Degradation and modification of metallaboranes. Part 4: Synthesis and characterization of a series of hybrid bimetallaborane clusters of the type [2,2,2-(PPh3)2(CO)-nido-2-OsB4H 7-3-(BH2PPh2)CxHyPPh 2RuCl2(p-cym)]

Article abstract of DOI:10.1016/j.ica.2004.10.015

Reactions between a series bidentate phosphines, with the general formula PPh₂(CH₂)_nPPh₂, and the air stable hexaborane(10) analogue [2,2,2-(PPh₃)₂(CO)-nido-2-OsB ₅H₉] (1), afford species of the type [{(PPh ₃)₂(CO)OsB₄H₇}-3-{BH ₂PPh₂(CH₂)_n(PPh₂)}] (2) which contain a pendent PPh₂ group. In solution 2 can undergo an intramolecular substitution reaction to form the species [{(PPh ₃)(CO)OsB₄H₇}-η²-3,2-{BH ₂PPh₂(CH₂)_n(PPh₂)}] (4). In spite of this, chemistry at the pendent PPh₂ group may be studied and herein are reported the results of reactions of 2 with the organometallic reagent [(p-cym)RuX₂]₂ (X = Cl, I) to afford hybrid bimetallaborane clusters of the type [2,2,2-(PPh₃) ₂(CO)-nido-2-OsB₄H₇-3-(BH₂PPh ₂)C_xH_yPPh₂RuCl₂(p-cym)] (5) The species obtained include [2,2,2-(PPh₃)₂(CO)-nido- 2-OsB₄H₇·3-(BH₂·dppe·Ru(p- cym)Cl₂)] (5a), [2,2,2-(PPh₃)₂(CO)-nido-2- OsB₄H₇·3-(BH₂·dppp·Ru(p- cym)Cl₂)] (5b), [2,2,2-(PPh₃)₂(CO)-2-nido- OsB₄H₇·3-(BH₂·dpph·Ru(p- cym)Cl₂)] (5c), [2,2,2-(PPh₃)₂(CO)-nido-2- OsB₄H₇-3-(BH₂·dppx·Ru(p-cym) Cl₂)] (5d) and [2,2,2-(PPh₃)₂(CO)-nido-2- OsB₄H₇-3-(BH₂·dppe·Ru(p- cym)I₂)] (6). Species 5d was also prepared from the reaction between 1 and the known compound·[dppx·Ru(p-cym)Cl₂. Species 5a-5d and 6 were characterized by elemental analysis, high resolution mass spectrometry and NMR spectrometry; the latter affording some novel features for this series of compounds. Structure determination by X-ray diffraction was not successful but a structure of the analogue [BH₃·(PPh ₂)(CH₂)₆(PPh₂)·Ru(p-cym) Cl₂] (7) is reported.

Full text of DOI:10.1016/j.ica.2004.10.015

Inorganica Chimica Acta 358 (2005) 1545–1556
www.elsevier.com/locate/ica
Degradation and modification of metallaboranes. Part 4:
Synthesis and characterization of a series of hybrid
bimetallaborane clusters of the type
[2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2PPh2)
CxHyPPh2RuCl2(p-cym)]
*
Paul McQuade, Rudolph E.K. Winter, Nigam P. Rath, Lawrence Barton
Department of Chemistry, Biochemistry and the Center for Molecular Electronics, University of Missouri – St. Louis, St. Louis, MO 63121, USA
Received 6 August 2004; accepted 4 October 2004
Available online 28 October 2004
This paper is dedicated to a nice man, Professor F. Gordon A. Stone in honor of his 80th birthday and a career which defined
organometallic chemistry
Abstract
Reactions between a series bidentate phosphines, with the general formula PPh2(CH2)nPPh2, and the air stable hexaborane(10)
analogue [2,2,2-(PPh3)2(CO)-nido-2-OsB5H9] (1), afford species of the type [{(PPh3)2(CO)OsB4H7}-3-{BH2PPh2(CH2)n(PPh2)}] (2)
which contain a pendent PPh2 group. In solution 2 can undergo an intramolecular substitution reaction to form the species
[{(PPh3)(CO)OsB4H7}-g2-3,2-{BH2PPh2(CH2)n(PPh2)}] (4). In spite of this, chemistry at the pendent PPh2 group may be studied
and herein are reported the results of reactions of 2 with the organometallic reagent [(p-cym)RuX2]2 (X = Cl, I) to afford hybrid
bimetallaborane clusters of the type [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2PPh2)CxHyPPh2RuCl2(p-cym)] (5) The species
obtained include [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7 Æ3-(BH2 ÆdppeÆRu(p-cym)Cl2)] (5a), [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7 Æ3-
(BH2 ÆdpppÆRu(p-cym)Cl2)] (5b), [2,2,2-(PPh3)2(CO)-2-nido-OsB4H7 Æ3-(BH2 ÆdpphÆRu(p-cym)Cl2)] (5c), [2,2,2-(PPh3)2(CO)-nido-
2-OsB4H7-3-(BH2 ÆdppxÆRu(p-cym)Cl2)] (5d) and [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 ÆdppeÆRu(p- cym)I2)] (6). Species 5d
was also prepared from the reaction between 1 and the known compoundÆ[dppxÆRu(p-cym)Cl2. Species 5a–5d and 6 were charac-
terized by elemental analysis, high resolution mass spectrometry and NMR spectrometry; the latter affording some novel features for
this series of compounds. Structure determination by X-ray diffraction was not successful but a structure of the analogue
[BH3 Æ(PPh2)(CH2)6(PPh2)ÆRu(p-cym)Cl2] (7) is reported.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Boron hydrides; Metallaboranes; Ruthenium; Phosphines; NMR spectroscopy
1. Introduction
aboranes and bidentate bases have not received much
attention, although reactions with simple bases have at-
tracted increased interest in recent years [2]. These reac-
tion with base might be expected to lead to adducts with
more open structures [3], however they actually tend to
proceed either by degradation of the cluster framework
or by initial rearrangement of the cluster followed by
degradation. An example of this is given in Scheme 1,
We recently described reactions of bidentate bases
with the metallahexaborane [2,2,2-(PPh3)2(CO)-nido-
OsB5H9 (1) [1]. Such reactions between small metall-
*
Corresponding author. Tel.: +3145265334; fax: +3145165342.
E-mail address: lbarton@umsl.edu (L. Barton).
0020-1693/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2004.10.015

1546
P. McQuade et al. / Inorganica Chimica Acta 358 (2005) 1545–1556
which shows the reactions of bidentate phosphines with
1 and subsequent rearrangement of the product [1a]. In
this reaction one end of the ligand attaches to one of the
basal boron atoms in the cage and, after rearrangement,
the phosphine moiety remains attached to an exopolyhe-
dral BH2 group bonded to a basal boron atom in an
osmapentaborane cage. The other end of the phosphine
ligand remains uncoordinated and is therefore amenable
to further chemistry. This process, which has been
shown to be reversible, forms species of the type
[2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 ÆPPh2CxHyP-
Ph2)] (2) from 1. Further chemistry may occur involving
loss of phosphine–borane to afford the lower homologue
species [2,2,2-(PPh3)2(CO)-nido-2-OsB4H8] (3) or intra-
molecular substitution to form products of type 4, as
shown in Scheme 1. The latter species [{(PPh3)(CO)
OsB4H7}-g2-3,2-{BH2PPh2(CH2)n(PPh2)}] (4) is formed
by replacement of a PPh3 group on Os by the pendant
PPh2 group on the cage and its formation may be pre-
cluded by the use of bidentate phosphines with less flex-
ible backbones [1c] However, chemistry may be
conducted at the pendent PPh2 group, as we demon-
strated previously [1a], and this paper describes the for-
mation of some hybrid systems, one of which is
illustrated in Fig. 1, either by direct reaction with species
of type 2 or by reaction of mono-functionalized biden-
tate phosphines with 1.
Fig. 1. Proposed structure for [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7 Æ3-
(BH2 ÆdppeÆRu(p-cym)Cl2)] (5a) showing the numbering system.
nonvolatile air sensitive materials [4]. Solvents used were
reagent grade and were dried before use. Products were
isolated by radial chromatography (Harrison Research,
Palo Alto, CA) under a dry N2 atmosphere using a 25
cm diameter circular plate coated with 0.1 cm of silica
gel (EM Science), made from aqueous slurries followed
by drying at 70 ꢁC. 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 at
202.5 MHz for phosphorus-31 and on a Varian Unity
Plus 300 spectrometer operating at 96.2 MHz for 11B,
299.9 MHz for 1H and 121.4 MHz for 31P nuclei. Chem-
ical shifts are reported in ppm for CDCl3 solutions, un-
less otherwise stated, to low field (high frequency) of
1
Et2OÆBF3 for 11B, of SiMe4 for H and of 85% H3PO4
for 31P. Mass spectra were measured on a JEOL MSta-
tion JMS700 and elemental analyses were carried out by
Atlantic Microlabs Inc., Norcross, GA.
2. Experimental
2.2. Starting materials and reagents
2.1. General procedures
B5H9 was obtained from laboratory stock, and
distilled on a high vacuum line before use. [2,2,2-
Volatile materials were manipulated using a standard
high vacuum line, and dry box techniques were used for
Scheme 1.

