Binding modes of a mixed donor multidentate iminobisphosphane ligand to the triosmium cluster: The crystal structures of [{Os3(CO)11}2(PNCHP)], [Os3(μ-H)(μ3-PNCP)(CO)7] and [Os3(μ-H)(μ2-PNCP)(CO)8]

Article abstract of DOI:10.1016/S0022-328X(00)00348-X

The triosmium clusters [Os₃(CO)₁₁(CH₃CN)] and [Os₃(CO)₁₀(CH₃CN)₂] react with 2-(diphenylphosphino)-N-[2-(diphenylphosphino)benzylidene]benzeneamine (PNCHP) to give [{Os₃(CO)₁₁}₂(PNCHP)] (1), two coordination isomers of [Os₃(CO)₁₁(PNCHP)] (2a) and (2b), and 1,1-[Os₃(CO)₁₀(PNCHP)] (3), respectively. When (3) is reacted with trimethylamineoxide the major product is [Os₃(μ-H)(CO)₇(μ₃-PNCP)] (4) with two geometrical isomers of [Os₃(μ-H)(CO)₈(μ₂-PNCP)] (5a) and (5b) being minor products. The clusters have been fully characterised by spectroscopic means and the structures of 1·CH₂Cl₂, 4·1.5CH₂Cl₂ and 5a established by single-crystal X-ray analyses. In 1 PNCHP bridges two osmium triangles equatorially. In 4 the imine hydrogen of PNCHP has migrated to the osmium cluster and PNCP acts as a triply bridging nine electron donor, while in 5a PNCP acts as a doubly bridging seven electron donor ligand.

Full text of DOI:10.1016/S0022-328X(00)00348-X

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 609 (2000) 2–9
Binding modes of a mixed donor multidentate iminobisphosphane
ligand to the triosmium cluster: the crystal structures of
[{Os3(CO)11}2(PNCHP)], [Os3(m-H)(m3-PNCP)(CO)7] and
[Os3(m-H)(m2-PNCP)(CO)8]
Eric W. Ainscough *1, Andrew M. Brodie *2, Anthony K. Burrell,
Steven M.F. Kennedy
Department of Chemistry, Institute of Fundamental Sciences, Massey Uni6ersity, Pri6ate Bag 11-222, Palmerston North, New Zealand
Received 9 February 2000; received in revised form 23 May 2000
Abstract
The triosmium clusters [Os3(CO)11(CH3CN)] and [Os3(CO)10(CH3CN)2] react with 2-(diphenylphosphino)-N-[2-(diphenylphos-
phino)benzylidene]benzeneamine (PNCHP) to give [{Os3(CO)11}2(PNCHP)] (1), two coordination isomers of
[Os3(CO)11(PNCHP)] (2a) and (2b), and 1,1-[Os3(CO)10(PNCHP)] (3), respectively. When (3) is reacted with trimethylamineoxide
the major product is [Os3(m-H)(CO)7(m3-PNCP)] (4) with two geometrical isomers of [Os3(m-H)(CO)8(m2-PNCP)] (5a) and (5b)
being minor products. The clusters have been fully characterised by spectroscopic means and the structures of 1·CH2Cl2,
4·1.5CH2Cl2 and 5a established by single-crystal X-ray analyses. In 1 PNCHP bridges two osmium triangles equatorially. In 4 the
imine hydrogen of PNCHP has migrated to the osmium cluster and PNCP acts as a triply bridging nine electron donor, while in
5a PNCP acts as a doubly bridging seven electron donor ligand. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Osmium cluster; Crystal structure; Iminophosphane
report PNCHP or 2-PPh2(C6H4NꢀCHC6H4)2-PPh2,
shown in Fig. 1, can be viewed as an extension of the
1. Introduction
ligand 2-PPh2(C6H4NꢀCHPh) which is found, minus
the imino hydrogen, as a triply bridging seven electron
donor in the complex [Ru3(m-H)(CO)6(m3-CPhꢀNC6-
H4PPh2)(m-dppm)] [2]. The ligand PNCHP has the po-
tential to donate an additional two electrons to the
cluster, making the ligand a rare example of a triply
bridging nine electron donor. The only other example is
found in the complex [Os3(m-H)(CO)6(m3-PPh2CH2P-
(Ph)C6H4CNR)(PPh3)]. However, in this case the ligand
is not reacted directly with the triosmium cluster but
formed from a subsequent CꢁC coupling reaction [3].
We report here, the reaction products of PNCHP with
[Os3(CO)10(CH3CN)2] followed by addition of trimethyl-
amineoxide in situ in order to encourage the higher
degrees of substitution desired. PNCHP was also re-
acted with [Os3(CO)11(CH3CN)] and [Os3(CO)10-
(CH3CN)2] in the absence of trimethylamineoxide. In
Doubly bridging ligands which donate more than six
electrons to trinuclear clusters of ruthenium and os-
mium are uncommon and even fewer examples exist
where the ligand is triply bridging [1]. The ligand in this
Fig. 1. The ligand 2-(diphenylphosphino)-N-[2-(diphenylphosphino)-
benzylidene]benzeneamine (PNCHP).
