Trans-Carbonyliodotris(triphenyl-stibine-κSb)rhodium(I)

Article abstract of DOI:10.1107/S0108270102018747

The crystal structure of the title compound, [RhI(C₁₈H₁₅Sb)₃-(CO)], represents a rare example of a crystallographically characterized five-coordinate Rh¹-SbPh₃ complex. The compound crystallizes with the I-Rh-CO core on a threefold rotation axis, with three crystallographically equivalent triphenylstibine ligands. Selected geometric parameters are: Rh-I = 2.7159 (8), Rh-Sb = 2.5962 (4), Rh-C_CO = 1.825 (6) and C_CO-O 1.153 (6) A, and Sb-Rh-I = 89.374 (10) and Sb-Rh-C_CO = 90.626 (10)°. The cone angle of the SbPh₃ ligand was determined as 137°, according to the Tolman model.

Full text of DOI:10.1107/S0108270102018747

metal-organic compounds
ligands around the Rh atom with angles of exactly 120ꢀ.
Accordingly, the OCÐRhÐI core is exactly linear and the
C1ÐRhÐSb and IÐRhÐSb angles are close to 90ꢀ, at
90.626 (10) and 89.374 (10)ꢀ, respectively.
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
An IÐRhÐSbÐC11 torsion angle of 175.77 (10)ꢀ indicates
phenyl ring 1 (C11±C16) points almost directly towards the
CO moiety, whereas rings 2 (C21±C26) and 3 (C31±C36) are
staggered with respect to the RhÐI bond, with IÐRhÐSbÐ
C21 and IÐRhÐSbÐC31 torsion angles of 63.88 (11) and
57.89 (9)ꢀ, respectively. These speci®c geometric orientations
may account for the observation that the SbPh3 ligands are
marginally displaced towards the larger I ligand.
trans-Carbonyliodotris(triphenyl-
stibine-jSb)rhodium(I)
Stefanus Ottoa*² and Andreas Roodtb
aDepartment of Chemistry, University of the Free State, PO Box 339, Bloemfontain
9300, South Africa, and bDepartment of Chemistry, Rand Afrikaans University,
PO Box 524, Johannesburg 2006, South Africa
Based on molecular models, Tolman (1977) predicted that
increasing the MÐL or LÐC (M is a metal and L is a ligand)
Ê
Correspondence e-mail: fanie.otto@sasol.com
bond lengths by 0.1 A (for ligands containing donor atoms
other than P) would result in a 3±5ꢀ decrease in the cone angle
of the ligand. In this regard, the effective cone angle, as
de®ned earlier (Otto et al., 2000), utilizes the observed RhÐSb
bond distance, and the cone angle for SbPh3 in (I) was
calculated as 137ꢀ. This value is in excellent agreement with
both Tolman's prediction and the average of 139ꢀ for six
independent SbPh3 ligands obtained during a previous study
(Otto & Roodt, 2002).
In Table 2, compound (I) is compared with related trans-
[Rh(X)CO(LPh3)n] (n = 2 or 3; L is Sb or P) complexes,
illustrating the effect of different X ligands on the geometric
parameters of four- and ®ve-coordinate SbPh3 complexes of
RhI. From these data, it is clear that the RhÐSb bond length
Received 29 August 2002
Accepted 11 October 2002
Online 8 November 2002
The crystal structure of the title compound, [RhI(C18H15Sb)3-
(CO)], represents a rare example of a crystallographically
characterized ®ve-coordinate RhI±SbPh3 complex. The
compound crystallizes with the IÐRhÐCO core on a
threefold rotation axis, with three crystallographically equiva-
lent triphenylstibine ligands. Selected geometric parameters
are: RhÐI = 2.7159 (8), RhÐSb = 2.5962 (4), RhÐCCO
Ê
=
=
1.825 (6) and CCOÐO 1.153 (6) A, and SbÐRhÐI
89.374 (10) and SbÐRhÐCCO = 90.626 (10)ꢀ. The cone angle
of the SbPh3 ligand was determined as 137ꢀ, according to the
Tolman model.
Ê
of 2.5962 (4) A in (I) is comparable with the value of
Comment
Although stibine complexes of Rh have been known since the
1950s (Vallarino, 1957), surprisingly few crystallographic
studies of these complexes have been reported to date. As has
been pointed out in earlier investigations (Ugo et al., 1969;
Otto & Roodt, 2002), several experimental problems may
arise during the characterization of these complexes, making
X-ray crystallography the method of choice. As part of our
systematic investigation of these systems (Otto et al., 2002;
Otto & Roodt, 2002), we obtained single crystals of trans-
carbonyliodotris(triphenylstibine-ꢀSb)rhodium(I), (I), and
the crystal structure is presented here.
Compound (I) (Fig. 1) crystallizes with an almost perfect
trigonal±bipyramidal geometry in the trigonal space group P3.
The packing in the crystal is governed by van der Waals forces
alone; no signi®cant intermolecular interactions are observed.
The OCÐRhÐI core is situated along the threefold rotation
axis, resulting in three crystallographically equivalent SbPh3
Figure 1
A view of the structure of (I), showing the atom-numbering scheme and
displacement ellipsoids at the 30% probability level. H atoms have been
omitted for clarity. The complex is numbered with the ®rst digit of the
phenyl rings referring to the number of the ring (1±3) and the second digit
referring to the number of the atom within the ring (1±6) [symmetry
codes: (i) x ‡ y; 1 x; z; (ii) 1 y; x y ‡ 1; z].
² Current address: Sasol Technology Research and Development, Sasol,
PO Box 1, Sasolburg 1947, South Africa.
Acta Cryst. (2002). C58, m565±m566
DOI: 10.1107/S0108270102018747
# 2002 International Union of Crystallography m565

