Chemistry of a metallathiaborane cluster. 5. Reaction of [8,8-(η2-dppm)-8-(7eta;1-dppm)-nido-8,7-RhSB9 H10] and its derivatives with organotransition-metal reagents

Article abstract of DOI:10.1021/om020480y

The phosphine ligands on [8,8-(PPh₃)₂-mrfo-8,7-RhSB₉H₁₀] (2) may be replaced by the bidentate phosphine dppm {dppm = [(CH₂)(PPh₂)₂]} to form the species [8,8-(η²-dppm)-8-(η¹-dppm)-nido-8,7-RhSB₉ H₁₀] (3). The latter reacts with [Ru(η⁶-p-cym)(μ-Cl)₂]₂ to afford [8,8-η²-{(μ-Cl)₂Ru(η⁶-p-cym)(dppm)}- nido-8,7-RhSB₉H₁₀] (4), which contains the group [(μ-Cl)₂Ru-(η⁶-p-cym)(dppm)] that coordinates in a multidentate mode to Rh, in 77% yield. Similar chemistry using [Cp*Ir(μ-Cl)₂]₂ {Cp* = [η⁵-C₅(CH₃)₅]} affords the related species [8,8-η²-{(μ-Cl)₂Cp*Ir(dppm)}-nido-8,7-RhSB ₉H₁₀] (5), and [8,8-η²-{(μ-Cl)₂Cp*Rh(dppm)}-nido-8,7-RhSB ₉H₁₀] (6) is obtained from the reaction between 2 and [Cp*RhCl₂(η¹-dppm)]. Reactions of 3 with [IrCl(CO)(PPh₃)₂] or [RhCl(PPh₃)₃] result in removal of dppm. [RhCl(PPh₃)₃] reacts with 3 to afford [1-PPh₃-{l,3-(μ-dppm)}-closo-1,2-RhSB₉H₁₀] (7), but on reaction for extended periods [8-Cl-{8,9-(μ-dppm)}-10-PPh₃-mdo-8,7-RhSB₉H₇ ] (8) is also formed. Reaction between 7 and dppe {dppe = [(CH₂)₂(PPh₂)₂]} gives [1,l-(η²-dppe)-3-(η¹-dppm)-closo-l,2-RhSB₉ H₈] (9), which when treated with [Ru(η⁶-p-cym)(μ-Cl)₂]₂, affords [1.1-(η²-dppe)-3-η¹-{(dppm)Ru(η⁶-p- cym)Cl₂)}-closo-l,2-RhSB₉H₈] (10), in which the rhodathiaborane cage has a pendent metalligated dppm group at the 3-position. A rationale for the formation of 7 and 8 in the reaction of 3 with [RhCl(PPh₃)₃] is presented, and it provides evidence for the pathways for reactions of the other metal-containing moieties with 3. The existence of 8 provides support for some earlier proposals concerning the chemistry of 3. The new species 4, 5, 6, 8, and 10 are characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and in the case of 4, 8, and 10, crystal structure determinations.

Full text of DOI:10.1021/om020480y

Organometallics 2002, 21, 5505-5514
5505
Ch em istr y of a Meta lla th ia bor a n e Clu ster . 5.† Rea ction of
[8,8-(η2-d p p m )-8-(η1-d p p m )-n id o-8,7-Rh SB9H10] a n d Its
Der iva tives w ith Or ga n otr a n sition -Meta l Rea gen ts
Oleg Volkov,‡ Nigam P. Rath, and Lawrence Barton*
Department of Chemistry & Biochemistry and the Center for Molecular Electronics,
University of Missouri-St. Louis, St. Louis, Missouri 63121
Received J une 19, 2002
The phosphine ligands on [8,8-(PPh3)2-nido-8,7-RhSB9H10] (2) may be replaced by the
bidentate phosphine dppm {dppm ) [(CH2)(PPh2)2]} to form the species [8,8-(η2-dppm)-8-
(η1-dppm)-nido-8,7-RhSB9H10] (3). The latter reacts with [Ru(η6-p-cym)(µ-Cl)2]2 to afford [8,8-
η2-{(µ-Cl)2Ru(η6-p-cym)(dppm)}-nido-8,7-RhSB9H10] (4), which contains the group [(µ-Cl)2Ru-
(η6-p-cym)(dppm)] that coordinates in a multidentate mode to Rh, in 77% yield. Similar
chemistry using [Cp*Ir(µ-Cl)2]2 {Cp* ) [η5-C5(CH3)5]} affords the related species [8,8-η2-{(µ-
Cl)2Cp*Ir(dppm)}-nido-8,7-RhSB9H10] (5), and [8,8-η2-{(µ-Cl)2Cp*Rh(dppm)}-nido-8,7-
RhSB9H10] (6) is obtained from the reaction between 2 and [Cp*RhCl2(η1-dppm)]. Reactions
of 3 with [IrCl(CO)(PPh3)2] or [RhCl(PPh3)3] result in removal of dppm. [RhCl(PPh3)3] reacts
with 3 to afford [1-PPh3-{1,3-(µ-dppm)}-closo-1,2-RhSB9H8] (7), but on reaction for extended
periods [8-Cl-{8,9-(µ-dppm)}-10-PPh3-nido-8,7-RhSB9H7] (8) is also formed. Reaction between
7 and dppe {dppe ) [(CH2)2(PPh2)2]} gives [1,1-(η2-dppe)-3-(η1-dppm)-closo-1,2-RhSB9H8] (9),
which when treated with [Ru(η6-p-cym)(µ-Cl)2]2, affords [1,1-(η2-dppe)-3-η1-{(dppm)Ru(η6-p-
cym)Cl2)}-closo-1,2-RhSB9H8] (10), in which the rhodathiaborane cage has a pendent metal-
ligated dppm group at the 3-position. A rationale for the formation of 7 and 8 in the reaction
of 3 with [RhCl(PPh3)3] is presented, and it provides evidence for the pathways for reactions
of the other metal-containing moieties with 3. The existence of 8 provides support for some
earlier proposals concerning the chemistry of 3. The new species 4, 5, 6, 8, and 10 are
characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and in the case
of 4, 8, and 10, crystal structure determinations.
In tr od u ction
reactions involving metal-promoted alkyne7d and nor-
bornadiene7e insertion into BH bonds. Approaches to
catalysis have typically involved interconversion of closo/
exo-nido metallacarborane complexes so as to open up
potential coordination sites.2 Extensions of the chem-
istry of these exo-nido metallacarboranes involved the
formation of metal complexes of boranes or metallacar-
boranes with a transition metal auxiliary not part of
the cage. This has led to a series of bimetallacarboranes
and some interesting organometallic chemistry associ-
ated with these species. The examples of metallaboranes
containing exo-polyhedral transition metal auxiliaries
are limited to a few systems, especially those involving
a second metal-containing moiety connected to the cage
with at least two connecting bonds. Species based on
11- or 12-vertex closo-clusters involving bridging H, O,
or halogen atoms between cage borons and the exo-
polyhedral metal moiety have been described.8-14 Ex-
amples from the nido class of polyhedral metallaboranes
are much less common. Structures A and B,10 shown
in Chart 1, are examples of nido-carboranes with exo-
polyhedral metal auxiliaries, and they have been known
for quite some time. These species are precursors to
structures of the type C and D,2c,d,10,14 also shown in
Chart 1.
The idea of carrying out organometallic chemistry1
or even catalysis2 on metallaborane clusters is certainly
not new. The chemistry can involve ligand exchange,3
ligand addition,4 or metal(s) incorporation either into
the cage5 or as exo-polyhedral moieties.6 Ligands can
also react with each other at the metal site in a
metallaborane.7 For example, two acetylene groups have
been coupled to form a metallacyclopenta-2,4-dienyl
moiety7a or a noncyclic butadienyl moiety.7b Other
reactions of alkynes and alkenes with metallaboranes
which appear to take place at the metal center include
aromatization of norbornadiene at a Rh center7c and
† For Part 4, see ref 16d.
‡ Permanent address: Institute of Inorganic Chemistry, Russian
Academy of Sciences, 630090, Novosibirsk, Russia.