1 *Corresponding
author.
Fax:
+64-6-3505682;
email:
e.ainscough@massey.ac.nz
2 *Corresponding author.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00348-X

E.W. Ainscough et al. / Journal of Organometallic Chemistry 609 (2000) 2–9
3
nitrogen atom, are available to substitute for the aceto-
nitrile ligand(s), hence, potential for several coordina-
tion isomers exist [4].
2. Results and discussion
2.1. Synthesis
The osmium cluster compounds described in this
report are depicted schematically in Fig. 2. The
PNCHP bridged dicluster species [{Os3(CO)11}2-
(PNCHP)] (1) was synthesised by reacting a half mole
equivalent of the ligand PNCHP with [Os3(CO)11-
(MeCN)]. The dimer is also obtained as a major
product when attempting to synthesise the monomers,
and coordination isomers of [Os3(CO)11(PHCNP)], (2a)
and (2b) by reacting one mole equivalent of the ligand
PNCHP with [Os3(CO)11(MeCN)]. The monomer 2a
was isolated by TLC, however, the monomer 2b could
not be separated from the dimer 1. 1,1-[Os3(CO)10-
(PNCHP)] (3) was synthesised by reacting the ligand
PNCHP with [Os3(CO)10(MeCN)2]. When 3 is reacted
in situ with one or two equivalents of trimethylami-
neoxide, [Os3(m-H)(CO)7(m3-PNCP)] (4) is obtained as
the major product with two coordination isomers of
[Os3(m-H)(CO)8(m2-PNCP)] (5a) and (5b) as minor
products. 5a and 5b are also observed in the ageing of
3.
Fig. 2. The complexes showing the various coordination modes of
PNCHP, where PNCHP is depicted by PꢁNꢀCHꢁP.
NMR and IR spectroscopic data for the complexes
1–5 are tabulated in Table 1 and mass spectral and
microanalytical results are reported in the experimental
section. FAB-mass spectral data for all the complexes
recorded showed the expected molecular ion peaks with
these cases the PNCHPs three inequivalent lone pairs of
electrons, from the two phosphorus atoms and one
Table 1
NMR and IR spectroscopic data for complexes 1–5
c
Complex
1H-NMR (ppm) a
31P-NMR (ppm) b
w(CO) (cm−1
)
OsꢁH
CHꢀN
J(PH) (Hz)
1
8.63
8.35
0.87
−1.9
−1.8
2107m
2019vs
2108m
2078w
1988m
2057s
2054s
1984sh
2033s
2032s
1952sh
2020vs
2a
−14.5
1989m
1980sh
1958sh
d
2b
3
9.07d
5.83 e
6.4
−0.19
27.0
−15.3
18.8
2093m
1995sh
2038vs
1952s
2058s
1937w
2056m
1985s
2009vs
1935sh
1994vs
1927sh
2034s
2009vs
1940sh
1968m
1961sh
1984m
1923sh
1967m
4
−14.76dd
34.0, 5.7
33.4
14.6
5a/b f
−14.52dd
−14.97dd
35.3, 4.5
41.4, 5.1
32.9
31.2
26.3
19.1
1960sh
a Recorded at 270 MHz, chemical shifts are in ppm relative to Si(CH3)4, solvent CDCl3.
b Recorded at 109 MHz, chemical shifts are in ppm relative to 85% H3PO4, solvent CHCl3.
c In CHCl3.
d Contaminated with 1.
e Tentative assignment.
f A 1:1 mixture of two geometric isomers.

4
E.W. Ainscough et al. / Journal of Organometallic Chemistry 609 (2000) 2–9
Fig. 3. ORTEP diagram for one molecule of [{Os3(CO)11}2(PNCHP)] (1) showing the numbering system used. Thermal ellipsoids are at the 50%
probability level. Hydrogen atoms have been omitted for reasons of clarity.
the appropriate isotopic abundances and fragmentation
patterns corresponding to the loss of successive car-
bonyl ligands.
2.2. Description of the crystal structures 1·CH2Cl2,
4·1.5CH2Cl2 and 5a
Inspection of the infrared spectroscopic data shows a
typical lowering of the carbonyl stretching energies
from 1 through 5 consistent with the increasing degree
of carbonyl substitution in the complex by the PNCHP
ligand. 1 exhibited bands typical of [Os3(CO)11] species
[11,15] which is confirmed by its X-ray structure. Like-
wise for 2a which gave a spectrum with no significant
differences from 1. Most [M3(CO)10(LꢁL)] clusters,
where M is Os or Ru and LꢁL is a bidentate ligand,
tend to be found as 1,2-isomers [5]. However 3 was
assigned the 1,1-isomer with equatorial bound phos-
phorus atoms, due to the similarity of its metal–car-
bonyl stretching region to other such species and
dissimilarity to other isomers of [Os3(CO)10L2] [6–
10,13,14].
