in 1a ; hence, the migration of the
hydride shows less discrimination. In 1b, the difference
in chemical shift between the acetylenic carbons is even
smaller (4 ppm) and, correspondingly, the regioselec-
tivity is poorer.
In conclusion, the nickel(0)-dcpe fragment shows the
ability to form unusual η2-coordinated alkynylphosphine
complexes, which can be protonated to give bidentate
three-membered vinylphosphine species. Although the
organometallic chemistry of the latter complexes seems
to be limited, their reactions with a further 1 equiv of
HCl provide an entry into the formation of (Z)-vinyl-
phosphines. The overall reaction can be seen as a mild
cis hydrogenation of alkynylphosphines, which could
provide a route to a range of substituted vinylphos-
phines that would not otherwise be easily accessible.
ZAB-2SEQ spectrometer by the fast-atom bombardment (FAB)
technique or on a Micromass Tof Spec 2E instrument by the
MALDI/TOF technique. Unfortunately, attempts to obtain
satisfactory elemental analyses for the new compounds de-
scribed here were unsuccessful. Although stable in solution
in the absence of air, the nickel(0) complexes 1a ,c decomposed
on storage. The stable solid HCl adducts 2a ,c and 3c were
thermally sensitive and also tenaciously retained solvents,
which could not be removed in vacuo without decomposition
of the sample. The presence of solvents was confirmed by X-ray
crystallography in two cases (see below).
Sta r tin g Ma ter ia ls. The complexes [Ni(η2-C2H4)(dcpe)]46
and [Ni(η2-Ph2PCtCPh)(dcpe)]7 and the (alkynyl)diphenylphos-
phines Ph2PCtCR (R ) Me, Ph, CO2Me)47-49 were prepared
by published procedures.
P r ep a r a tion of [Ni(η2-P h 2P CtCMe)(d cp e)] (1a ). Ph2-
PCtCMe (55 mg, 0.25 mmol) was added at 0 °C to a stirred
suspension of [Ni(C2H4)(dcpe)] (126 mg, 0.247 mmol) in diethyl
ether (10 mL). After 30 min, 31P NMR monitoring of the yellow
solution indicated that the reaction was complete, and the
solution was evaporated in vacuo to dryness to obtain 1a
quantitatively as a pale yellow powder. Yellow crystals suitable
for X-ray analysis were obtained from pentane at 0 °C.
IR (Nujol): 2923 (vs), 2854 (vs), 2725 (w), 2666 (w), 1758
(s, CtC), 1584 (w), 1569 (w), 1461 (s), 1377 (s), 1168 (m), 1026
(m), 1001 (m), 856 (m), 735 (m), 695 (m), 655 (m), 511 (m) cm-1
.
1H NMR (300 MHz, C6D6): δ 1.05-2.05 (m, 48H, CH2 and CH
of dcpe), 2.59 (d, 3H, J HP ) 6.7, CH3), 7.03-7.16 (m, 6H, Harom),
7.86 (t, 4H, J HH ) 6.9, Harom). 13C{1H} NMR (125.7 MHz,
C6D6): δ 17.69 (ddd, J CP ) 12.4, 6.9, 2.3, CH3), 22.25 (t, J CP
)
19.4, CH2), 22.79 (t, J CP ) 19.1, CH2), 25.90-30.12 (m, CH2 of
C6H11), 34.99 (dd, J CP ) 15.6, 4.1, CH of C6H11), 35.40 (dd, J CP
) 16.5, 4.1, CH of C6H11), 120.42 (ddd, J CP ) 47.1, 42.6, 4.8,
C1), 127.75 (s, CHPh), 128.22 (d, J CP ) 6.7, CHPh) (coupling
constant obtained from APT experiment at 75.4 MHz), 133.88
(d, J CP ) 20.2, CHPh), 142.76 (dd, J CP ) 15.6, 4.1, CPh), 146.63
(ddd, J CP ) 41.5, 18.3, 6.2, C2). 31P{1H} NMR (80.96 MHz,
Exp er im en ta l Section
3
2
C6D6): δ -15.4 (dd, J PP ) 37.0, 24.0), 67.6 (dd, J PP ) 46.3,
3J PP ) 24.0), 72.9 (dd, J PP ) 46.3, J PP ) 37.0). FAB-MS
2
3
Gen er a l P r oced u r es. All experiments, unless otherwise
specified, were carried out under argon with use of standard
Schlenk techniques. All solvents were dried and degassed
before use. NMR spectra were recorded on a Varian XL-200E
(1H at 200 MHz, 13C at 50.3 MHz, 31P at 81.0 MHz), a Varian
Gemini 300BB (1H at 300 MHz, 13C at 75.4 MHz, 31P at 121.4
(tetraglyme, C41H61NiP3): m/z 705 (MH+).
