Macropolyhedral boron-containing cluster chemistry. [PtMe2(PMe2Ph)2] as a cluster metallating agent. Isolation and characterisation of nineteen-vertex [(PMe2Ph)HPt-η4-syn-B18H 19(PMe2Ph)] and eighteen-vertex [(PMe2Ph)2PtS2B15H 14(NHCOMe]

Article abstract of DOI:10.1016/S0022-328X(97)00666-9

[PtMe₂(PMe₂Ph)₂] reacts quantitatively with [nido-B₁₀H₁₄], [arachno-4-SB₈H₁₂] and [nido-7-SB₁₀H₁₂] to give [(PMe₂Ph)₂PtB₁₀H₁₂], [(PMe₂Ph)₂PtSB₈H₁₀] and [(PMe₂Ph)₂PtSB₁₀H₁₀]. With [syn-B₁₈H₂₂] it gives nineteen-vertex [(PMe₂Ph)HPt-η⁴-syn-B₁₈H ₁₉(PMe₂Ph)]¹ and only smaller amounts of [(PMe₂Ph)₂Pt-η⁴-syn-B₁₈H ₂₀], whereas with [(anti)-9,9′-S₂B₁₆H₁₆] a complex product mixture is generated from which eighteen-vertex [(PMe₂Ph)₂PtS₂B₁₅H ₁₄(NHCOMe)]¹ is isolatable after treatment with MeCN in air.

Full text of DOI:10.1016/S0022-328X(97)00666-9

Journal of Organometallic Chemistry 557 (1998) 181–185
Macropolyhedral boron-containing cluster chemistry. [PtMe2(PMe2Ph)2]
as a cluster metallating agent. Isolation and characterisation of
nineteen-vertex [(PMe2Ph)HPt-p4-syn-B18H19(PMe2Ph)] and
eighteen-vertex [(PMe2Ph)2PtS2B15H14(NHCOMe]1
Pervinder Kaur a, Annette Brownless a, Sarath D. Perera a, Paul A. Cooke a, Toma´s Jel´ınek a,b
,
'
a,
b
a
&
John D. Kennedy *, Bohumil St´ıbr , Mark Thornton-Pett
a School of Chemistry, Uni6ersity of Leeds, Leeds LS2 9JT, UK
b
&
Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, 25068 Rez' u Prahy, Czech Republic
Received 8 July 1997
Abstract
[PtMe2(PMe2Ph)2] reacts quantitatively with [nido-B10H14], [arachno-4-SB8H12] and [nido-7-SB10H12] to give
[(PMe2Ph)2PtB10H12], [(PMe2Ph)2PtSB8H10] and [(PMe2Ph)2PtSB10H10]. With [syn-B18H22] it gives nineteen-vertex [(PMe2Ph)HPt-
p4-syn-B18H19(PMe2Ph)]1 and only smaller amounts of [(PMe2Ph)2Pt-p4-syn-B18H20], whereas with [(anti)-9,9%-S2B16H16] a
complex product mixture is generated from which eighteen-vertex [(PMe2Ph)2PtS2B15H14(NHCOMe)]1 is isolatable after treatment
with MeCN in air. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Macropolyhedral; Metallaboranes; Platinum
The horizons of boron-containing cluster chemistry
are extended considerably by the recognition that the
simple single-cluster borane and heteroborane building
blocks can be fused with common edges or faces to
generate extended contiguous ‘macropolyhedral’ cluster
species [1]. An important sub-discipline of boron-con-
taining single-cluster chemistry is that of the metalla-
heteroboranes, which has hitherto been dominated by
the carbametallaboranes [2]. However, there is now
increasing interest and activity in other metallaheterob-
oranes, particularly thiametallaboranes [3–10]. Recent
reports on a variety of thiametallaboranes describe
{MSB8}, [3] {MSB9}, [3–6] {MSB10}, [7] {MS2B6}, [8]
{MS2B7}, [9,10] {MS2B8}, [6] {MS2B9}, [6] and
{M2S2B7} [9] single-cluster species. It is of interest to
extend metallaheteroborane chemistry into the macro-
polyhedral area. Here the macropolyhedral dithiabo-
rane substrate [(anti)-9,9%-S2B16H16] (schematic cluster
structure III) [11] is a convenient entry into this field,
but reactions of transition-element halide complexes in
the presence of base have so far given considerable
cluster rearrangements, [12] and we sought a milder
cluster metallating reagent to help explore the field