2.2.1. Crystal structure of
[{Os3(CO)11}2(PNCHP)](1)·CH2Cl2
X-ray analyses of 1 shows two independent molecules
in the asymmetric unit. One of these is affected by
disorder of the osmium triangle as discussed in Section
3. Both molecules in all other respects are essentially
the same except for the symmetry generated imine
bond lengths C(127)ꢁC(127%) (1.266(17) A) and
C(227)ꢁC(227%) (1.316(18) A). It is unlikely that this
difference is a real effect and probably arises from the
crystallographically imposed symmetry which is
present. One of the molecules is depicted in Fig. 3.
The structure shows two ‘Os3(CO)11’ moieties bridged
by one PNCHP via the P atoms. The P atoms are
coordinated in equatorial positions relative to the os-
mium triangle. A centre of inversion lies at the mid-
point of the imine bond therefore it was not possible to
distinguish the imino N from the imino C. Eleven
carbonyl ligands occupy the remaining coordination
sites to give a slightly distorted octahedral geometry for
each osmium. OsꢁP, OsꢁCO and OsꢁOs bond lengths,
listed in Table 2, are identical to those reported for
[Os3(CO)11(PPh3)] [11] and similar to another reported
iminophosphino-Os3(CO)11 species and the comparable
complex [{Os3(CO)11}2(dppa)] (dppa is bis(diphenyl-
phosphino)acetylene) [15,16].
,
,
Table 2
,
Selected
bond
lengths
(A)
and
angles
(°)
for
[{Os3(CO)11}2(PNCHP)](1)·CH2Cl2 with estimated standard devia-
tions in parentheses
Os(4)ꢁOs(5)
Os(5)ꢁOs(6)
2.8990(5)
2.8844(4)
Os(4)ꢁP(2)
OsꢁCO
2.374(2)
1.881(9)–
1.960(11)
Os(4)ꢁOs(6)
2.9191(5)
C(227)ꢁC(227%) 1.316(18)
P(2)ꢁOsꢁCOeq 99.2(3)
OCeqꢁOsꢁCOeq 100.7(4)–
102.7(5)
OCaxꢁOsꢁCOeq 87.7(4)–95.1(4)

E.W. Ainscough et al. / Journal of Organometallic Chemistry 609 (2000) 2–9
5
Fig. 4. ORTEP diagram for the complex [Os3(m-H)(m3-PNCP)(CO)7] (4) showing the numbering system used. Thermal ellipsoids are at the 50%
probability level. Hydrogen atoms and solvent have been omitted for reasons of clarity.
2.2.2. Crystal structure of
[Os3(v-H)(CO)7(v3PNCP)](4)·1.5CH2Cl2
interaction of the imine bond with the osmium cluster
[19–21]. In the PNCHP free-ligand the phosphane moi-
eties are trans to the imine bond [18], however they are
Complex 4, shown in Fig. 4, has at its centre an
osmium triangle with the three OsꢁOs bond lengths at
2.7644(2) [Os(1)ꢁOs(2)], 2.8523(2) [Os(1)ꢁOs(3)] and
1
cis in 4. The hydride that was observed by H-NMR
could not be located in the X-ray structure, but a cavity
along the Os(1)ꢁOs(3) edge, as determined by the angles
C(600)ꢁOs(3)ꢁOs(1) (113.23(14)°), C(700)ꢁOs(3)ꢁOs(1)
(108.68(13)) and C(100)ꢁOs(1)ꢁOs(3) (118.47(13)°), sug-
gests a suitable position for H. In addition the longest
OsꢁOs bond is at this edge which is consistent with a
bridging H [22] and in the analogous system [Ru3(m-
H)(CO)6(m3-CPhꢀNC6H4PPh2)(m-dppm)] [20] the H is
proposed to bridge what would effectively be the
Os(1)ꢁOs(3) edge in 4.