P r ep a r a t ion of [Ni(η2-P h 2P CtCCO2Me)(d cp e)] (1b ).
Ph2PCtCCO2Me (44 mg, 0.16 mmol) was added at 0 °C to a
stirred suspension of [Ni(C2H4)(dcpe)] (83 mg, 0.16 mmol) in
diethyl ether (10 mL). After 2 h, 31P NMR monitoring of the
yellow solution indicated that the reaction was complete and
quantitative. Cooling of the solution to 0 °C yielded 1b as a
yellow crystalline solid.
MHz), or a Varian Inova-500 instrument (1H at 500 MHz, 13
C
at 125.7 MHz) at 298 K unless otherwise specified. The
chemical shifts (δ) for 1H and 13C are given in ppm relative to
residual signals of the solvent and to external 85% H3PO4 for
31P. The spectra of all nuclei (except 1H) were 1H-decoupled.
The coupling constants (J ) are given in Hz with an estimated
error of (0.2 Hz unless otherwise stated. The numbering
scheme used in the description of the 13C NMR data is Ph2-
PC1tC2R. Infrared spectra were measured on a Perkin-Elmer
Spectrum One instrument. Mass spectra were obtained on a
IR (Nujol) 2924 (vs), 2854 (vs), 2723 (w), 2666 (w), 1735 (m,
CtC), 1665 (m, CdO), 1583 (w), 1460 (s), 1376 (m), 1194 (m),
1
1177 (w), 748 (w), 733 (w), 700 (w) cm-1. H NMR (300 MHz,
C6D6): δ 1.05-2.12 (m, 48H, CH2 and CH of dcpe), 3.46 (s,
3H, CH3), 7.01 (m, 2H, Harom), 7.09 (m, 4H, Harom), 7.80 (m,
4H, Harom). 13C{1H} NMR (125.7 MHz, C6D6): δ 22.09 (t, J CP
) 18.7, CH2), 22.30 (t, J CP ) 20.5, CH2), 26.49-30.00 (m, CH2
of C6H11), 34.83 (dd, J CP ) 17.9, 3.2, CH of C6H11), 35.18 (dd,
J CP ) 18.3, 3.2, CH of C6H11), 50.64 (s, OCH3), 128.11 (s, CHPh),
128.26 (d, J CP ) 6.9, CHPh), 134.02 (d, J CP ) 20.4, CHPh), 136.43
(ddd, J CP ) 56.6, 44.6, 6.5, C1), 140.62 (ddd, J CP ) 39.8, 18.7,
5.9, C2), 141.15 (dd, J CP ) 12.9, 3.8, CPh), 171.93 (m, CdO).
(36) Karsch, H. H. Chem. Ber. 1984, 117, 783.
(37) Bresadola, S.; Longato, B.; Morandini, F. J . Organomet. Chem.
1977, 128, C5.
(38) Lindner, E.; Starz, K. A.; Eberle, H.-J .; Hiller, W. Chem. Ber.
1983, 116, 1209.
(39) Dawkins, G. M.; Green, M.; J effery, J . C.; Sambale, C.; Stone,
F. G. A. J . Chem. Soc., Dalton Trans. 1983, 499.
(40) Grist, N. J .; Hogarth, G.; Knox, S. A. R.; Lloyd, B. R.; Morton,
D. A. V.; Orpen, A. G. J . Chem. Soc., Chem. Commun. 1988, 673.
(41) Lindner, E.; Ku¨ster, E. U.; Hiller, W.; Fawzi, R. Chem. Ber.
1984, 117, 127.
(42) Acum, G. A.; Mays, M. J .; Raithby, P. R.; Solan, G. A. J . Chem.
Soc., Dalton Trans. 1995, 3049.
