Os3(CO)11(BiPh3): The missing link in osmium-bismuth cluster chemistry

Article abstract of DOI:10.1016/j.jorganchem.2015.02.005

Abstract The room temperature reaction of Os₃(CO)₁₁(NCCH₃) with BiPh₃ afforded the substituted derivative Os₃(CO)₁₁(BiPh₃) which decomposed rapidly. The X-ray crystallographic study is reported, together with that of the stibine and arsine analogues.

Full text of DOI:10.1016/j.jorganchem.2015.02.005

Journal of Organometallic Chemistry 783 (2015) 46e48
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Note
Os3(CO)11(BiPh3): The missing link in osmiumebismuth cluster
chemistry
,
*
Suat Ping Oh a, Ying-Zhou Li b, Weng Kee Leong b
a Department of Chemistry, National University of Singapore, Kent Ridge, Singapore 119260, Singapore
b Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link,
Singapore 637371, Singapore
a r t i c l e i n f o
a b s t r a c t
Article history:
The room temperature reaction of Os3(CO)11(NCCH3) with BiPh3 afforded the substituted derivative
Os3(CO)11(BiPh3) which decomposed rapidly. The X-ray crystallographic study is reported, together with
that of the stibine and arsine analogues.
Received 18 November 2014
Received in revised form
4 February 2015
Accepted 5 February 2015
Available online 13 February 2015
© 2015 Elsevier B.V. All rights reserved.
Keywords:
Osmium
Bismuth
Carbonyl cluster
Introduction
BieC bond cleavage, and cluster fragmentation and condensation.
Significantly, no cluster containing an intact BiPh3 ligand was
Heteronuclear clusters containing a main group element with a
transition metal are of interest because of the very different
chemistry exhibited by the components. We have, for many years
now, been interested in osmium carbonyl clusters containing the
heavier group 15 elements. In particular, we have uncovered a lot of
novel reactivity associated with osmiumeantimony clusters. The
elements in group 15 exhibit characters ranging from the non-
metallic (N and P) through metalloid (As and Sb) to metallic (Bi),
and we believe that the interesting chemistry of osmiumeanti-
mony clusters may be related to this increasing metallic character
as we go down group 15 [1]. It is thus reasonable to expect that
moving on to bismuth should yield even more contrasting
chemistry.
observed [3a], even though the initial reaction product was ex-
pected to be Os3(CO)11(BiPh3), 3d. We wish to report here that we
have been able to isolate 3d from the reaction and characterize it
crystallographically.
Results and discussion
The cluster 3d can be isolated in low yields, and in an impure
form, from the reaction of 1a with 2d. A similar result was obtained
using Os3(CO)11(COE) (where COE ¼ cyclooctene), 1b. Cluster 3d is
thermally not very stable; solutions decomposed slowly even at
and below ambient temperatures, although the solid could be
stored for several days at 0 ꢀC. Although we were able to obtain a
reasonably clean IR spectrum of the product, a pure sample eluded
us despite numerous attempts over several years! Fortuitously, we
were able to obtain a diffraction quality crystal during an attempt at
recrystallization; an ORTEP plot showing the molecular structure is
given in Fig. 1.
The single-crystal structural study of the phosphine derivative,
viz., Os3(CO)11(PPh3), 3a, has already been reported in a landmark
study by Bruce et al. [4] Although aspects of the chemistry of the
arsine [5], and stibine [5a,6], analogues have been reported, their
solid-state structures have not been determined. We have thus
determined the structures of the arsine and stibine analogues, 3b
The first report on the synthesis of osmiumebismuth clusters
appeared almost 30 years ago [2], and it took a pause of more than
two decades before their chemistry was looked at again [3]. In the
latter work, it was reported that the reaction of the lightly-stabi-
lized cluster Os3(CO)11(NCCH3), 1a, with BiPh3, 2d, afforded five
products, viz., Os2(CO)8(m-BiPh), Os(CO)4Ph2, Os4(CO)14(m- -
h3
OCC6H5)(m4-Bi), Os4(CO)15Ph(m4-Bi) and Os5(CO)19Ph(m4-Bi), via
* Corresponding author. Tel.: þ65 6592 7577.