P. McQuade et al. / Inorganica Chimica Acta 358 (2005) 1545–1556
1547
(PPh3)2(CO)-nido-2-OsB5H9] (1) was prepared accord-
ing to the literature method [5]. 1,4-Dibromo benzene
(Eastman Organic) was used as received and
a,a0dibromo-p-xylene (Eastman) was sublimed before
use. RuCl3.XH2O (Alfa) and R(ꢀ)-a-Phellandren
C10H16, (Fluka) were used as received. The phosphines
[(PPh2)2(CH2)3] (dppp), obtained from Strem,
[(PPh2)2(CH2)3] (dppe) and [(PPh2)2(CH2)6] (dpph),
both obtained from Aldrich, were used as received.
[PPh2CH2C6H4CH2PPh2] (dppx) [6] was prepared
[(PPh3)2(CO)OsB5H9]) of a red solid which was charac-
terized as [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2Ædp-
peÆRu(p-cym)Cl2)] (5a). Attempts to grow crystals of
5a suitable for X-ray diffraction were unsuccessful; gen-
erally these attempts produced only amorphous red
spheres. The methods employed included slow diffusion
of C6H14 into a C6H6/CH2Cl2 solution containing 5a at
5 ꢁC, slow diffusion of Et2O into a CDCl3 solution
containing 5a at ꢀ20 ꢁC. In addition to these methods
slow evaporation of a CH2Cl2/C6H14 solution of 5a at
ꢀ20 ꢁC was also attempted. Crystallization experi-
ments had to be carried out at lowered temperature
due to the slow degradation of 5a in solution at room
temperature, and we ascribed this slow degradation as
the reason for our inability to obtain crystal structures
according
to
literature
methods
and
PPh2CH2C6H4CH2PPh2 ÆRu(p-cym)Cl2
{dppxÆRu(p-
cym)Cl2} as described previously [7] from dppx and
[Ru(p-cym)Cl2]2. The latter was prepared from
RuCl3.XH2O and R(ꢀ)-a-Phellandren [8] and [Ru(p-
cym)I2]2 was prepared by adding NaI to a saturated
1
of the hybrid clusters. H NMR (CDCl3): p-cymene, (d
aqueous
solution
of
[Ru(p-cym)Cl2]2
(2a)]
[9].
and
in ppm) 0.96 (d, J = 7.04 Hz, 3H, CHMe2), 0.93 (d,
J = 7.02 Hz, 3H, CHMe2), 1.80 (s, 3H, Me), 2.52 (sept,
J = 6.95 Hz, 1H, CHMe2), 4.99 (d, J = 5.93 Hz, 1H,
MeC6H4CHMe2), 5.14 (d, J = 6.05 Hz, 1H,
MeC6H4CHMe2), 5.19 (overlapping pair of d, 2H,
MeC6H4CHMe2); PPh2CH2CH2PPh2, (d in ppm) 2.85
(m, 2H, CH2PPh2 ÆRu(p-cym)Cl2), 2.34 (m, 2H,
BH2 ÆPPh2CH2), 6.96–7.81 (m, 50H, Ph, this also in-
cludes Phenyl protons on PPh3 groups which are coor-
dinated to Os center). The remaining 1H data along
with 31P and 11B can be found in Table 1 [10]. Elemen-
tal Anal.: 5a for C73H77B5P4Cl2O1Os1Ru1, Calc. C,
[{(PPh3)2(CO)OsB4H7}-3-(BH2 Ædppe)]
[{(PPh3)2(CO)OsB4H7}-3-(BH2 Ædppp)] (2b)] [1a], and
[{(PPh3)2(CO)OsB4H7}-3-(BH2 Ædppx)] (2d) [1c] were
prepared as described previously.
2.3. Preparation of [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7- 3-
(BH2ÆdppeÆRu(p-cym)Cl2)] (5a), [2,2,2-(PPh3)2(CO)-
nido-2-OsB4H7 Æ3-(BH2 Ædppp-Ru(p-cym)Cl2)] (5b) and
[2,2,2-(PPh3)2(CO)-2-nido-OsB4H7-3-(BH2 ÆdpphÆRu
(p-cym)Cl2)] (5c)
The procedures and results for 5a, 5b and 5c were
very similar so details are only given for 5a. A one
necked 50 mL round bottom flask containing a stir
bar was charged with 52 mg (0.065 mmol) of
(PPh3)2(CO)OsB5H9 and 80 mg (0.20 mmol) of dppe.
Freshly distilled CH2Cl2 (20 mL), was added and the
solution stirred for 12 h. at room temperature. 150
mg (0.25 mmol) of [Ru(p-cym)Cl2]2 was then added
and the solution stirred for a further 10 min. After con-
centrating the solution to 1 mL, it was applied to the
radial chromatograph using CH2Cl2 as the mobile
phase. A single fraction was obtained which gave a yel-
low solution containing (PPh3)2(CO)OsB4H8 (3) and
58.05; H, 5.14. Found: C, 57.68; H, 5.21%. LRMS:
12
FAB (3-NBA and CsI). Calc. for
C
1H7711B410B1
73
31P235Cl216O1192Os1102Ru1133Cs1 [M + Cs]+ 1644.25,
obs. 1644 [11]. The mass envelope for the observed
spectrum for 5a matches that calculated from known
isotopic abundances of the constituent elements and
is given as supplementary material.
37 mg (43% yield based on [(PPh3)2(CO)OsB5H9] of the
red solid [(PPh3)2(CO)OsB4H7 Æ3-(BH2 ÆdpppÆRu(p-
cym)Cl2)] (5b) was obtained in a similar process using 45
mg (0.56 mmol) 1, 90 mg (0.22 mmol) dppp and 160 mg
(0.26 mmol) [Ru(p-cym)Cl2)]2. Again extensive attempts
to grow crystals suitable for X-ray analysis were unsuc-
1
[2,2-(PPh3)(CO)-nido-2-OsB4H7-3,2-(BH2 Ædppe)]
(4).
cessful. H NMR (CDCl3): p-cymene, (d in ppm) 0.76
PPh3 was also present in this fraction, and is formed
in the conversion of [2,2,2-(PPh3)2(CO)-nido-2-
OsB4H7-3-(BH2 Ædppe)] 2a to [2,2-(PPh3)(CO)-nido-2-
(d, J = 6.87 Hz, 3H, CHMe2), 0.75 (d, J = 6.99 Hz, 3H,
CHMe2), 1.82 (s, 3H, Me), 2.50 (m, 1H, CHMe2), 5.04
(d, J = 6.01 Hz, 1H, MeC6H4CHMe2), 5.02 (d, J = 5.96
Hz, 1H, MeC6H4CHMe2), 5.21 (d, J = 5.68 Hz, 2H,
MeC6H4CHMe2); PPh2CH2CH2CH2PPh2, (d in ppm)
2.66 (m, 1H, CH2PPh2 ÆRu(p-cym)Cl2), 2.50 (m, 1H,
CH2PPh2 ÆRu(p-cym)Cl2), 1.34 (m, 1H, CH2CH2CH2),
1.22 (m, 1H, CH2CH2CH2) 2.16 (m, 1H, BH2 ÆPPh2CH2),
2.07 (m, 1H, BH2 ÆPPh2CH2), 6.92–7.79 (m, 50H, Ph). The
remaining NMR data are listed in Table 1. Elemental
Anal.: 5b for C74H79B5P4Cl2O1Os1Ru1, Calc. C, 58.30;
1
OsB4H7-3,2-(BH2 Ædppe)] 4a, illustrated in Scheme 1.
A trace amount of [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-
3-(BH2 ÆPPh3)] was also observed produced by subse-
quent reaction of PPh3 with (PPh3)2(CO)OsB5H9
[1a,2a]. CH3CN was then slowly added to the eluent
until a red band was detected. The red solution ob-
tained from this band was reduced to dryness on a ro-
tary evaporator giving 32 mg (33% yield based on
H, 5.22. Found: C, 56.43; H, 5.78%. LRMS: FAB (3-
1H7911B410B131P235Cl2
12
NBA and CsI). Calc. for
C
74
16O1192Os1102Ru1133Cs1 [M + Cs]+ 1658.27, obs. 1658.
1
Identified from NMR spectra. See reference [10].

