Chlorobis(triphenylphosphine)nickel(I)

Article abstract of DOI:10.1107/S010827010200032X

Crystals of the title compound, [NiCl(C₁₈H₁₅P)₂], contain one molecule per asymmetric unit with no short intermolecular interactions. This is noteworthy since previous studies have reported that the formally 15-electron species oligomerizes in the solid state. The nickel(I) centre has a distorted trigonal-planar coordination geometry, the origin of which is suggested to be electronic in nature.

Full text of DOI:10.1107/S010827010200032X

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
a tetrahydrofuran (THF) solvate of (I) (Ellis & Spek, 2000).
The latter contains no short intermolecular interactions.
Although not characterized crystallographically, other
compounds of the formulation [NiX(PR3)2] have been studied
by different analytical techniques, but these compounds are
reported to be either oligomeric (X = Cl, Br; R = Ph; Lappert
ISSN 0108-2701
Chlorobis(triphenylphosphine)nickel(I)
È
& Speier, 1974; Cundy & Noth, 1971) or dimeric with a square-
planar con®guration [X = Cl, Br; R = cyclohexyl (Cy); Aresta
et al., 1975] in the solid state.
Nicholas C. Norman, A. Guy Orpen, Michael J. Quayle
and George R. Whittell*
Consistent with the ®ndings of Ellis & Spek (2000), complex
(I) is monomeric in the crystal, with the nickel(I) coordination
geometry being best described as distorted trigonal±planar
(Fig. 1). This is particularly noteworthy as the formally 15-
electron species might well be expected to oligomerize, as
previously suggested (Lappert & Speier, 1974). The NiÐCl
School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, England
Correspondence e-mail: g.whittell@auckland.ac.nz
Received 26 November 2001
Accepted 7 January 2002
Online 13 February 2002
Ê
bond length [2.1666 (6) A; Table 1] is comparable to that
Ê
observed in [NiCl(PPh3)2]ÁTHF [2.1481 (6) A], but signi®-
cantly shorter than in both polymorphs of [NiCl(PPh3)3]
Ê
[2.2785 (9) and 2.2933 (17) A; Cassidy & Whitmire, 1991; Ellis
Crystals of the title compound, [NiCl(C18H15P)2], contain one
molecule per asymmetric unit with no short intermolecular
interactions. This is noteworthy since previous studies have
reported that the formally 15-electron species oligomerizes in
the solid state. The nickel(I) centre has a distorted trigonal±
planar coordination geometry, the origin of which is suggested
to be electronic in nature.
&
Spek, 2000]. The NiÐP distances [2.2536 (5) and
Ê
2.2393 (5) A] and ClÐNiÐP angles [123.56 (2) and
121.12 (2)ꢀ] in (I) differ signi®cantly from one another, and
are also different to the corresponding parameters in
Ê
[NiCl(PPh3)2]ÁTHF [2.2091 (6) and 2.2012 (6) A, and
126.98 (2) and 121.33 (2)ꢀ, respectively], which also has crys-
tallographically independent triphenylphosphine ligands. This
distortion of the trigonal plane is consistent with the chemical
inequivalence of the phosphorus nuclei as suggested by elec-
tron spin resonance studies on a single crystal of [CuBr-
(PPh3)2] doped with (I) (Nilges et al., 1977). A distorted
trigonal±planar geometry is also apparent in [Ni{N(Si-
Me3)2}(PPh3)2] (Bradley et al., 1972), although the NiÐP bond
Comment
Although little evidence has been presented to con®rm the
existence of a nickel(II)±boryl compound, nickel(0) (Sugi-
nome et al., 1998) and nickel(II) (Gridnev et al., 1993)
complexes have been shown to catalyse certain alkyne bora-
tion reactions by mechanisms which are proposed to involve
such species. As part of our continuing studies into the
syntheses of transition metal±boryl complexes, we therefore
attempted a direct stoichiometric preparation. The reaction
between B-chlorocatecholborane and bis(triphenylphos-
phine)(ethene)nickel(0) failed to afford the desired oxidative±
addition product, instead yielding chlorobis(triphenyl-
phosphine)nickel(I), (I), and chlorotris(triphenylphosphine)-
nickel(I) as part of a product mixture (Whittell, 2000).
Ê
lengths [2.220 (4) and 2.213 (4) A] are equivalent. These,
however, are signi®cantly shorter than those in (I) and longer
than those in [NiCl(PPh3)2]ÁTHF. Nonetheless, common to all
Complexes of nickel(I) are far less numerous than those of
either nickel(0) or nickel(II), with most of those isolated as
solids containing phosphine or arsine ligands (Sacconi et al.,
1987). Of those containing halide ions and monodentate
phosphines, only [NiX(PPh3)3] (X = Cl, Br) had been char-
acterized by X-ray crystallography prior to this study (Cassidy
& Whitmire, 1991; Mealli et al., 1983). These compounds
dissociate in benzene solution to afford the title compound
(Heimbach, 1964) or its bromide analogue (Porri et al., 1967),
respectively, in addition to free triphenylphosphine. While this
manuscript was in preparation, a new polymorph of
[NiCl(PPh3)3] was reported, along with the crystal structure of
Figure 1
The molecular structure of the title compound with ellipsoids drawn at
the 50% probability level. H atoms have been omitted for clarity.
m160 # 2002 International Union of Crystallography
DOI: 10.1107/S010827010200032X
Acta Cryst. (2002). C58, m160±m161