E-mail address: chmlwk@ntu.edu.sg (W.K. Leong).
http://dx.doi.org/10.1016/j.jorganchem.2015.02.005
0022-328X/© 2015 Elsevier B.V. All rights reserved.

S.P. Oh et al. / Journal of Organometallic Chemistry 783 (2015) 46e48
47
the OseE bond with the stability of the clusters 3x since the in-
crease in this length is the least in going from Sb to Bi. We have
therefore sought to gain some insight through a computation of the
free energy change (D
Gꢀ) for the formation of 3x from 1a and 2x
using density functional theory (Table 2). The trend is very clear;
the reaction is less favoured going from P to Bi. In fact, the free
energy suggests that the formation of 3d is highly disfavoured [8]. It
is therefore plausible that 3d may easily dissociate to, for example,
an “Os3(CO)11” fragment. Such a fragment could readily insert into a
BieC bond, and may account for the reaction products observed by
Adams et al. [3]; thermolysis of a sample of 3d which was slightly
contaminated with 2d afforded a number of products, among
which were the clusters Os4(CO)14(m-h
3-OCC6H5)(m4-Bi) and
Os4(CO)15Ph(m4-Bi) and Os5(CO)19Ph(m4-Bi) reported earlier [3a].
Experimental
Fig. 1. ORTEP plot of 3d. Thermal ellipsoids are drawn at the 50% probability level.
All reactions and manipulations were carried out under nitrogen
by using standard Schlenk techniques. Solvents were purified,
dried, distilled, and stored under nitrogen prior to use. Routine
NMR spectra were acquired as CDCl3 solutions on a Bruker ACF300
NMR spectrometer. Chemical shifts reported are referenced to that
for the residual proton of the solvent. ESI mass spectra were ob-
tained on a Finnigan MAT95XL-T spectrometer, at 50 ꢀC, using
methanol with sodium methoxide. Microanalyses were carried out
by the microanalytical laboratory at the National University of
Singapore. The clusters 1a and 1b were prepared according to the
literature methods [9,10]. All other reagents were from commercial
sources and used as supplied. The clusters 3b and 3c were prepared
from the reaction of 1a with 2b and 2c, respectively.
Hydrogen atoms have been omitted for clarity.
and 3c, respectively, as well. To the best of our knowledge, this
represents the first complete series of an organometallic cluster
containing a group 15 ligand which has been structurally charac-
terized. Selected bond parameters for all four clusters are collected
in Table 1.
Clusters 3aec are isomorphic and isostructural; they all crys-
tallize in the monoclinic space group C2/c with essentially similar
unit cell parameters. The crystal of 3d differs by virtue of its con-
taining a dichloromethane solvate. Otherwise, the molecular pa-
rameters of 3aed show trends which are nicely consistent with the
identity of the group 15 element (E), and the observations which
have been made earlier by Bruce et al. in their study on the phos-
phine and arsine derivatives. For example, the Os2eOs1-E bond
angle decreases as we move from E ¼ P to E ¼ Bi, and the Os1eOs2
bond which is cis to the group 15 ligand (2x) is the longest of the
three OseOs bonds in each case. All the structures are also of the “E”
conformation defined by Pomeroy et al. [7].
Synthesis of Os3(CO)11(BiPh3), 3d
A sample of 1a (88 mg, 96 mmol) and BiPh3, 2d, (43 mg, 98 mmol)
dissolved in toluene (10 ml) was placed in a Carius tube, degassed
by three cycles of freezeepumpethaw, and then heated in an oil
bath at 40 ꢀC for 20 min, during which the colour changed from
orange yellow to brown. After solvent removal, the crude was
extracted with hexane and 3d crystallized out at low temperature.
The OseE bond lengths are correlated to the covalent radii of E
(1.06, 1.20, 1.40 and 1.46 Å for P, As, Sb and Bi, respectively), but
otherwise, there is no obvious correlation between the length of
Similarly, a mixture of 1b (40 mg, 40 mmol) and 2d (100 mg,
0.20 mmol) in DCM (20 ml) stirred at room temperature for 12 h
afforded a brown-yellow suspension. Removal of the solvent fol-
lowed by TLC separation with DCM/Hex (1:3, v/v) as eluent afforded
unreacted BiPh3 as the first colourless band, followed by a yellow
band which comprised a mixture of 2d and 3d (Rf ¼ 0.60).