Table 1
11B, 1H and 31P NMR (d in ppm) data for [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 ÆdppeÆRu(p-cym)Cl2)] (5a), [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 ÆdpppÆRu(p-cym)Cl2)] (5b), [2,2,2-
(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 ÆdpphÆRu(p-cym)Cl2)] (5c), [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 ÆdppxÆRu(p-cym)Cl2)] (5d) and [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 ÆdppeÆRu(p-
cym)I2)] (6)
Species
[Compound 5a]a
[Compound 5b]a
[Compound 5c]a
[Compound 5d]a
[Compound 6]a
Mode/atom
P(2)b
31P{1H}
+13.85m
31P{1H}
31P{1H}
31P{1H}
31P{1H}
+13.91m
+13.58t J = 9.84 Hz
+8.66d J = 9.86 Hz
+18.48br
+13.93quint J = 9.70 Hz
+ 9.10d J = 8.56 Hz
+18.81br
+13.88t J = 10.59 Hz
+9.15d J = 9.86 Hz
+22.67br
P(1)b
P(3)
+9.86d J = 8.36 Hz
+22.28brc
+22.28brc
+9.50d J = 9.41 Hz
+23.45d J = 27.25 Hz
+18.00d J = 31.38 Hz
P(4)
+23.98d J = 1.90 Hz
+24.05s
+29.06d J = 4.88 Hz
Mode/atom
11B
1H{11B}
11B
1H{11B}
11B
1H{11B}
11B
1H{11B}
11B
1H{11B}
4
+8.95
+8.95
+5.27
d
+9.18
9.18
+5.33
d
+8.53
8.53
+5.33
d
+8.14
+8.14
+5.30
d
+8.27
+8.27
15.35
29.29
ꢀ37.76
+5.34
d
3
5
ꢀ16.20
ꢀ29.10
ꢀ38.03
+1.16
+0.087
ꢀ15.95
ꢀ29.54
ꢀ38.65
+1.26
ꢀ0.040
ꢀ16.47
ꢀ30.05
ꢀ38.30
+1.10
+0.018
ꢀ14.98
ꢀ29.41
ꢀ36.55
+1.23
ꢀ0.13
+1.21
+0.00
1
60,6
+1.43, +1.55
ꢀ1.67
+1.44, +1.29
ꢀ1.82
+1.39, +1.59
ꢀ1.71
+1.33, +1.52
ꢀ1.57
+1.58, +1.44
ꢀ1.65
H(3,4)
H(4,5)
H(2,5)
H(2,3)e
a
ꢀ2.36
ꢀ2.40
ꢀ2.31
ꢀ2.32
ꢀ2.32
ꢀ10.41
ꢀ10.41
ꢀ10.45
ꢀ10.39
ꢀ10.41
ꢀ9.36d J = 41.01 Hz
ꢀ9.55d J = 45.01 Hz
ꢀ9.18d J = 41.67 Hz
ꢀ9.24d J = 42.01 Hz
ꢀ9.37d J = 43.11 Hz
CDCl3, 298 K.
b
c
P(2) is coupling with both P(1) and P(3). P(1) is only coupling with P(2).
Signals due to P(3) and P(4) overlap.
Site of BH2(PPh2) substituent.
Doublets due to 2J(31P–1H)trans coupling.
d
e

