Coordination and cluster compounds of ruthenium with the [hypho-1,2-S 2B6H9]- Ligand

Article abstract of DOI:10.1039/b502846a

The reaction between [tmndH][hypho-1,2-S₂B₆H ₉] (tmnd = N,N,N′,N′-tetramethylnaphthalene-1,8-diamine) and [RuCl(PPh₃)₂(η⁵-Cp)] in CH ₂Cl₂ at room temperature afforded two ruthenathiaboranes, [5-(η⁵-Cp)-5-(PPh₃)-5,4,6-RuS₂B ₆H₉], 1, and [Ru(η¹-1,2-S₂B ₆H₉)(PPh₃)₂(η⁵-Cp)], 2, in 6 and 48% yields, respectively. The heating of a solution of [Ru(η¹-1,2-S₂B₆H₉)(PPh ₃)₂(η⁵-Cp)] 2 in CH₂Cl ₂ at reflux temperature afforded 1 in 59% yield. Compound 1 could be described as either a hypho nine-vertex {RuS₂B₆} cluster or a coordination compound of ruthenium which contains a bidentate η²-dithiaborate cluster ligand; the latter description is preferred. Compound 2 contains an eight-atom hypho-type {1,2-S₂B ₆} cage bonded to the ruthenium atom of the {Ru(PPh₃) ₂(η⁵-Cp)} unit by one sulfur atom and may be described as a compound of ruthenium coordinated η¹- to the dithiaborate cluster ligand. The reaction between [tmndH][hypho-1,2-S₂B ₆H₉] and [RuCl₂(η⁶-MeC ₆H₄Prⁱ)]₂ in CH₂Cl ₂ at room temperature afforded [5-(η⁶-MeC ₆H₄Prⁱ)-arachno-5,4,6-RuS₂B ₆H₈] 3, in 94% yield. Further reaction of 3 and PMePh ₂ afforded another arachno {RhS₂B₆}cluster, [5-(η⁶-MeC₆H₄Prⁱ)-8-(PMePh ₂)-arachno-5,4,6-RuS₂B₆H₆], 4, in 25% yield. Compounds 1,2 and 4 were characterised with single crystal X-ray analyses. The Royal Society of Chemistry 2005.

Full text of DOI:10.1039/b502846a

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F U L L P A P E R
Coordination and cluster compounds of ruthenium with the
[hypho-1,2-S2B6H9]− ligand†
George Ferguson,*a John F. Gallagher,b John D. Kennedy,c Donogh M. McCarthyd and
Trevor R. Spalding*d
a School of Chemistry, The University, St. Andrews, Fife, Scotland UK KY16 9ST.
E-mail: gf3@st-andrews.ac.uk
b Department of Chemistry, Dublin City University, Dublin, Ireland
c Department of Chemistry, University of Leeds, Leeds, UK LS2 9JT
d Department of Chemistry, University College Cork, National University of Ireland, Cork,
Ireland. E-mail: t.spalding@ucc.ie
Received 25th February 2005, Accepted 19th April 2005
First published as an Advance Article on the web 4th May 2005
The reaction between [tmndH][hypho-1,2-S2B6H9] (tmnd = N,N,Nꢀ,Nꢀ-tetramethylnaphthalene-1,8-diamine) and
5
5
[RuCl(PPh3)2(g -Cp)] in CH2Cl2 at room temperature afforded two ruthenathiaboranes, [5-(g -Cp)-5-(PPh3)-5,4,6-
1
5
RuS2B6H9], 1, and [Ru(g -1,2-S2B6H9)(PPh3)2(g -Cp)], 2, in 6 and 48% yields, respectively. The heating of a solution
1
5
of [Ru(g -1,2-S2B6H9)(PPh3)2(g -Cp)] 2 in CH2Cl2 at reflux temperature afforded 1 in 59% yield. Compound 1 could
be described as either a hypho nine-vertex {RuS2B6} cluster or a coordination compound of ruthenium which
2
contains a bidentate g -dithiaborate cluster ligand; the latter description is preferred. Compound 2 contains an
5
eight-atom hypho-type {1,2-S2B6} cage bonded to the ruthenium atom of the {Ru(PPh3)2(g -Cp)} unit by one sulfur
1
atom and may be described as a compound of ruthenium coordinated g - to the dithiaborate cluster ligand. The
reaction between [tmndH][hypho-1,2-S2B6H9] and [RuCl2(g -MeC6H4Pri)]2 in CH2Cl2 at room temperature afforded
6
[5-(g -MeC6H4Pri)-arachno-5,4,6-RuS2B6H8], 3, in 94% yield. Further reaction of 3 and PMePh2 afforded another
6
arachno {RhS2B6}cluster, [5-(g -MeC6H4Pri)-8-(PMePh2)-arachno-5,4,6-RuS2B6H6], 4, in 25% yield. Compounds
6
1, 2 and 4 were characterised with single crystal X-ray analyses.
6
reported, namely, [2,3-(g -MeC6H4Pri)2-closo-2,3,1-Ru2SB9H9]
Introduction
5, [7-Cl-2,3-(g -MeC6H4Pri)2-closo-2,3,1-Ru2SB9H8] 6, [2-(g -
6
6
We have investigated transition-element compounds of het-
eroborane ligands from the viewpoints of (a) the coordina-
tion of a hetero-atom to the transition element by a single
bond1 and (b) the incorporation of the transition element
as a cluster vertex with several multicentre bonds between
the transition element and heteroborane unit.1–3 Most of the
reaction chemistry used to synthesise borane cluster complexes
of transition elements involves reactions between cluster-based
anions and transition-element compounds that contain easily
removable ligands such as anionic halide and hydride, or neutral
ligands such as carbonyls and phosphines.4 The mechanisms
of formation of transition-element heteroborane clusters are
not well understood but it is reasonable to assume that in
many cases the initial steps involve the expulsion of a labile
ligand from the transition-element coordination sphere and
its replacement by a coordinate bond between the transition
element and the heteroborane. Further condensation resulting
in a more intimate incorporation of the metal-centre into the
boron-containing matrix may then occur. Two questions arise:
“Can examples of coordination compounds that are initially
formed be isolated?” And “can they then be converted into the
more condensed transition-element heteroborane cluster com-
plexes?” If cluster ligands with “open” architectures are used,
for example hypho clusters, an ancillary question may arise, “at
what stage do the initially formed compounds become clusters?”