more systematically. We now report preliminary results
from the reaction between [S2B16H16] and the
organoplatinum species [PtMe2(PMe2Ph)2] to yield the
macropolyhedral dithiaplatinaborane [(PMe2Ph)2PtS2
B15H14 (NHCOMe)] (schematic cluster structure IV). In
general we have found that [PtMe2(PMe2Ph)2] is a
useful reagent for the platination of many polyhedral
* Corresponding author. Tel.: +44 113 2336414; fax: +44 113
2336565; e-mail: johnk@chem.leeds.ac.uk
1 4,9-bis(dimethylphenylphosphine)-9-(hydrido)-nido-decaborano-
(5%,6%:7,8)-nido-9-platinaundecaborane (compound 2) and 10,10-bis(-
dimethylphenylphosphine)-7-(acetamid-N-yl)-nido-9%-thiadecaborano-
(5%,6%:6,7)-nido-9,10-thiaplatinadecaborane (compound 4).
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(97)00666-9

182
P. Kaur et al. / Journal of Organometallic Chemistry 557 (1998) 181–185
type, 6iz. nido-type [(PMe2Ph)2PtB10H12], [14] arachno-
type [(PMe2Ph)2PtSB8H10] [15] and closo-type
[(PMe2Ph)2PtSB10H10] [7], respectively, 6ia methane
loss. This reaction is effectively a simple replacement of
two acidic bridging hydrogen atoms by the
{Pt(PMe2Ph)2} moiety. We intend to report more fully
on the generality of this reaction in due course. In an
extension of this reaction to the well-known macropoly-
hedral substrate syn-B18H22 (compound 1, schematic
structure I), by contrast, the reaction is not such a
simple replacement of two bridging hydrogen atoms by
the {Pt(PMe2Ph)2} moiety to give known [16]
[(PMe2Ph)2Pt-p4-syn-B18H20]. Instead, in C6D6 solution
at room temperature on a reaction scale of ca. 45 mmol,
boron-containing cluster species. A similar elimination
of methane has previously been employed for metalla-
borane synthesis using [AuMe(PPh3)] as a reagent [13].
As part of this work, we also find that a convenient new
alternative to the classical Grignard route for the
preparation of [PtMe2(PMe2Ph)2] is to use the reaction
of methyllithium in toluene solution, which is commer-
cially available2
the
new
nineteen-vertex
cluster
compound
[(PMe2Ph)HPt-p4-syn-B18H19(PMe2Ph)] (compound 2,
schematic cluster structure II) is the predominant
product (45%). Orange air-stable compound 2 is char-
acterised by NMR spectroscopy3 and by single-crystal
X-ray diffraction analysis (Fig. 1)4. A much smaller
quantity (13%) of the otherwise expected isomer
[(PMe2Ph)2Pt-p4-syn-B18H20] [16] is formed. The differ-
ent course of reaction undergone by the fused-cluster
macropolyhedral
nido-decaborano-nido-decaborane
[B18H22], compared to that of the single-cluster nido-de-
caborane [B10H14], is of interest. A differential reactivity
has recently been noted also for reactions with alkyl
isocyanides [11,17]
3 Crystallographic
results
for
[(PMe2Ph)HPt-p4-syn-
B18H19(PMe2Ph)] (compound 2). Crystals were obtained from
dichloromethane/hexane. All measurements were made on a Stoe
STADI 4 diffractometer using graphite-monochromated Mo–Ka ra-
˚
diation (u=0.71073 A) and ꢀ-q scans, with 3838 reflections collected
up to 50° in 2q. An absorption correction was applied based on
azimuthal C scans (max. and min. transmission factors 0.1104 and
0.0639, respectively). The structure was solved by heavy-atom meth-
ods (SHELXS-86) [20] and was refined anisotropically by full-matrix
least-squares analysis based on all unique F2 (SHELXL-93) [21].