,
2.8290(2) A (Os(2)ꢁOs(3)), as listed in Table 3. An
electron count of 48 electrons for the complex is sup-
portive of three OsꢁOs bonds [12]. The imine bond
NꢁC of the PNCP ligand caps the osmium triangle
across its mid-point with the N atom lying directly
above the Os(1)ꢁOs(3) vector, relative to the plane of
the osmium triangle, and the C atom likewise above the
Os(2)ꢁOs(3) vector. The imine-to-osmium triangle
bonding distances are 2.130(3) [NꢁOs(1)], 2.210(3)
,
A
[NꢁOs(2)], 2.050(4) [C(1)ꢁOs(2)] and 2.253(4)
[CꢁOs(3)]. The P atoms P(1) and P(2) are coordinated
to Os(3) and Os(1), respectively in equatorial positions
and have PꢁOs bond lengths of 2.3368(10) and
Table 3
,
Selected bond lengths (A) and angles (°) for [Os3(m-H)(m3-
PNCP)(CO)7](4)·1.5CH2Cl2 with estimated standard deviations in
parentheses
,
2.3326(10) A which are typical for an osmiumꢁ
arylphosphane bond [3,13–16]. Therefore the PNCP
ligand is formally a nine-electron donor. To our knowl-
edge only one other nine-electron donor ligand to Os or
Ru has been reported [3,17]. The remaining coordina-
tion sites on the osmium triangle are filled by seven
carbonyl ligands to give a distorted octahedral geome-
try around each Os atom. The OsꢁCO bond lengths
Os(1)ꢁOs(2)
Os(1)ꢁOs(3)
Os(2)ꢁOs(3)
Os(3)ꢁP(1)
Os(1)ꢁP(2)
2.7644(2) Os(1)ꢁN
2.8523(2) Os(2)ꢁC
2.8290(2) Os(3)ꢁN
2.3368(10) Os(3)ꢁC
2.3326(10) OsꢁCO
CꢁN
2.130(3)
2.050(4)
2.210(3)
2.253(4)
1.881(4)–1.933(5)
1.414(5)
NꢁOs(1)ꢁP(2) 80.65(9)
CꢁOs(3)ꢁP(1) 80.23(10) P(1)ꢁOs(3)ꢁOs(1)
Os(1)ꢁNꢁOs(3) 82.16(11) C(100)ꢁOs(1)ꢁOs(3) 118.47(13)
Os(2)ꢁCꢁOs(3) 82.06(13) C(600)ꢁOs(3)ꢁOs(1) 113.23(14)
C(700)ꢁOs(3)ꢁOs(1) 108.68(13)
P(2)ꢁOs(1)ꢁOs(3)
96.74(2)
145.30(3)
,
ranged from 1.881(4)–1.933(5) A. The imine bond NꢁC
,
at a length of 1.414(5) A has lengthened considerably
,
relative to 1.296(8) A found in the free-ligand [18].
However, this lengthening is expected as a result of the

6
E.W. Ainscough et al. / Journal of Organometallic Chemistry 609 (2000) 2–9
Fig. 5. ORTEP diagram for the complex [Os3(m-H)(m2-PNCP)(CO)8] (5a) showing the numbering system used. Thermal ellipsoids are at the 50%
probability level. Hydrogen atoms have been omitted for reasons of clarity.
2.2.3. Crystal structure of [Os3(v-H)(CO)8(v2-PNCP)]
(5a)
−14.76 ppm as a doublet of doublets. The coupling
constants of 34.0 and 5.6 Hz have been assigned to
2J(HP) hydride coupling to inequivalent P atoms. The
hydride has been postulated, based on crystallographic
evidence, to lie almost trans to one P atom and cis to
the other as depicted in Fig. 2. Therefore the larger
coupling constant has been assigned to the H involved
in the trans-like HꢁOsꢁP angle and the smaller coupling
constant to the H in the cis HꢁOsꢁP angle [19]. 31P-
NMR signals at 33.4(s) and 14.6(s) ppm support both
phosphorus atoms being coordinated in solution [23].
[Os3(m-H)(CO)8(m2-PNCP)] exists as two isomers
(Fig. 2 (5a) and (5b)) since it shows two hydride signals.
They are at −14.52 and −14.97 ppm and both have a
Complex 5a, shown in Fig. 5 with selected bond
lengths and angles listed in Table 4, can be viewed as a
‘one carbonyl-group removal’ step away from the previ-
ously discussed structure of 4. Therefore the PNCP
ligand binds to the osmium triangle in a similar fashion
to 4 except that the distances 3.680(9) [NꢁOs(3)] and
,
3.610(9) A [C(1)ꢁOs(3)] are clearly non-bonding. In this
case the PNCP ligand acts formally as a 7-electron
donor. Again, the imine bond NꢁC(1) has lengthened
,
relative to the free ligand (from 1.296(8) to 1.334(12)A)
,
but not to the extent found in 4 (1.414(5) A), this is
expected for a m2-imidoyl group compared with a m3-
imidoyl group in terms of the electron density available
for back-bonding into the antibonding orbital of the
NꢀC bond [21]. The N and C(1) were unable to be
distinguished from one another due to a half occupancy
of each atom disordered over the two sites, hence a
swapping of the N and C(1) labels of Fig. 5 gives the
2
doublet of doublets splitting pattern with J(HP) cou-
pling constants of 35.3 and 4.5 Hz and 41.4 and 5.1 Hz,
respectively. The integral ratio of the two hydride sig-
Table 4
1
isomer 5b. This was supported by the H-NMR spec-
,
Selected bond lengths (A) and angles (°) for [Os3(m-H)(m2-
PNCP)(CO)8] (5a) with estimated standard deviations in parentheses
trum where two hydride signals are observed in a 1:1
ratio (Table 1). The hydride was not located but is
proposed to be found bridging the Os(1)ꢁOs(2) bond
for the same reasons discussed for 4 above.