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Our contributions to this area are twofold. We have
used the redox flexibility of some iridanonaboranes to
10.1021/om020480y CCC: $22.00 © 2002 American Chemical Society
Publication on Web 11/09/2002

5506 Organometallics, Vol. 21, No. 25, 2002
Volkov et al.
Ch a r t 1
phosphine ligands with unsaturated metallahetero-
boranes.16,17 The isoelectronic pair of metallahetero-
boranes, [9,9-(PPh3)2-nido-9,7,8-RhC2B8H11] (1)18 and
[8,8-(PPh3)2-nido-8,7-RhSB9H10] (2),19 are two electrons
short of the number notionally required to satisfy the
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Chemistry of a Metallathiaborane Cluster
Organometallics, Vol. 21, No. 25, 2002 5507
Sch em e 1
Exp er im en ta l Section
Solvents used were reagent grade and were dried before use.
Some reactions were carried out using a Schlenk line and
standard techniques for handling air-sensitive compounds.26
2, 3, [1-PPh3-{1,3-(µ-dppm)}-closo-1,2-RhSB9H8] (7), and [1,1-
(η2-dppe)-3-(η1-dppm)-closo-1,2-RhSB9H8] (9) were prepared
according to literature methods: 219b from the reaction be-
tween Cs[SB9H12]
27 and [RhCl(PPh3)3],28 3 from 2 and dppm,16b
7 from 2 and 3,16d and 9 from 7 and dppe.16d The organotransi-
tion-metal reagents [Ru(η6-p-cym)(µ-Cl)2]2,29 [Cp*Ir(µ-Cl2)]2,30
and [Cp*Rh(µ-Cl)2]231 were prepared using literature methods.
PPh3 and dppe were obtained from Aldrich, dppm was obtained
from Strem, and [Cp*RhCl2(η1-dppm)] was prepared from the
reaction between [Cp*Rh(µ-Cl)2]2 and dppm as described in
the literature.32 NMR spectroscopy was carried out on a Bruker
ARX 500 spectrometer operating at 500.1 MHz for proton,
160.5 MHz for boron-11, and 202.5 MHz for phosphorus-31.
Chemical shifts are reported at 25 °C in ppm for CD2Cl2
solutions to low field (high frequency) of Et2O‚BF3 for 11B, of
SiMe4 for 1H, and of 85% H3PO4 for 31P. Elemental analyses
were obtained from Atlantic Microlabs Inc., Norcross, GA.
NMR spectra were run on all samples sent for mass spectra
and crystal growth was generated from NMR samples, after
spectral analysis. The samples were evaporated to dryness and
then dissolved in the appropriate solvent for subsequent
crystallization. The mass spectra were measured in the FAB
mode on a J EOL MStation J MS-70 spectrometer using 3-ni-
trobenzyl alcohol (3-NBA, or 3-NBA/CsI).
P r ep a r a tion of [8,8-η2-{(µ-Cl)2Ru (η6-p-cym )(d p p m )}-
n id o-8,7-Rh SB9H10] (4). A sample of [Ru(η6-p-cym)(µ-Cl)2]2
(20 mg, 0.033 mmol) was added under nitrogen to a solution
of [8,8-(η2-dppm)-8-(η1-dppm)-nido-8,7-RhSB9H10] (3) (30 mg,
0.030 mmol) in CH2Cl2 (ca. 10 mL) and stirred overnight at
room temperature. Then the solution was filtered over SiO2
to remove chromatographically immobile components and
reduced in volume. Addition of pentane gave a red precipitate,
isolated as 23 mg of a species which was characterized as [8,8-
η2-{(µ-Cl)2Ru(η6-p-cym)(dppm)}-nido-8,7-RhSB9H10]‚0.5CH2-
Cl2 (4: 0.023 mmol, 77% yield). Single crystals of this
compound precipitated from CH3CN/Et2O. Anal. Calcd for
chemistry of the rhodathiaborane cluster 2, whose
structure is illustrated in Scheme 1, has received more
attention than the metallacarborane cluster 1. The
latter is identical to 2 except that the C(H)C(H) atom
string replaces the isoelectronic SB(H) atom string in
the open face of the cluster. The molecules 1 and 2 have
a formal skeletal electron count that conforms to a closo-
cluster, but the open cage structure is clearly that of a
nido-cluster.21 The apparent electronic unsaturation in
2, and in related species with square planar 16-electron
metal centers, has been the subject of much discussion
in the literature.21-23 We will not repeat that herein but
simply note that a consequence of this unsaturation is
a rich chemistry.16-19,22-25 Species 2 is stable, easily
prepared, and reactive toward both electrophiles and
nucleophiles. In particular, the reactions of 2 with Lewis
bases, L (where L ) CO, PMe2Ph, or CH3CN),19 or L2
{where L2 ) dppm, dppe, or dppp which is [C3H6-
(PPh2)2]},16b result in either addition of the ligand, L or
L2, to the metal center or addition and substitution, or
in terminal hydrogen substitution on the RhSB9 cage.
Reaction of 2 with [RhCl(PPh3)3] is reported to form
closo 12-vertex bimetallic species.19b Of particular per-
tinence to the present work is the formation of [8,8-(η2-
dppm)-8-(η1-dppm)-nido-8,7-RhSB9H10] (3) from the re-
action between dppm and 2. Herein we report the
results of a study of the reactions of 3 with additional
metal reagents in efforts to form heterobimetallathia-
boranes and also to probe the reaction pathways exhib-
ited by this fascinating system. A minor aspect of this
work has appeared in a preliminary communication.16c
C
35H46B9Cl2P2RhRuS(CH2Cl2)0.5: C, 43.71; H, 4.86. Found: C,
44.21; H, 4.57. 11B NMR: δ 14.9 (v br, 1B), 10.2 (d, J (H,B) )
103 Hz, 1B), 7.8 (v br, 1B), 1.7 (d, J (H,B) ) 115 Hz, 1B), -0.8
(v br, 1B), -18.2 (d, J (H,B) ) 137 Hz, 1B), -20.6 (d, J (H,B) )
103 Hz, 1B), -22.3 (d, J (H,B) ) 140 Hz, 1B), -31.8 (v br, 1B).
31P{1H} NMR: δ 31.8 (br d, J (P,Rh) ) 153 Hz, 1P), 26.6(d,
J (P,P) ) 4 Hz, 1P). 1H NMR (500 MHz, CD2Cl2, 25 °C): δ
7.76-6.94 (m, 20H; C6H5), 5.80 (d, J (H,H) ) 6 Hz, 1H; MeC6H4-
CHMe2), 5.37 (d, J (H,H) ) 6 Hz, 1H; MeC6H4CHMe2), 4.99 (d,
J (H,H) ) 6 Hz, 1H; MeC6H4CHMe2), 4.71 (d, J (H,H) ) 6 Hz,
1H; MeC6H4CHMe2), 4.37 and 3.06 (each td, J (H,H) ) 13 Hz,
J (H,P) ) 14 Hz, 2H; Ph2PCH2PPh2), 2.44 (sept, J (H,H) ) 7
Hz, 1H; MeC6H4CHMe2), 1.78 (s, 3H; MeC6H4CHMe2), 1.23 (d,
J (H,H) ) 7 Hz, 3H; MeC6H4CHMe2), 1.01 (d, J (H,H) )7 Hz,
3H; MeC6H4CHMe2). Additional 1H{11B} NMR: δ 3.74 (1H,
BH), 3.49 (1H, BH), 2.90 (2H, BH), 2.50 (1H, BH), 1.73 (1H,
BH), 1.29 (1H,BH), 1.09 (1H, BH), 0.94 (1H, BH), -2.08 (1H,
µ-H). HR-MS (FAB with 3-NBA/CsI) m/z calcd for C35H46B9-
Cl2CsP2RhRuS: 1066.0229 (M + Cs+), found 1066.0233. The
(20) (a) Williams, R. E. Adv. Inorg. Chem. Radiochem. 1976, 18, 67.
(b) Wade, K. Adv. Inorg. Chem. Radiochem. 1976, 18, 60. (c) Rudolph,
R. W. Acc. Chem. Res. 1976, 9, 446.
(21) (b) Nishamura, E. Footnote in ref 18.
(22) (a) Adams, K. J .; McGrath, T. D.; Thomas, R. Ll.; G. M.; Weller,
A. S.; Welch, A. J . J . Organomet. Chem. 1997, 527, 283. (b) Adams, K.
J .; McGrath, T. D.; Rosair, G. M.; Weller, A. S.; Welch, A. J . J .