Phenyl rings were restrained to be of C2v symmetry. Ligand hydrogen
atoms were included with a riding model; cluster-associated hydrogen
atoms were refined freely. The complex was found to have crystallised
as a racemic twin and was accordingly refined as such. The final
wR(F2) for 3363 unique reflections was 0.0732 with a conventional
R(F) of 0.0275 [for 3259 reflections with I\2.0|(I)] for 418 parame-
ters. Crystal data: C16H42B18P2Pt. M=686.11, 0.58×0.45×0.30 mm
.
Many boron-containing cluster compounds with
open-face bridging and/or endo hydrogen atoms are
Brønsted acids. With single-cluster species in this cate-
gory we find that [PtMe2(PMe2Ph)2] is often an excel-
lent metallaborane synthon under mild conditions. For
example, it reacts quantitatively with [nido-B10H14],
[arachno-4-SB8H12] and [nido-7-SB10H12] in neutral sol-
vents at 20–50°C to give recognised species of known
˚
˚
orthorhombic, space group P212121, a=8.398(3) A, b=16.659(4) A,
3
−3
˚
˚
c=22.197(6) A, U=6601.8(16) A , Z=4, Dc=1.486 Mg m
,
F(000)=1344, v(Mo–Ka)=4.631 mm−1, T=210 K.
4 NMR data for [(PMe2Ph)HPt-p4-syn-B18H19(PMe2Ph)] (com-
pound 2), CDCl3 solution at 294–297 K, ordered as l(11B) [l(1H) for
directly bound hydrogen]: ca. +12.8 {+3.49], ca. +12.8 [+3.58],
ca. +10.4 [-], ca.+3.8 [+3.11], ca.+3.8 [+2.82], ca. +0.7 [+
2.93], ca. +0.7 [+2.96], ca. +0.7 [+3.68], ca. −3.2 [+2.93], ca.
−3.2 [+2.28], ca. −3.3 [+2.28], −5.7 [-], −7.8 [PMe2Ph site,
1J(31P–11B) ca. 130 Hz, 1J(195Pt–11B) ca. 190 Hz], −15.1 (broad)
[+2.34], −24.1 [−0.38], −27.6 [−0.06], −35.4 [+0.99], −40.9
[+0.16]; additionally l(1H)(vH) −0.07 and −0.72, −2.18 and
2 Preparation
of
[PtMe2(PMe2Ph)2]:
A
suspension
of
[PtCl2(PMe2Ph2)] in dry toluene (12 ml) is cooled to −78°C and a
solution of methyllithium in diethylether (Aldrich, 1.55 M, 2.84 ml;
4.40 mmol MeLi) is added. The mixture is stirred at −78°C for 2 h
and then water (10 ml) added (still at −78°C) to give a pale brown
precipitate. Additional toluene (15 ml) is added, the mixture filtered
at room temperature and the layers separated. The toluene layer is
dried with MgSO4 and the solvents evaporated under reduced pres-
sure. Dissolution of the oily residue in minimum diethyl ether,
addition of pentane, and storage at ca.+4°C overnight gives white
crystals of [PtMe2(PMe2Ph)2] (600–650 mg; ca. 80%).
2
−3.47, l(1H)(PtH) −2.50 [1J(195Pt–1H) 519 Hz, J(31P–1H) 31 Hz];
l(31P)(223 K) −6.3 (sharper) [1J(195Pt–31P) 3170 Hz] and −11.9
(broader) [1J(31P–11B) ca. 130 Hz].

P. Kaur et al. / Journal of Organometallic Chemistry 557 (1998) 181–185
183
troscopy6. The cluster unit of this new compound has
the eighteen-vertex nido-decaborano-nido-decaborane
macropolyhedral structure of the starting substrate
[S2B16H16] (schematic cluster structure III) except that it
has a {Pt(PMe2Ph)2} moiety as a cluster constituent at
the 10-position instead of a {BH} unit (schematic clus-
ter structure IV), and that it has gained an acetamido
group at the B(5) position.
Compound 4 has several features of interest that
suggest interesting future macropolyhedral chemistries.