Table 1
Common atomic labelling scheme and selected bond lengths (Å) and angles (ꢀ) for
clusters 3aed.
3d: IR (CH2Cl2)
n
(CO): 2109m, 2058s, 2033s, 2021s, 1991w,
1977w, 1953w cmꢁ1
;
1H NMR (C6D6)
d
7.56 (dd, 6H, PhH), 7.06 (t,
6H, PhH), 7.00 (t, 3H, PhH).
Thermolysis of 3d
A sample of 3d (19 mg, slightly contaminated with 2d) obtained
from the reaction of 1b and 2d was dissolved in dry hexane (20 ml)
and the yellow solution refluxed for 3 h, resulting in a dark brown
Cluster
E
3aa
3b
3c
3d
P
As
Sb
Bi
Os1eOs2
Os2eOs3
Os3eOs1
Os1eE
Os2eOs1eOs3
Os1eOs2eOs3
Os1eOs3eOs2
Os2eOs1eE
Dihedral angleb
2.9183(7)
2.8861(7)
2.8905(8)
2.370(2)
59.58(1)
59.73(2)
60.69(2)
102.59(6)
8.4
2.9148(7)
2.8871(6)
2.8727(9)
2.4670(9)
59.842(8)
59.355(18)
60.802(19)
100.596(18)
8.4
2.9176(4)
2.8955(4)
2.8682(3)
2.6054(5)
60.053(9)
59.127(9)
60.820(9)
97.762(13)
6.8
2.9050(6)
2.8837(7)
2.8468(5)
2.6909(6)
60.170(15)
58.914(15)
60.916(15)
96.497(19)
9.8
Table 2
Computed D
Gꢀ for the reaction of 1 and 2x to form 3x.
a
x
a
b
c
d
Data obtained from Ref. [4].
b
Dihedral angle between the CaxeOs2eCaxeOs3 and CaxeOs3eCaxeOs2 planes of
the Os2(CO)8 unit as defined in Ref. [7].
D
Gꢀ, kJ molꢁ1
ꢁ4.9
ꢁ3.4
þ8.4
þ38.2

48
S.P. Oh et al. / Journal of Organometallic Chemistry 783 (2015) 46e48
solution. After removal of the solvent, the residue was first subject
to a flash column using DCM/Hex (1:2, v/v) as eluent, to give an
orange eluate which was purified further by TLC with DCM/Hex
(1:4, v/v) as eluent. Several products in small quantities were
separated, of which the identified bands were: Os3(CO)12 (Rf ¼ 0.80,
thank Drs Lip Lin Koh, Yongxin Li and Rakesh Ganguly, and Ms Geok
Kheng Tan, for assistance with the crystallographic studies.
Appendix B. Supplementary data
light yellow), 2d (Rf ¼ 0.70, colourless), Os4(CO)14
(m-h
2-O]
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2015.02.005.
CPh)(m4-Bi) (Rf ¼ 0.40, orange) [3], and Os5(CO)19Ph(m4-Bi)
(Rf ¼ 0.30, red) [3].
X-ray crystal structure determinations
References
Crystals were mounted on quartz fibres. X-ray data were
[1] Y.-Z. Li, R. Ganguly, W.K. Leong, Organometallics 33 (2014) 3867e3878 (and
references therein).
collected on a Bruker AXS APEX system, using Mo K
a radiation,
with the SMART suite of programs [11]. Data were processed and
corrected for Lorentz and polarization effects with SAINT [12], and
for absorption effects with SADABS [13]. Structural solution and
refinement were carried out with the SHELXTL suite of programs
[14]. Crystal and refinement data are summarized in Table S1.
The structures were solved by direct methods to locate the
heavy atoms, followed by difference maps for the light, non-
hydrogen atoms. In 3d, a disordered dichloromethane solvate was
found. The disorder was modelled with two alternative sites, with
occupancies summed to unity, and appropriate restraints on bond
and thermal parameters applied. Organic hydrogen atoms were
placed in calculated positions and refined with a riding model. All
non-hydrogen atoms were generally given anisotropic displace-
ment parameters in the final model.
[2] H.G. Ang, C.M. Hay, B.F.G. Johnson, J. Lewis, P.R. Raithby, A.J. Whitton,
J. Organomet. Chem. 330 (1987) C5eC11.
[3] (a) R.D. Adams, W.C. Pearl Jr., Inorg. Chem. 49 (2010) 7170e7175;
(b) R.D. Adams, Y. Kan, Q. Zhang, J. Organomet. Chem. 751 (2014) 475e481.