Organomet. Chem. 1998, 550, 315.
(26) Shriver, D. F.; Drezdon, M. A. The Manipulation of Air-Sensitive
Compounds; J ohn Wiley: New York, 1986.
(27) Rudolph, R. W.; Pretzer, W. R. Inorg. Synth. 1983, 22, 226.
(28) Osborn, J . A.; Wilkinson, G. Inorg. Synth. 1990, 28, 77.
(29) Bennett, M. A.; Huang, T.-N.; Matteson, T. W.; Smith, A. K.
Inorg. Synth. 1982, 21, 74.
(30) Ball, R. G.; Graham, W. A. G.; Heineky, D. M.; Hoyars, J . K.;
McMaster, A. D.; Mattson, B. M.; Michel, S. T. Inorg. Chem. 1990, 29,
2023.
(31) Kang, J . W.; Moseley, K.; Maitlis, P. M. J . Am. Chem. Soc. 1969,
91, 5970.
(23) (a) Kennedy, J . D. Main Group Metal Chem. 1989, 12, 149. (b)
Barton, L.; Bould, J .; Rath, N. P.; Fang, H. Inorg. Chem. 1996, 35,
2062. (c) Murphy, M. P.; Spalding, T. R.; Cowey, C.; Kennedy, J . D.;
Thornton-Pett, M.; Holub, J . J . Organomet. Chem. 1998, 550, 151 (d)
Bould, J .; Cooke, P. A.; Do¨rfler, U.; Kennedy, J . D.; Barton, L.; Rath,
N. P.; Thornton-Pett, M. Inorg. Chim. Acta 1999, 285, 290.
(24) (a) Ferguson, G.; Lough, A. L.; Coughlan, S.; Spalding, T. R.
Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1992, C48, 440. (b)
Murphy, M.; Spalding, T. R.; Ferguson, G.; Gallagher, J . F. Acta
Crystallogr., Sect. C: Cryst. Struct. Commun. 1992, C48, 638.
(25) Adams, K. J .; McGrath, T. D.; Welsh, A. J . Acta Crystallogr.,
Sect. C: Cryst. Struct. Commun. 1995, C51, 401.
(32) Valderrama, M.; Contreras, R.; Bascun˜an, M.; Alegria, S.
Polyhedron 1995, 14, 2239.

5508 Organometallics, Vol. 21, No. 25, 2002
Volkov et al.
mass envelopes for the measured masses match quite well with
those calculated from the known isotopic abundances of the
constituent elements.
to the reaction mixture, and the resulting red solution was
stirred at room temperature for 3 days. Subsequent prepara-
tive column chromatography, using CH2Cl2 as the eluent,
afforded two products characterized as [1-PPh3-{1,3-(µ-dppm)}-
closo-1,2-RhSB9H8]16d (7: 21 mg, 0.024 mmol; 37%) and [8-Cl-
{8,9-(µ-dppm)}-10-PPh3-nido-8,7-RhSB9H7] (8: 15 mg, 0.016
mmol; 25%). Single crystals of 8 were obtained by slow
diffusion of Et2O into CH2Cl2 solution. Anal. Calcd for C43H44B9-
ClP3RhS: C, 56.05; H, 4.81. Found: C, 55.92; H, 4.90. 11B
NMR: δ 20.2 (v br, 1B), 1.2 (v br, 1B), -1.7 (v br, 1B), -2.7 (v
br, 1B), -5.8 (d, J (H,B) ) 130 Hz, 1B), -8.5 (d, J (H,B) ) 110
Hz, 1B), -23.2 (d, J (H,B) ) 105 Hz, 1B), -25.2 (d, J (H,B) )
138 Hz, 1B), -27.4 (v br, 1B). 31P{1H} NMR: δ 35.2 (dd,
J (P,Rh) ) 160 Hz, J (P,P) ) 85 Hz, 1P), 21.9 (v br, 1P), 18.6
P r ep a r a tion of [8,8-η2-{(µ-Cl)2Cp *Ir (d p p m )}-n id o-8,7-
Rh SB9H10] (5). To a solution of 3 (30 mg, 0.030 mmol) in CH2-
Cl2 (ca. 20 mL) was added [Cp*Ir(µ-Cl)2]2 (24 mg, 0.030 mmol)
under N2, and the reaction mixture was stirred at room
temperature overnight. Then the solution was filtered over
SiO2, and a yellow component was collected. Addition of
pentane gave 14 mg of a yellow product, which was character-
ized as [8,8-η2-{(µ-Cl)2Cp*Ir(dppm)}-nido-8,7-RhSB9H10]‚1.5CH2-
Cl2 (5: 0.014 mmol, 40%). Anal. Calcd for C35H47B9Cl2IrP2-
RhS(CH2Cl2)1.5: C, 38.04; H, 4.37. Found: C, 38.11; H, 4.47.
11B NMR: δ 15.6 (v br, 1B), 10.3 (d, J (H,B) ) 130 Hz, 1B), 8.8
(v br, 1B), 1.7 (v br, 1B), -0.8 (v br, 1B), -18.3 (d, J (H,B) )
137 Hz, 1B), -20.6 (d, J (H,B) ) 145 Hz, 1B), -22.2 (d,
J (H,B) ) 158 Hz, 1B), -32.2 (v br, 1B). 31P{1H} NMR (202.5
MHz, CD2Cl2, 25 °C): δ 32.9 (d, J (P,Rh) ) 153 Hz, 1P), 3.7 (s,
1P). 1H{31P} NMR: δ 7.69-6.99 (m, 20H; C6H5), 4.36 and 3.47
(each d, J (H,H) ) 14 Hz, 2H; Ph2PCH2PPh2), 1.32 (s, 15H; C5-
1
(br d, 1P). H NMR: δ 8.11-6.53 (m, 35H; C6H5), 3.90 (br m,
1H; Ph2PCH2PPh2), 2.93 (br m, 1H; Ph2PCH2PPh2). Additional
1H{11B} NMR: δ 4.73 (1H, BH), 2.78 (2H, BH), 2.24 (2H, BH),
1.87 (1H, BH), 1.35 (1H, BH). HR-MS (FAB with 3-NBA) m/z
calcd for C43H44B9ClP3RhS: 921.2026 (M+), found 921.1923.
The mass envelopes for the measured masses match quite well
with those calculated from the known isotopic abundances of
the constituent elements.
1
(CH3)5). Additional H{11B} NMR: δ 3.65 (1H, BH), 3.50 (1H,
BH), 2.89 (2H, BH), 2.59 (1H, BH), 2.56 (1H, BH), 1.65 (1H,
BH), 1.10 (1H, BH), 0.98 (1H, BH), -2.01 (1H, µ-H). HR-MS
(FAB with 3-NBA/CsI) m/z calcd for C35H47B9Cl2CsIrP2RhS:
1158.0879 (M + Cs+), found 1158.0858. The mass envelopes
for the measured masses match quite well with those calcu-
lated from the known isotopic abundances of the constituent
elements.
