Polyhedral ruthenaborane chemistry. Approaches to encapsulated boron cores. The isolation and characterisation of the partially encapsulated isocloso 10-vertex {RuB9} cluster compound [(PPh3)RuB 9H9{RuCl2</

Article abstract of DOI:10.1016/j.inoche.2004.09.006

[RuCl₂(Ph₃)₂] with [arachno-B ₉H₁₄]^- gives [(PPh₃)RuB ₉H₉{RuCl₂(PPh₃)₂} ₂], which has an isocloso 10-vertex {RuB

Full text of DOI:10.1016/j.inoche.2004.09.006

Inorganic Chemistry Communications 8 (2005) 147–150
www.elsevier.com/locate/inoche
Polyhedral ruthenaborane chemistry. Approaches to
encapsulated boron cores. The isolation and characterisation of
the partially encapsulated isocloso 10-vertex {RuB9}
cluster compound [(PPh3)RuB9H9{RuCl2(PPh3)2}2]
a
Young-Hee Kim , Lawrence Barton , Nigam P. Rath , John D. Kennedy
b
b
a,
*
a
The School of Chemistry of the University of Leeds, Leeds, LS2 9JT, UK
b
Department of Chemistry of the University of Missouri, St. Louis, Missouri, MO 63121, USA
Received 23 July 2004; accepted 12 August 2004
Available online 15 December 2004
Abstract
[RuCl2(Ph3)2] with [arachno-B9H14]À gives [(PPh3)RuB9H9{RuCl2(PPh3)2}2], which has an isocloso 10-vertex {RuB9} core geom-
etry that is partially encapsulated by exo-polyhedral {RuCl2(PPh3)2} units that cap {RuB2} triangular faces with one {RuClRu} and
two {RuHB} bridges each. The structure engenders focus on the several new compound classes emerging in polyhedral boron-
containing cluster chemistry.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Metallaboranes; Encapsulated clusters; Cluster categories; Ruthenium-borane cluster; Transition-element hydrides; NMR spectroscopy;
X-ray diffraction
Interesting molecular species emerge, and interesting
new chemistry is portended, when polyhedral boron
cores are surrounded by skins of hydrophilic hydroxy
groups, as in the [B12(OH)12]2À anion [1], and by skins
of lipophilic organyl groups, such as in the
[B12(CH3)12]2À anion and related species [2,3]. Related
to these new structural types are the proposed ꢀmegal-
oboraneꢁ clusters in which a polyhedral boron core is
encapsulated by a skin of cross-linked boron hydride
units [4–6]. Here we present preliminary results on a
structural system that represents an initial step towards
the extension of this polyhedral encapsulation concept
to the synthesis of species based on polyhedral boron
cores surrounded by a skin of units based on transi-
tion-element centres, rather than a skin of hydrocarbon
or hydroxy ligands.
Reactions of [RuCl2(PPh3)3] with the [nido-B9H12]À
or [arachno-B9H14]À anions have been reported to
produce the monometallaboranes [6,6,6-(PPh3)2H-
5-(PPh3)-nido-6-RuB9H12] (compound 1) and [1,1,1-
(PPh3)HCl-5,6-(PPh3)2-isocloso-1-RuB9H7] (compound
2) [7]. From this same reaction system we now report
the isolation of an interesting triple-ruthenium species
of formulation [(PPh3)RuB9H9{RuCl2(PPh3)2}2] (com-
pound 3). Thus, the reaction of [RuCl2(PPh3)3] (961
mg, 1 mmol) and [NEt4][arachno-B9H14] (974 mg, 4
mmol) in CH2Cl2 (80 ml) for 18 h gave a red solution.
Short-column chromatography on silica using CH2Cl2
as liquid phase thence resulted in the isolation of several
products, purified by preparative TLC on silica gel G
using CH2Cl2 as developing solvent. Identified species
are: (a) known compound 1 (red, RF 0.91; 272 mg;
*
Corresponding author. Tel.: +44 113 233 6414; fax: +44 113 233
6565.