(43) Conole, G.; Hill, K. A.; McPartlin, M.; Mays, M. J .; Morris, M.
J . J . Chem. Soc., Chem. Commun. 1989, 688.
(44) Lehotkay, T.; Wurst, K.; J aitner, P.; Kreissl, F. J . J . Organomet.
Chem. 1998, 553, 103.
(45) Hartley, F. R. In Comprehensive Organometallic Chemistry;
Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon: Oxford,
U.K., 1982; Vol. 6, p 702.
3
31P{1H} NMR (121.4 MHz, C6D6): δ -13.7 (dd, J PP ) 34.3,
19.0), 72.9 (dd, 2J PP ) 31.5, 3J PP ) 19.0), 74.4 (app. t, J ) 33.2).
FAB-MS (C42H61NiO2P3, tetraglyme): m/z 749 (MH+), 663.
[Ni(η2-P h 2P CtCP h )(d cp e)] (1c).9 13C{1H} NMR (125.7
MHz, C6D6): δ 21.99 (t, J CP ) 19.5, CH2), 22.59 (t, J CP ) 19.4,
(46) Bennett, M. A.; Hambley, T. W.; Roberts, N. K.; Robertson, G.
B. Organometallics 1985, 4, 1992.
(47) Charrier, C.; Chodkiewicz, W.; Cadiot, P. Bull. Soc. Chim. Fr.
1966, 1002.
(48) Carty, A. J .; Hota, N. K.; Ng, T. W.; Patel, H. A.; O’Connor, T.
J . Can. J . Chem. 1971, 49, 2706.
(49) Montlo, D.; Suades, J .; Dahan, F.; Mathieu, R. Organometallics
1990, 9, 2933.

Ni(0) Complexes with η2-Alkynylphosphines
Organometallics, Vol. 20, No. 5, 2001 987
CH2), 26.63 (CH2), 27.48-27.74 (m, CH2), 29.15, 29.39 (CH2),
30.02-30.18 (m, CH2), 35.14 (dd, J CP ) 16.0, 3.4, CH), 35.71
(dd, J CP ) 16.7, 3.8, CH), 124.42 (CH), 127.53, 127.86, 127.91
(CH), 128.20 (d, J CP ) 7, CHPPh), 133.96 (d, J CP ) 20.1, CHPPh),
140.38 (ddd, J CP ) 25.0, 19.5, 5.5, C1), 141.36 (ddd, J CP ) 10.5,
5.0, 3.2, CPh), 141.95 (dd, J CP ) 14.8, 4.0, CPPh), 150.27 (ddd,
J CP ) 41.0, 19.0, 5.3, C2).
33.3, Ni-C), 136.3 (dt, J CP ) 6.6, 3.3, CPh), 147.0 (m, dCH).
31P{1H} NMR (81.0 MHz, CD2Cl2): δ -88.6 (br dd, 2J PP ) 181
2
2
( 1, 30 ( 1), 73.1 (br d, J PP ) 30 ( 1), 75.5 (br d, J PP ) 181
( 1). 31P{1H} NMR (121.4 MHz, CD2Cl2, 253 K): δ -89.3 (dd,
2
2
2J PP ) 179.0, 32.0), 72.4 dd, J PP ) 32.0, 3.0), 74.9 (dd, J PP
)
179.0, 3.0). EI-MS (C41H62ClNiP3): m/z 766 (18, M - Cl), 607
(3), 561 (10), 515 (80), 339 (100), 287 (63), 286 (67).
Rea ction of [Ni(η2-P h 2P CtCMe)(d cp e)] (1a ) w ith HCl.
A solution of [Ni(η2-Ph2PCtCMe)(dcpe)], freshly prepared from
[Ni(C2H4)(dcpe)] (330 mg, 0.65 mmol) and Ph2PCtCMe (150
mg, 0.65 mmol) in diethyl ether (20 mL), was cooled to 0 °C.
A solution of HCl in diethyl ether (0.65 mmol) was added
dropwise. Monitoring by 31P NMR spectroscopy indicated the
complete disappearance of [Ni(η2-Ph2PCtCMe)(dcpe)] and
formation of some [NiCl2(dcpe)]. The orange solution was
layered with hexane (20 mL) and set aside at -10 °C. The
complex [NiCl(C(dCHMe)PPh2-κP,C1)(dcpe)] (2a ; 304 mg, 63%)
was obtained as a heat- and moisture-sensitive crystalline
solid. Red crystals suitable for X-ray crystallography were
obtained from pentane at -10 °C.