In contrast to compound 2, it arises from an effective
boron-vertex replacement to give an eighteen-vertex
cluster, rather than metal-vertex addition to give a
nineteen-vertex product. Further, the observed cluster-
atom disposition in compound 4 suggests it does not
arise from simple open-face metal-vertex addition fol-
lowed by boron-vertex elimination. Rather, the effective
displacement of the boron vertex B(10) (vertex B in
schematic III) by the platinum centre (schematic IV)
suggests
an
off-open-face
attack
in
the
{S(9)B(4)B(1)B(5)} region (heavier lines in structure
III). The site of the acetamido substituent on the nido-
decaborano-nido-decaborane eighteen-vertex unit is ad-
jacent to the cluster fusion linkage, equivalent to that of
the phosphine ligand in compound 2. It is also the same
as the ligand site in [(ligand)B18H20] species that can be
formed from [anti-B18H22] with two-electron ligands in
the presence of oxidizing agents [17,18]. These common
sites of attack suggest a quite specific activation of this
boron position on this type of cluster. In order to form
the acetamido substituent at this position in compound
4, ligand attack by MeCN solvent has presumably
occurred, followed by hydrolysis either on silica or in
air. There also seems to be a driving force to retain the
With the eighteen-vertex macropolyhedral dithiabo-
rane [(anti)-9,9%-S2B16H16] (compound 3, schematic
cluster structure III) the reaction is more complex.
Reaction between [S2B16H16] and [PtMe2(PMe2Ph)2]
in CH2Cl2 for 18 h at room temperature, followed
by chromatography on silica in air using MeCN as
liquid phase, revealed several coloured reaction prod-
ucts in low yield. Of these the only product that we
have so far been able to purify (by repeated chro-
matography) in sufficient quantity for assessment (ca.
4%; reaction scale ca. 200 mmol) is the purple air-
stable eighteen-vertex dithiaplatinaborane [(PMe2Ph)2-
PtS2B15H14(NHCOMe)] (compound 4, schematic clus-
ter structure IV). This is characterised by single-crystal
X-ray diffraction analysis (Fig. 2)5 and NMR spec-
nido-decaborano-nido-decaborane
eighteen-vertex
macropolyhedral shape. This therefore may have a
particular stability, as noted elsewhere in carbaborane
[18] and in azaborane [19] macropolyhedral systems.
We currently continue our investigations of the reac-
tions of [S2B16H16] with other transition-element sys-
tems, as well as attempting to isolate additional
products from its reaction with [PtMe2(PMe2Ph)2] re-
ported here.
5 Crystallographic results for [(PMe2Ph)2PtS2B15H14(NHCOMe)]
(compound 4): Crystals were obtained from dichloromethane/hexane.
Data collection was as for compound 2, but for 12167 reflections,
2qmax=50°, with max. and min. transmission factors 0.6917 and
0.5101, respectively. Structure solution and refinement were similar to
compound 2. The final wR(F2) for 5830 unique reflections was 0.0654
with a conventional R(F) of 0.0264 [for 4736 reflections with I\
2.0|(I)] for 422 parameters. Crystal data: C18H40B15NOP2PtS2. M=
769.81, 0.61×0.53×0.38 mm, monoclinic, space group I2/a,
6 NMR data for [(PMe2Ph)2PtS2B15H14(NHCOMe)] (compound
4), CDCl3 solution at 294–297 K, ordered as l(11B) [l(1H) for
directly bound hydrogen]: +26.7 [+4.96], +9.6 [+3.89], +5.2
[+3.36], −3.7 [+4.49, nJ(195Pt–1H) ca. 100 Hz, nJ(31P–1H) ca. 20
Hz (doublet)], −5.4 [-], −8.3 [-], −10.8 [2.23], −10.8 [−1.67],
−11.9 [-], −12.1 [+1.11], −16.0 [+1.35], −17.2 [+1.24], −25.7
[+1.08], −29.1 [+0.69], −34.0 [+1.64]; additionally l(1H)(vH)
+0.07 and −1.67, l(1H)(NH) +5.80, l(1H)(COCH3) +2.21;
l(31P)(223 K) −5.3 [1J(195Pt–31P) 2930 Hz] and −7.2 [1J(195Pt–31P)
3423 Hz], 2J(31P–31P) 27 Hz.
˚
˚
˚
a=24.626(3) A, b=9.6266(15) A, c=28.261(4) A, i=99.802(9)°,
3
U=6601.8(16) A , Z=8, Dc=1.549 Mg m−3
, F(000)=3024,
˚
v(Mo–Ka)=4.492 mm−1, T=220 K.