P. McQuade et al. / Inorganica Chimica Acta 358 (2005) 1545–1556
1549
Additional mass spectral data for 5b are given as supple-
mentary material.
3.42 (m, 1H, BH2 ÆPPh2CH2), 3.66 (m, 1H,
BH2 ÆPPh2CH2), 3.83 (d, JH–P = 8.96 Hz, CH2PPh2 ÆR-
u(p-cym)Cl2), 6.11 (d, J = 7.58 Hz, CH2C6H4CH2), 6.39
2
Similarly 23 mg (47% yield) of 5c was obtained from
the reaction of 25 mg (0.031 mmol) of 1 with 100 mg
(0.22 mmol) of dpph and 165 mg (0.27 mmol) of freshly
prepared [Ru(p-cym)Cl2]2. The resulting product mix-
ture was worked up as described for 5a to afford the
red solid [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 Ædp-
phÆRu(p-cym)Cl2)] (5c). Again attempts to produce
crystals suitable for X-ray diffraction proved unsuccess-
(11 (d, J = 7.58 Hz, CH2C6H4CH2)), 7.02–7.82 (m, 50H,
1
Ph). The remaining H data along with 31P and 11B can
be found in Table 1. Elemental Anal.: 5d for
C79H81B5P4Cl2O1Os1Ru1, Calc. C, 59.68; H, 5.14%.
Found: C, 59.55; H, 5.59%. LRMS: FAB (3-NBA and
CsI). [M + Cs]+: 1720.28, obs. 1720. The mass envelope
for the observed spectrum for 5d matches that calculated
from known isotopic abundances of the constituent ele-
ments, as illustrated in Supp Table 4.
1
ful. H NMR (CDCl3): p-cymene, (d in ppm) 0.78 (d,
J = 6.89 Hz, 3H, CHMe2), 0.77 (d, J = 6.81 Hz, 3H,
CHMe2), 1.92 (s, 3H, Me), 2.52 (sept, J = 6.96 Hz,
1H, CHMe2), 5.06 (m, 2H, MeC6H4CHMe2), 5.24 (d,
J = 5.62 Hz, 2H, MeC6H4CHMe2); PPh2(CH2)6PPh2,
(d in ppm) 2.42 (m, 2H, CH2PPh2 ÆRu(p-cym)Cl2), 0.90
(m, 2H, CH2CH2PPh2 ÆRu(p-cym)Cl2), 1.00–1.42 (m,
6H, CH2CH2CH2CH2CH2CH2), 2.22 (m, 1H,
BH2 ÆPPh2CH2), 1.95 (m, 1H, BH2 ÆPPh2CH2), 6.95–
7.91 (m, 50H, Ph). The remaining NMR data are found
in Table 1. Elemental Anal.: 5c for C77.5H86B5P4
Cl3O1Os1Ru1, i.e., 5c containing 0.5 moles CH2Cl2,
Calc. C, 57.85; H, 5.39. Found: C, 57.40; H, 5.44%.
2.5. Alternative preparation of [2,2,2-(PPh3)2(CO)-nido- 2-
OsB4H7-3-(BH2 ÆdppxÆRu(p-cym)Cl2)] (5d) from 1 and
[dppxÆRu(p-cym)Cl2]
A 50 mL round bottom flask was charged with 45
mg of [dppxÆRu(p-cym)Cl2] (58 mmol) and 51 mg
(1.1eq) of (PPh3)2(CO)OsB5H9; 15 mL of CH2Cl2 was
added and the mixture refluxed for 17 h. The solvent
1
was then removed and the 31P, H and 11B NMR spec-
trum of the crude product indicated the presence of 5d
along with decomposition products. Purification was
effected using radial chromatography by dissolution
of the product mixture in the minimum volume of
CH2Cl2 and application to a 1 mm plate where elution
with CH2Cl2 removed the non-ruthenium containing
species. Addition of 10% CH3CN to the CH2Cl2 re-
sulted in the formation a red band, and addition of a
further 10% CH3CN allowed isolation of a third band.
The first and third bands consisted of 1 along with
some impurities and a red non-boron containing sub-
stances, respectively. The second band afforded 49 mg
(54% yield) of the red solid [2,2,2-(PPh3)2(CO)-nido-2-
OsB4H7-3-(BH2 ÆdppxÆRu(p-cym)Cl2)] (5d). Attempts
to grow crystals suitable for X-ray diffraction proved
unsuccessful but NMR spectra were identical to those
described in the previous section.
LRMS: FAB (3-NBA and CsI). Calc. for
12
C
1H8511B410B131P235Cl216O1192Os1102Ru1133Cs1 [M +
77
Cs]+ 1700.31, obs. 1700. Additional mass spectral data
for 5c are given in Table 3 in the supplementary material.
2.4. Preparation of [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-
3-(BH2 ÆdppxÆRu(p-cym)Cl2)] (5d)
To a 50 mL 2-necked round bottom flask containing
45 mg (0.056 mmol) of (PPh3)2(CO)OsB5H9 in the dry
box was added 100 mg (0.21 mmol) of dppx. 20 mL of
CH2Cl2 was added on the vacuum line and the mixture
stirred at ambient temperature for 12 h. Then 160 mg
(0.22 mmol) of [Ru(p-cym)Cl2]2 was added under N2
flow and the mixture was stirred for 10 min. during
which time a brown precipitate formed. Exposure to
air and filtration through a 1 cm plug of celite afforded
a red clear solution. The solution was then concentrated
to 1 mL under reduced pressure and applied to the ra-
dial chromatograph using CH2Cl2 as the mobile phase.
The single fraction initially obtained gave a yellow solu-
tion which proved to be [(PPh3)2(CO)OsB4H8] along
with traces of phosphine boranes. Slow elution with
CH3CN allowed isolation of a red band which afforded
41 mg (46% yield based on [(PPh3)2(CO)OsB5H9)] of a
red solid that was characterized as [2,2,2-(PPh3)2(CO)-
nido-2-OsB4H7-3-(BH2 ÆdppxÆRu(p-cym)Cl2)] (5d). At-
tempts to grow crystals suitable for X-ray diffraction
2.6. Preparation of [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-
3-(BH2 ÆdppeÆRu(p-cym)I2)] (6)
In a process analogous to that for the preparation of
5b, the product mixture from the reaction between 60
mg (0.075 mmol) of 1, 62 mg (0.16 mmol) of dppe and
157 mg (0.16 mmol) of [Ru(p-cym)I2]2 in CH2Cl2 was
applied to the radial chromatograph using CH2Cl2 as
the mobile phase. Three bands were detected from this
separation. The first band afforded a yellow solution
which contained species 3, 4, and 1, along with a trace
1
again proved unsuccessful. H NMR (CDCl3): p-cym-
amount
(BH2 ÆPPh3)]. The second band afforded a violet solution
identified as [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-
of
[2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-
ene, (d in ppm) 0.87 (apparent t, J = 6.67 Hz, 6H,
CHMe2), 1.81 (s, 3H, Me), 2.48 (sept, J = 6.67 Hz,
1H, CHMe2), 5.11 (m, 2H, MeC6H4CHMe2), 5.23 (m,
2H, MeC6H4CHMe2); PPh2CH2C6H4PPh2, (d in ppm)
(BH2 ÆdppeÆRu(p-cym)I2)] (6). The third band also
gave a violet solution and this was shown by NMR

1550
P. McQuade et al. / Inorganica Chimica Acta 358 (2005) 1545–1556
spectroscopy to consist of trace amounts of [dppeÆ(R-
u(p-cym)I2)2] and [Ru(p-cym)I2]2 starting material.
From this separation 49 mg (39% yield, based on
(PPh3)2(CO)OsB5H9), of 6 was obtained. Again at-
tempts to grow crystals suitable from X-ray study were
J = 6.60 Hz, 2H, MeC6H4CHMe2); PPh2(CH2)6PPh2,
(d in ppm) 2.05 (quart, J = 5.28 Hz, 2H,
BH3 ÆPPh2CH2), 1.56 (m, 2H, BH3 ÆPPh2CH2CH2),
1.14 (m, 4H, BH3 ÆPPh2CH2CH2CH2CH2), 0.99 (m,
2H CH2CH2 ÆRu(p-cym)Cl2), 2.52 (m, 2H, CH2PPh2 ÆR-
u(p-cym)Cl2), 7.39–7.81 (m, 20H, Ph); BH3, (d in ppm)
1
unsuccessful. H NMR (CDCl3): p-cymene, (d in ppm)
2
0.86 (d, J = 6.61 Hz, 3H, CHMe2), 0.85 (d, J = 6.49
Hz, 3H, CHMe2), 2.06 (s, 3H, Me), 3.08 (m, 1H,
CHMe2), 4.85 (d, J = 5.81 Hz, 1H, MeC6H4CHMe2),
5.02 (d, J = 6.00 Hz, 1H, MeC6H4CHMe2), 5.15 (d,
J = 5.91 Hz, 1H, MeC6H4CHMe2), 5.19 (d, J = 5.74
Hz, 1H, MeC6H4CHMe2); PPh2CH2CH2PPh2, (d in
ppm) 3.08 (m, 2H, CH2PPh2 ÆRu(p-cym)I2), 2.20 (m,
2H, BH2 ÆPPh2CH2), 6.95–7.90 (m, 50H, Ph). The
remaining 1H data along with 31P and 11B can be found
0.89 (d, JH–P = 16.09 Hz, 3H, BH3). 31P{1H} NMR
(CDCl3): (d in ppm) 15.79 (br, BH3 ÆPPh2CH2), 23.96
(s, CH2PPh2 ÆRu(p-cym)Cl2). 11B{1H} NMR (CDCl3):
(d in ppm) ꢀ39.42 (s, BH3). HRMS: Calc. for
1H4931P235Cl111B1102Ru1 [MꢀCl]+ 739.2135, obs.
12
C
739.2160, standard deviation 3.4 ppm.
40
2.8. X-ray structure determination of [BH3Æ(PPh2)(CH2)6
(PPh2)ÆRu(p-cym)Cl2] (7)
in
Table
1.
Elemental
Anal.:
13a
for
C73H77B5P4I2O1Os1Ru1, Calc. C, 51.78; H, 4.58. Found:
C, 51.16; H, 5.10%. LRMS: Fab (3-NBA and CsI). Calc.
for C73H78B5P4I2O1Os1Ru1[M + Cs + H]+ 1828.39, obs
1828. The mass envelope for the observed spectrum of
6 matches that calculated from known isotopic abun-
dances of the constituent elements and the data are gi-
ven in Supplementary Table 5.
Red irregular crystals of 7 were formed from a
CH2Cl2/Et2O solution at 5 ꢁC. A crystal with dimen-
sions 0.38 · 0.33 · 0.20 mm3 was mounted on a glass
fiber in a random orientation. Preliminary examination
and data collection was performed using a Bruker
SMART Charge Coupled Device (CCD), detector sys-
tem, single crystal X-ray diffractometer using graphite
monochromated Mo Ka radiation (k = 0.71073)
equipped with a sealed tube X-ray source at ꢀ60 ꢁC.
Preliminary unit cell constants were determined with
a set of 45 narrow frames (0.3ꢁ in -) scans. The data
set collected consists of 4028 frames of intensity data
collected with a frame width of 0.3ꢁ in - and counting
time of 30 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
packages [12] 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 of 61725 reflec-
tions (5ꢁ < 2h < 56ꢁ). Collected data were corrected for
systematic errors using SADABS [13] based on the Laue
symmetry using equivalent reflections. The integration
process yielded 46346 reflections of which 9059 were
independent.
2.7. Preparation of [BH3 Æ(PPh2)(CH2)6(PPh2)ÆRu(p-
cym)Cl2] (7)
Dpph, 357 mg (0.47 mmol), was dissolved in 15 mL
of freshly distilled CH2Cl2 in a 50 mL round bottom
flask containing a stir bar. A 10 mL solution of CH2Cl2
containing 44 mg (0.072 mmol) [Ru(p-cym)Cl2]2 was
added and the mixture stirred at ambient temperature
for 30 min. Passage through a 1 cm silica gel plug gave
a colorless filtrate. CH3CN was then passed through the
silica plug resulting in a deep red solution which was
transferred to a 2-neck 50 mL flask and reduced to dry-
ness on a rotary evaporator. The flask was then attached
to the vacuum line, evacuated, and 20 mL of CH2Cl2
condensed in at ꢀ196 ꢁC. After warming to ꢀ78 ꢁC,
1.3 mL of BH3 Æthf solution (1.3 mmol) was added under
a dynamic flow of dry N2, The solution was stirred at
this temperature for 15 min and then allowed to warm
slowly to room temperature at which time it was ex-
posed to air and passed through a 1 cm plug of silica giv-
ing a colorless filtrate. CH3CN was then poured through
the silica plug forming a deep red colored solution which
was then reduced to 1 mL in volume and applied to the
radial chromatograph using CH2Cl2 as the mobile
phase. CH3CN was then slowly added to the eluent until
a red band was detected. The red solution obtained from
this band was evacuated to dryness affording 39 mg
(69.9%) of a red solid which was characterized as
Crystal data and intensity data collection parameters
are listed in Table 2. Structure solution and refinement
were carried out using the SHELXTL-PLUS [14] software
package. The structure was solved by the Patterson
ꢀ
method and refined successfully in the space group P1.
Full matrix least-squares refinement was carried out by
P
2
minimizing
wðF 2o ꢀ F 2cÞ . The non-hydrogen atoms
were refined anisotropically to convergence. All cage
hydrogen atoms were located and refined freely. The
other hydrogen atoms were treated using an appropriate
riding model (AFIX m3). A projection view of the mol-
ecule with non-hydrogen atoms represented by 50%
1
[BH3 Æ(PPh2)(CH2)6(PPh2)ÆRu(p-cym)Cl2] (7). H NMR
(CDCl3): p-cymene, (d in ppm) 0.89 (d, J = 6.96 Hz,
6H, CHMe2), 1.88 (s, 3H, Me), 2.52 (m, 1H, CHMe2),
5.08 (d, J = 6.00 Hz, 2H, MeC6H4CHMe2), 5.26 (d,