E-mail address: johnk@chem.leeds.ac.uk (J.D. Kennedy).
1387-7003/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2004.09.006

148
Y.-H. Kim et al. / Inorganic Chemistry Communications 8 (2005) 147–150
C(501)
C(107)
C(507)
C(513)
C(201)
P(5)
Cl(1)
Cl(2)
C(207)
P(1)
Cl(3)
P(2)
C(101)
Cl(4)
C(113)
Ru(1)
Ru(3)
C(213)
B(3)
Ru(2)
B(4)
B(6)
B(7)
B(9)
B(2)
B(5)
C(313)
P(3)
P(4)
C(407)
C(301)
C(401)
B(8)
B(10)
C(307)
C(413)
Fig. 1. ORTEP-type drawing of the crystallographically determined molecular structure of [(PPh3)RuB9H9{RuCl2(PPh3)2}2](compound 3). P-phenyl
group atoms, apart from the ipso carbon ones, are omitted for clarity. Cluster hydrogen atoms were not reliably locatable from the diffraction
analysis, but NMR spectroscopy2 demonstrates metallaborane hydrogen atoms bridging the Ru(2)B(2), Ru(2)B(5), Ru(3)B(3) and Ru(3)B(6) vectors
(schematic structure I) and in exo-terminal positions on B(4), B(7), B(8), B(9) and B(10). Distances from the Ru(1) atom are: to P(1) 2.468(3), to Cl(1)
2.462(2), to Cl(2) 2.448(3), to B(2) 2.099(11), to B(3) 2.181(11), to B(4) 2.094(12), to B(5) 2.338(11), to B(6) 2.302(11), and to B(7) 2.361(11), distances
from the Ru(2) atom are: to P(2) 2.306(3), to P(3) 2.324(3), to Cl(1) 2.497(2), to B(2) 2.231(11), and to B(5) 2.569(10) and distances from the Ru(3)
˚
atom are: to P(4) 2.347(3), to P(5) 2.335(3), to Cl(2) 2.480(2), to B(3) 2.237(11), and to B(6) 2.513(11) A. Interboron distances are within the range
˚
1.67(2)–1.88(2) A.
27%) [6]; (b) new [(PPh3)RuB9H9{RuCl2(PPh3)2}2]
(orange, compound 3; RF 0.85; 534 mg; 28%); and (c)
known compound 2 (yellow, RF 0.67; 43 mg; 4%) [6].
Other components, present in smaller quantities, are as
yet unidentified. The solid-state molecular structure of
atoms, were located, apart from the four bridging
hydrogen atoms and the five terminal hydrogen atoms
on the cluster, which, however, were readily confirmed
1
by H–11B(selective) NMR experiments.2
The core cluster unit of compound 3 is seen to
have a characteristic 10-vertex {RuB9} metallaborane
isocloso geometry which engenders the characteristic
10-vertex isocloso {MB9} 3:3:3 11B relative intensity
NMR resonance grouping as typified by the simple
models [1,1,1-H(PMe3)2-isocloso-1-IrB9H9] and [1-(g6-
MeC6H4CHMe2)-isocloso-1-RuB9H9] [8,9]. Uniquely,
however, there are in addition two exopolyhedral
ruthenium atoms, numbered Ru(2) and Ru(3), each
encompassed in a {RuCl(PPh3)2} unit bonded to the
central {RuB9} cluster via a {RuCllRu} bridge and
two {RuHlB} bridges to give octahedral bonding
geometry about the metal centres in each case
(Scheme 1). This type of {RuCllRu} linkage is as in
[(PPh3)2ClRuClRu (PPh3)B10H8(OEt)2] [10], which
has only one such {RuCl2(PPh3)2} unit bound to a