Os(1)ꢁOs(2)
Os(1)ꢁOs(3)
Os(2)ꢁOs(3)
Os(1)ꢁP(1)
Os(2)ꢁP(2)
2.9377(9) Os(2)ꢁN
2.8565(8) Os(1)ꢁC(1)
2.9218(7) OsꢁCO
2.322(3) C(1)ꢁN
2.320(2)
2.130(8)
2.130(9)
1.874(11)–1.940(11)
1.334(12)
2.3. NMR spectroscopic studies
NꢁOs(2)ꢁP(2)
C(1)ꢁOs(1)ꢁP(1) 74.1(2)
79.6(2)
P(1)ꢁOs(1)ꢁOs(2) 112.30(6)
P(2)ꢁOs(2)ꢁOs(1) 140.36(6)
NMR spectroscopic data are given in Table 1. The
hydride of [Os3(m-H)(CO)7(m3-PNCP)] (4) resonates at

E.W. Ainscough et al. / Journal of Organometallic Chemistry 609 (2000) 2–9
7
nals is 1:1 in the 1H-NMR spectrum of the same
crystals used for the crystallographic study. This ratio is
reproducible. However, the 1H-NMR spectrum
recorded on a sample eluted from the chromatography
band from which the crystals are grown (i.e. crude 5a/b)
show an integral ratio of 3:1 in favour of the signal at
−14.97 and again this is reproducible. Therefore it is
proposed that the product prefers to crystallise with the
isomers in a 1:1 ratio. The 31P-NMR of the crystals
used for the X-ray diffraction study show four peaks, at
32.9(s), 31.2(s), 26.3(s) and 19.1(s) ppm. The peaks at
32.9 and 26.3 ppm have been tentatively assigned to
one of the hydride isomers and the peaks at 31.2 and
19.1 ppm to the other hydride isomer. The closely
related compound 4 has similar 31P-NMR signals at
33.4 and 14.6 ppm.
spectra were obtained using a Varian VG70-250S dou-
ble-focussing magnetic sector spectrometer by the
LSIMS method using m-nitrobenzyl alcohol as the
matrix. Isotope abundance simulations were performed
to identify the parent ion. Microanalyses were per-
formed by the Campbell Microanalytical Laboratory,
University of Otago. Melting points were determined
on a Bausch & Lomb hot plate melting point apparatus
and are uncorrected with respect to calibration.
[Os3(CO)11(CH3CN)] and [Os3(CO)10(CH3CN)2] were
prepared according to literature preparations. Solvents
were dried by standard procedures. All reactions were
carried out under an inert atmosphere.
3.2. Syntheses
1
The H-NMR spectrum of [{Os3(CO)11}2(PNCHP)]
3.2.1. [{Os3(CO)11}2(PNCHP)] (1)
(1) exhibits a singlet resonance at 8.63 ppm compared
with the free ligand value of 8.92(d) ppm which has
been assigned to the imine proton. Other peaks present
in the region 7.8–5.6 ppm were assigned to the 28
aromatic protons as confirmed by peak area integra-
tion. As expected, two singlets were observed in the
31P-NMR spectrum at 0.87 and −1.8 ppm, both con-
sistent with coordinated P atoms.
The coordination isomer 2a displays an imine proton
singlet at 8.35 while 2b displays a doublet at 9.07 ppm.
This phenomenon has been fully documented [18]. Both
compounds show two peaks in their 31P-NMR spectra,
as shown in Table 1, consistent with one coordinated
and one non-coordinated P atom. Although 2b could
not be separated from 1, 2a could be isolated pure.
Subtraction of the NMR signals for pure 1 from that of
the 1/2b mixture enabled the assignments to be made
for 2b.
[Os3(CO)11(CH3CN)] (0.251 g, 0.273 mmol) dissolved
in dichloromethane (ca. 15 ml) and PNCHP (0.0749 g,
0.136 mmol) dissolved in the same solvent (ca. 3 ml)
were combined and the mixture stirred at room temper-
ature for 2.5 h. n-Hexane vapour was diffused into the
reaction mixture to initiate crystallisation. The product,
[{Os3(CO)11}2(PNCHP)] (0.198 g, 63%) was isolated as
large orange crystals, washed with n-pentane, and air-
dried. M.p: 176°C (dec). (Found: C, 30.32; H, 0.96; N,
0.61; C59H29NO22Os6P2 requires: C, 30.71; H, 1.27; N,
0.61). M+ 192Os) 2307.