3c. IR (CH2Cl2): 3020 (w), 2933 (m), 2854 (w), 1479 (s, br),
1446 (s, br), 1095 (m), 1010 (m), 865 (w), 808 (m), 533 (w), 504
1
(w) cm-1. H NMR (200 MHz, CD2Cl2): δ 0.90-2.65 (m, 48H,
dcpe), 6.36 (dd, J HP ) 10.4, 1.8, dCH), 7.05-7.80 (m, 15H).
13C{1H} NMR (50.3 MHz, CD2Cl2): δ 19.00-25.00 (br m,
PCH2), 26.10-30.30 (br m, CH2), 36.33 (d, J CP ) 12.5, PCH),
36.58 (d, J CP ) 12.5, PCH), 125.30 (br s, CH), 127.33 (CH),
127.80-129.20 (m, CH), 142.60-142.99 (m, C), 147.16-147.46
(m, C). 31P{1H} NMR (81.0 MHz, CD2Cl2): δ -28.7 (dd, 4J PP
)
)
2
4
2
17.9, 6.0), 62.1 (dd, J PP ) 21.1, J PP ) 6.0), 66.5 (dd, J PP
21.1, 4J PP ) 17.9). EI-MS (C41H62ClNiP3): m/z 766 (1, M - Cl),
515 (17), 339 (100), 286 (11), 257 (19).
Rea ction of [Ni(η2-P h 2P CtCCO2Me)(d cp e)] (1b) w ith
HCl. As described above, an diethyl ether solution of 1b,
prepared from [Ni(C2H4)(dcpe)] (0.1 mmol) and Ph2PCtCCO2-
Me (0.1 mmol), was cooled to 0 °C. A solution of HCl in diethyl
ether (0.09 mmol) was added dropwise, forming an orange
solution containing a mixture of [NiCl(C(dCHCO2Me)PPh2-
κP,C1)(dcpe)] (2b) and [NiCl(η1-C(CO2Me)dCH(PPh2)(dcpe)]
IR (CH2Cl2): 3037 (w), 2935 (s), 2855 (m), 1481 (s, br), 1447
1
(s), 1271 (m), 1260 (m), 865 (w), 489 (w) cm-1. H NMR (500
MHz, CD2Cl2): δ 0.90-2.20 (m, 48H, dcpe), 2.11 (dd, 3H, J HH
3
) 6.4, J HP ) 2.0, CH3), 6.88 (ddq, 1H, J PP ) 32.7, 8.0, J HH
)
6.4, dCH), 7.40-7.60 (m, 10H, Harom). 13C{1H} NMR (125.7
MHz, CD2Cl2): δ 20.10-20.80 (m, PCH2), 22.90-23.50 (m,
PCH2), 25.36 (dd, J CP ) 9.8, 6.8, CH3), 25.80-30.40 (m, CH2),
34.91 (d, J CP ) 20.7, PCH), 35.53 (d, J CP ) 22.0, PCH), 125.36
(d, J CP ) 54.9, CPh), 129.84 (d, J CP ) 13.4, CHPh), 131.58 (d,
J CP ) 3.7, CHPh), 133.18 (d, J CP ) 12.2, CHPh), 135.10 (ddd,
(3b) in
a
3:2 ratio as shown by 31P NMR spectroscopy
(estimated yield 80%). Attempted crystallization did not
separate the isomers and no further purification was carried
out.
J CP ) 52 ( 0.5, 41 ( 0.5, 11 ( 0.5, Ni-C), 146.78 (dd, J CP
)
2b. 31P{1H} NMR (81.0 MHz, CD2Cl2): δ -97.1 (br t, 2J PP
)
10.1, 5.2, dCH). 31P{1H} NMR (81.0 MHz, CD2Cl2): δ -100.2
87 ( 1), 68.0 (br), 69.1 (br). 31P{1H} NMR (121.4 MHz, C6D6,
333 K): δ -98.7 (t, 2J PP ) 92 ( 1), 66.7 (br), 67.5 (br). 31P{1H}
2
2
(dd, J PP ) 181.9, 29.8), 73.5 (dd, J PP ) 30.0, 4.2), 76.5 (dd,
2J PP ) 181.9, 4.2). FAB-MS (3-nitrophenyl octyl ether, C41H62
ClNiP3): m/z 705 (M - Cl).