metal-organic compounds
Ê
2.5981 (5) A found in the analogous ®ve-coordinate Cl
Ê
complex, but is slightly longer than the values of 2.568 (2) A in
Table 1
Selected geometric parameters (A, ).
ꢀ
Ê
Ê
the acetyl complex and 2.5655 (2) A in the four-coordinate Cl
complex. Not many RhÐI bond distances are known for
complexes of this kind, but the RhÐI bond length of
RhÐC1
RhÐSb
RhÐI
1.825 (6)
2.5962 (4)
2.7159 (8)
2.140 (3)
SbÐC21
SbÐC31
C1ÐO
2.143 (3)
2.129 (3)
1.153 (6)
SbÐC11
Ê
2.7159 (8) A in (I) is considerably longer than the value of
Ê
2.683 (1) A determined for trans-[RhI(CO)(PPh3)2] (Basson et
C1ÐRhÐSb
SbÐRhÐI
C11ÐSbÐC21
C11ÐSbÐC31
90.626 (10)
89.374 (10)
99.57 (12)
C21ÐSbÐC31
C11ÐSbÐRh
C21ÐSbÐRh
C31ÐSbÐRh
96.21 (12)
112.73 (9)
124.39 (8)
118.84 (8)
al., 1990). This may be a result of the increased steric crowding
in the ®ve-coordinate complex or the increased electron
density introduced by the three SbPh3 ligands. A similar
observation was made in relation to the RhÐCl bond
distances of the four- and ®ve-coordinate triphenylstibine
complexes (Otto & Roodt, 2002) listed in Table 2, where an
101.04 (12)
IÐRhÐSbÐC11
IÐRhÐSbÐC21
175.77 (10)
63.88 (11)
IÐRhÐSbÐC31
57.89 (9)
Ê
elongation from 2.315 (3) to 2.4094 (18) A was induced by the
increase in coordination number.
Table 2
Comparative X-ray data for trans-[Rh(X)CO(LPh3)n] complexes.
Experimental
Ê
RhÐC1 (A)
Ê
RhÐL (A)
Ê
RhÐX (A)
X
n
L
Reference
NaI (17 mg, 0.113 mmol) was added to a nitrogen-¯ushed solution of
the [Rh(ꢁ-Cl)(CO)2]2 dimer (20 mg, 0.051 mmol) in acetone (5 ml).
The reaction medium immediately took on a deep-red colour and was
stirred for a further 5 min after addition. Stirring was then discon-
tinued and SbPh3 (126 mg, 0.357 mmol) dissolved in acetone (7 ml)
was added carefully so as to avoid the least disturbance to the solu-
tion. Deep-red rectangular crystals of (I) soon started separating
from the solution; yields > 80% based on Rh were obtained. Spec-
Cl
Cl
I
I
COCH3
2
3
2
3
3
Sb
Sb
P
Sb
Sb
1.797 (13)
1.875 (7)
1.81 (1)
1.825 (6)
1.91 (2)
2.5655 (2)
2.5981 (5)
2.326 (2)
2.5962 (4)
2.568 (2)
2.315 (3)
2.4094 (18)
2.683 (1)
2.7159 (8)
2.095 (16)
a
a
b
c
d
References: (a) Otto & Roodt (2002); (b) Basson et al. (1990); (c) this work; (d)
Lamprecht et al. (1986).
1
troscopic analysis, IR (KBr, ꢂ): 1977 cm (CO); IR (dichloro-
structure: SHELXS97 (Sheldrick, 1997); program(s) used to re®ne
structure: SHELXL97 (Sheldrick, 1997); molecular graphics:
DIAMOND (Brandenburg, 1999); software used to prepare material
for publication: SHELXL97.
1
methane, ꢂ): 1978 cm (CO).
Crystal data
[RhI(C18H15Sb)3(CO)]
Mr = 1316.97
Trigonal, P3
Mo Kꢃ radiation
Cell parameters from 4642