In order to investigate these questions, we have prepared some
ruthenium complexes of the [hypho-1,2-S2B6H9]− anion. Whilst
C6Me6)-closo-2,1-RuSB8H8] 7, [11-Cl-7-(g -MeC6H4Pri)-nido-
6
7,8-RuSB9H10] 8,7 [5-(g -C6Me6)-arachno-5,4,6-RuS2B6H8] 9 and
6
[5-(g -C6Me6)-5-Cl-hypho-5,4,6-RuS2B6H9] 10.8 Of these, the
6
two compounds which have the {RuS2B6} skeleton, 9 and 10,
were structurally characterised by single crystal X-ray analyses.8
4
The ruthenium-to-cage interactions in 9 and 10 were of the g
(Ru to S2B2) and g (Ru to S,Sꢀ) types, respectively, see diagrams
2
I and II.
1
2
there are many reports of g and g Ru–S bonded coordination
complexes with a variety of sulfur ligands,6 the number of
ruthenium derivatives of thiaboranes is relatively small. As
far as we are aware, only six ruthenathiaboranes have been
† Metallaheteroborane chemistry. Part 17.1
T h i s j o u r n a l i s
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 5
D a l t o n T r a n s . , 2 0 0 5 , 1 9 7 9 – 1 9 8 4
1 9 7 9
©

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1
Numerous compounds with monohapto (g ) r-bonds between
transition elements and heteroborane ligands containing B,
C, P, As and Ge have been previously reported. Examples
1
5
1
include [Fe(g -PB10H12)(CO)2(g -Cp)], [Fe(g -1,2-GeCHB10H10)-
(CO)2(g -Cp)]9 and, [Fe(g -As2B9H10)(CO)2(g -Cp)].1,9 However,
5
1
5
the only previously reported metallathiaborane in which one
1
sulfur cluster atom acts solely as the donor site is [Ir(g -
S2B9H10)(PPh3)3(H)2], 11, prepared by the treatment of [arachno-
2,3-S2B9H10]− with [IrCl(PPh3)3] in dichloromethane solution at
room temperature.2
In the present work we describe the synthesis of four new rut-
5
henathiaboranes [5-(g -Cp)-5-(PPh3)-hypho-5,4,6-RuS2B6H9] 1,
1
5
6
[Ru(g -hypho-1,2-S2B6H9)(PPh3)2(g -Cp)] 2, [5-(g -MeC6H4Pri)-
arachno-5,4,6-RuS2B6H8], 3, and [5-(g -MeC6H4Pri)-8-(PMePh2)-
6
arachno-5,4,6-RuS2B6H6], 4. Compound 2 is the first reported
ruthenathiaborane in which the only interaction between the
ruthenium centre and the thiaborane ligand is a monohapto
Ru–S r bond. The conversion of the monohapto bonding mode
in 2 into a dihapto bonding mode in 1 is demonstrated and the
alternative descriptions of 1 either as a coordination complex, or
as a cluster, are examined. The effect of changing the ruthenium
1
Fig.
1
ORTEP plot of the major part of [Ru(g -1,2-S2B6H9)-
5
(PPh3)2(g -Cp)] 2, showing the numbering scheme; for clarity, only
the first carbon is shown for each phenyl ring and the minor oc-
cupancy sites (S2A, S2B) of S(2) are omitted. Ellipsoids are shown
5
6
reagent from [RuCl(PPh3)2(g -Cp)] to [RuCl2(g -MeC6H4Pri)]2
4
is to generate an g -{S2B2}-ligating arachno {RuS2B6} cluster
˚
at the 30% probability level. Selected interatomic distances (A) and
angles (◦): Ru1–S1 2.4017(9), Ru1–P1 2.3576(9), Ru1–P2 2.3319(9),
S1–B5 1.879(5), S1–B6 1.888(4), S2–B3 1.852(7), S2–B7 1.866(6),
B3–B4 1.798(9), B3–B8 1.813(7), B3–B7 1.947(8), B4–B8 1.733(7),
B4–B5 1.796(8), B5–B8 1.828(7), B5–B6 2.000(7), B6–B8 1.791(6),
B6–B7 1.814(7), B7–B8 1.794(7); S1–Ru1–P2 87.19(3), S1–Ru1–P1
92.88(3), P1–Ru1–P2 99.51(3), B5–S1–Ru1 116.98(17), B5–S1–B6
64.1(2), B6–S1–Ru1 114.67(4), B3–S2–B7 63.2(2). There are no unusual
distances or angles within the PPh3 or Cp ligands and the Ru to Cp
parameters are normal.
compound, 3, directly. Compounds 2, 1 and 3/4, respectively,
thereby represent successive steps in the incorporation of a metal
centre into a cluster, ultimately to form a condensed contiguous
6
metalladihtiaborane skeleton. (Note. The g -MeC6H4Pri ligand
will be represented by ‘p-cymꢀ in all further formulae).
Results and discussion
Syntheses
5
1
Compounds [5-(g -Cp)-5-(PPh3)-5,4,6-RuS2B6H9] 1 and [Ru(g -
bond between one sulfur atom of the thiaborane cage and the
ruthenium atom. Important interatomic distances and angles for
2 are given in the legend to Fig. 1. Compound 2 is only the second
example of a compound in which a sulfur atom in a thiaborane
cage is involved in an unsupported donor–acceptor bond to
the transition element. The previously reported compound was
5
1,2-S2B6H9)(PPh3)2-(g -Cp)] 2 were synthesised by the reaction
between the [1,2-hypho-S2B6H9]− anion and [RuCl(PPh3)2(g -
5
Cp)]. The reaction of equimolar amounts of [1,2-hypho-S2B6H9]−
5
and [RuCl(PPh3)2(g -Cp)] in dichloromethane for five days
5
1
afforded [5-(g -Cp)-5-(PPh3)-5,4,6-RuS2B6H9] 1 and [Ru(g -1,2-
5
S2B6H9)(PPh3)2(g -Cp)] 2 in 6% and 48% yields, respectively.
[Ir(g -S2B9H10)(PPh3)3H2] 11.2
1
Both 1 and 2 were purified by preparative t.l.c. and crystallised
from dichloromethane–hexane and toluene–hexane solutions,
respectively. When compound 2 was heated in dichloromethane
solution at reflux temperature for three weeks it was converted
to 1 in 59% yield. This conversion was accompanied by loss of
PPh3 and suggests that the formation of 1 may be a stepwise
process in which compound 2 is the intermediate (Scheme 1).
In this diffraction analysis, it should be noted that, whereas
the S1 atom in compound 2 was located on a single crystallo-
graphic site, the other sulfur atom was found to be disordered
unequally over three positions, i.e. S2, S2A and S2B, but only
˚
S2 is shown in Fig. 1. The Ru1–S1 distance, of 2.4017(9) A, is
significantly longer (3 × su) than the Ru–S distance in sev-
5
eral other {Ru(PPh3)2(g -Cp)}-containing compounds, e.g. in
5
10
˚
[Ru(C3H6S)(PPh3)2 (g -Cp)][CF3SO3] at 2.3459(20) A, and in
5
11
˚
[Ru(PhCH2CH2SH)(PPh3)2(g -Cp)][BF4] at 2.369(2) A, but
5
similar to that in [Ru(C6H11SH)(PPh3)2(g -Cp)][BF4] at 2.389(2)
12
˚
A.