-
NMR (121.4 MHz, CD2Cl2, 183 K): (a) δ -92.5 (br d, J PP )
185 ( 2), 73.7 (br), 77.5 (br d, J PP ) 180 ( 2); (b) δ -105.0 (br
d, J PP ) 225 ( 2), 65.0 (br d, J PP ) 227 ( 2), 70.0 (br).
In a similar reaction, a solution of 1a in diethyl ether (20
mL), freshly prepared from [Ni(C2H4)(dcpe)] (369 mg, 0.72
mmol) and Ph2PCtCPMe (160 mg, 0.72 mmol), was treated
with a solution of HCl in diethyl ether (1.44 mmol) at 0 °C.
After the mixture was stirred at room temperature for 1 h,
hexane (20 mL) was added and the solid [NiCl2(dcpe)] was
removed by filtration through Celite. The oily residue obtained
after removal of the solvent was extracted with pentane and
chromatographed on acidic alumina. Removal of the solvent
yielded pure (Z)-Ph2PCHdCHMe (105 mg, 65%), whose 1H,
13C, and 31P NMR data were identical with those reported.11,12
Rea ction of [Ni(η2-P h 2P CtCP h )(d cp e)] (1c) w ith HCl.
A solution of 1c, prepared from [Ni(C2H4)(dcpe)] (398 mg, 0.78
mmol) and Ph2PCtCPh (223 mg, 0.78 mmol), in diethyl ether
(20 mL) was cooled to 0 °C. Dropwise addition of a solution of
HCl in diethyl ether (0.78 mmol) gave an orange precipitate
and a deep red solution. The suspension was centrifuged and
the solution decanted. The solution was concentrated in vacuo
to ca. 1/2 volume, layered with hexane, and set aside at -10
°C to yield 379 mg (61%) of [NiCl(C(dCHPh)PPh2-κP,C1)(dcpe)]
(2c). Red crystals suitable for X-ray crystallography were
obtained from diethyl ether at -10 °C.
4
3b. 31P{1H} NMR (81.0 MHz, CD2Cl2): δ -13.3 (d, J PP
)
2
2
4
16.5), 67.7 (d, J PP ) 29.8), 69.4 (dd, J PP ) 29.8, J PP ) 16.5).
Rea ction of [NiCl(C(dCHMe)P P h 2-KP ,C1)(d cp e)] (2a )
w ith CS2. In a NMR tube under nitrogen, a solution of 2a in
CD2Cl2 was treated with an excess of CS2. After 20 h at 25 °C,
31P NMR monitoring showed the reaction to be complete and
the formation of 4a to be quantitative. Attempted crystalliza-
tions did not yield crystals suitable for X-ray analysis.
4a . IR (CH2Cl2): 2933 (m), 2855 (w), 1486 (s, br), 1447 (s),
1438 (s), 1067 (m), 865 (m), 531 (m) cm-1. 1H NMR (500 MHz,
CD2Cl2): δ 1.00-2.20 (m, 51H, dcpe + CH3), 6.72 (br d, 1H,
J HP ) 62.5, dCH), 7.50-7.80 (m, 10H, Harom). 13C{1H} NMR
(50.3 MHz, CD2Cl2): δ 20.25-20.70 (m, PCH2), 24.20 (dd, J CP
) 16.5, 6.6, CH3), 26.00-32.02 (m, CH2), 35.69 (d, J CP ) 21.4,
CH), 36.14 (d, J CP ) 19.7, CH), 125.74 (d, J CP ) 72.6, CPh),
130.07 (d, J CP ) 11.9, CHPh), 132.88 (d, J CP ) 9.6, CHPh), 134.17
(d, J CP ) 2.9, CHPh), 137.07 (dd, J CP ) 19.8, 4.7, Ni-C), 155.82
(dd, J CP ) 7.8, 1.5, dCH), 236.45 (dd, J CP ) 71.4, 16.5, CS2).