P. McQuade et al. / Inorganica Chimica Acta 358 (2005) 1545–1556
1551
Table 2
Crystal data and structure refinement for 7
probability ellipsoids, and showing the atom labeling is
presented in Fig. 2.
Empirical formula
Formula weight
Temperature (K)
C40H49BCl2P2Ru
774.51
223(2)
Selected bond lengths and angles are given in Table 3,
and a complete list of bond length and angles as well as
listings of positional and isotropic displacement coeffi-
cients for hydrogen atoms, anisotropic displacement
coefficients for the non-hydrogen atoms can be found
in the supplementary material.
˚
Wavelength (A)
0.71073
triclinic
Crystal system
Space group
ꢀ
P1
Unit cell dimensions
˚
a (A)
˚
10.0759(1)
12.1798(1)
16.0963(1)
90.109(1)
93.07(1)
b (A)
˚
c (A)
3. Results
a (ꢁ)
b (ꢁ)
c (ꢁ)
The reaction between the nido-ofhexaborane,
(PPh3)2(CO)OsB5H9 (1), and bidentate phosphines of
the type PPh2CxHyPPh2, affords species 2 as illustrated
in Scheme 1. If a solution of [2,2,2-(PPh3)2(CO)-nido-
2-OsB4H7-3-(BH2 ÆPPh2CxHyPPh2)] (2a, 2b, 2c) [1a], is
allowed to stand rearrangement to species 4, also shown
in Scheme 1, proceeds. In this process the distal end of
the BH2 ÆPPh2CxHyPPh2 moiety, an uncoordinated
phosphine, displaces a phosphine ligand on the Os atom
to afford [{(PPh3)(CO)OsB4H7}-g2-3,2-{BH2 ÆPPh2Cx-
HyPPh2}] (4). The basicity of the pendent phosphine in
species of type 2 was demonstrated by the reaction of
[2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 ÆPPh2C3H6P-
Ph2)] (2b) with BH3 Æthf to afford [2,2,2-(PPh3)2(CO)-
nido-2-OsB4H7-3-(BH2 ÆPPh2C3H6PPh2 ÆBH3)] [1a]. To
probe the reactivity of this uncoordinated phosphine
further in species 2a–2c, it was allowed to react with
the species [Ru(p-cym)Cl2]2. The dimer of the 16-
electron ruthenium species is cleaved by phosphines to
produce a monomeric species of the type PR3 ÆRu(p-
cym)Cl2 [15]. The (g6-p-cym)ruthenium(II) complex
was selected because it has been used as a vertex in met-
106.427(1)
3
˚
Volume (A )
1891.72(3)
2
1.360
Z
Density (calculated) (Mg/m3)
Absorption coefficient (mmꢀ1
F(000)
)
0.667
804
Crystal size (mm3)
h Range for data collection
Index ranges
0.38 · 0.33 · 0.20
1.74–28.00.
ꢀ13 6 h 6 13, ꢀ16 6 k 6 16,
ꢀ21 l 6 21
Reflections collected
46346
9059 [0.04]
Independent reflections [Rint
Completeness to h = 28.00ꢁ
Absorption correction
Maximum and minimum
transmission
]
99.0%
empirical
0.8781 and 0.7855
Refinement method
full-matrix least-squares on F2
9059/3/430
1.043
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
R1 = 0.0270, wR2 = 0.0617
R1 = 0.0358, wR2 = 0.0658
0.435 and ꢀ0.435
Largest differential peak and
ꢀ3
˚
hole (e A
)
and thus only one of these experiments is included in
this report. Reasons for the low yields include degrada-
tion of the metal-containing species on the silica surface
during purification by thin layer chromatography or
incomplete removal of product from the silica surface.
NMR experiments on the crude reaction mixture indi-
cated that there was essentially quantitative conversion
of 2a to 5a. The proposed structure of [2,2,2-
(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 ÆPPh2C2H4PPh2 ÆR-
u(p-cym)Cl2)] (5a) given in Fig. 1 conforms to the
elemental analytical and mass spectral data presented
1
allaboranes [16] and there are characteristic H NMR
signals for the p-cymene group. The latter acts as a good
indicator that the final product contains the Ru(p-
cym)Cl2 fragment. Further, the chloride present on the
ruthenium center can be replaced by larger halide or ha-
lide analogue [9] and thereby provide information on the
role the halide has on the system.
Stirring a mixture of 1 and excess [(PPh2)2(CH2)3]
(dppe) in CH2Cl2 for 12 hours followed by addition of
a small excess of [Ru(p-cym)Cl2]2 affords a red solid in
which the distal end of the BH2 ÆPPh2C2H4PPh2 moiety
has been functionalized to form [2,2,2-(PPh3)2(CO)-
nido-2-OsB4H7-3-(BH2 ÆPPh2C2H4PPh2 ÆRu(p-cym)Cl2)]
(5a). The overall yield of this reaction is relatively low
(33% yield based on 1), presumably due to the compet-
ing intramolecular reaction 2a undergoes to produce 4a.
In an effort to preclude this, a different synthetic route
was utilized in which one end of the bidentate phosphine
was already attached to the Ru(p-cym)Cl2 fragment
prior to reaction with 1. A typical process, utilizing
the two approaches, is illustrated in Scheme 2. Surpris-
ingly, this did not increase the yield by more than 25%
Fig. 2. Structure of [BH3 Æ(PPh2)(CH2)6(PPh2)ÆRu(p-cym)Cl2] (7) with
elipsoids drawn at the 50% probability level. H atoms on phenyl rings
and their substituents are omitted for clarity.