central eleven-vertex isocloso {RuB10} cluster, rather
than two {RuCl2(PPh3)2} units bound to a 10-vertex
isocloso {RuB9} cluster as in compound 3 described
here. The binding mode is also related to the metal-
to-cluster bonding system in [{(PPh3)2Ru}-l,l,l-(Me-
COO)3-l,l-H2-{RuB10H7}], also based on a central
1
compound 3 (Fig. 1) is consistent with the bulk
2
NMR properties. All atoms, including most hydrogen
1
X-ray diffraction analysis: [(PPh3)RuB9H9{RuCl2(PPh3)2}2]Æ
(CH2Cl2)1.25(C6H6)0.5, CH2Cl2/C6H6 solvate of compound 3,
C
CH2Cl2/C6H12), a = 17.9276(5), b = 20.0446(6), c = 26.4539(7) A,
94.25H89.5B9Cl6.5P5Ru3, M = 2007.93, orthorhombic, P21 2121 (from
˚
3
a = b = c = 90°, U = 9506.3(5) A , Dcalc = 1.403 mg mÀ3, Z = 4, Mo
˚
Ka, k = 0.71073 A, l = 0.782 mmÀ1, T = 193(2) K, R1 = 0.058 for
˚
12511 reflections with I > 2r(I), and wR2 = 0.115 for all 19,404
independent reflections; CCDC reference number CCDC 245961.
Solution and refinement programs were from the SHELX suite (G.M.
Sheldrick, University of Go¨ttingen).
2
Measured NMR data for compound 3, CDCl3 solution at 293 K,
ordered as assignment d(11B)/ppm [d(1H)/ppm in square brackets]:
BH(2) and BH(3) +8.73 [À9.12] and +77.4 [À8.38], BH(4) +85.0
2
[+9.39], BH(5) and BH(6) ca. À29.9 [À1.65, with J(1H–31P)(trans) 22
Hz] and ca. À29.9 [À3.55, with 2J(1H–31P)(trans) 47 Hz], À14.6
[À0.45], BH(8) +20.9 [+2.60], BH(9) and BH(10) ca. +27.5 [+2.88] and
ca. +27.5 [+2.25]; additionally d(1H)(Ph) around ca. +7.5 (unresolved
multiplets) and, at 233 K, d(31P) [with approx 2J(31P–31P) values in
square brackets]: +49.8 [29 Hz], +46.4 [25 Hz], + 48.4 [25 Hz], +41.6
[29 Hz] and +18.7 (no fine structure observed in 31P–{1H} spectrum).

Y.-H. Kim et al. / Inorganic Chemistry Communications 8 (2005) 147–150
149
Cl(3)
dride cluster surface. This last type of exo-cluster hetero-
atom molecular assembly motif contrasts in turn with
another emerging new general structural type, exempli-
fied by species such as [(C5Me5)2Ir2CSB6H8], and
[C6B6H6] and its derivatives [20,21], which exhibit sepa-
rate metal and/or heteroatom strings and domains with-
in individual boron-containing clusters rather than in
exo-skeletal positions. This last ꢀcomposite clusterꢁ
chemistry contrasts in turn to the ꢀhybrid clusterꢁ phe-
nomenon, as noted, for example, by Sneddon and co-
workers in the hypho-type species MeCS2NB7H9 [22],
in which there are mutually exclusive domains of cluster
structure and domains of classical two-electron two-
centre main-group chain and ring chemistry. It is also
distinct from the multicluster assemblies in which indi-
vidual diverse sub-groupings conjoin with one common
metal atom and are non-contiguous, such as {Ru3}/
{RuB10} [23], {Au6}/{AuB10} [24] and C2B10Mo/{Mo2-
S4}/{MoC2B10} [25].