P r ep a r a t ion of [1,1-(η2-d p p e)-3-η1-{(d p p m )R u (η6-p -
cym )Cl2)}-closo-1,2-Rh SB9H8] (10). [Ru(η6-p-cym)(µ-Cl)2]2
(22 mg, 0.036 mmol) was added to a solution of [1,1-(η2-dppe)-
3-(η1-dppm)-closo-1,2-RhSB9H8] (9) (30 mg, 0.029 mmol) in
CH2Cl2 (ca. 25 mL). After 3 h stirring under N2 at room
temperature, the solution was reduced in volume, and an
orange solid was precipitated when EtOH was added. Recrys-
tallization in CH2Cl2/pentane gave rise to the isolation of 32
mg of a product which was characterized as [1,1-(η2-dppe)-3-
η1-{(dppm)Ru(η6-p-cym)Cl2)}-closo-1,2-RhSB9H8]‚CH2Cl2 (10:
0.023 mmol, 79%). Crystals suitable for X-ray analysis were
grown by layering a CH2Cl2 solution of the product with
pentane. Anal. Calcd for C61H68B9Cl2P4RhRuS(CH2Cl2): C,
52.65; H, 4.99. Found: C, 52.33; H, 4.97. 11B NMR: δ 38.0 (d,
J (P,B) )112 Hz, 1B), 26.9 (d, J (H,B) ) 138, 1B), 0.9 (v br,
3B), -16.9 (v br, 2B), -27.4 (v br, 2B). 31P{1H} NMR: δ 60.9
(br d, J (P,Rh) ) 154 Hz, 2P), 25.7(v br, 1P), 24.6 (br d,
J (P,P) ) 48 Hz, 1P). 1H NMR: δ 7.52-6.79 (m, 40H; C6H5),
5.09 and 4.94 (each d, each 2H; MeC6H4CHMe2), 4.33, 2.59,
and 2.34 (each br m, each 2H; Ph2PCH2PPh2 and Ph2PCH2-
CH2PPh2), 2.35 (sept, J (H,H) ) 7 Hz, 1H; MeC6H4CHMe2), 1.79
(s, 3H; MeC6H4CHMe2), 0.92 (d, J (H,H) ) 7 Hz, 6H; MeC6H4-
CHMe2). Additional 1H{11B} NMR: δ 2.66 (1H, BH), 1.96 (3H,
BH), 0.49 (2H, BH), -0.02 (2H, BH). HR-MS (FAB with
3-NBA/CsI) m/z calcd for C61H68B9Cl2CsP4RhRuS: 1462.1437
(M + Cs+), found 1462.1416. The mass envelopes for the
measured masses match quite well with those calculated from
the known isotopic abundances of the constituent elements.
Str u ctu r e Deter m in a tion . Crystals were mounted on
glass fibers in random orientations. Preliminary examination
and data collection were performed using a Bruker SMART
CCD detector system using graphite-monochromated Mo KR
radiation (λ ) 0.71073 Å) equipped with a sealed tube X-ray
source. Preliminary unit cell constants were determined with
a set of 45 narrow frame (0.3° in ω) scans. The data set
collected typically consists of 3636 frames with a frame width
of 0.3° in ω and counting time of 15 s/frame at a crystal-to-
detector distance of 4.930 cm. The double pass method of
scanning was used to exclude any noise. The collected frames
were integrated using an orientation matrix determined from
the narrow frame scans. SMART and SAINT software
packages33a were used for data collection and data integration.
Analysis of the integrated data did not show any decay. Final
cell constants were determined by a global refinement of xyz
centroids. Collected data were corrected for systematic errors
P r ep a r a tion of [8,8-η2-{(µ-Cl)2Cp *Rh (d p p m )}-n id o-8,7-
Rh SB9H10] (6). [Cp*RhCl2(η1-dppm)] (37 mg, 0.053 mmol) was
added to a solution of 2 (20 mg, 0.026 mmol) in CH2Cl2 (ca. 10
mL) under N2. The reaction mixture was stirred at room
temperature for 2 h. After this time, the solution was filtered
over silica gel, and an orange component was collected.
Recrystallization in CH2Cl2/pentane gave rise to the isolation
of a product characterized as [8,8-η2-{(µ-Cl)2Cp*Rh(dppm)}-
nido-8,7-RhSB9H10]‚1.5CH2Cl2 (6: 16 mg, 0.017 mmol; 58%).
Anal. Calcd for C35H47B9Cl2P2Rh2S(CH2Cl2)1.5: C, 41.24; H,
4.74. Found: C, 41.44; H, 4.81. 11B NMR: δ 15.1 (v br, 1B),
10.3 (d, J (H,B) ) 125 Hz, 1B), 8.1 (v br, 1B), 1.9 (v br, 1B),
-1.2 (v br, 1B), -18.5 (d, J (H,B) ) 135 Hz, 1B), -20.6 (d,
J (H,B) ) 125 Hz, 1B), -22.4 (d, J (H,B) ) 145 Hz, 1B), -32.2
(v br, 1B). 31P{1H} NMR: δ 33.9 (dd, J (P,Rh) ) 153 Hz,
J (P,P) ) 7 Hz, 1P), 28.6 (dd, J (P,Rh) ) 144 Hz, J (P,P) ) 7
Hz, 1P). 1H{31P} NMR (500 MHz, CD2Cl2, 25 °C): δ 7.79-6.98
(m, 20H; C6H5), 4.32 and 3.32 (each d, J (H,H) ) 14 Hz, 2H;
Ph2PCH2PPh2), 1.33 (s, 15H; C5(CH3)5). Additional 1H{11B}
NMR: δ 3.80 (1H, BH), 3.51 (1H, BH), 2.89 (2H, BH), 2.55
(1H, BH), 2.52 (1H, BH), 1.81 (1H, BH), 1.12 (1H, BH), 0.96
(1H, BH), -2.07 (1H, µ-H). HR-MS (FAB with 3-NBA/CsI) m/z
calcd for C35H47B9Cl2CsP2Rh2S: 1068.0320 (M + Cs+), found
1068.0341. The mass envelopes for the measured masses
match quite well with those calculated from the known isotopic
abundances of the constituent elements.
P r ep a r a tion of [1-P P h 3-{1,3-(µ-d p p m )}-closo-1,2-Rh -
SB9H8] (7) fr om 2 a n d [Rh Cl(P P h 3)3]. dppm (50 mg, 0.130
mmol) was added to a solution of 2 (50 mg, 0.065 mmol) in
CH2Cl2 (ca. 20 mL) under N2, and the reaction mixture was
stirred at room temperature for 15 min. After this time, [RhCl-
(PPh3)3] (70 mg, 0.076 mmol) was added, and the reaction
mixture was stirred for 2 h. Then the red solution was filtered
over SiO2 to remove chromatographically immobile compo-
nents and reduced in volume. Addition of pentane resulted in
the isolation of 38 mg of orange solid, characterized by mass
and NMR spectra as the previously reported [1-PPh3-{1,3-(µ-
dppm)}-closo-1,2-RhSB9H8]16d (7: 0.043 mmol, 66%).
P r ep a r a tion of [8-Cl-{8,9-(µ-d p p m )}-10-P P h 3-n id o-8,7-
Rh SB9H7] (8). dppm (50 mg, 0.130 mmol) was added to a
solution of 2 (50 mg, 0.065 mmol) in CH2Cl2 (ca. 20 mL) under
N2, and the reaction mixture was stirred at room temperature
for 15 min. Then [RhCl(PPh3)3] (60 mg, 0.065 mmol) was added
(33) (a) SMART and SAINT; Bruker Analytical X-Ray: Madison,
WI, 2001. (b) SADABS: Blessing, R. H. Acta Crystallogr. 1995, A51,
33. (c) Sheldrick, G. M. SHELXTL-Plus; Bruker Analytical X-Ray
Division: Madison, WI, 2001.

Chemistry of a Metallathiaborane Cluster
Organometallics, Vol. 21, No. 25, 2002 5509
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t for [8,8-η2-{(µ-Cl)2Ru (η6-p-cym )(d p p m )}-n id o-8,7-Rh SB9H10
(4), [8-Cl-{8,9-(µ-d p p m )}-10-P P h 3-n id o-8,7-Rh SB9H7] (8), a n d
]
[1,1-(η2-d p p e)-3-η1-{(d p p m )Ru (η6-p-cym )Cl2)}-closo-1,2-Rh SB9H8] (10)
4
8
10
empirical formula
fw
C
41H55B9Cl2N3P2RhRuS
C45.5H49B9Cl6P3RhS
1133.72
C62H70B9Cl4P4RhRuS
1414.19
1056.05
temp/K
223(2) K
180(2) K
223(2) K
wavelength/Å
cryst syst
space group
0.71073 Å
monoclinic
P21/c
0.71073 Å
monoclinic
P21/c
0.71073 Å
monoclinic
P21/n
R/Å
12.781(3)
13.405(4)
28.450(7)
90
91.480(18)
90
4873(2)
4
1.440
0.900
16.4160(4)
20.7474(5)
16.8186(4)
90
115.631(2)
90
5164.6(2)
4
1.458
14.7117(7)
20.0133(10)
22.9074(12)
90
107.165(3)
90
6444.2(6)
4
1.458
â/Å
ø/Å
R/deg
â/deg
γ/deg
V/Å-3
Z
D(calc)/Mg m-3
abs coeff/mm-1
cryst size/mm
F(000)
0.808
0.827
0.30 × 0.26 × 0.14
0.30 × 0.22 × 0.14
0.16 × 0.08 × 0.04
2144
2300
2880
θ range for data collcn/deg
1.43 to 28.00
-16 e h e 16
-17 e k e 17
-37 e l e 37
89319
11587 [R(int) ) 0.09]
0.8844 and 0.7740
11587/38/569
1.053
1.96 to 26.37
-20 e h e 18
-25 e k e 25
-21 e l e 21
101621
10519 [R(int) ) 0.12]
0.8953 and 0.7936
10519/3/632
1.061
1.79 to 28.00
-19 e h e 18
-26 e k e 26
-30 e l e 30
87223
15447 [R(int) ) 0.09]
0.9677 and 0.8790
15447/3/781
1.012
index ranges
no. of reflens collected
no. of ind reflens
max. and min. transmn
no. of data/restraints/params
goodness-of-fit on F2
final R indices [I > 2σ(I)] R1
0.0680
0.2004
1.403 and -2.242
0.0704
0.1903
1.343 and -1.393
0.0612
0.1044
0.665 and -0.596
wR2 (all data)
largest diff peak and hole/e Å-3
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) in [8,8-η2-{(µ-Cl)2Ru (η6-p-cym )(d p p m )}-
n id o-8,7-Rh SB9H10] (4)
using SADABS33b based on the Laue symmetry using equiva-
lent reflections.