The S1–B5 and S1–B6 distances in compound 2 are 1.879(5)
˚
and 1.888(4) A, respectively. These values are at the lower end of
the range of S–B distances in previously studied {RuS2B6} rut-
6
henathiaboranes, i.e. in [5-(g -C6Me6)-arachno-5,4,6-RuS2B6H8]
Scheme 1 Syntheses of compounds 1 and 2 near here.
6
˚
9 at 1.880(10) to 1.939(9) A and in [5-(g -C6Me6)-5-(Cl)-hypho-
8
˚
5,4,6-RuS2B6H9] 10 at 1.887(25) to 1.943(19) A. As is common
for metal derivatives of boranes and heteroboranes, a large range
Compound 3, [5-(p-cym)-arachno-5,4,6-RuS2B6H8], was iso-
lated in 94% yield from the reaction between the [hypho-1,2-
of distances was observed for the B–B interactions in compound
1–4
6
S2B6H9]− anion and [RuCl2(g -p-cym)]2 in CH2Cl2 for five days
˚
2, varying from 1.733(7) to 2.000(7) A. As mentioned below
˚
for compound 1, the largest interboron distance of 2.000(7) A
at room temperature. When 3 was treated with a tenfold excess
of PMePh2 in solution in refluxing toluene for three weeks, it
afforded [5-(p-cym)-8-(PMePh2)-arachno-5,4,6-RuS2B6H6], 4, in
25% yield.
is approaching the bonding limit. The ruthenium–phosphorus
1
5
distances in [Ru(g -1,2-S2B6H9)(PPh3)2(g -Cp)] 2, Ru1–P1 and
Ru1–P2, are significantly different from each other at 2.3574(9)
˚
and 2.3320(9) A, respectively. Similar differential distances have
been reported in compounds with non-cluster ligands, e.g., in
Crystal and molecular structures
[Ru(C3H6S)(PPh3)2(Cp)] [CF3SO3] at 2.3616(18) and 2.3576(19)
10
(a) [Ru(g1-1,2-S2B6H9)(PPh3)2(g5-Cp)] 2. The molecular
structure of compound 2 (Fig. 1), as determined by single-
crystal X-ray diffraction analysis, shows that there is a single
A, in [Ru(PhCH2CH2SH)(PPh3)2(Cp)][BF4] at 2.349(2) and
˚
2.344(2) A,11 and in [Ru(C6H11SH)(PPh3)2(Cp)][BF4] at 2.345(2)
˚
12
˚
and 2.360(2) A.
1 9 8 0
D a l t o n T r a n s . , 2 0 0 5 , 1 9 7 9 – 1 9 8 4

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(b) [5-(g5-Cp)-5-(PPh3)-5,4,6-RuS2B6H9] 1. The results of a
single-crystal X-ray diffraction analysis of 1 show that the ruthe-
nium atom is bonded to both sulfur atoms of the S2B6H9 cage but
not to any boron atom (Fig. 2). The molecule may be regarded as
Important interatomic distances and angles for 1 are given
in the legend to Fig. 2. The Ru5–S4 and Ru5–S6 distances
˚
in compound 1 are 2.3977(14) and 2.3945(15) A, respectively.
These distances are the same within 3 × su as those of 2.409(4)
6
6
˚
electronically equivalent to previously reported [5-(g -C6Me6)-
and 2.402(4) A in [5-(g -C6Me6)-5-Cl-hypho-5,4,6-RuS2B6H9] 10,
5-Cl-hypho-5,4,6-RuS2B6H9] 10,8 i.e. as based on a hypho nine-
vertex {RuS2B6} cluster system. The hypho nine-vertex geometry
formally derives from icosahedral closo twelve-vertex by removal
of three vertices5 as shown in diagram II. Alternatively, the
hypho eight-vertex [1,2-S2B6H9]− dithiaborane cage anion may
be viewed as a chelating S,Sꢀ-ligand where each sulfur atom acts
but longer than those in [5-(g -C6Me6)-arachno-5,4,6-RuS2B6H8]
9, where Ru7–S6 is 2.369(2) A and Ru7–S8 is 2.367(2) A.
6
8
˚
˚
The latter, smaller, values may be compared with Ru–S dis-
2
tances in the ruthenium-chelated xanthate compound [Ru(g -
n
5
˚
S2CSPr )(PPh3)(g -Cp)], Ru–S1, 2.374(4) A and Ru–S2, 2.362(2)
14
˚
A. The S–B interatomic distances in 1 range from 1.897(7) to
1.919(7) A. Similar variations were also found in [5-(g -C6Me6)-
5
+
6
˚
as a two-electron donor to the {Ru(PPh3)(g -Cp)} unit in a
2
5
similar fashion to the [S2CX]− ligand in [Ru(g -S2CX)(PPh3)(g -
5-Cl-hypho-5,4,6-RuS2B6H9] 10, i.e. from 1.89(3) to 1.943(19)
Cp)], where X = NR2, OR,13 or SPrn.14
A. A large range of B–B distances is observed in compound
8
˚
1–4
˚
1, from 1.732(10) to 1.969(10) A, typical of borane species,
˚
although the highest value, of 1.969(10) A, is somewhat long,
and nears the arbitrary 2.0 A distance often taken as the limit of
˚
a significant covalent interboron bonding interaction. A similar
situation exists in compound 2 above. These long interboron
distances involve the boron atoms which are also bonded to
sulfur atoms.
(c) [5-(p-cym)-8-(PMePh2)-5,4,6-arachno-RuS2B6H6], 4. The
structural analysis of crystals of compound 4 revealed that it
has a typical nine-vertex arachno structure with the ruthenium
atom occupying a position adjacent to both sulfur atoms, Fig. 3.
Formally, its arachno nine-vertex geometry derives from a closo
eleven-vertex structure by the removal of two adjacent vertices5
as shown in diagram I. Important interatomic distances and
angles are given in the legend to Fig. 3.