31P{1H} NMR (81.0 MHz, CD2Cl2): δ 30.3 (dd, 4J PP ) 5.7, 2.2),
2
4
2
4
71.0 (dd, J PP ) 34.5, J PP ) 5.7), 75.8 (dd, J PP ) 34.5, J PP
2.2). MALDI/TOF MS (C42H62ClNiP3S2): m/z 788 (100, M+
C2H4).
)
-
The decanted orange solid was dissolved in CH2Cl2, the
solution was filtered through Celite, and the solvent was
evaporated in vacuo. Crystallization from toluene gave 30 mg
(5%) of yellow [NiCl(η1-C(Ph)dCH(PPh2)(dcpe)] (3c). Crystals
suitable for X-ray analysis were obtained by diffusion of
pentane into a solution of 3c in chlorobenzene.
Rea ction of [NiCl(C(dCHP h )P P h 2-KP ,C1)(d cp e)] (2c)
w ith CS2. In a sealed Schlenk tube, a solution of 2c (50 mg,
0.06 mmol) in CH2Cl2 (10 mL) was treated with an excess of
CS2 (0.025 mL). After 5 days at 28 °C, 31P NMR monitoring
showed the formation of ca. 40% of 4c, together with decom-
position products and remaining starting material. 31P{1H}
2c. IR (CH2Cl2): 2934 (m), 2856 (w), 1486 (s, br), 1447 (s),
1438 (s), 865 (m), 500 (w) cm-1.1H NMR (200 MHz, CD2Cl2):
δ 0.90-2.40 (m, 48H, dcpe), 7.15-7.85 (m, 16H). 13C{1H} NMR
(50.3 MHz, CD2Cl2): δ 19.80-21.60 (br m, PCH2), 22.30-23.80
(br m, PCH2), 25.60-30.30 (br m, CH2), 34.60-35.80 (m, PCH),
124.10 (dt, J CP ) 55.3, 2.6, CPPh), 128.20 (CHPh), 129.14 (CHPh),
4
NMR (81.0 MHz, CD2Cl2): δ 35.1 (dd, J PP ) 5.6, 2.5), 63.5
2
4
2
4
(dd, J PP ) 28.2, J PP ) 2.5), 65.3 (dd, J PP ) 28.2, J PP ) 5.6).
Rea ction of [NiCl(C(dCHMe)P P h 2-KP ,C1)(d cp e)] (2a )
w ith CO2. A solution of 2a in THF was stirred for 70 h at
room temperature under 1 atm of technical grade CO2.
Monitoring by 31P NMR spectroscopy showed the reaction to
be complete. The insertion complex 5a was the major species,
129.67 (CHPh), 129.98 (d, J CP ) 12.7, CHPPh), 131.92 (d, J CP
)
3.3, CHPPh), 132.94 (d, J CP ) 12.6, CHPPh), 135.43 (dd, J ) 41.9,

988 Organometallics, Vol. 20, No. 5, 2001
Ta ble 6. Cr ysta l a n d Str u ctu r e Refin em en t Da ta for Com p ou n d s 1a , 2a ,c, a n d 3c
Bennett et al.