Crystal data and intensity data collection parameters are
listed in Table 1. Structure solution and refinement were
carried out using the SHELXTL-PLUS software package.33c
The structures were solved by direct methods and refined
successfully in the space group P21/n (4) and P21/c (8 and 10).
Full matrix least-squares refinement was carried out by
Rh(8)-B(9)
Rh(8)-S(7)
Rh(8)-P(1)
Rh(8)-Cl(2)
Ru(1)-Cl(1)
B(9)-B(10)
B(11)-S(7)
2.145(7)
2.338(2)
2.264(2)
2.489(2)
2.386(1)
1.841(11)
1.913(9)
Rh(8)-B(4)
Rh(8)-B(3)
Rh(8)-Cl(1)
Ru(1)-P(2)
Ru(1)-Cl(2)
B(10)-B(11)
Ru(1)-centroid
2.145(7)
2.155(8)
2.593(2)
2.320(2)
2.414(2)
1.844(13)
1.705(6)
minimizing ∑w(Fo - Fc2)2. The non-hydrogen atoms were
2
refined anisotropically to convergence. The boron cage hydro-
gen atoms were located and refined freely. Other hydrogens
were treated using an appropriate riding model (AFIX m3).
All the three compounds contain solvent of crystallization. The
crystal lattice of 8 contains a molecule of CH2Cl2, 4 crystallizes
with three molecules of CH3CN, and 10 crystallizes with 2.5
molecules of CH2Cl2. The final residual values and other
structure refinement parameters are listed in Table 1. The
structures of the molecules, showing the atom labeling, are
presented in Figures 1, 2, and 3 for compounds 4, 8, and 10,
respectively, and selected bond lengths and angles are given
in Tables 2-4.
Complete listings of the atomic coordinates for the non-
hydrogen atoms and the geometrical parameters, positional
and isotropic displacement coefficients for hydrogen atoms, and
anisotropic displacement coefficients for the non-hydrogen
atoms are deposited with the Cambridge Crystallographic
Data Center (CCDC #XXX, YYY, and ZZZ for 4, 8, and 10,
respectively).
B(9)-Rh(8)-B(4)
B(4)-Rh(8)-S(7)
B(4)-Rh(8)-B(3)
B(9)-Rh(8)-P(1)
S(7)-Rh(8)-P(1)
B(9)-Rh(8)-Cl(1)
S(7)-Rh(8)-Cl(1)
P(1)-Rh(8)-Cl(1)
B(4)-Rh(8)-Cl(2)
B(3)-Rh(8)-Cl(2)
Cl(1)-Rh(8)-Cl(2)
C(1)-P(1)-C(8)
C(8)-P(1)-Rh(8)
C(2)-P(1)-C(2)
P(2)-Ru(1)-Cl(2)
50.4(3)
90.7(2)
49.6(3)
86.4(2)
B(9)-Rh(8)-S(7)
B(9)-Rh(8)-B(4)
S(7)-Rh(8)-B(3)
B(4)-Rh(8)-P(1)
90.5(2)
50.4(3)
54.1(2)
86.4(2)
171.96(6) B(3)-Rh(8)-P(1)
178.9(2)
88.44(6) B(3)-Rh(8)-Cl(1)
87.67(5) B(9)-Rh(8)-Cl(2)
151.7(2)
147.9(2)
119.0(2)
129.3(2)
91.7(2)
101.8(2)
94.73(6)
91.40(5)
85.83(5)
B(4)-Rh(8)-Cl(1)
S(7)-Rh(8)-Cl(2)
P(1)-Rh(8)-Cl(2)
78.64(4) P(2)-Ru(1)-Cl(2)
105.4(3)
115.6(2)
99.3(3)
C(20)-P(2)-Ru(1) 109.31(18)
C(20)-P(2)-C(1) 99.8(3)
C(14)-P(2)-Ru(1) 118.8(2)
84.30(5)
85.83(5) Cl(1)-Ru(1)-Cl(2)
Ru(1)-Cl(1)-Rh(8) 97.24(5) Ru(1)-Cl(2)-Rh(8) 97.24(5)
S(7)-B(3)-Rh(8)
B(9)-B(4)-B(1)
B(9)-B(4)-Rh(8)
B(1)-B(4)-Rh(8)
67.5(2)
108.8(6)
64.8(3)
B(4)-B(9)-Rh(8)
B(9)-B(4)-B(5)
B(5)-B(4)-Rh(8)
B(1)-B(3)-Rh(8)
64.8(3)
59.2(5)
116.3(5)
116.8(5)
117.3(5)
B(11)-S(7)-Rh(8) 110.6(3)
B(10)-B(9)-Rh(8) 110.7(8)
Resu lts a n d Discu ssion
cym)] complexes. We have noted previously that such
species tend to move very slowly during chromatography
or actually stick to the plate.34 Elemental analysis and
high-resolution mass spectrometry support the formula-
tion of 4. Single crystals of 4‚(CH3CN)3, suitable for
X-ray crystallography, precipitated from CH3CN/Et2O
The reaction between [Ru(η6-p-cym)(µ-Cl)2]2 and [8,8-
(η2-dppm)-8-(η1-dppm)-nido-8,7-RhSB9H10] (3) in CH2-
Cl2, followed by passage through silica gel, affords a red
crystalline product, which was characterized as [8,8-η2-
{(µ-Cl)2Ru(η6-p-cym)(dppm)}-nido-8,7-RhSB9H10] (4), in
77% yield. Unidentified materials that were slow to
move on silica are assumed to be [dppm-RuCl2(η6-p-
(34) (a) McQuade, P.; Barton, L. Unpublished results. (b) McQuade,
P. Spec. Publ.-R. Soc. Chem. 2000, 253, 271.

5510 Organometallics, Vol. 21, No. 25, 2002
Volkov et al.