Some asymmetry is observed among the Ru–S distances in
˚
compound 4, with Ru5–S4 at 2.3649(12) A and Ru5–S6 at
˚
2.3786(12) A, but these distances are similar to those of 2.369(2)
6
˚
and 2.367(2) A in [5-(g -C6Me6)-arachno-5,4,6-RuS2B6H8] 9, the
Fig. 2 ORTEP plot of [5-(Cp)-5-(PPh3)-hypho-5,4,6-RuS2B6H9] 1,
only other arachno nine-vertex {RuS2B6} cluster compound that
showing the numbering scheme; Ellipsoids are shown at the 30%
has been structurally defined.8 The two Ru–B distances in 4, of
◦
˚
probability level. Selected interatomic distances (A) and angles ( ):
Ru5–P1 2.3016(13), S4–B1 1.919(7), Ru5–S4 2.3977(14), S4–B9 1.899(6),
Ru5–S6 2.3945(15), S6–B2 1.908(7), S6–B7 1.897(7), B1–B2 1.795(9),
B1–B3 1.779(9), B1–B9 1.968(10), B2–B3 1.800(9), B2–B7 1.969(10),
B3–B7 1.825(10), B3–B8 1.732(10), B3–B9 1.822(9), B7–B8 1.788(11),
B8–B9 1.782(9); P1–Ru5–S4 91.88(5), P1–Ru5–S6 92.09(5), S4–Ru5–S6
91.46(5), Ru5–S4–B1 108.1(2), Ru5–S4–B9 107.3(2), Ru5–S6–B7
107.5(2), Ru5–S6–B2 109.0(2), B2–B1–S4 115.8(4), B1–B2–S6 114.8(4),
S6–B7–B8 125.5(4), S4–B9–B8 125.7(4), B7–B8–B9 108.3(5). There are
no unusual distances or angles within the PPh3 or Cp ligands and the
Ru to Cp parameters are normal.
˚
˚
2.283(5) A for Ru5–B1 and of 2.294(5) A for Ru5–B2, also com-
˚
pare with the values of 2.235(8) and 2.246(9) A in compound 9.
The B–B distances in 4 range from 1.724(8) to 1.888(7) A. A sim-
ilar variation exists in [5-(g -C6Me6)-5,4,6-arachno-RuS2B6H8]
˚
6
9, where the B–B distances range from 1.735(14) to 1.951(12)
8
˚
A. It is noteworthy that in both 4 and 9 the B–B interactions
that are flanked by a sulfur atom or a ruthenium fragment
are the longest. The S–B interactions bridged by the {Ru(p-
˚
cym)} unit, i.e. S4–B1 at 1.936(5) and S6–B2 at 1.914(5) A,
Fig. 3 ORTEP plot of [5-(p-cym)-8-(PMePh2)-arachno-5,4,6-RuS2B6H6] 4, showing the numbering scheme. Ellipsoids are shown at the 30%
◦
˚
probability level. Selected interatomic distances (A) and angles ( ): Ru5–S4 2.3649(11), Ru5–S6 2.3786(12), Ru5–B1 2.283(5), Ru5–B2 2.294(5),
P1–B8 1.903(5), S4–B1 1.936(5), S4–B9 1.885(5), S6–B2 1.914(5), S6–B7 1.889(6), B1–B2 1.848(7), B1–B3 1.782(7), B1–B9 1.888(7), B2–B3 1.782(7),
B2–B7 1.889(8), B3–B7 1.724(8), B3–B8 1.764(7), B3–B9 1.740(7), B7–B8 1.787(8), B8–B9 1.752(7); S4–Ru5–S6 101.47(4), S4–Ru5–B1 49.20(13),
S6–Ru5–B2 48.32(13), B1–Ru5–B2 47.63(18), Ru5–S4–B9 109.79(16), Ru5–S6–B7 109.61(18), P1–B8–B3 114.8(3), P1–B8–B7 118.0(3), P1–B8–B9
113.4(3), B7–B8–B9 110.3(4). There are no unusual distances or angles within the PPh2Me or p-cym ligands and the Ru to p-cym parameters are
normal.
D a l t o n T r a n s . , 2 0 0 5 , 1 9 7 9 – 1 9 8 4
1 9 8 1

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are longer than those bridged by boron atoms, i.e. S(4)–B(9) at
1.885(5) and S(6)–B(7) at 1.889(6) A. Also noteworthy is that the
NMR spectroscopy
˚
For compounds 1, 2 and 4 the results of multinuclear and
multiple resonance spectroscopy, as recorded for the individual
compounds in the relevant experimental sections below, were en-
tirely consistent with the solid-state structures established from
the single-crystal X-ray diffraction analyses (Figs. 1, 2 and 3, re-
spectively), confirming that the crystals selected in each case were
representative of the bulk samples. Comparison with previously
reported NMR data8 for its {Ru(C6Me6)} analogue similarly
supported the [5-(p-cym)-5,4,6-arachno-RuS2B6H8] constitution
of compound 3. Salient points of comparison or of other
interest are summarized in the following three paragraphs. For
all compounds it may be noted that there was a general absence
of [11B–11B] correlations between pairs of boron atoms flanked by
heteroatoms or by hydrogen bridges. This is a well-recognized
range of S–B distances in compound 4, from 1.884(5) to 1.936(5)
˚
A, was similar to those observed for compound 9, 1.880(10) to
6
˚
1.939(9) A, and for [5-(g -C6Me6)-5-Cl-hypho-5,4,6-RuS2B6H9]
8
˚
10, from 1.89(3) to 1.936(5) A.
An additional noteworthy point is the location of the endo-
terminal hydrogen atom on B(8) in compound 4. This is as found
for many analogues such as the 4-L-arachno-B9H13 series that
have all-boron clusters, in which L is a two-electron donor ligand
in the equivalent position to that of PMePh2 in compound 4.15
In the species [5-(p-cym)-arachno-5,4,6-RuS2B6H8] 3, which does
not have a two-electron ligand on a cluster boron atom, there
is no such endo-terminal hydrogen atom, even though arachno
nine-vertex cluster character also obtains. Instead, there are two
bridging hydrogen atoms to the B(8) position, from the B(7)
and B(9) positions that flank it, approximately disposed as in
the hypho-type species 2 (Fig. 1). This is consistent with the
behaviour in all-boron arachno nine-vertex clusters.15
1
phenomenon, and signifies a smaller coupling J(11B–11B) for
such environments, and is consistent with the longer interboron
distances often observed for these positions, and therefore
weaker direct interboron bonding, and concurs with the struc-
tural discussion section above. These small 1J(11B–11B) couplings
implicit here are generally parallelled by small vicinal couplings
3J(1H–1H) between any hydrogen atoms bound to the two boron
atoms in question, similarly reducing the incidence of observa-
tions of interproton correlations in [1H–1H]-COSY work.