(
3.2.2. [Os3(CO)11(PCHNP)] (2a)
[Os3(CO)11(CH3CN)] (0.100 g, 0.109 mmol) dissolved
in dichloromethane (ca. 10 ml) and PNCHP (0.0597 g,
0.109 mmol) in ca. 3 ml of the same solvent were
combined and then heated under reflux for 30 min. The
solvent was removed in vacuo giving yellow–orange
microcrystals, which were purified by TLC, eluting with
dichloromethane/n-hexane (2:1). Two major bands
were obtained with Rf values of 0.91 and 0.53, respec-
tively. The first band afforded a 5:1 mixture of
[{Os3(CO)11}2(PNCHP)] (1):[Os3(CO)11(PNCHP)] (2b)}
(0.0384 g, 12%) as a yellow powder, the second band
gave [Os3(CO)11(PNCHP)] (2a) (0.0252 g 16%) as a
yellow powder, after isolation by filtration, washing
with n-pentane and air-drying. M.p: 203°C (dec). MH+
The 31P-NMR signal shifts for 3 (Table 1), relative to
the free PNCHP ligand, were consistent with the coor-
dination of both P atoms to the osmium triangle. The
1H-NMR signal at 5.83 ppm assigned to the imino-pro-
ton is at a considerably higher frequency than normally
found for the coordinated ligand [4]. Unlike many
osmium–carbonyl clusters, the 13C-NMR spectrum of 3
showed the carbonyl ligands to be non-fluxional at
room temperature and the cluster to have very low
symmetry due to the complexity and number of 13C
resonances in the metal–carbonyl region of the
spectrum.
(
192Os) 1430.
3.2.3. 1,1-[Os3(CO)10(PNCHP)] (3)
[Os3(CO)10(CH3CN)2] (0.0955 g, 0.102 mmol) dis-
solved in dichloromethane (ca. 10 ml) and PNCHP
(0.0562 g, 0.102 mmol) in ca. 3 ml of the same solvent
were combined. The mixture was stirred at room tem-
perature for 2 h. The solvent volume was reduced in
vacuo and the reaction mixture purified by TLC, elut-
ing with 3:1 dichloromethane–n-hexane. The major
band was extracted into dichloromethane and the
product precipitated with hexamethyldisiloxane as an
3. Experimental
3.1. General methods
NMR measurements were performed on a JEOL
GX270W spectrometer. IR spectra were recorded on a
Perkin–Elmer FT-IR Paragon 1000 instrument. Mass

8
E.W. Ainscough et al. / Journal of Organometallic Chemistry 609 (2000) 2–9
Table 5
Crystallographic data for [{Os3(CO)11}2(PNCHP)](1)·CH2Cl2, [Os3(m-H)(m3-PNCP)(CO)7](4)·1.5CH2Cl2 and [Os3(m-H)(m2-PNCP)(CO)8] (5a/b)
Compound
1·CH2Cl2
4·1.5CH2Cl2
5a/b
Empirical formula
Formula weight
Temperature (K)
C
60.51H32Cl3O20.50Os6P2
C45H30Cl2NO7Os3P2
1400.14
200(2)
C45H29NO8Os3P2
1344.23
171(2)
2396.49
203(2)
,
Wavelength (A)
0.71073
Triclinic
0.71073
Triclinic
0.71073
Triclinic
Crystal system
Space group
(
(
(
P1
P1
P1
Unit cell dimensions
,
a (A)
11.14790(10)
17.003(2)
19.5194(2)
105.3140(10)
104.9670(10)
98.2070(10)
3358.00(5)
11.50110(10)
11.7702(2)
17.2844(2)
70.5570(10)
86.44(1)
78.6220(10)
2162.98(5)
11.289(3)
11.709(3)
17.143(5)
84.433(3)
77.697(3)
70.918(4)
2091.3(9)
2
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
Volume (A )
Z
2
2
Dcalc (Mg m−3
)
2.370
11.545
2.150
9.039
2.135
9.223
Absorption coefficient (mm−1
)
Crystal size (mm3)
0.56×0.30×0.18
1.14–27.46
−135h514, −215k521,
−255l524
31 036
0.40×0.36×0.28
1.25–27.46°.
−145h514, −155k515,
−225l522
21 157
0.68×0.48×0.30
1.95–26.42
−135h514, −145k514,
−215l521
26 697
Theta range for data collection (°)
Index ranges
Reflections collected
Independent reflections
Absorption correction
Max. and min. transmission
Completeness of data in 2q
Refinement method
14 322 [Rint=0.0533]
9351 [Rint=0.0195]
8407 [Rint=0.0664]
Semi-empirical from equivalents Semi-empirical from equivalents Semi-empirical from equivalents
0.2304 and 0.0596
100%
0.1863 and 0.1227
100%
0.1684 and 0.0619
100%
Full-matrix least-squares on F2 Full-matrix least-squares on F2 Full-matrix least-squares on F2
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I\2|(I)] a
R indices (all data)
14322/976/906
0.930
R1=0.0478, wR2=0.1289
R1=0.0667, wR2=0.1473
Mixed
9351/0/536
1.153
R1=0.0230, wR2=0.0584
R1=0.0261, wR2=0.0607
Mixed
8407/0/517
1.003
R1=0.0428, wR2=0.1010
R1=0.0640, wR2=0.1102
Mixed
Hydrogen treatment
Largest differrence peak and hole
2.954 and −3.044
1.185 and −1.424
3.201 and −3.955
−3
,
(e A
)
a wR2=[ꢀ[w(F2o−F2c)2]/ꢀ[w(F2o)2]]1/2 where w−1=[|2(F2o)+(aP)2+bP] for 5a (a=0.061; b=0.0), 4·1.5CH2Cl2 (a=0.10; b=0.0), and
1·CH2Cl2 (a=0.0267; b=4.2293) P=[max(F2o, 0)+2Fc2]/3. The structures were refined of F2o using all data; R1=ꢀꢁꢁFoꢁ−ꢁFcꢁꢁ/ꢀꢁFoꢁ.