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) in [8-Cl-{8,9-(µ-d p p m )}-10-P P h 3-n id o-8,7-
Rh SB9H7] (8)
Rh(8)-B(3)
Rh(8)-B(9)
Rh(8)-P(1)
Rh(8)-S(7)
Rh(8)-Cl(1)
S(7)-B(11)
2.173(7)
2.183(6)
2.274(2)
2.330(2)
2.370(2)
1.925(7)
P(1)-C(1)
P(2)-C(1)
P(2)-B(9)
P(3)-B(10)
B(9)-B(10)
B(10)-B(11)
1.855(6)
1.811(6)
1.926(6)
1.949(7)
1.731(9)
1.746(9)
B(3)-Rh(8)-B(9)
B(3)-Rh(8)-B(4)
B(9)-Rh(8)-B(4)
B(3)-Rh(8)-P(1)
B(9)-Rh(8)-P(1)
B(4)-Rh(8)-P(1)
B(3)-Rh(8)-S(7)
83.6(2) B(9)-Rh(8)-S(7)
48.9(2) P(1)-Rh(8)-S(7)
88.8(2)
171.8(1)
47.9(2) B(34c)-Rh(8)-Cl(1) 153.2(2)
117.5(2) B(9)-Rh(8)-Cl(1)
93.1(2) P(1)-Rh(8)-Cl(1)
84.3(2) S(7)-Rh(8)-Cl(1)
54.7(2) B(9)-Rh(8)-S(7)
136.6(2)
94.35(6)
89.77(5)
88.8(2)
109.8(3)
128.0(4)
119.7(4)
103.5(3)
109.1(5)
132.4(4)
114.4(4)
108.8(3)
B(11)-S(7)-Rh(8) 105.8(2) C(14)-P(2)-C(20)
C(8)-P(1)-C(2)
C(8)-P(1)-C(1)
C(2)-P(1)-C(1)
C(8)-P(1)-Rh(8)
C(2)-P(1)-Rh(8)
C(1)-P(1)-Rh(8)
C(14)-P(2)-C(1)
102.2(3) B(10)-B(9)-P(2)
105.8(3) B(10)-B(9)-Rh(8)
102.0(3) P(2)-B(9)-Rh(8)
119.7(2) B(9)-B(10)-B(11)
116.8(2) B(9)-B(10)-P(3)
108.5(2) B(11)-B(10)-P(3)
103.9(3) P(2)-C(1)-P(1)
F igu r e 1. Molecular structure of [8,8-η2-{(µ-Cl)2Ru(η6-p-
cym)(dppm)}-nido-8,7-RhSB9H10] (4). Displacement ellip-
soids are drawn at the 50% level. The phenyl rings on
phosphorus, ipso-carbon atoms excepted, are omitted for
clarity, as are all the H atoms on carbon.
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) in [1,1-(η2-d p p e)-3-η1-{(d p p m )Ru -
(η6-p-cym )Cl2)}-closo-1,2-Rh SB9H8] (10)
starting complex 3. One Cl ligand, Cl(1), is in the plane
of the open face of the cluster, trans to B(9), and the
other, Cl(2), is perpendicular to the face, trans to the
B(3)-B(4) axis, with the Cl-Rh-Cl angle ca. 79°. The
P atom coordinated to Rh is trans to S. The other angles
around Rh conform quite well to octahedral geometry:
Cl(1)-Rh-B(9) is 179°, P(1)-Rh-S is 172°, B(9)-Rh-S
is 90°, and P(1)-Rh-Cl(1) is 88°. The orientation
around the Ru atoms is not unusual, also conforming
to a pseudo-octahedral arrangement, as is seen in
typical [Ru(η6-p-cym)Cl2]-phosphine complexes,35 and
the orientations around the two P atoms are those of
somewhat distorted tetrahedra. Interestingly, the four-
atom ring Ru-Cl(2)-Rh-Cl(1) is almost a perfect
square, with the internal angles, centered at the previ-
ously listed atoms, being 84.3°, 99°, 79°, and 97°,
respectively. The cage dimensions do not deviate from
those found in related systems, except that the bonds
to Rh are shorter by 0.05-0.08 Å, presumably due to
the electron-withdrawing influence of the Cl lig-
ands.16a,b,19,22,24,25
NMR spectral data for 4 are consistent with the
structure given in Figure 1. The 11B NMR spectrum
consists of nine broad signals in the range δ ) +14.9 to
-31.8. Three of them are very broad, and presumably
are those bonded to Rh. The noncage protons associated
with the p-cymene group, the phenyl groups on P, and
the CH2 group on dppm were all identified in their NMR
spectra, and additional resonances, assigned to nine
boron-bonded terminal hydrogen atoms and one bridg-
ing hydrogen atom (-2.08 ppm), were observed. The
expected two 31P{1H} resonances were also observed:
a broad doublet assigned to the P atom on Rh trans to
the sulfur atom at 31.8 ppm (J 31P-103Rh ) 153 Hz) and
a doublet at 26.6 ppm (J 31P-31P ) 4 Hz) assigned to
the P atom coordinated to the Ru atom.
Rh(1)-B(3)
Rh(1)-S(2)
Rh(1)-B(7)
Rh(1)-B(5)
Ru(2)-Cl(1)
S(2)-B(5)
B(3)-B(7)
B(3)-B(6)
B(5)-B(6)
2.115(5)
2.3611(11)
2.395(5)
2.468(5)
2.3985(12)
1.929(5)
1.714(6)
1.711(7)
1.855(7)
Rh(1)-P(2)
Rh(1)-P(1)
Rh(1)-B(6)
Rh(1)-B(4)
Ru(2)-P(4)
Ru(2)-Cl(2)
S(2)-B(4)
2.2670(11)
2.2794(11)
2.374(5)
2.410(5)
2.3687(12)
2.4085(12)
1.953(6)
1.927(5)
1.839(7)
P(3)-B(3)
B(4)-B(7)
B(3)-Rh(1)-S(2)
B(7)-Rh(1)-B(4)
P(4)-Ru(2)-Cl(1)
120.55(13) C(1)-C(2)
1.527(5)
84.44(4)
68.10(17)
68.78(18)
44.99(17) P(2)-Rh(1)-P(1)
86.78(4) B(6)-Rh(1)-B(7)
C(57)-Ru(2)-Cl(2) 160.28(15) B(4)-Rh(1)-B(5)
C(53)-Ru(2)-Cl(2) 112.14(13) C(56)-Ru(2)-Cl(2) 122.56(15)
C(55)-Ru(2)-Cl(2) 93.39(15) C(54)-Ru(2)-Cl(2) 89.55(14)
Cl(1)-Ru(2)-Cl(2)
B(5)-S(2)-Rh(1)
B(8)-S(2)-Rh(1)
C(9)-P(1)-C(1)
C(1)-P(1)-C(3)
C(1)-P(1)-Rh(1)
C(21)-P(2)-C(2)
C(2)-P(2)-C(15)
C(2)-P(2)-Rh(1)
88.91(4) C(52)-Ru(2)-Cl(2) 148.51(13)
69.42(16) P(4)-Ru(2)-Cl(2)
99.00(16) B(5)-S(2)-B(4)
85.86(4)
90.5(2)
67.17(15)
101.62(19)
121.04(14)
115.36(14)
106.2(2)
B(4)-S(2)-Rh(1)
101.47(19) C(9)-P(1)-C(3)
109.11(14) C(9)-P(1)-Rh(1)
105.09(19) C(3)-P(1)-Rh(1)
102.0(2)
C(21)-P(2)-C(15) 100.08(19)
108.34(14) C(21)-P(2)-Rh(1) 121.92(14)
C(28)-P(3)-C(34) 108.29(18) C(15)-P(2)-Rh(1) 117.15(15)
C(34)-P(3)-C(27) 107.04(18) C(28)-P(3)-C(27) 109.21(19)
C(34)-P(3)-B(3)
C(40)-P(4)-C(46) 104.9(2)
114.67(19) C(28)-P(3)-B(3)
C(27)-P(3)-B(3)
110.58(19)
106.89(19)
C(46)-P(4)-C(27) 107.06(19) C(40)-P(4)-C(27) 107.61(19)
P(3)-B(3)-Rh(1) 138.8(2) C(40)-P(4)-Ru(2) 115.48(16)
C(46)-P(4)-C(27) 107.06(19) C(46)-P(4)-Ru(2) 111.21(14)
B(6)-B(3)-B(7)
B(6)-B(3)-Rh(1)
B(9)-B(3)-Rh(1)
S(2)-B(4)-Rh(1)
S(2)-B(5)-Rh(1)
C(1)-C(2)-P(2)
102.5(3)
75.9(2)
110.3(3)
C(27)-P(4)-Ru(2) 110.18(13)
B(9)-B(3)-P(3)
B(7)-B(3)-Rh(1)
110.9(3)
76.7(2)
126.4(3)
124.4(3)
109.4(3)
64.53(15) B(7)-B(4)-S(2)
63.56(16) B(6)-B(5)-S(2)
107.6(3)
C(2)-C(1)-P(1)
solutions. Compound 4 has the molecular structure
depicted in Figure 1, and it can be described as an 11-
vertex nido-rhodathiaundecaborane with an exo-poly-
hedral ligand that chelates the rhodium through a
phosphine and a pair of Cl ligands on the Ru atom. The
multidentate ligand is formally a neutral dppm molecule
with one of the PPh2 groups coordinated to the Ru atom
in the [Ru(η6-p-cym)Cl2] moiety. The orientation around
the Rh atom in 4 is pseudo-octahedral, as it is in the
During the formation of 4, presumably the [Ru(η6-p-
cym)(µ-Cl)2]2 dimer is cleaved by the dangling PPh2
group on 3. This is then followed by replacement of the
bidentate dppm ligand in 3 by a lone pair of electrons
(35) Serron, S. A.; Nolan, S. P.; Abramov, Yu. A.; Brammer, L.;
Petersen, J . L. Organometallics 1998, 17, 104.