[Ni(η2-Ph2PCtCMe)-
(dcpe)] (1a )
[NiCl{C(dCHMe)PPh2-
κP,C1}(dcpe)] (2a )
[NiCl{C(dCHPh)PPh2-
κP,C1}(dcpe)] (2c)
[NiCl{C(Ph)dCHPPh2}
(dcpe)] (3c)
(a) Crystal Data
C41H62ClNiP3
chem formula
C
41H61NiP3
C46H64ClNiP3‚
1.5C4H10O‚0.5C6D6
954.33
C46H64ClNiP3‚
0.53C6H5Cl‚3H2O
917.79
fw
705.55
742.03
cryst syst
unit cell dimens
a (Å)
b (Å)
c (Å)
monoclinic
monoclinic
orthorhombic
monoclinic
11.9211(3)
17.6797(6)
18.1966(5)
11.7832(4)
21.0922(6)
16.2440(4)
24.6269(2)
16.4198(2)
25.9681(3)
16.6280(4)
16.5289(4)
19.8549(5)
R (deg)
â (deg)
94.922(2)
93.393(2)
102.579(1)
γ (deg)
V (Å3)
3821.0(2)
P21/c (No. 14)
1.226
4030.1(2)
P21/c (No. 14)
1.22
10500.7(3)
Pbca (No. 61)
1.268
5326.0(2)
P21/n (No. 14)
1.145
space group
Dc (g cm-3
Z
)
4
4
8
4
F(000)
1520
1624
4112
1963
color, habit
yellow, block
0.30 × 0.12 × 0.10
6.61 (Mo KR)
red, block
0.07 × 0.10 × 0.17
7.00 (Mo KR)
red, plate
0.28 × 0.24 × 0.07
5.49 (Mo KR)
yellow, needle
0.40 × 0.22 × 0.12
5.67 (Mo KR)
cryst dimens (mm)
µ (cm-1
)
(b) Data Collection and Processing
Nonius KappaCCD
diffractometer
X-radiation
2θmax (deg)
data collected (h, k, l)
Mo KR (graphite monochromator)
55.4
47.2
54.94
50.12
(-19, -19, -23) to
(19, 19, 23)
(-15, -23, -23) to
(15, 23, 23)
(-13, -23, -18) to
(13, 23, 17)
(-31, -21, -33) to
(31, 21, 33)
no. of rflns
total
41 676
34 024
175 892
76 825
unique (Rint/%)
obsd
abs cor (transmissn
factors)
8833 (7.2)
6282 (I > 2σ(I))
multiscan (0.939-0.822)
5979 (6.0)
4643 (I > 3σ(I))
integration (0.906-0.953)
11 959 (6.4)
8861 (I > 3σ(I))
multiscan (0.848-0.967)
9390 (11.2)
4249 (I > 3σ(I))
multiscan (0.685-0.942)
decay (%)
nil
(c) Structure Analysis and Refinement
direct methods (SIR92)
structure soln
refinement
full-matrix least squares
no. of params
R(obsd data) (%)
Rw(obsd data (%)
406
5.1
6.2
415
4.3
4.6
540
4.8
7.3
520
6.1
7.8
but decomposition products, including [NiCl2(dcpe)] (δP 81) and
Cy2P(O)CH2CH2P(O)Cy2 (δP 48), were also present. Attempted
crystallization by layering the solution with hexane led only
to decomposition.
at calculated positions (C-H ) 0.95 Å) and periodically
recalculated but not refined. The maximum and minimum
peaks in the final difference Fourier map were 0.38 and -0.41
e/Å3, respectively.
4
31P{1H} NMR (81.0 MHz, C6D6): δ 31.8 (dd, J PP ) 22.4,
In the crystal structure of 2a , the molecular species was
clearly defined, but a very marginal disorder was observed in
one cyclohexyl ring; hence, the carbon atoms C(18), C(19), and
C(20) were best modeled by displacement ellipsoids. All non-
hydrogen atoms were refined anisotropically by full-matrix
least squares. Hydrogen atoms were included at calculated
positions (C-H ) 0.96 Å) and left riding with their carbon of
attachment. The maximum and minimum peaks in the final
difference Fourier map were 0.44 and -0.40 e/Å3, respectively.
In the crystal structure of 2c‚1.5C4H10O‚0.5C6D6, the mo-
lecular species (2c) and one diethyl ether solvent molecule were
clearly defined, but other disordered solvent molecules were
also present. They were assigned to a disordered 1:1 mixture
of benzene, arising from the reference solvent used for the 31P
NMR monitoring, and diethyl ether. Restraints were imposed
upon these solvent molecules, all the atom sites were given a
common isotropic displacement factor, and the relative oc-
cupancies of the two units were refined. Hydrogen atoms were
placed at calculated positions for 2c and for the ordered diethyl
ether molecule but were not included in the disordered region.
The maximum and minimum peaks in the final difference
Fourier map were 0.587 and -0.568 e/Å3, respectively, located
in the disordered solvent area.
2
4
2
6.4), 62.6 (dd, J PP ) 35.0, J PP ) 22.4), 69.2 (dd, J PP ) 35.0,
4J PP ) 6.4).
Rea ction of [NiCl(C(dCHP h )P P h 2-KP ,C1)(d cp e)] (2c)
w ith CO2. In a similar reaction, a solution of 2c in THF was
treated with technical grade CO2 to give the unstable complex
5c as the major species (see text).