P(5)
P(3)
P(4)
H
H
Ru(2)
Ru(3)
5
7
3
P(2)
Cl(4)
Cl(2)
Cl(1)
Ru(1)
H
2
6
H
4
P(1)
Scheme 1.
eleven-vertex isocloso {RuB10} cluster [11]. There are
also parallels in the structure of [{Cu(PPh3)}2-l,
l-H2-{ReB9H7CPh}] that is based on a central ele-
ven-vertex {ReCB9} core [12]. The result in compound
3 is an incipient partial encapsulation of the cen-
tral {RuB9} core by a developing ruthenium hydride
skin.
It is interesting to speculate that this partial encapsu-
lation of the central {RuB9} unit by the other two ruthe-
nium centres may presage a new general structural type
based on a more complete encapsulation of a polyhedral
boron hydride core by a sheath of linked metal centres.
Similarly, encapsulations of carbon hydride cores could
also be envisaged, as presaged by species such as [Ru6
(C10H6)(PPh)(CO)14] [13]. This structural principle
contrasts with and complements recently reported
earlier-transition-element metallaborane species such as
[(g5-C5Me5)2Re2B7H7], [(g5-C5Me5)2W2B7H9] and [(g5-
C5Me5)3W3HB8H8] [14], which may conversely presage
central polymetal cores encapsulated by boron hydride
skins. Experimental approaches to these latter could in-
clude the replacement of halides on earlier transition-
element polyhalopolymetal anions such as [Mo6Cl14]2À
via substitution by anionic boron hydride moieties.
These considerations draw attention to other globular
borane-based structural principles that are contempora-
neously emerging. Thus in addition to species such as
the [B12 Me12]2À, [B12(OH)12]2À and [B12(OR)12]2À dia-
nions that are based on borons-only cores surrounded
by hydrocarbon, hydroxy, or organyloxy skins [1,2,14–
17], features of species such as [(CO)(PMe3)2Ir
Acknowledgements
We thank Dr. R. Greatrex for his good offices, Dr. J.
Bould for stimulating discussions, and the EPSRC (UK)
and the NSF (USA) for instrumental grants.
Appendix A. Deposited data
Crystallographic data for compound 3 are deposited
at the Cambridge Crystallographic Data Centre, CCDC,
deposition no. CCDC 245961. These data can be ob-
tained free of charge at www.ccdc.cam.ac.uk/conts/
retrieving.html [or from the Cambridge Crystallo-
graphic Data Centre, 12, Union Road, Cambridge
CB2 1EZ, UK; fax: (internat.) +44-1223/336-033; E-
mail: deposit@ccdc.cam.ac.uk].
References
[1] T. Peymann, A. Herzog, C.B. Knobler, M.F. Hawthorne, Angew.
Chem., Int. Ed. 38 (1999) 1062.
[2] T. Peymann, C.B. Knobler, M.F. Hawthorne, J. Am. Chem. Soc.
121 (1999) 5601.
B26H24Ir(PMe3)2],
[(C5Me5)3Ir3B18H15(OH)]
and
[3] T. Peymann, C.B. Knobler, M.F. Hawthorne, Chem. Commun.
(1999) 2039.
[(PPh3)3(PPh2)2Pd3B20H16Pd(PPh3)] suggest families of
very big boranes based on borons-only cores sur-
rounded by boron hydride skins [4,5,18,19]. Species such
as [(CH2CH2C5H4N)-arachno-B10H10 (NC5H4-closo-
C2B10H11)] similarly may presage carbons-only cores
surrounded by boron hydride skins [21]. Another novel
cluster structural principle emerging from a consider-
ation of the structure of [(PPh3)2(PPh2)Pd3B20H16
Pd(PPh3)] [4] is that consisting of a string of alternating
metal and non-metal atoms attached to the borane hy-
[4] H.-J. Yao, C.-H. Hu, J. Sun, R.-S. Jin, P.-J. Zheng, J. Bould, R.
Greatrex, J.D. Kennedy, D.L. Ormsby, M. Thornton-Pett,
Collect. Czech. Chem. Commun. 64 (1999) 927.
[5] J. Bould, W. Clegg, S.J. Teat, L. Barton, N.P. Rath, M.