[4] M.I. Bruce, M.J. Liddell, C.A. Hughes, B.W. Skelton, A.H. White, J. Organomet.
Chem. 347 (1988) 157e180.
[5] (a) J. Shen, Y. Gao, Q. Shi, F. Basolo, Inorg. Chem. 27 (1988) 4236e4239;
(b) C.T. Tay, W.K. Leong, J. Organomet. Chem. 625 (2001) 231e235.
[6] (a) Y. Liu, W.K. Leong, R.K. Pomeroy, Organometallics 17 (1998) 3387e3389;
(b) W.K. Leong, G. Chen, Organometallics 20 (2001) 2280e2287.
[7] V.M. Hansen, A.K. Ma, K. Biradha, R.K. Pomeroy, M.J. Zaworotko, Organome-
tallics 17 (1998) 5267e5274.
[8] It has been suggested by a reviewer that the large free energy value obtained
for 3d may be due to the inadequacy of the B3LYP density-functional for such
systems. We have carried out the same computation using the M06 density-
functional and obtained a value of þ26.0 kJ molꢁ1
.
[9] J.N. Nicholls, M.D. Vargas, Inorg. Synth. 28 (1990) 232e235.
ꢀ
[10] H.Z.S. Lee, W.K. Leong, S. Top, A. Vessieres, ChemMedChem
9 (2014)
1453e1457.
[11] SMART Version 5.628, Bruker AXS Inc, Madison, Wisconsin, USA, 2001.
[12] SAINTþ Version 6.22a, Bruker AXS Inc, Madison, Wisconsin, USA, 2001.
[13] G.M. Sheldrick, SADABS, 1996.
Computational studies
[14] SHELXTL Version 5.1, Bruker AXS Inc, Madison, Wisconsin, USA, 1997.
[15] C. Adamo, V. Barone, J. Chem. Phys. 108 (1998) 664e675.
[16] Y. Zhao, D. Truhlar, Theor. Chem. Acc. 120 (2008) 215e241.
[17] A.W. Ehlers, M. Bohme, S. Dapprich, A. Gobbi, A. Hollwarth, V. Jonas,
K.F. Kohler, R. Stegmann, A. Veldkamp, G. Frenkling, Chem. Phys. Lett. 208
(1993) 111e114.
Geometry optimizations were carried out by DFT utilizing the
MPW1PW91 [15], or M06 density-functionals [16]. The LANL2DZ
(Los Alamos effective core potential double-z) basis set, together
with polarization functions [17], were employed for the heavy
atoms, viz., Os, P, As, Sb and Bi; the 6-311 þ G(2d,p) basis set was
used for all the other atoms. Spin-restricted calculations were used
for geometry optimization, and harmonic frequencies were then
calculated to characterize the stationary points as equilibrium
structures with all real frequencies, and to evaluate zero-point
energy (ZPE) corrections. All calculations were performed using
the Gaussian 09 suite of programs [18].
[18] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb,
J.R. Cheeseman, J.A. Montgomery Jr., T. Vreven, K.N. Kudin, J.C. Burant,
J.M. Millam, S.S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi,
G. Scalmani, N. Rega, G.A. Petersson, H. Nakatsuji, M. Hada, M. Ehara,
K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, M. Klene, X. Li, J.E. Knox, H.P. Hratchian, J.B. Cross, C. Adamo,
J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi,
C. Pomelli, J.W. Ochterski, P.Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador,
J.J. Dannenberg, V.G. Zakrzewski, S. Dapprich, A.D. Daniels, M.C. Strain,
O. Farkas, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J.V. Ortiz,
Q. Cui, A.G. Baboul, S. Clifford, J. Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko,
P. Piskorz, I. Komaromi, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng,
A. Nanayakkara, M. Challacombe, P.M.W. Gill, B. Johnson, W. Chen,
M.W. Wong, C. Gonzalez, J.A. Pople, Gaussian 03, Gaussian Inc, Wallingford CT,
2004.
Acknowledgements
This work was supported by the National University of Singapore
and the Nanyang Technological University (No. M4011158). We