Comments on the description of species 1 either as a coordination
compound or as a hypho RuS2B6 cluster compound
1
5
Whereas compound 2, [Ru(g -hypho-1,2-S2B6H9)(PPh3)2(g -
1
Cp)], is readily described as an g -mode coordination complex
5
between the eight-vertex cluster ligand [hypho-1,2-S2B6H9]−,
For [5-(g -Cp)-5-(PPh3)-5,4,6-RuS2B6H9] 1 the symmetrical
5
mirror-plane structure was readily apparent from the relative
intensities of the cluster 11B and 1H resonance signals, as was its
overall similarity with its previously described Ru-chlorinated
and a ruthenium centre, compound 1, [5-(g -Cp)-5-(PPh3)-5,4,6-
RuS2B6H9], can be described either as a coordination compound
2
of the bidentate g -bonded eight vertex [hypho-1,2-S2B6H9]−
6
ruthenadithiaborane congener [5-(g -C6Me6)-5-Cl-hypho-5,4,6-
ligand and a ruthenium centre, or as a nine-vertex hypho cluster
compound in which the {RuS2B6} unit defines the nine-vertex
core. It is not possible to choose between these descriptions on
the basis of the evidence from the solid state structure analysis
or the NMR spectroscopic results, vide infra. Comparison of the
RuS2B6H9] 10.8 The principal difference from 10 was the 11B(7,9)
resonance at d(11B) +8.4 ppm, which is at significantly lower
field, by over 10 ppm, other differences at less than 5.4 ppm not
1
5
being remarkable. For [Ru(g -1,2-S2B6H9)(PPh3)2(g -Cp)] 2 the
11B and H spectra were somewhat more complex, consistent
1
˚
Ru–S distances in 1, of 2.3978(14) and 2.3941(15) A, with Ru–
with the less symmetrical molecular structure (Fig. 2), but
readily assignable by comparison with the data for the free
[hypho-1,2-S2B6H9]− anionic ligand, for the neutral species [5-
S distances in coordination compounds such as the bidentate
2
5
xanthate derivative [Ru(g -S2CSPrn)(PPh3)(g -Cp)] at 2.374(4)
14
˚
and 2.362(2) A, or monodentate sulfur-ligand species such
5
5
10
˚
(g -Cp)-5-(PPh3)-5,4,6-RuS2B6H9] 1 just mentioned, and for [5-
as [Ru(C3H6S)(PPh3)2(g -Cp)][CF3SO3] at 2.3459(20) A and
6
(g -C6Me6)-Cl-hypho-5,4,6-RuS2B6H9] 10.8 In particular, data
5
11
˚
[Ru(PhCH2CH2SH)(PPh3)2(g -Cp)][BF4] at 2.369(2) A}, and
were very similar to those of the free [hypho-1,2-S2B6H9]− anion,
consistent with a description as a simple coordination complex
of this anion, as discussed in the text above. Thus, the 11B
resonances at ca. +5.0 ppm due to the B(3)B(5) pair are only
slightly upfield, by ca. 2.0 ppm, compared with the resonance for
the free anion,16 and the B(4) and B(8) resonances at d(11B) −26.6
and −54.5 ppm, respectively, in compound 2 are similarly only at
slightly higher field than those of the corresponding resonances
in the free anion: these high similarities adduce to the conclusion
that compound 2 can be best regarded as a metal–ligand complex
as discussed below.
6
in the arachno cluster [(g -C6Me6)-arachno-5,4,6-RuS2B6H8] 9
8
˚
at 2.369(2) and 2.367(2) A, shows the distances in 1 are
somewhat longer. However, the distance in 1 is similar to that
5
12
˚
in [Ru(C6H11SH)(PPh3)2(g -Cp)][BF4] at 2.389(2) A and the
1
5
˚
compound [Ru(g -1,2-S2B6H9)(PPh3)2(g -Cp)] 2 at 2.4021(9) A.
Thus no distinction can be made between coordinate bonds and
cluster bonds on the basis of bond length.
Since compound 1 does not necessarily require the descriptor
“cluster” for the bonding between the ruthenium and S2B6
atoms, it can be described as a coordination complex of
2
ruthenium and the g -[hypho-1,2-S2B6H9]− ligand similar to
2
5
the bidentate xanthate derivative [Ru(g -S2CSPrn)(PPh3)(g -
For [5-(p-cym)-arachno-5,4,6-RuS2B6H8] 3, as with compound
1 above, the mirror-plane symmetry is manifest in the relative
Cp)].14 Likewise compound 10, [5-(g -C6Me6)-5-Cl-hypho-5,4,6-
6
1
intensity patterns for the cluster 11B and H resonances. The
RuS2B6H9], could be equally described as a coordination com-
assignment of the bridging hydrogen resonances to their posi-
tions, as summarized in the experimental section, is noteworthy.
In particular, and in contrast to compound 4 (Fig. 3; see
also structural and NMR and discussions above and below,
respectively), bridging hydrogen atoms were apparent between
B(7) and B(8), and between B(8) and B(9). Overall, the NMR pa-
rameters measured for 3 are in clear parallel to the corresponding
parameters reported for the closely related and previously char-
acterised {Ru(C6Me6)} analogue,8 clearly confirming the [5-(p-
cym)-arachno-5,4,6-RuS2B6H8] constitution and configuration.
The compound [5-(p-cym)-8-(PMePh2)-arachno-5,4,6-RuS2B6H6]
plex rather than as a contiguous {RuS2B6} cluster compound, i.e.
2
6
as [RuCl(g -S,Sꢀ-hypho-1,2-S2B6H9)(g -C6Me6)]. While both “co-
ordination complex” and “cluster” descriptions appear equally
2
5
valid for 1 and 10, a description of [Ru(g -S2CSPrn)(PPh3)(g -
Cp)] as a {RuS2C} arachno cluster would not be regarded as
helpful by most chemists even though it is recognized that
delocalized bonding exists in the xanthate ligand.
However, whereas compound 2 is clearly a coordination
complex, compounds 3 and 4 are definitely clusters. Thus the
sequence of compounds 2 → 1→ 3/4 shows a progressive
increase in the amount of metal-to-cluster bonding as the orbital
availability on the metal centre increases as the number of
phosphine ligands on the {M(Ar)(PR3)n} fragments is reduced
from two to zero. Where does the complex-to-cluster change
occur? In the present work, the answer would appear to be
between the structures represented in compounds 1 and 3/4.
1
4 similarly had 11B and H NMR spectra consistent with the
molecular plane of symmetry (Fig. 3). Even though its gross
arachno nine-vertex {5,4,6-RuS2B6} description is as that for
compound 3 above, there are in this case substantial differences
in cluster-atom shielding. The most notable difference between
1 9 8 2
D a l t o n T r a n s . , 2 0 0 5 , 1 9 7 9 – 1 9 8 4

View Article Online
3 and 4 is the substantial downfield shift of the 11B(3) resonance,
of over 35 ppm, from −49.2 ppm in 3 to −12.4 ppm in 4.