orange powder, washed with n-pentane, and air-dried
to give 1,1-[Os(CO)10(PNCHP)] (0.0280 g, 27%). The
compound is very soluble in all common solvents.
Found: C, 37.48; H, 2.19; N, 0.89. C49H31Cl2NO10OsP2
taken to dryness in vacuo. The product was crystallised
from dichloromethane/n-hexane by vapour diffusion to
give the product as large orange crystals (0.0404 g,
30%). M.p: 182°C (dec). Found: C, 38.82; H, 2.13; N,
1.15. C45H31Cl2NO7Os3P2 requires: C, 38.66; H, 2.19;
requires: C, 37.44; H, 2.29; N, 1.04). [MꢁH]+ 192Os)
(
1400. 13C-NMR l CO (CDCl3): 193.22(d), 5.49;
193.18(s); 190.46(d) 7.32; 190.16(s); 188.59(d), 6.72;
186.72(d), 6.71 Hz; 179.68(d), 3.67; 178.49(d), 2.44;
172.67(d), 2.44 Hz; 170.32(s).
N, 0.98). M+ 192Os) 1317.
(
3.2.5. [Os3(v-H)(CO)8(v2-PNCP)] (5a/b)
[Os3(CO)10(CH3CN)2] (0.0910 g, 0.0976 mmol) and
PNCHP (0.0538 g, 0.0979 mmol) were combined in
dichloromethane (ca. 12 ml) and heated to reflux for 30
min. Freshly sublimed trimethylamineoxide (0.0147 g,
0.196 mmol) in dichloromethane (ca. 5 ml) was added
dropwise to the red reaction mixture, resulting in a
colour change to very dark-brown after 1 h. After a
further 1 h when the reaction mixture became red
again, it was allowed to cool. It was passed through a
small alumina column (200–400 mesh) to remove any
excess trimethylamineoxide, eluting with dichloro-
3.2.4. [Os3(v-H)(CO)7(v3-PNCP)] (4)
[Os3(CO)10(CH3CN)2] (0.0960 g, 0.103 mmol) and
PNCHP (0.0561 g, 0.102 mmol) were combined in
dichloromethane (45 ml) and stirred at room tempera-
ture for 110 min, to form 1,1-[Os3(CO)10(PNCHP)] in
situ. Freshly sublimed trimethylamineoxide (0.0155 g,
0.206 mmol) in acetonitrile (ca. 5 ml) was added drop-
wise to the red–orange solution over 135 min. The
reaction mixture was stirred for a further 22 h then

E.W. Ainscough et al. / Journal of Organometallic Chemistry 609 (2000) 2–9
9
methane. The solvent was then removed in vacuo. The
Acknowledgements
crude reaction product(s) was run down a silica gel
(100–200 mesh) column, eluting successively with 0, 1,
10, and 100% solutions of methanol in dichloro-
methane, to give an orange, yellow, yellow and yellow
band, respectively. The fractions were taken to dryness
in vacuo. The major band was the first orange band
and this was further purified by TLC, eluting with
dichloromethane. The product was crystallised from
dichloromethane–n-hexane by vapour diffusion to give
the product as red–orange crystals (0.0014 g, 1%).
Microanalytical data could not be obtained due to
We thank the Massey University Research Fund for
financial support.
References
[1] E.W. Abel, F. Gordon, A. Stone, G. Wilkinson (Eds.), Compre-
hensive Organometallic Chemistry II: A Review of the Literature
1982–1984, Pergamon, Oxford, 1995, pp. 700–709 (and refer-
ences within).
[2] C.J. Adams, M.I. Bruce, O. Ku¨hl, B.W. Skelton, A.H. White, J.
Organomet. Chem. 445 (1993) C6.
[3] K.L. Lu, H.J. Chen, P.Y. Lu, S.Y. Li, F.E. Hong, S.M. Peng,
G.H. Lee, Organometallics 13 (1994) 585.
[4] E.W. Ainscough, A.M. Brodie, A.K. Burrell, S.M.F. Kennedy,
J.M. Waters, P.D. Buckley, J. Chem. Soc. Dalton Trans. (ac-
cepted for publication).
insufficient amount of sample. M+ 192Os) 1345. This
(
compound is also observed in the ageing of 3 and in the
synthesis of 4.
[5] E.W. Abel, F. Gordon, A. Stone, G. Wilkinson (Eds.), Compre-
hensive Organometallic Chemistry II: A Review of the Literature
1982–1984, Pergamon, Oxford, 1995, p. 715 (and references
within).