184
P. Kaur et al. / Journal of Organometallic Chemistry 557 (1998) 181–185
Fig. 1. ORTEX [22] drawing of [(PMe2Ph)HPt-p4-syn-B18H19(PMe 2Ph)] (compound 2) with P-organyl atoms, except the ipso carbon ones,
omitted for clarity. For convenience of presentation, structure II and this drawing show different enantiomers. The compound differs from the
previously reported conventional isomer by the interchange of a hydride unit and a phosphine ligand between the B(4) and Pt(9) positions.
Selected interatomic dimensions (in pm) are Pt(9)–B(4) 218.6(7), Pt(9)–B(5) 222.2(9), Pt(9)–B(8) 223.9(8), Pt(9)–B(10) 235.4(9) and Pt(9)–P(9)
228.2(2). There is a close intercluster platinum–hydrogen contact, Pt(9)–H(2%), of 295(13), the associated Pt(9)–B(2%) distance being 293(1). The
P(9)–Pt(9)–H(9) angle is 80(5)°. The common boron–boron edge, B(7)–B(8), is 184.8(11) and there are characteristically ‘long’ nido ten-vertex
‘gunwale’ open-face interboron distances B(7)–B(11), B(7%)–B(8%) and B(7)–B(10%) of 199.6(12) 195.6(12) and 200.10(12), respectively.
Fig. 2. ORTEX [22] drawing of [(PMe2Ph)2PtS2B15H14(NHCOMe)] (compound 4), with P-organyl atoms, except the ipso carbon ones, omitted
for clarity. Selected interatomic dimensions (in pm) are Pt(10)–S(9) 232.2(1), Pt(10)–B(8) 223.2(5), Pt(10)–B(4) 238.9(5), Pt(10)–B(5) 239.1(4),
Pt(10)–P(1) 227.9(10) and Pt(10)–P(2) 231.1(1). The P(1)–Pt(10)–P(2) angle is 97.33(4)°. The common boron–boron edge, B(6)–B(7), is 178.4(6).
No long ‘gunwale’ open-face interboron distances (contrast compound 2) are now evident, with B(7)–B(8), B(7%)–B(8%) and B(6)–B(10%) at
179.2(7), 185.8(9) and 188.3(6), respectively. Sulphur–boron distances are: S(9)–B(4) 196.5(6), S(9)–B(8) 188.6(5), S(9%)–B(4%) 195.3(6), S(9%)–B(8%)
188.7(8) and S(9%)–B(10%) 186.3(5).

P. Kaur et al. / Journal of Organometallic Chemistry 557 (1998) 181–185
185
Ferguson, G.F. Gallagher, Yi Wei, D. O’Connell, J.C. Patter-
Acknowledgements
Contribution no. 70 from the Rez
&
son, T.R. Spalding, J.D. Kennedy, R. Mac´ıas, B. St´ıbr, J.
Chem. Soc. Dalton Trans. (1996) 3323; W.R. Hertler, F. Klan-
berg, E.L. Muetterties, Inorg. Chem. 6 (1967) 1696.
&
'
–Leeds Anglo–
Czech Polyhedral Collaboration (ACPC). We thank the
EPSRC for a studentship (to Pervinder Kaur) and for
other support (grant nos. GR/J/56929 and GR/K/
05818), and The University of Leeds (for a Lowson
Fellowship to Annette Brownless), The Royal Society
(London), The Grant Agency of the Academy of Sci-
ences of the Czech Republic (grant no. A4032701) and
Borax Europe for support. We also thank Dr Nesli
Ziler for her helpful and friendly co-operation.
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