metal-organic compounds
and L0 have cone angles greater than 45ꢀ (Tolman, 1977). The
lability of the MoÐP(cy)3 bond in such complexes may arise,
in part, from the ligand cone angle of 170ꢀ and may account
for the dif®culty in preparation of the analogous complex cis-
{[ꢀ1-P(cy)3]2}W(CO)4 by Boyles et al. (1985). Rates of ligand
dissociation reactions from cis-(ꢀ1-L)(ꢀ1-L0)Mo(CO)4 also
point to the type of metal ion and the size of the ligand as
important kinetic controlling factors (Laboy et al., 1995;
Cortes-Figueroa et al., 1997). As part of a systematic study
testing the relationships between structure and reactivity in
these complexes, the synthesis and structures of the title
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
cis-Tetracarbonylbis(tricyclohexyl-
phosphine)molybdenum(0) and
pentacarbonyl(tricyclohexylphos-
phine)molybdenum(0)
compounds,
cis-tetracarbonylbis(tricyclohexylphosphine)-
molybdenum(0), (I), and pentacarbonyl(tricyclohexyl-
phosphine)molybdenum(0), (II), are reported. The structure
of (I) is a redetermination of that reported by Watson et al.
(1994), which was based on a very limited data set.
Jose E. Cortes-Figueroa,a Madeline S. Leon-Velazquez,a
Johanna Ramos,a Jerry P. Jasinski,b David A. Keene,b
Jeffrey D. Zubkowskic and Edward J. Valented*
The structures of (I) and (II) are shown in Figs. 1 and 2,
respectively. In (I), the Mo atom has a considerably distorted
octahedral coordination geometry, as indicated by the P1Ð
MoÐP2 bond angle of 104.8 (1)ꢀ (ideal value 90ꢀ) and the
molecular distortion from C2v symmetry. This is accompanied
by a contraction of the opposite C2ÐMoÐC3 angle to
84.2 (2)ꢀ, and of the adjacent P1ÐMoÐC3 and P2ÐMoÐC2
angles to 86.5 (2) and 84.8 (2)ꢀ, respectively. The sterically
crowded environment at the Mo atom is further indicated by
the distortions of the equatorial trans bond angles for P1Ð
MoÐC2 [169.9 (2)ꢀ], P2ÐMoÐC3 [167.6 (2)ꢀ] and C4ÐMoÐ
C1 [171.8 (3)ꢀ] from the 180ꢀ ideal. The MoÐCax bond
aOrganometallic Chemistry Research Laboratory, Department of Chemistry, Univer-
sity of Puerto Rico, Mayaguez, PR 00681, Puerto Rico, bDepartment of Chemistry,
Keene State College, Keene, NH 03435-2001, USA, cDepartment of Chemistry,
Jackson State University, Jackson, MS 39217, USA, and dDepartment of Chemistry,
Mississippi College, Clinton, MS 39058-4036, USA
Correspondence e-mail: valente@mc.edu
Received 30 May 2000
Accepted 2 October 2000
In the present redetermination of the complex cis-tetra-
carbonylbis(tricyclohexylphosphine)molybdenum(0),
(I),
[Mo(C18H33P)2(CO)4] or cis-{ꢀ1-[P(C6H11)3]2}Mo(CO)4, the
Mo atom has a distorted octahedral geometry with a large PÐ
MoÐP angle of 104.8 (1)ꢀ. A strong trans in¯uence on the
carbonyls in (I) is seen in a shortening of the MoÐC and a
lengthening of the CÐO distances opposite the phosphines
compared with those that are cis. This in¯uence is greatly
diminished in the complex pentacarbonyl(tricyclohexyl-
phosphine)molybdenum(0), (II), [Mo(C18H33P)(CO)5] or
{ꢀ1-[P(C6H11)3]}Mo(CO)5, the core of which has a slightly
distorted C4v geometry.
Ê
lengths, averaging 2.040 (8) A, are trans to each other and are
signi®cantly (about 10 s.u.'s) longer than the MoÐCeq
Ê
distances, which average 1.924 (8) A and are both trans to P.
Both MoÐP bond distances are similar and average
Ê
2.655 (2) A, which is signi®cantly longer than the average
MoÐP distance in phosphine±pentacarbonyl±molybdenum
1
Ê
complexes such as (II) [2.594 (1) A], [ꢀ -PPh3]Mo(CO)5
Comment
Tricyclohexylphoshine dissociates from cis-{ꢀ1-[P(cy)3]2}tetra-
carbonylmolybdenum(0) (cy is cyclohexyl) to produce a
mixture of {ꢀ2-[P(cy)3]2}tetracarbonylmolybdenum(0) and [ꢀ1-
P(cy)3]pentacarbonylmolybdenum(0) (Cortes-Figueroa et al.,
Figure 1
1997). Ligand dissociation from cis-(ꢀ1-L)(ꢀ1-L0)Mo(CO)4
produces (ꢀ2-L0)Mo(CO)4, for L = P(cy)3, triphenylphosphine
or piperidine and L0 = P(cy)3 or triphenylphosphine, where L
The molecular structure of complex (I) showing the atom-numbering
scheme. Displacement ellipsoids are at the 50% probability level and H
atoms have been omitted for clarity.
ꢁ
Acta Cryst. (2000). C56, 1435±1437
# 2000 International Union of Crystallography Printed in Great Britain ± all rights reserved 1435
Cortes-Figueroa, Jose E.