This difference is associated with the contrasting differences
in the disposition of the inner-sphere endo/bridging hydrogen
atoms about the open-face B(7), B(8) and B(9) positions, as
mentioned in the structural discussion above. The phenomenon
is categorised by Herˇma´neks ‘l-H Ruleꢀ,17 and is classically
manifested in the ca. 30 ppm difference in 11B shielding at
the B(2) and B(4) positions when nido-B10H14 and the [arachno-
B10H14]2− anion are compared. In the more directly relevant nine-
vertex arachno system, the phenomenon is exhibited by the
[arachno-B9H14]− anion itself, which exhibits both types of site.15
[5-(Cp)-5-(PPh3)-5,4,6-RuS2B6H9], 1, and [Ru(g1-1,2-S2B6H9)-
(PPh3)2(g5-Cp)] 2. To
a solution of [tmndH][hypho-1,2-
S2B6H9] (0.050 g, 0.138 mmol) in dichloromethane (15 ml) was
5
added [RuCl(PPh3)2(g -Cp)] (0.100 g, 0.138 mmol). The orange
reaction mixture was stirred for 5 days at room temperature.
It was concentrated under reduced pressure and subjected to
preparative t.l.c. (CH2Cl2–hexane) (6 : 4). Two yellow bands
were extracted into dichloromethane. Crystallisation of the
first yellow compound (RF 0.9) from CH2Cl2–hexane (1 : 1)
5
afforded orange crystals of [5-(g -Cp)-5-(PPh3)-5,4,6-RuS2B6H9]
1 (0.005 g, 6.4%). (Found: C, 48.9; H, 5.2. C23H29B6PRuS2
requires C, 48.8; H 5.2%). IR: mmax (KBr) 2568(s)(BH), 2558(s),
1
2539(s), 2521(vs), 2508(s) (BH) cm−1. 11B and H NMR data
(CDCl3, 298 K) ordered as assignment d(11B) [d(1H) of directly
attached proton]: BH(7,9) +8.4 [+3.74], BH(1,2) −22.7 [+1.41],
BH(8) −23.9 [+2.37], BH(3) −50.4 [−0.34]. Additional data are
as follows: d(1H)(phenyl) +7.27 to +7.59, d(1H)(C5H5) +4.15,
d(1H)(l-7,8 and 8,9) −1.55, d(1H)(l-1,2) −1.79; d(31P)(PPh3)
+49.8.
Conclusions
What is seen in the results from the present work is the pro-
gression from coordination complex to cluster as electrons
are removed from the transition-element site. The structural
sequence 2 → 1→ 3/4 illustrates the Wadian principles5 of suc-
cessive effective removal of electrons resulting in the formation
of more closed species, viz,
Crystallisation of the second yellow band (RF 0.5) from
1
toluene–hexane (1 : 1) yielded orange crystals of [Ru(g -1,2-
5
S2B6H9)(PPh3)2(g -Cp)] 2 (0.055 g, 48.2%). (Found: C, 59.8;
H, 5.6. C41H44B6P2RuS2 requires C, 59.4; H 5.6%). IR: mmax
(KBr) 2552(s), 2528(s,sh), 2514(s), 2493(s) (BH) cm−1. 11B and
1H NMR data (CD2Cl2 298 K) ordered as assignment
d(11B)[d(1H) of directly attached proton]: BH(7/9) +5.0 [+3.47]
and [+3.45], BH(1/2) −21.3 [+1.76], BH(1/2) −23.6 [+1.90],
BH(8) −26.6 [+2.24], BH(3) −54.5 [−0.48]. Additional data are
as follows: d(1H)(phenyl) +6.87 to +7.72, d(1H)(C5H5) +4.35,
d(1H)(l-7,8 and 8,9) −1.11 and −1.65, d(1H)(l-1,2) +0.44;
d(31P)(PPh3)(294 K) +41.9 (doublet) and +37.7 (doublet),
2J(31P–31P) 37.5 Hz.
Successive removal of both two-electron phosphine ligands
can be regarded as the successive removal of two electron pairs
from the cluster count, so the core nine-atom assembly goes from
coordination complex or ‘pre-hyphoꢀ cluster, 2 to coordination
complex/hypho cluster 1 and thence to an arachno cluster,
examples of which are seen in 3 and 4. Wade’s rules are also
an effective count of orbital availability: successive removal of
the two phosphine ligands releases one and then two ruthenium
orbitals for bonding into the cluster, resulting in successively
more condensed species.
Reaction of [Ru(g1-1,2-S2B6H9)(PPh3)2(g5-Cp)] 2 in refluxing
dichloromethane solution
1
5
A sample of [Ru(g -1,2-S2B6H9)(PPh3)2(g -Cp)] 2 (0.05 g,
0.060 mmol) was dissolved in CH2Cl2 (20 ml) and the solution
heated to reflux temperature for 3 weeks. The yellow reaction
mixture was concentrated under reduced pressure and subjected
to preparative t.l.c. (CH2Cl2–hexane) (6 : 4). A yellow band (RF
0.9) was extracted into dichloromethane. This was identified
Experimental
5
spectroscopically (IR and NMR) as [5-(g -Cp)-5-(PPh3)-5,4,6-
General procedures
RuS2B6H9] 1 (0.020 g, 58.5%).
5
The compounds [RuCl(PPh3)2(g -Cp)] and [Ru(p-cym)Cl2]2 were
[5-(p-cym)-arachno-5,4,6-RuS2B6H8]. 3. To a solution of
[tmndH][hypho-1,2-S2B6H9] (0.025 g, 0.069 mmol) was added
[Ru(p-cym)Cl2]2 (0.021 g, 0.034 mmol). The orange mixture
was stirred for 2 h at room temperature whereupon it was
concentrated under reduced pressure and subjected to prepar-
ative t.l.c. (CH2Cl2–hexane) (7 : 3). A single yellow band (RF
0.9) was extracted into CH2Cl2. Crystallisation from CH2Cl2–
hexane afforded orange crystals of [5-(p-cym)-arachno-5,4,6-
RuS2B6H8] 3 (0.024 g, 93.7%). (Found: C, 32.5; H, 5.9.
C10H22B6RuS2 requires C, 32.3; H, 6.0%). IR:mmax (KBr) 2574(m),
2556(m), 2543(s), 2527(vs), 2507(s), 2494(m))(BH) cm−1 11B and
1H NMR data (CDCl3 300 K) ordered as assignment d(11B)
[d(1H) of directly attached proton] {observed splitting from
1J11B–1H)/Hz}: BH(7,9) +3.7 [+3.65]{150}, BH(1,2) −13.9
[+2.33]{165}, BH(8) −33.8 [+1.82]{ca. 145}, BH(3) −49.2
[+0.40]{145}. Additional data are as follows: d(1H)[(CH3)2-
CHC6H4CH3] +5.65 (2H, doublet) and +5.48 [2H, dou-
blet, 3J(1H–1H) 5.4 Hz], d(1H)[(CH3)2CHC6H4CH3] +2.75.