1552
P. McQuade et al. / Inorganica Chimica Acta 358 (2005) 1545–1556
Scheme 2.
herein although crystals suitable for X-ray analysis were
not available.
to the methylene protons adjacent to the BH2 ÆPPh2
group.
The 31P{1H} NMR spectrum of 5a at 298 K exhib-
ited three resonances in 2:1:1 area ratio. A broad one
assigned to overlapping dppe signals (+22.28 ppm),
and two signals from the PPh3 groups coordinated
to the Os center. When cooled to 260 K the signal as-
signed to the dppe ligand could be resolved into two
doublets at +22.21 (J = 35.19 Hz) and +23.15
(J = 36.87 Hz) ppm which 2D 1H–31P-COSY experi-
ments allowed assignment as the phosphorus atom
bound to the BH2 moiety and that bound to the ruthe-
nium center, respectively. The 11B NMR spectrum of
5a gave the expected 4 peaks in 2:1:1:1 area ratio con-
firming the presence of five boron atoms. The data are
found in Table 1 and correspond well to those for the
other osmahexaboranes to which a phosphine is coor-
dinated [1,2a]. Of note is the resonance at ꢀ38.03 ppm
arising from the BH2 moiety directly bound to a phos-
phorus atom of the dppe ligand; in the expected range
The resonances for the p-cymene ligand were quite
interesting and somewhat unexpected and they differed
at 298 and 260 K. A schematic representation of the
p-cymene ligand along with a numbering scheme is
shown in Fig. 3. At room temperature two sets of dou-
blets at +0.96 and +0.93 ppm assigned to the two-me-
thyl groups occupying positions
1
and 10 were
observed, but at 260 K these signals coalesce to a com-
plex multiplet. The methyne proton at position 2 is ob-
served as the expected septet and the methyl group at
position 5 is observed as a singlet at both temperatures.
At room temperature an apparent triplet and two dou-
blets in a 2:1:1 ratio are observed for the aromatic pro-
tons, assigned to the protons occupying positions 4 and
Table 3
˚
Selected bond distances (A) and angles (ꢁ) for (7)
Ru–P(1)
Ru–Cl(2)
2.3626(4)
2.4020(4)
1.8307(18)
1.923(3)
Ru–Cl(1)
2.4270(5)
1.8198(19)
1.8363(18)
1.818(2)
P(1)–C(111)
P(1)–C(11)
P(2)–C(211)
P(2)–C(221)
C(15)–C(16)
1
for phosphine–borane moieties [17]. The H{11B} spec-
P(1)–C(121)
P(2)–B(1)
P(2)–C(16)
C(11)–C(12)
trum of 5a afforded the expected nine resonances of
area ratio one assigned to five terminal and four bridg-
ing hydrogen atoms. At room temperature two com-
plex multiplets at +2.85 and +2.34 ppm were
observed for the methylene protons on the dppe back-
bone. At 260 K three resonances were observed for
these methylene protons in a 1:1:2 area ratio. The first
two, at +2.80 and +2.73 ppm, both complex multi-
plets, were assigned to the methylene protons adjacent
to the PPh2 ÆRu(p-cym)Cl2 fragment and the reso-
nance of area ratio two, at +2.29 ppm, was assigned
1.8233(19)
1.521(2)
1.815(2)
1.526(3)
P(1)–Ru–Cl(1)
88.074(16)
89.568(17)
106.68(8)
111.76(5)
113.46(6)
106.45(9)
111.34(11)
116.34(11)
115.69(14)
P(1)–Ru–Cl(2)
82.895(15)
103.86(8)
100.78(8)
118.98(6)
106.12(9)
103.59(9)
112.21(11)
120.73(14)
113.93(16)
Cl(1)–Ru–Cl(2)
C(111)–P(1)–C(11)
C(111)–P(1)–Ru
C(11)–P(1)–Ru
C(111)–P(1)–C(121)
C(121)–P(1)–C(11)
C(121)–P(1)–Ru
C(221)–P(2)–C(211)
C(211)–P(2)–C(16)
C(211)–P(2)–B(1)
C(12)–C(11)–P(1)
C(12)–C(13)–C(14)
C(221)–P(2)–C(16)
C(221)–P(2)–B(1)
C(16)–P(2)–B(1)
C(15)–C(16)–P(2)