31P{1H} NMR (81.0 MHz, CD2Cl2): δ 32.4 (d, J PP ) 13.5),
4
2
4
2
64.8 (dd, J PP ) 34.0, J PP ) 13.5), 66.0 (d, J PP ) 34.0).
X-r a y Cr ysta llogr a p h y. Crystal data and details of data
collection, data processing, structure analysis, and structure
refinement are given in Table 6.
All four crystals were mounted in silicone oil on a glass fiber
and measured at -73 °C. The structures were solved by direct
methods (SIR92)50 and expanded with use of Fourier tech-
niques (DIRDIF94).51 The intensities of the reflections were
processed by use of the computer programs Denzo and
Scalepak.52
The non-hydrogen atoms of 1a were refined anisotropically
by full-matrix least squares. Hydrogen atoms were included
(50) Altomare, A.; Cascarano, M.; Giacovazzo, C.; Guagliardi, A.;
Burla, M. C.; Polidori, G.; Camalli, M. J . Appl. Crystallogr. 1994, 27,
435.
(51) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
de Gelder, R.; Israel, R.; Smits, J . M. M. The DIRDIF-94 Program
System; Technical Report of the Crystallographic Laboratory; Univer-
sity of Nijmegen, Nijmegen, The Netherlands, 1994.
(52) Otwinowski, Z.; Minor, W. In Methods in Enzymology; Carter,
C. W., J r., Sweet, R. M., Eds.; Academic Press: New York, 1997; Vol.
276, p 307.

Ni(0) Complexes with η2-Alkynylphosphines
Organometallics, Vol. 20, No. 5, 2001 989
The crystal of 3c‚0.53C6H5Cl‚3H2O was of poor quality and
diffracted weakly, but the molecular species (3c) was clearly
defined. Molecules of chlorobenzene were also present, but the
occupancy was clearly less than 1. Restraints were imposed
upon these solvent molecules, and they were refined. Another
region of solvation was attributed to molecules of water. They
were solved with constraints on occupancy, and their hydrogen
atoms were not located.
All the calculations were performed with use of the crystal-
lographic software packages maXus,53 teXsan,54 and Xtal.55
The neutral atom scattering factors were taken from ref 56
for structure 1a , from ref 57 for structure 2a , and from ref 58
for structure 2c. ∆f ′ and ∆f′′ values and mass attenuation
coefficients were taken from ref 58 for all structures.
Note Ad d ed in P r oof. Other examples of monomeric
tungsten complexes that contain a η2-diphenylphosphi-
novinyl fragment have recently been reported.59
Ack n ow led gm en t. J .C. gratefully acknowledges the
receipt of a Summer Research Scholarship from the
Research School of Chemistry, Australian National
University. M.R.K. thanks the Alexander von Humboldt
Foundation for a Feodor von Lynen Fellowship, and
E.W. is grateful to the Australian Research Council for
the award of a QEII Research Fellowship.
Su p p or tin g In for m a tion Ava ila ble: Tables giving X-ray
data for 1a , 2a , 2c‚1.5C4H10O‚0.5C6D6, and 3c‚0.53C6H5Cl‚
3H2O. This material is available free of charge via the Internet
at http://pubs.acs.org.
(53) Mackay, S.; Gilmore, C. J .; Edwards, C.; Stewart, N.; Shank-
land, K. maXus Computer Program for the Solution and Refinement
of Crystal Structures; Nonius, MacScience, and The University of
Glasgow, 1999.
OM000895O
(54) TEXSAN: Single-Crystal Structure Analysis Software, version
1.8; Molecular Structure Corp., 3200 Research Forest Drive, The
Woodlands, TX 77381, 1997.
(55) XTAL3.0 Reference Manual, Universities of Lamb and Perth,
1990.
(56) Cromer, D. T.; Waber, J . T. International Tables for X-ray
Crystallography; Kynoch Press: Birmingham, U.K., 1974; Vol. IV.
(57) Waasmaier, D.; Kirfel, A. Acta Crystallogr., Sect. A 1995, A51,
416.
(58) International Tables for Crystallography; Wilson, A. J . C., Ed.;
Kluwer Academic: Dordrecht, The Netherlands, 1992; Vol. C.
(59) Ipaktschi, J .; Klotzbach, T.; Du¨lmer, A. Organometallics 2000,
19, 5281.