Chemistry of a Metallathiaborane Cluster
Organometallics, Vol. 21, No. 25, 2002 5511
Sch em e 2
on each of the two Cl ligands on Ru. The additional
[RuCl2(η6-p-cym)] moieties remaining in solution would
complex to the released dppm. The structure of 4 is
novel. The dppm-ligated Ru moiety [RuCl2(η6-p-cym)-
(dppm)] coordinates to the Rh atom through a PPh2
group and also through two Cl ligands on Ru, thus
forming a Rh-(µ-Cl)2-Ru moiety in which the two
metals are also linked through a bridging dppm ligand.
In the formation of 4, replacement of the bidentate dppm
on 3 by the two Cl ligands maintains the electronic
configuration of the octahedrally coordinated Rh atom
as an 18-electron metal center. This satisfies the metal
center electronically and also maintains the correct
nido-skeletal electron count of the cluster, the ligand
functioning as a six-electron donor. 4 is similar to the
species [8,8-η2-{(η2-BH3)(dppm)}-nido-8,7-RhSB9H10],
which we described previously,16a and is shown as
structure E in Chart 1. The latter contains a BH3‚dppm
moiety, which functions as a multidentate ligand, but
in that case the BH3 group uses two of its H atoms in
three-center two-electron bonds to Rh, whereas in 4 the
interactions are normal two-electron two-center bonds.
The reaction between 3 and [Cp*Ir(µ-Cl)2]2 in CH2-
Cl2 at ambient temperature affords the analogous
species [8,8-η2-{(µ-Cl)2Cp*Ir(dppm)}-nido-8,7-RhSB9H10]
(5) as a yellow solid in 47% yield. Although we were
unable to obtain crystals suitable for X-ray analysis,
elemental analysis and high-resolution mass spectrom-
etry indicated the composition and NMR spectra also
supported our formulation of the species whose proposed
structure is given in Scheme 1. The 11B spectrum
exhibits nine signals, whose chemical shift values are
very close to those for 4. Similarly the 1H spectrum
exhibits signals corresponding to 10-cage-bonded H
atoms at chemical shifts very similar to those for 4. The
bridging H atom is observed at -2.01 ppm. The rhodium
analogue of 5, [8,8-η2-{(µ-Cl)2Cp*Rh(dppm)}-nido-8,7-
RhSB9H10] (6), was obtained from the reaction between
[Cp*RhCl2(η1-dppm)] and [8,8-(PPh3)2-nido-8,7-RhSB9H10]
(2) in CH2Cl2 under N2. The isolated and purified orange
product was characterized as 6 and obtained in 65%
yield. We carried out the reaction of the preformed
ligand [Cp*RhCl2(η1-dppm)] with 2 to see if we obtained
the same type of product as 5, and indeed we did. The
NMR spectral data for 6 are very similar to those for 5,
and the formulation was confirmed by elemental analy-
sis and high-resolution mass spectrometry. We again
were unable to grow crystals suitable for X-ray analysis,
but we are confident that the structure of 6 is the same
as that depicted in Scheme 1.
The reaction between 3 and other coordinatively
unsaturated organometallic reagents provided new
insights into this system. Reaction between 3 and [IrCl-
(CO)(PPh3)2] afforded unstable product mixtures con-
taining small amounts of the previously reported species
[1-PPh3-{1,3-(µ-dppm)}-closo-1,2-RhSB9H8] (7)16d and
other unidentifiable products. It appeared that the Ir
reagent served to remove dppm from the metal center
prior to subsequent chemistry. If [RhCl(PPh3)3] is added
to a solution of freshly prepared 3 in CH2Cl2, and the
reaction mixture stirred for 2 h, the only isolable
product, in 66% yield, is 7. The reaction is illustrated
in Scheme 2. Apparently some exchange of PPh3 for
dppm on the Rh center occurs, and the metal reagent
serves to coordinate dppm. If the reaction mixture is
stirred for 3 days prior to workup, two products are
obtained. One was compound 7, obtained in 37% yield.
The 11B NMR spectrum of the second product exhibits
nine resonances, five of which were very broad, but the
proton spectrum exhibited resonances corresponding to
seven cage hydrogen atoms, none of which were assign-
able to bridging H atoms. The 31P spectrum indicated
the presence of three phosphorus atoms, one bonded to
Rh and the other two bonded to boron. A crystal
structure determination identified the species as [8-Cl-
{8,9-(µ-dppm)}-10-PPh3-nido-8,7-RhSB9H7] (8), and the
structure is given in Figure 2 and also illustrated in
Scheme 2.
The structure of 8 is that of a nido-rhodathiaborane
cluster with a dppm ligand bridging the metal and the
B(9) position in the open face. A PPh3 molecule is bonded
to B(10), also in the open face, and the Rh atom bears
a Cl ligand. The orientation around Rh is essentially
square planar. We and others have noted that for such
16-electron square planar metallaboranes containing Pt,
Pd, or Rh the electron count is two electrons short of
the count required by the PSEPT.23 This is the case for
8, in which the seven BH groups contribute 14 e-, the
S atom contributes 4 e-, the two B‚PR3 groups contrib-
ute 6 e-, and the Cl-Rh-PR3 moiety does not contribute

5512 Organometallics, Vol. 21, No. 25, 2002
Volkov et al.
to the metal center in the rhodathiaborane cluster, along
with concomitant loss of H2 as the free PPh2 group of
the dppm coordinates to the cage, would result in the
formation of 7. The H2 would come from loss of a
terminal and the bridging H atom. Previously we
prepared 7 in a ligand exchange reaction between 2 and
3.16d Reaction between 3 and [RhCl(PPh3)3] for extended
periods of time results in the formation of species 8.
Perhaps this reaction occurs with a precursor to 7,
although there are obvious unanswered questions about
the formation of 8. A plausible route to 8 would involve
replacement of PPh3 with the more nucleophilic Cl-,
thereby releasing more PPh3, which then attacks a cage
boron atom. The dimeric bridging-chloride reagents
cannot abstract dppm to form stable species in which
dppm bonds in a bidentate mode nor, of course, can it
release PPh3. Thus a different reaction pathway is
followed and formation of bimetallic clusters is observed.
F igu r e 2. Molecular structure of [8-Cl-{8,9-(µ-dppm)}-10-
PPh3-nido-8,7-RhSB9H7] (8). Displacement ellipsoids are
drawn at the 50% level. The H atoms on carbon are all
omitted for clarity.
Of particular interest to us was the structure of 8,
especially the dppm moiety bridging the Rh atom and
position 9 in the open face of the cage. We have noted
previously that 3 thermally converts to a mixture of two
red species, which we have been unable to separate
completely.16d Our conclusions are described elsewhere
and are summarized in Scheme 3. In the scheme we
propose that 3 converts to either [3-(η1-dppm)-1,1-(η2-
dppm)-closo-1,2-RhSB9H8] (11′) or [1-(η1-dppm)-1,3-(µ-
dppm)-closo-1,2-RhSB9H8] (11′′) via the species T, which
has two electrons more than the “saturated” species 3
and contains a dppm ligand bridging the metal and the
9-position on the cage. We suggest that our observation
of this bridging ligand in 8 adds credence to our proposal
that T or a very similar species is the precursor to 11′
and 11′′.
any skeletal electrons to the cluster. Thus 8, which
contains 11 vertexes, has 12 skeletal electron pairs, and
since it has a nido-structure, it is two electrons short of
the required number. This compound is isoelectronic
with 7, whose structure is that of a closo-11 vertex
cluster, with an open four-sided “face” reminiscent of
the series of iso-nido 11-vertex clusters which have been
discovered in recent years.36
The angles around Rh in 8 reflect the near square-
planar geometry. The angles B(9)-Rh-P(1) and Cl-
Rh-P(1) are close to the required 90° at ca. 94.3° and
93.1°, respectively. Also the axis S-Rh-P(1) is almost
linear at 171.8°, but distortion from the idealized
geometry is seen by the angle B(9)-Rh-Cl, which is
ca. 136°. Other interesting features of the structure of
8 are the bond distances in the open face of the cage
and the Rh-P distances. They are all slightly shorter
than those in 3 and also in the related species 2. This
may be due to the inductive effects of the phosphine
ligands on the cage boron atoms and also the absence
of a bridging H atom in 8. High-resolution mass
spectrometry also confirmed the formulation of 8, and
elemental analysis data attested to the purity of the
material we isolated.