P. McQuade et al. / Inorganica Chimica Acta 358 (2005) 1545–1556
1553
40 overlapping, and at 3 and 30, respectively. At 260 K
the triplet resolves into two doublets, each of area ratio
one; the higher field pair assigned to 4 and 40, and the
lower field pair to 3 and 30; all assignments made on
the basis of 2D HH-COSY and HH-ROESY experi-
ments. The NMR data, all of which conform to the
structure given in Fig. 1 are listed in Table 1.
Similar results were obtained when using the phos-
phines [(PPh2)2(CH2)3] (dppp) and [(PPh2)2(CH2)6]
(dpph), resulting in the formation of 5b and 5c, respec-
tively. Mass spectral data were obtained for both and
although the elemental analysis for 5b were not as good
as those for 5a and 5c, the data obtained from NMR
spectroscopy, shown in Table 1, along with mass spec-
tral data confirmed the formulation of 5b.
center, which is inequivalent. Such coupling is observed
for 5a–c but in this case it represents a 7-bond interac-
tion between the two dppx ligand P atoms (7JP–P
=
4.88 Hz). Coupling of this type has been observed before
in similar systems and confirmed by 2D[31P–31P]-COSY
experiments [1,18].
Since changing the nature of the bidentate phos-
phines used did not affect the NMR spectroscopic prop-
erties of the hybrid system, the next step was to change
the halide present on the ruthenium fragment. Thus we
replaced the chloride by iodide in the starting [Ru(p-
cym)Cl2]2 complex [9] to see if the halide played a role
in these systems. The reaction conditions used were sim-
ilar to those in which 5a was isolated. Briefly dppe was
allowed to react with 1 to form [2,2,2-(PPh3)2(CO)-
nido-2-OsB4H7-3-(BH2 ÆPPh2C2H4PPh2)] (2a), and to
this a slight excess of [Ru(p-cym)I2]2 added. From this
reaction mixture a deep red solid, identified as [2,2,2-
Since the NMR spectra for the p-cymene ligands in
5a, 5b and 5c were similar in spite of varying the length
of the alkyl bridge in the bidentate phosphines, we chose
to use the rigid backboned species dppx. Reactions of 1
with phosphines with rigid backbones such as
(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2
ÆPPh2C2H4P-
Ph2 ÆRu(p-cym)I2)] (6) was isolated in 39% yield. The
overall yield is comparable to that obtained for 5a
(33%) and we ascribe the slight increase to the ease in
which 2d was removed from the silica surface since
CH3CN was not required to aid removal from the sur-
face of the silica, as it was for the isolation of 5a. Spec-
tral data for 6 were quite similar to those for 5a–d, with
some subtle differences. The dppe 31P resonances for 5a
were broad at 298 K but sharpened at 260 K to two dou-
blets, however the spectrum for 6 at 298 K resembled
that for 5a at 260 K and did not change appreciably
on cooling.
As part of this overall study, we prepared a series of
bidentate phosphines which had organotransition metal
and borane moieties at each end. This work will be de-
scribed in detail in the next paper in this series, but here-
in we describe the structure of the species
[BH3 Æ(PPh2)(CH2)6(PPh2)ÆRu(p-cym)Cl2] (7). At ꢀ78
ꢁC and under a flow of N2, BH3 Æthf was introduced into
a CH2Cl2 solution of [C6H12PPh2 ÆRu(p-cym)Cl2], pre-
pared in situ from dpph and [Ru(p-cym)Cl2]2. Essentially
a quantitative yield of 7 was obtained as a red solid,
although due to adherence of 7 to the silica gel during
purification, the isolated yield was 70%. Two peaks of
equal area were observed in the 31P{1H} NMR spectrum
of 7, the sharper of the two, falling at +23.96 ppm, was
assigned to the phosphine directly bound to the ruthe-
nium moiety. The second quite broad peak, observed
at +15.79 ppm was assigned to the phosphine bonded
to the BH3 fragment. Coupling between the two P atoms
was not observed. The 11B{1H} spectrum of 7 contained
a single resonance at ꢀ39.42 ppm, typical for a phos-
phine–borane moiety [6–8]. The 1H{11B} NMR spec-
trum of 7 is given in the experimental section and all
the protons were fully identified. Of note is the fact that
for the p-cym ligand, a single doublet is observed at
+0.89 ppm, assigned to the methyl groups at positions
PPh2XPPh2
{X = 1,4-C6H4
(arphos)},
1,4-
CH2C6H4CH2 (dppx), and Fe(C5H4)2 (dppf) had previ-
ously been examined in our laboratory [1c]. In a typical
reaction, dppx was allowed to react with 1 to produce
the
species
[2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-
(BH2 ÆPPh2CH2C6H4CH2PPh2)] (2d), which was then
treated with [Ru(p-cym)Cl2]2 to form the red solid
[2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 ÆPPh2CH2C6-
H4CH2PPh2 ÆRu(p-cym)Cl2)] (5d). The isolated yield of
5d obtained (46%) was higher than that for its precursor
2d, presumably because in solution 2d can react further
to form the linked cluster system [{2,2,2-(PPh3)2(CO)-
nido-2-OsB4H7}2] (dppx) [1c], however coordination to
the metal center in 5d this precludes this formation. It
was also found by monitoring the 31P{1H} NMR spec-
trum over time that the stability of 5d in solution was
higher than that of its precursor 2d.
Species 5a–d were also prepared by the reaction be-
tween 1 and the bidentate phosphine to which a [(p-
cym)RuCl2] moiety was coordinated to one end. We
only describe that for 5d, which was formed in 54% yield
from 1 and [dppxÆRu(p-cym)Cl2] (Scheme 2). Spectral
data for the cage and the p-cym moiety in 5d were sim-
ilar to those for 5a–c, and are given in Table 1. Similarly,
the spectra for the hydrocarbon linker in 5d are not unu-
sual and are given in the experimental section. The 31P
resonance for the dppx P atom bonded to the Ru center
is observed as a doublet, due to coupling to the other P
(4)
(3)
(1)
(2)
(5)
(1')
(4')
(3')
Fig. 3. A schematic representation of the p-cymene ligand showing the
numbering scheme.

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P. McQuade et al. / Inorganica Chimica Acta 358 (2005) 1545–1556
1 and 10 and single doublets were observed for each of
the pairs of aromatic protons, 3/30 and 4/40. All other
protons were assigned and all assignment made on the
basis of 2D NMR experiments carried out at 303 K.
Red irregular crystals of 7 suitable for X-ray analysis
were formed from a CH2Cl2/Et2O solution at 5 ꢁC. The
structure resembles that expected for 5a except that the
(PPh3)2(CO)OsB4H7–BH2 moiety has been replaced by a
BH3 group. There are no unexpected features associated
with the structure of 7. The environment around P(1),
which is coordinated to the Ru moiety, deviates from
ideal tetrahedral geometry to a greater degree than that
around P(2). For P(1) the angles range from ca. 100.78–
118.98ꢁ, and for P(2) the angles range from ca. 103.59–
116.34ꢁ. The angles around P(1) deviate further from an
ideal tetrahedral geometry than they do around P(2) be-
cause the Ru moiety is much more sterically encumber-
ing than the BH3 moiety coordinated to P(2). Small
differences can also be seen for the P–C(alkyl) bond
lengths. Thus P(1)–C(11) has a bond length of 1.836(2)
phosphine, changing the nature of the chain and also
the halogen bonded to the Ru atom did not alter this
observation. The only changes we did observe was
that for 5d, 31P–31P coupling was observed between
the two dppx P atoms; seven bond coupling presuma-
bly facilitated by delocalization through the p-cloud of
the arene ring, and the effect on the line widths of the
resonances for P(3) and P(4) in 6. The effects on the
p-cym ligand were more profound for 5a than for
5b or 5c, suggesting that the proximity of the nido-
osmaborane cluster increases this influence. Attempts
to prepare the dppm ([(PPh2)2CH2]) analogue of 5a–
d were unsuccessful, so observation of the effect of
shortening the length of the alkyl backbone was not
possible.
The NMR data obtained for 5a–d and 6 indicated
that only a single species was present in solution and
2D NMR experiments suggested that there were neither
anomalous couplings nor short range through-space
interactions to account for the observed doubling pat-
tern. The only remaining feature that could have caused
these doublings was the nido-osmapentaborane cluster
tethered at the distal end of the PPh2CxHyPPh2 ÆRu(p-
cym)Cl2 moiety. This hypothesis is further enhanced
since this anomalous phenomenon was not observed
for 7 which contains a BH3 group rather than the
nido-osmapentaborane moiety [(PPh3)2(CO)OsB4H7
(BH2)].
˚
˚
A, while for P(2)–C(16) a bond length of 1.823(2) A is
observed and this, perhaps may be ascribed to P(1)
donating more electron density to ruthenium than P(2)
donates to boron.
4. Discussion
This study has demonstrated that species of the type
[{(PPh3)2(CO)OsB4H7}-3-{BH2PPh2(CH2)n(PPh2)}] (2)
can be used as substrates for the formation of hybrid
systems of the type [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-
3-(BH2PPh2)CxHyPPh2RuCl2(p-cym)]. (5) This is in
spite of the tendency for 2 to undergo intramolecular
substitution reactions. This latter behavior precluded
isolation of crystals suitable for X-ray analysis however
NMR spectra, high resolution mass spectrometry and
elemental analysis confirmed the structures. Further-
more, a crystal structure determination of the closely re-
lated species [BH3 Æ(PPh2)(CH2)6(PPh2)ÆRu(p-cym)Cl2]
(7), along with detailed NMR studies supports our con-
clusions about the identity of 5a–d and 6.
Perhaps the most unusual observation was the pro-
ton NMR data for the p-cym ligands in 5a–d and 6.
Since the p-cym moiety has a plane of symmetry, it
was expected that only 5 resonances would be ob-
served, a singlet for the unique methyl group, a septet
for the i-propyl proton, a doublet for the methyl
groups of the i-propyl moiety and two doublets in
an AB pattern for the aromatic protons. This however
was not the case since in addition to the septet and
the singlet, two resonances for each of the methyl
groups at positions 1, 10 (see Fig. 3), and two sets
of doublets for each of the two pairs of equivalent
aromatic protons at positions 3,30 and 4,40 were ob-
served. Altering the chain length of the bidentate
The type of behavior observed for the p-cymene lig-
and has been previously reported in the literature in
cases where there is asymmetry at the metal center
[19]. The only asymmetric feature in the series of species
5a–d and 6 resides in the osmaborane cluster. The ap-
pended BH2 at position 3 on the osmaborane cluster
in species of type 2 and those containing monodentate
phosphines [1a] exhibit two inequivalent terminal pro-
ton resonances for 6 and 60 (see Table 1 and Fig. 1),
which feature symmetrical, mirror-image fine structure
1
which we attribute to long range H and 31P coupling
and which results in an apparent doublet structure. This
is consistent with the structure because the two hydro-
gens are on a prochiral center and are, therefore, diaster-
eotopic thus exhibiting different chemical shifts and
splitting each other. Technically the nido-osmapentabo-
rane cluster renders the protons on the p-cymene ligand
diastereotopic, but in some cases the chiral cluster is ele-
ven bonds removed from the p-cymene ligand and thus
the effect would be expected to be minimal. This is not
the case however, as experimental observations portend
to the contrary. We mentioned earlier that the NMR
spectra obtained for 6 at 298 K were similar to those ob-
tained for 5a at 260 K. This suggested that the halide
present at the ruthenium center does play some role in
the diastereotopic behavior observed at the p-cymene
ligand. One possible explanation for this is that in solu-
tion the nido-osmapentaborane cluster is associating, via