(1H, septet), d(1H)[(CH3)2CHC6H4CH3] + 2.17 (3H, sin-
glet), d(1H)[(CH3)2CHC6H4CH3] +1.31 [6H, doublet, 3J(1H–1H)
6.8 Hz], d(1H)[(l-7,8) and (l-8,9)] −1.49.
used as supplied by the Aldrich Chemical Co. The dithiab-
orate salt [tmndH][hypho-1,2-S2B6H9], (tmnd = N,N,Nꢀ,Nꢀ-
tetramethylnaphthalene-1,8-diamine), was a generous gift from
ˇ
Prof. B. St´ıbr and coworkers and is gratefully acknowledged. Pu-
rification of solvents and products, and manipulative procedures
for recording spectra used in this work have been described in
previous Parts of this series.1 Infrared spectra were recorded as
KBr discs on a Perkin-Elmer Paragon 1000 FT-IR spectrometer.
Carbon and hydrogen elemental analyses were performed at
University College Cork on a Perkin-Elmer 240C microanalyser.
NMR spectra were recorded on Bruker ARX 250 and DRX
1
500 spectrometers, using 11B, 11B-{ H(broadband)}, 1H, 1H-
11
1
11
1
{ B(broadband)}, H-{ B(selective)}, [11B–11B]-COSY]-{ H},
[1H–1H]-COSY-{ B} and 31P{ H} techniques in combined
analytical procedures as described in previous Parts of this
series.1 Chemical shifts d are expressed in parts per million
(ppm) to high frequency (low field) relative to N 100 MHz
11
1
for H (nominally internal SiMe4), N 32.083972 MHz for 11B
1
(nominally internal [BF3(OEt2)]) and N 40.480 730 MHz for 31
P
(nominally 85% H3PO4), using deuterated solvent 2D resonances
as internal secondary standards. Splittings arising from cou-
plings 1J(11B–1H) are taken from resolution-enhanced (line-
narrowed) 11B spectra with digital resolution 4 Hz. For broad-
ened 11B resonances, the splitting observed will be smaller than
the coupling constant J(11B–1H) from which the splitting arises.
Reaction of [5-(p-cym)-arachno-5,4,6-RuS2B6H8] with PMePh2
To a solution of [5-(p-cym)-arachno-5,4,6-RuS2B6H8] 3 (0.05 g,
0.134 mmol) in toluene (10 ml) was added PMePh2 (0.25 ml,
D a l t o n T r a n s . , 2 0 0 5 , 1 9 7 9 – 1 9 8 4
1 9 8 3

View Article Online
˚
1.34 mmol). The mixture was stirred at reflux temperature for
16 h whereupon it was concentrated under reduced pressure and
subjected to preparative t.l.c. with CH2Cl2–hexane solvent (6 : 4).
An orange band (RF 0.5) was extracted into dichloromethane.
Crystallisation from toluene–heptane (1 : 1) afforded orange
crystals of [5-(p-cym)-8-(Ph2MeP)-arachno-5,4,6-RuS2B6H6] 4
(0.019 g, 24.8%). (Found C, 48.6; H, 5.8. C23H33B6PRuS2
requires C, 48.4; H, 5.8%). IR: mmax (KBr) 2521(vs), 2491(s),
2458(vs)(BH) cm−1. 11B and 1H NMR data (CDCl3 297 K)
ordered as assignment d(11B) [d(1H) of directly attached pro-
1.24(4) A] and the terminal B–H atoms were refined with B–H
˚
1.10(4) A restraints. All other H atoms were allowed for as riding
with the normal SHELXL-97 constraints
X-Ray analysis of [5-(p-cym)-8-(Ph2MeP))-arachno-5,4,6-
RuS2B6H6] 4. Crystal Data. C23H33B6PRuS2, M = 570.51,
monoclinic, P21/c, a = 11.0430(10), b = 10.1578(7), c =
◦
−3
˚
˚
24.528(2) A, b = 94.168(7) , Z = 4, Dx = 1.381 g cm , U =
3
˚
2744.1(4) A , F(000) = 1168, k(Mo-Ka) = 0.7107 A, l =
0.793 mm−1, T = 294(1) K, R = 0.0432 for 4115 observed
reflections, Rw = 0.1036 for all 6264 unique reflections. Boron
cage H atoms were located from a difference synthesis and their
1
ton] { J11B–1H)/Hz}: BH(7,9) +10.8 [+3.96]{ca.145}, BH(3)
−12.4 [+1.52]{ca. 141}, BH(1,2) -20.8 [+1.73]{ca. 158},
BH(8) −47.9 [−1.28]{ca. 134}. Additional data are as fol-
lows: d(1H)[phenyl(PPh2Me)] +7.42 to +7.64, aromatic 1H
resonances from cym C6H4 at +5.53 [doublet, 3J(1H–1H)
5.8 Hz] and +5.37 [doublet], d(1H)[Me2CH] +2.79 [septet,
3J(1H–1H) 7.0 Hz], methyl resonances at d(1H) +2.14 [singlet],
+1.92 [doublet, 2J(31P–1H) 11.0 Hz] and +1.30 ppm. [doublet];
d(31P)(PPh2Me)(300 K) +12.6, 1J(11B–31P) ca. 115 Hz.
˚
coordinates normalised to give a B–H distances of 1.10 A; these
H atom contributions were then included but not refined in the
final calculations. All other H atoms were allowed for as riding
with the normal SHELXL-97 constraints.
Acknowledgements
ˇ
We thank Prof. B. St´ıbr (Institute of Inorganic Chemistry of
the Academy of Sciences of the Czech Republic) for his friendly
interest and cooperation. G. F. thanks the NSERC (Canada)
and J. D. K. thanks the UK EPSRC for instrument support.
D. McC. thanks FORBAIRT, Ireland, for a studentship.
Crystal structure analyses
Data for compounds 1, 2 and 4 were collected with an Enraf-
Nonius CAD4 diffractometer. The data were corrected for
absorption using psi-scans or ABSORB;18 structure solution
used NRCVAX18 and refinement was with SHELXL-97.19
PLATON20 was used for the molecular graphics. Full details in
CIF format for the three structures are available from the CCDC
(reference numbers 264502, 264503 and 264504 for compounds
1, 2 and 4, respectively). Accurate cell dimensions and crystal
orientation were determined by least squares procedure from 25
reflections obtained using graphite-monochromatised Mo-Ka
References
1 For Part 16: see J. Bould, J. D. Kennedy, G. Ferguson, F. A. Deeney,
G. M. O’Riordan and T. R. Spalding, J. Chem. Soc., Dalton Trans.,
2003, 4557.