Reactions proceed differently when [IrCl(CO)(PPh3)2]
or [RhCl(PPh3)3] is allowed to react with 3, as opposed
to when the chloride dimer [Ru(η6-p-cym)(µ-Cl)2]2, [Cp*Ir-
(µ-Cl)2]2, or presumably [Cp*Rh(µ-Cl)2]2 reacts with 3.
It appears that the reaction of 3 with the organometallic
reagents differs in accord with the ability of the latter
to remove dppm from 3 and coordinates dppm in a
bidentate mode. The monomeric Rh and Ir reagents can
remove dppm, which become bidentate as the resulting
complex loses a mole of PPh3. This PPh3 is available in
solution for further reaction with 3, allowing the forma-
tion of [1-PPh3-{1,3-(µ-dppm)}-closo-1,2-RhSB9H8], 7,
which we observe in the cases involving [IrCl(CO)-
(PPh3)2] or [RhCl(PPh3)3]. Accordingly, addition of PPh3
We had also previously noted that the reaction
between [1-PPh3-{1,3-(µ-dppm)}-closo-1,2-RhSB9H8] (7)
and dppe affords [1,1-(η2-dppe)-3-(η1-dppm)-closo-1,2-
RhSB9H8] (9),16d as illustrated in Scheme 2. As part of
our study of potential metal derivatives of the RhSB9
cluster, we decided to see if we could metalate 9 at the
pendant PPh2 position. Treatment of 9 with [Ru(η6-p-
cym)(µ-Cl2)]2 in CH2Cl2 followed by workup allows
isolation of an orange solid, [1,1-(η2-dppe)-3-η1-{(dppm)-
Ru(η6-p-cym)Cl2)}-closo-1,2-RhSB9H8] (10), in 79% yield.
The reaction is illustrated in Scheme 2. 11B NMR
spectra indicate the presence of nine boron atoms, and
the proton spectrum exhibits four resonances assignable
to eight terminal boron-bonded atoms on the cage. The
31P NMR spectrum shows the expected four P atoms in
2:1:1 ratio. Elemental analysis and high-resolution mass
spectrometry supported the proposed formulation, and
crystals suitable for X-ray analysis afforded a structure
that confirmed it. The structure is given in Figure 3,
and it is a closo-RhSB9H8 cluster in which the rhoda-
thiaborane cage has a pendent metal-ligated dppm
group at the 3-position.
The structure of the RhSB9 cage in the bimetallic
species 10 is very similar to that of 9. Thus the angles
B(9)-B(3)-P(3), Rh-B(3)-P(3), B(9)-B(3)-Rh, and
S-Rh-B(3) are 110.9°, 138.8°, 110.3°, and 120.55° in
9, respectively, and 114.79°, 136.6°, 112.8°, and 120.97°
in 10, respectively. The orientation of the pendant
[(dppm)Ru(η6-p-cym)Cl2)] group relative to the cage is
interesting. The planes defined by the atoms Rh-B(3)-
(36) (a) Bown, M.; Fontaine, X. L. R.; Greenwood, N. N.; Kennedy,
J . D.; Thornton-Pett, M. Organometallics 1987, 6, 2254. (b) Nestor,
K.; Fontaine, X. L. R.; Greenwood, N. N.; Kennedy, J . D.; Plesˇek, J .;
Sˇtibr, B.; Thornton-Pett, M. Inorg. Chem. 1989, 28, 2219. (c) Bould,
J .; Rath, N. P.; Barton, L. Acta Crystallogr., Sect. C: Cryst. Struct.
Commun. 1997, C53, 416. (d) Bown, M.; Gruner, B.; Sˇtibr, B.; Fontaine,
X. L. R.; Thornton-Pett, M.; Kennedy, J . D. J Organomet. Chem. 2000,
614/615, 269.

Chemistry of a Metallathiaborane Cluster
Organometallics, Vol. 21, No. 25, 2002 5513
Sch em e 3
example the angles B(3)-P(3)-C(27) and C(27)-P(4)-
Ru(2) are 106.89(19)° and 110.18(13)°, respectively,
whereas P(3)-C(27)-P(4) is 130.7(2)°, reflecting the
greater steric requirements of the PPh2 groups relative
to the CH2 groups. As expected the Ru atom is pseudo-
octahedrally coordinated by the two Cl atoms, P(4), and
the “tricoordinate” (p-cym) ligand. Thus the angles Cl-
(1)-Ru-Cl(2), Cl(1)-Ru-P(4), and Cl(2)-Ru-P(4) are
all close to 90°, at 88.9°, 86.8°, and 85.9°, respectively.
The cage itself is quite similar to analogous systems.
The angle between the planes S(2)-Rh(1)-B(3) and
P(1)-Rh(1)-P(2) is 101°, quite close to the ideal value
of 90°.
Su m m a r y
We have exploited the chemistry of the novel species
[8,8-(η2-dppm)-8-(η1-dppm)-nido-8,7-RhSB9H10] (3) by
preparing a series of bimetallathiaboranes on a RhSB9
cluster template. These include nido-species containing
the metal pairs Rh/Ru, Rh/Ir, and Rh/Rh. In addition
we have prepared a closo-derivatives of 3 with a pendant
ligated metal moiety, which may portend applications
of these systems. Ligand exchange on 3 is stimulated
by the use of the more electrophilic coordinatively
unsaturated metal reagents [IrCl(CO)(PPh3)2] and [RhCl-
(PPh3)3], and the products of these reactions provided
us with support for our earlier suggestion for the
reaction pathway for rearrangement of species 3.
F igu r e 3. Molecular structure of [1,1-(η2-dppe)-3-η1-
{(dppm)Ru(η6-p-cym)Cl2)}-closo-1,2-RhSB9H8] (10). Dis-
placement ellipsoids are drawn at the 50% level. The
phenyl rings on phosphorus, ipso-carbon atoms excepted,
are omitted for clarity, as are all the H atoms on carbon.
P(3) and B(3)-P(3)-C(27) lie at 116.4° to each other,
reflecting minimization of steric crowding of the meth-
ylene H atoms on C(27). On the other hand, the planes
defined by the atoms B(3)-P(3)-C(27) and P(3)-C(27)-
P(4) deviate from coplanarity by 5.3°, and those defined
by the atoms P(3)-C(27)-P(4) and C(27)-P(4)-Ru by
6.2°; thus the atoms B(3), P(3), C(27), and Ru all lie
essentially on a plane. There is nothing unusual about
the geometry around the atoms on the backbone of the
pendant [(dppm)Ru(η6-p-cym)Cl2)] group. The orienta-
tion around the atoms P(3), P(4), and C(27) shows
deviations from ideality which reflect steric factors. For
Ackn owledgm en t. We acknowledge the NSF (Grant
No. CHE-9727570), the Missouri Research Board, and
UM-St. Louis for research grants to L.B., and the NSF,
the UM-St. Louis Center for Molecular Electronics, and
the Missouri Research Board for funds that helped
purchase the NMR, XRD, and MS facilities. We also

5514 Organometallics, Vol. 21, No. 25, 2002
Volkov et al.
parameters, atomic coordinates, bond distances and angles,
and anisotropic thermal parameters. This material is available
free of charge via the Internet at http://pubs.acs.org.
thank Prof. R. E. K. Winter and Mr. J . Kramer for the
MS data.
Su p p or tin g In for m a tion Ava ila ble: X-ray structural
data for 4, 8, and 10 including a summary of crystallographic
OM020480Y