P. McQuade et al. / Inorganica Chimica Acta 358 (2005) 1545–1556
1555
H
B
H
H
PPh3
B
B
H
B
Os
H
H
H
H
CO
PPh3
Cl
Cl
Ph
Ru
Cl
Ru
P
Cl
P
Ph
Ph
Ph
H
P
B
H
H
H
Ph
P
Ph
B
Ph
Ph
Fig. 4. Possible solution configurations of 5.
hydrogen bonding, to the halide at the ruthenium
center. Thus the nido-osmapentaborane cluster finds it-
self in closer proximity to the ruthenium center, magni-
fying the effect of this chiral unit on the p-cymene ligand.
Examples of conformations that could arise from this
interaction are shown in Fig. 4. The cartoon type depic-
tion given shows two possible conformations that could
exist in solution for species 5a and this could be ex-
tended to include the other species in the series. Unfor-
tunately we could not obtain further corroborating
evidence such as crystal structure data that would con-
firm this hypothesis. If this explanation is correct, it
would represent one of the first reported examples of a
chiral unit causing a diastereotopic effect on a ligand
that is up to eleven bonds removed from the chiral
moiety.
References
[1] (a) P. McQuade, K. Hupp, J. Bould, H. Fang, N.P. Rath, R.Ll.
Thomas, L. Barton, Inorg. Chem. 38 (1999) 5415;
(b) P. McQuade, in: M.G. Davidson, A.K. Hughes, T.B. Marder,
K. Wade (Eds.), Contemporary Boron Chemistry, Special Pub-
lication, vol. 253, Royal Society of Chemistry, 2000, pp. 271–275;
(c) P. McQuade, R.E.K. Winter, L. Barton, J. Organomet. Chem.
688 (2003) 82.
[2] (a) L. Barton, J. Bould, H. Fang, K. Hupp, N.P. Rath, C.
Gloeckner, J. Am. Chem. Soc. 119 (1997) 631;
(b) X. Lei, M. Shang, T.P. Fehlner, Organometallics 19 (2000)
5266;
(c) L.N. Pangan, Y. Kawano, M. Shimoi, Organometallics 19
(2000) 5575;
(d) Y. Kawano, K. Kawakami, M. Shimoi, Chem. Lett. (2001)
1006;
(e) L.N. Pangan, Y. Kawano, M. Shimoi, Inorg. Chem. 40 (2001)
1985;
(f) R. Macias, T.P. Fehlner, A.M. Beatty, Angew. Chem., Int. Ed.
41 (2002) 3860;
(g) R. Macias, T.P. Fehlner, A.M. Beatty, Organometallics 23
(2004) 2124.
Acknowledgements
[3] (a) R.E. Williams, Adv. Inorg. Chem. Radiochem. 18 (1976) 67;
(b) K. Wade, Adv. Inorg. Chem. Radiochem. 18 (1976) 60;
(c) R.W. Rudolph, Acc. Chem. Res. 9 (1976) 446.
[4] D.F. Shriver, M.A. Drezdon, The Manipulation of Air-Sensitive
Compounds, John Wiley, New York, 1986.
We acknowledge the NSF (Grant No. CHE-
9727570), the Missouri Research Board and UM-St.
Louis for research grants to LB, and the NSF, the
UM-St. Louis Center for Molecular Electronics and
the Missouri Research Board for funds that helped pur-
chase the XRD, NMR, and MS facilities. We also thank
Mr. Joe Kramer for help with the MS measurements.
[5] J. Bould, M.N. Greenwood, J.D. Kennedy, J. Organomet. Chem.
249 (1983) 11.
[6] D. Imhof, U. Burckhardt, K.-H. Dahmen, F. Joho, R. Nesper,
Inorg. Chem. 36 (1997) 1813.
[7] P. McQuade, N.P. Rath, L. Barton, Inorg. Chem. 38 (1999) 5468.
[8] M.A. Bennett, T.-N. Huang, T.W. Matteson, A.K. Smith, Inorg.
Synth. 21 (1982) 74.
Appendix A. Supplementary data
[9] R.A. Zelonka, M.C. Baird, Can. J. Chem. 50 (1972) 3063.
[10] Assignments of the NMR spectra listed in Table 1, were based on
detailed analyses previously reported in [1a,1c,5], and on spectra
and X-ray structural data for [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-
3-(BH2PPh2Me)] [2a] and for [2,2,2-(PPh3)2(CO)-nido-2-OsB5H9]
Supplementary data associated with this article can
be found, in the online version at doi:10.1016/
j.ica.2004.10.015.

1556
P. McQuade et al. / Inorganica Chimica Acta 358 (2005) 1545–1556
found in 5 and in J. Bould, J.D. Kennedy, R.Ll. Thomas, L.
Barton, N.P. Rath, Acta Crystallogr. Sect. C. 57 (2001) 1245.
(c) R.Ll. Thomas, A. J.J. Chem. Soc. Dalton Trans. (1997) 631;
(d) R.Ll. Thomas, L. Barton, Inorg. Chim. Acta 289 (1999) 134.
[17] (a) H. No¨th, B. Wrackmeyer, Nuclear Magnetic Resonance
Spectroscopy of Boron Compounds, Springer Verlag, Heidelberg,
1978, pp. 340–344;
[11] We found that the use of CsI in FAB Mass Spectrometry
substantially simplified the spectra by avoiding overlap of peak
envelops. See G. Siuzdak, S.V. Wendeborn, K.C. Nicolaou, Int.
J. Mass Spectrom. Ion Proc. 112 (1992) 79.
(b) K.C. Nainan, G.E. Ryschewitsch, Inorg. Chem. 8 (1969) 2671.
[18] (a) K. Gholivand, A.H. Mahmoudkhani, M. Khosravi, Phospho-
rus, Sulfur Silicon Relat. Elem. 106 (1995) 173;
(b) R. Macias, N.P. Rath, L. Barton, J. Chem. Soc., Chem.
Commun. (1998) 1091.
[12] Bruker Analytical X-ray Division, Madison, WI, 1998.
[13] R.H. Blessing, Acta Crystallogr. Sect. A. 51 (1995) 33.
[14] G.M. Sheldrick, Bruker Analytical X-ray Division, Madison, WI,
1999.
[15] S.A. Serron, S.P. Nolan, Yu.A. Abramov, L. Brammer, J.L.
Petersen, Organometallics 17 (1998) 104.
[16] (a) See for example: M. Bown, X.L.R. Fontaine, N.N. Green-
[19] (a) For example see: N. Nul, J.H. Nelson, Organometallics 18
(1999) 709;
(b) S. Fernadez, M. Pfeffer, V. Ritleng, C. Sirlin, Organometallics
18 (1999) 2390;
wood, J.D. Kennedy, M. Thornton-Pett, Organometallics
(1987) 2254;
6
(c) H. Brunner, R. Oeschey, B. Nuber, J. Chem. Soc., Dalton
Trans. (1996) 1499;
(d) J.W. Faller, J. Parr, Organometallics 19 (2000) 1829.
(b) J.H. Davis, E. Sinn, R.N. Grimes, J. Am. Chem. Soc. 111
(1989) 4776;