[6] A.J. Deeming, S. Donovan-Mtunzi, S.E. Kabir, J. Organomet.
Chem. 333 (1987) 253.
[7] G. Su¨ss-Fink, H. Jungbluth, J. Organomet. Chem. 352 (1988) 185.
[8] A.J Deeming, S. Donovan-Mtunzi, S.E. Kabir, P.J. Manning, J.
Chem. Soc. Dalton Trans. (1985) 1037.
[9] A.J. Deeming, M.B. Smith, J. Chem. Soc. Chem. Commun. (1993)
844.
[10] D. Heijdenrijk, J.T.B.H. Jastrzebski, G. van Koten, T. Maha-
biersing, C.H. Stam, K. Vrieze, R. Zoet, Organometallics 7 (1988)
2108.
[11] M.I. Bruce, C.A. Hughes, M.J. Liddell, B.W. Skelton, A.H.
White, J. Organomet. Chem. 347 (1988) 157.
[12] E.W. Abel, F. Gordon, A. Stone, G. Wilkinson (Eds.), Compre-
hensive Organometallic Chemistry II: A Review of the Literature
1982–1984, Pergamon, Oxford, 1995, p. 689 (and references
within).
[13] D. Braga, F. Grepioni, C. Gradella, B.F.G. Johnson, J. Lewis, M.
Monari, J. Chem. Soc. Dalton Trans. (1990) 2863.
[14] A.J. Deeming, S. Donovan-Mtunzi, K.I. Hardcastle, K. Henrick,
S.E. Kabir, M. McPartlin, J. Chem. Soc. Dalton Trans. (1988)
579.
3.3. Molecular structure determination of
[{Os3(CO)11}2(PNCHP)](1)·CH2Cl2,
[Os3(v-H)(CO)7(v3-PNCP)](4)·1.5CH2Cl2 and
[Os3(v-H)(CO)8(v2-PNCP)] (5a)
Data collection and refinement were performed as
previously described using a Siemens SMART diffrac-
tometer MoꢁKa radiation, graphite monochromator,
,
u=0.71073 A [24]. The relevant details are given in
Table 5. Refinements for 4·1.5CH2Cl2 and 5a were
routine. However, 1·CH2Cl2 contains a significant dis-
order. There are two independent molecules which are
generated by the symmetry operation. As a result of the
symmetry operation the imine nitrogen and carbon are
disordered and were modelled using carbon atoms.
Furthermore, one of the independent molecules has two
different orientations for the Os triangle. The disorder
was modelled using 86% occupancy for the major com-
ponent [Os(1a), Os(2a), Os(3a)] and 14% for the minor
[Os(1b), Os(2b), Os(3b)]. Unfortunately, it was not pos-
sible to identify the carbonyl ligands from difference
maps for the minor occupancy Os triangle and these
have been omitted from the refinement.
[15] C.J Adams, P. Braunstein, M.I. Bruce, S.C. Cea, W.R. Cullen,
P.A. Duckworth, P.A. Humphrey, O. Ku¨hl, B.W. Skelton, E.R.T.
Tiekink, A.H. White, J. Organomet. Chem. 467 (1994) 251.
[16] A.J. Amoroso, B.F.G. Johnson, J. Lewis, A.D. Massey, P.R.
Raithby, W.T. Wong, J. Organomet. Chem. 440 (1992) 219.
[17] E.W. Abel, F. Gordon, A. Stone, G. Wilkinson (Eds.), Compre-
hensive Organometallic Chemistry II: A Review of the Literature
1982–1984, Pergamon, Oxford, 1995, p. 709 (and references
within).
[18] X. Fan, MPhil Thesis, Massey University, New Zealand, 1995.
[19] M. Day, D. Espitia, K.I. Hardcastle, S.E. Kabir, E. Rosenberg,
Organometallics 10 (1991) 3550.
[20] C.J. Adams, M.I. Bruce, O. Ku¨hl, B.W. Skelton, A.H. White, J.
Organomet. Chem. 445 (1993) C6.
[21] R.D. Adams, N.M. Golembeski, Inorg. Chem. 17 (1978) 1969.
[22] E.W. Abel, F. Gordon, A. Stone, G. Wilkinson (Eds.), Compre-
hensive Organometallic Chemistry II: A Review of the Literature
1982–1984, Pergamon, Oxford, 1995, p. 715 (and references
within).
[23] S. Berger, S. Braum, H.-O. Kalinowski, NMR Spectroscopy of
the Non-metallic Elements, Wiley, Chichester, 1997, p. 835.
[24] A.K. Burrell, K.C. Gordon, S.E. Page, Inorg. Chem. 37 (1998)
4452.
4. Supplementary data
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 139389 for compound 1,
139390 for compound 4 and 139391 for compound 5a.
Copies of this information may be obtained free of
charge from: The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (Fax: +44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).