metal-organic compounds
Data collection
three complexes is a contraction of the PÐNiÐP angle rela-
tive to the ideal value (120ꢀ); 114.94 (2), 111.52 (2) and
107.0 (2)ꢀ for (I), [NiCl(PPh3)2]ÁTHF and [Ni{N(Si-
Me3)2}(PPh3)2], respectively. A review article by Eller et al.
(1977) inferred this to mean, in the case of the NiI±amide
complex, that the amide was of larger steric bulk than the
triphenylphosphine ligands, an assertion which is not consis-
tent with the presence of this same structural feature in both
(I) and [NiCl(PPh3)2]ÁTHF. Consideration of steric factors
alone would predict a PÐNiÐP angle for all three complexes
greater than 120ꢀ, as observed for the PÐCuÐP angle
[126.0 (1)ꢀ] in the copper(I) bromide analogue, [CuBr(PPh3)2]
(Davis et al., 1973), the molecular structure of which would be
expected to be determined solely by steric effects on account
of the d10 electron con®guration at copper. The angular
distortion most probably arises from a ®rst-order Jahn±Teller
effect which, for a d9 metal complex, is expected to destabilize
an ML3 structure from D3h to C2v symmetry (Albright et al.,
1985).
Bruker SMART CCD area-detector
diffractometer
! scans
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.720, Tmax = 0.924
18 753 measured re¯ections
6788 independent re¯ections
4961 re¯ections with I > 2ꢅ(I)
Rint = 0.035
ꢃmax = 27.5ꢀ
h = 8 ! 14
k = 22 ! 22
l = 20 ! 17
Re®nement
Re®nement on F2
R[F2 > 2ꢅ(F2)] = 0.031
wR(F2) = 0.072
S = 0.92
6788 re¯ections
361 parameters
H-atom parameters constrained
w = 1/[ꢅ2(Fo2) + (0.034P)2]
where P = (Fo2 + 2Fc2)/3
(Á/ꢅ)max = 0.001
3
Ê
Áꢆmax = 0.37 e A
3
Ê
0.32 e A
Áꢆmin
=
H atoms were constrained to idealized geometries at a distance of
Ê
0.95 A from their parent C atoms and with Uiso(H) = 1.2Ueq(C).
Data collection: SMART (Bruker, 1998); cell re®nement: SMART;
data reduction: SAINT (Bruker, 1998); program(s) used to solve
structure: SHELXTL (Bruker, 1997); program(s) used to re®ne
structure: SHELXTL; molecular graphics: SHELXTL.
Experimental
All manipulations were conducted under an atmosphere of dry di-
nitrogen or in vacuo, using standard glove-box techniques. The
solvents were dried over sodium and distilled under dinitrogen
immediately prior to use. ClB(cat) (cat is 1,2-O2C6H4) was purchased
from commercial sources and used without further puri®cation.
[Ni(ꢀ-C2H4)(PPh3)2] was prepared in accordance with the literature
We wish to thank the EPSRC for studentships (MJQ and
GRW).
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: BM1484). Services for accessing these data are
described at the back of the journal.
(Schramm
0.084 mmol) in toluene (ca 1 ml) was prepared in a small sample vial
and then transferred to similar vessel containing [Ni(ꢀ-
& Ibers, 1980). A solution of ClB(cat) (0.013 g,
a
C2H4)(PPh3)2] (0.046 g, 0.076 mmol). After ca 5 min at room
temperature, a cloudy dark-green solution resulted. Hexane (ca 4 ml)
was then added to the reaction mixture, resulting in the formation of
a dark-green precipitate. This was allowed to settle prior to removal
and ®ltration of the orange mother liquor. The mother liquor was
concentrated in vacuo to afford an orange oil, which was further
diluted with toluene (ca 1 ml) and transferred to a small Schlenk tube.
A hexane overlayer was added which, upon slow solvent diffusion at
251 K, afforded yellow crystals of (I) and orange crystals of
[NiCl(PPh3)3]. The latter were shown by X-ray crystallography to be
isomorphous with the polymorph reported by Ellis & Spek (2000).
References
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È
Crystal data
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3
[NiCl(C18H15P)2]
Mr = 618.70
Monoclinic, P21/c
Dx = 1.388 Mg m
Mo Kꢂ radiation
Cell parameters from 8192
re¯ections
Ê
a = 11.0778 (11) A
Ê
b = 17.535 (2) A
ꢃ = 2±25ꢀ
ꢄ = 0.88 mm
T = 173 (2) K
1
Ê
c = 15.4159 (18) A
ꢁ = 98.722 (8)ꢀ
V = 2960.0 (6) A
Z = 4
3
Ê
Plate, yellow
0.40 Â 0.25 Â 0.12 mm
Table 1
Selected geometric parameters (A, ).
ꢀ
Ê
Sacconi, L., Mani, F. & Bencini, A. (1987). Nickel in Comprehensive
Coordination Chemistry, Vol. 5, pp. 36, 39±44. New York: Pergamon Press.
Schramm, K. D. & Ibers, J. A. (1980). Inorg. Chem. 19, 2441±2448.
È
Sheldrick, G. M. (1996). SADABS. University of Gottingen, Germany.
Suginome, M., Matsuda, T. & Ito, Y. (1998). Organometallics, 24, 5233±5235.
Ni1ÐCl1
Ni1ÐP2
2.1666 (6)
2.2393 (5)
Ni1ÐP1
2.2536 (5)
114.94 (2)
Cl1ÐNi1ÐP1
Cl1ÐNi1ÐP2
121.12 (2)
123.56 (2)
P1ÐNi1ÐP2
Whittell, G. R. (2000). PhD thesis, University of Bristol, England.
ꢁ
Acta Cryst. (2002). C58, m160±m161
Nicholas C. Norman et al. [NiCl(C18H15P)2] m161