ˇ
2 R. Mac´ıas, J. Holub, J. D. Kennedy, B. St´ıbr and M. Thornton-Pett,
J. Chem. Soc., Chem. Commun., 1994, 2265.
3 M. Murphy, T. R. Spalding, J. D. Kennedy, M. Thornton-Pett, K. M.
Abdul Malik, M. B. Hursthouse and J. Holub, J. Chem. Soc., Chem.
Commun., 1994, 2403.
˚
radiation (k = 0.71073 A) following a procedure described in
detail elsewhere.1
4 J. D. Kennedy, Prog. Inorg. Chem., 1984, 32, 519; J. D. Kennedy,
Prog. Inorg. Chem., 1986, 34, 211.
X-Ray analysis of [5-(g5-Cp)-5-(PPh3)-hypho-5,4,6-RuS2B6H9]
1. Crystal Data. C23H29B6PRuS2, M = 566.50, monoclinic, Pc,
5 K. Wade, Adv. Inorg. Chem. Radiochem., 1976, 18, 1.
6 S. G. Davies, J. P. McNally and A. J. Smallridge, Adv. Organomet.
Chem., 1990, 1; A. Shaver, P.-Y. Plouffe, P. Bird and E. Livingstone,
Inorg. Chem., 1990, 29, 1826; H. Park, D. Minick, M. Draganjac,
A. W. Cordes, R. L. Hallford and G. Eggleton, Inorg. Chim. Acta.,
1993, 204, 195; W. Shaozu, L. Zenglu, Z. Yulan and L. Pingren,
Gazz. Chim. Ital., 1993, 123, 647; R. Prasad and U. C. Agarwala,
Transition Met. Chem., 1994, 19, 390; R. Prasad and U. C. Agarwala,
Polyhedron, 1992, 11, 1117; R. Prasad, J. Organomet. Chem., 1995,
486, 31.
◦
˚
a = 9.482(2), b = 14.275(5), c = 9.753(2) A, b = 93.49(2) ,
−3
3
˚
Z = 2, Dc = 1.428 g cm , U = 1317.7(6) A , F(000) = 576,
−1
˚
k(Mo-Ka) = 0.71073 A, l = 0.825 mm , T = 294 (1) K, R =
0.0348 for 2707 observed reflections, Rw = 0.0863 for all 3036
unique reflections. Space group Pc or P2/c from the systematic
absences; Pc assumed and confirmed by the analysis.
Flack value −0.02(4). The bridging H atoms in the boron cage
˚
were refined with restraints [B–H 1.24(4) A] and the terminal B–
˚
H atoms were refined with B–H 1.10(4) A restraints. All other H
7 M. Bown, X. L. R. Fontaine, N. N. Greenwood and J. D. Kennedy,
Z. Anorg. Allg. Chem., 1991, 602, 17.
8 K. Mazighi, P. J. Carroll and L. G. Sneddon, Inorg. Chem., 1992, 31,
3197.
atoms were allowed for as riding with the normal SHELXL-97
constraints.
X-Ray analysis of [Ru(g1-1,2-S2B6H9)(PPh3)2(g5-Cp)] 2.
Crystal Data. C41H44B6P2RuS2, M = 828.75, monoclinic, P21/c,
9 T. Yamamoto and L. J. Todd, J. Organomet. Chem., 1974, 67, 75.
10 H. Park, M. Draganjac, S. R. Scott, A. W. Cordes and G. Eggleton,
Inorg. Chim. Acta., 1994, 221, 157.
11 H. Park, D. Minick, M. Draganjac, A. W. Cordes, R. L. Hallford
and G. Eggleton, Inorg. Chim. Acta., 1993, 204, 195.
12 Y. Jiang, M. Draganjac and A. W. Cordes, J. Chem. Crystallogr.,
1995, 25, 653.
13 S. G. Davies, J. P. McNally and A. J. Smallridge, Adv. Organomet.
Chem., 1990, 1.
14 A. Shaver, P.-Y. Plouffe, P. Bird and E. Livingstone, Inorg. Chem.,
1990, 29, 1826.
15 J. Bould, R. Greatrex, J. D. Kennedy, D. L. Ormsby, M. G. S.
Londesborough, K. L. F. Callaghan, M. Thornton-Pett, T. R.
Spalding, S. J. Teat, W. Clegg, H. Fang, N. P. Rath and L. Barton,
J. Am. Chem. Soc., 2002, 124, 7431.
16 S. O. Kang and L. G. Sneddon, J. Am. Chem. Soc., 1989, 111, 3281.
17 S. Herˇma´nek, Chem. Rev., 1992, 92, 325.
18 E. J. Gabe, Y. Le Page, J.-P. Charland, F. L. Lee and P. S. White,
J. Appl. Crystallogr., 1989, 22, 384.
19 G. M. Sheldrick, SHELXL-97, Program for the Refinement of Crystal
Structures, University of Go¨ttingen, 1997.
˚
a = 11.0113(9), b = 18.7264(16), c = 19.840(2) A, b =
◦
−3
3
˚
95.546(10) , Z = 4, Dc = 1.352 g cm , U = 4072.0(7) A ,
−1
˚
F(000) = 1704, k(Mo-Ka) = 0.71073 A, l = 0.596 mm ,
T = 294(1) K, R = 0.0418, for 5438 observed reflections.
Rw = 0.0974 for all 8839 unique reflections. It became obvious
during the structure determination that there was some disorder
−3
˚
in the structure. Two small peaks (approximately 1 e A )
corresponding with other orientations for S atom S(2) were
visible and labelled as S(2A) and S(2B). Coordinates for these
two sites were determined from difference maps and included
2
˚
(with a Uiso value of 0.05 A ) but not refined in subsequent
calculations. Occupancy factor refinement using the SUMP
control in SHELXL97 led to occupancy values of 0.906(3),
0.051(2) and 0.043(2) for S(2), S(2A) and S(2B), respectively.
It was not possible to locate any other atoms corresponding
with the disordered low-occupancy S(2A) and S(2B) atoms and
all other atoms were refined with unit-occupancy. The bridging
H atoms in the boron cage were refined with restraints [B–H
20 A. L. Spek, PLATON Molecular Geometry and Graphics Program,
University of Utrecht, 1998.
1 9 8 4
D a l t o n T r a n s . , 2 0 0 5 , 1 9 7 9 – 1 9 8 4