re¯ections
Financial assistance from the South African NRF, and from
the Research Funds of the Rand Afrikaans University and the
University of the Free State, is gratefully acknowledged. The
authors thank the Chemical Centre of the University of Lund,
Sweden, for the use of their diffractometer for the data
collection.
ꢄ = 2.2±24.8ꢀ
Ê
a = 14.462 (2) A
1
Ê
c = 13.902 (3) A
Ê
V = 2518.2 (7) A
ꢁ = 2.56 mm
T = 293 (2) K
3
Z = 2
Dx = 1.737 Mg m
Parallelepiped, dark red
0.29 Â 0.10 Â 0.08 mm
3
Data collection
Siemens SMART CCD area-
detector diffractometer
! scans
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.493, Tmax = 0.815
24 940 measured re¯ections
5324 independent re¯ections
2651 re¯ections with I > 2ꢅ(I)
Rint = 0.094
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: JZ1526). Services for accessing these data are
described at the back of the journal.
ꢄ
max = 31.8ꢀ
h = 18 ! 21
k = 20 ! 20
l = 20 ! 20
References
Basson, S. S., Leipoldt, J. G. & Roodt, A. (1990). Acta Cryst. C46, 142±143.
Brandenburg, K. (1999). DIAMOND. Release 2.1c. Crystal Impact GbR,
Bonn, Germany.
Lamprecht, G. J., Van Biljon, C. P. & Leipoldt, J. G. (1986). Inorg. Chim. Acta,
119, L1±L4.
Otto, S., Mzamane, S. N. & Roodt, A. (2002). Modern Coordination Chemistry,
The Legacy of Joseph Chatt, edited by G. J. Leigh & N. Winterton, pp. 328±
339. London: Royal Society of Chemistry.
Re®nement
Re®nement on F2
R[F2 > 2ꢅ(F2)] = 0.031
wR(F2) = 0.056
S = 0.86
5324 re¯ections
185 parameters
H-atom parameters constrained
w = 1/[ꢅ2(Fo2) + (0.0154P)2]
where P = (Fo2 + 2Fc2)/3
(Á/ꢅ)max = 0.003
3
Ê
Áꢆmax = 0.43 e A
3
Ê
0.67 e A
Áꢆmin
=
Otto, S. & Roodt, A. (2002). Inorg. Chim. Acta, 331, 199±207.
Otto, S., Roodt, A. & Smith, J. (2000). Inorg. Chim. Acta, 303, 295±299.
Ê
H atoms were treated as riding, with CÐH = 0.93 A. Even though
È
Sheldrick, G. M. (1996). SADABS. University of Gottingen, Germany.
3
the structure contains solvent-accessible voids of 115 A , both the
Ê
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of
GoÈttingen, Germany.
Siemens (1995). SMART and SAINT. Versions 4.0. Siemens Analytical X-ray
Instruments Inc., Madison, Wisconsin, USA.
Tolman, C. A. (1977). Chem. Rev. 77, 313±348.
minimum and maximum residual electron-density peaks were smaller
than 1 e A 3, indicating that no molecular fragments remain unac-
Ê
counted for.
Data collection: SMART (Siemens, 1995); cell re®nement: SAINT
(Siemens, 1995); data reduction: SAINT; program(s) used to solve
Ugo, R., Bonati, F. & Cenini, S. (1969). Inorg. Chim. Acta, 3, 220±222.
Vallarino, L. (1957). J. Chem. Soc. pp. 2287±2292.
ꢁ
m566 Otto and Roodt [RhI(C18H15Sb)3(CO)]
Acta Cryst. (2002). C58, m565±m566