Thornton-Pett, J.D. Kennedy, in: Boron Chemistry at the
Millennium, Special Edition of Inorg. Chim. Acta 289 (1999) 95.
[6] J. Bould, M.G.S. Londesborough, D.L. Ormsby, J.A.H. Mac-
Bride, K. Wade, C.A. Kilner, W. Clegg, S.J. Teat, M. Thornton-
Pett, R. Greatrex, J.D. Kennedy, J. Organomet. Chem. 657 (2002)
256.

150
Y.-H. Kim et al. / Inorganic Chemistry Communications 8 (2005) 147–150
[7] J.E. Crook, M. Elrington, N.N. Greenwood, J.D. Kennedy, M.
Thornton-Pett, J.D. Woollins, J. Chem. Soc., Dalton Trans.
[16] C.-W. Tsang, Z. Xie, Chem. Commun. (2000) 1835.
[17] T. Peymann, C.B. Knobler, S.I. Khan, M.F. Hawthorne, Angew.
Chem. Int. Ed. 40 (2001) 644.
(1985) 2407.
[8] J. Bould, N.N. Greenwood, J.D. Kennedy, J. Chem. Soc., Dalton
Trans. (1990) 1451.
[18] J. Bould, J.D. Kennedy, L. Barton, N.P. Rath, J. Chem. Soc.,
Chem. Commun. (1997) 2405.
ˇ
[19] S.L. Shea, T. Jelınek, B. Stıbr, M. Thornton-Pett, J.D. Kennedy,
´
´
[9] Y.-H. Kim, P.A. Cooke, N.P. Rath, L. Barton, R. Greatrex, J.D.
Kennedy, M. Thornton-Pett, Inorg. Chem. Commun. 1 (1998)
375.
Inorg. Chem. Commun. 3 (2000) 169.
[20] P.A. Cooke, C. Price, M.G.S. Londesborough, J. Holub, B. St´ıbr,
ˇ
[10] M. Elrington, J.D. Kennedy, N.N. Greenwood, M. Thornton-
Pett, J. Chem. Soc., Chem. Commun (1984) 1398.
[11] X.L.R. Fontaine, N.N. Greenwood, J.D. Kennedy, M. Thorn-
ton-Pett, P.-J. Zheng, J. Chem. Soc., Chem. Commun. (1987)
1717.
M. Thornton-Pett, W. Clegg, S.J. Teat, J.D. Kennedy, J.
Organomet. Chem. 614/615 (2000) 57.
´ ´
[21] B. Gruner, T. Jelınek, Z. Plzak, J.D. Kennedy, D.L. Ormsby, R.
¨
ˇ
´
Greatrex, B. Stıbr, Angew. Chem., Int. Ed. 38 (1999) 1806.
[22] S.O. Kang, G.T. Furst, L.G. Sneddon, Inorg. Chem. 28 (1989)
2339.
[12] S. Du, J.A. Kauz, T.D. McGrath, F.G.A. Stone, Organometallics
22 (2003) 2842–2850.
[23] M. Bown, X.L.R. Fontaine, N.N. Greenwood, J.D. Kennedy, P.
MacKinnon, M. Thornton-Pett, J. Chem. Soc. Chem., Commun.
(1987) 442.
[13] A.J. Deeming, C.M. Martin, Angew. Chem., Int. Ed. 37 (1998)
1691.
[14] A.S. Weller, M. Shang, T.P. Fehlner, Chem. Commun. (1998)
1787.
[24] A.J. Wynd, S.E. Robins, D.A. Welch, A.J. Welch, J. Chem. Soc.,
Chem. Commun. (1985) 819.
[15] A.S. Weller, M. Shang, T.P. Fehlner, Organometallics 18 (1999)
853.
[25] J.H. Kim, M. Lamrani, J.W. Hwang, Y. Do, J. Chem. Soc.,
Chem. Commun. (1997) 1761.