C-H Activation of 3,3-diphenylcyclopropene in the reaction with Os(CO)2(PPh3)3: 3,3-diphenylcyclopropenyl, 2,2-diphenylcyclopropyl, and 3-phenylindenyl complexes of osmium(II)

Article abstract of DOI:10.1016/j.jorganchem.2006.08.022

Reaction between Os(CO)₂(PPh₃)₃ and 3,3-diphenylcyclopropene under quartz-halogen irradiation leads to C(sp²)-H bond activation and the formation of the 3,3-diphenylcyclopropenyl complex, OsH[C₃H(Ph-2)₂](CO)₂(PPh₃)₂ (1). When complex 1 is heated there is ring-opening of the cyclopropene ring and rearrangement to the 3-phenylindenyl complex, OsH[C₉H₆(Ph-3)](CO)₂(PPh₃)₂ (2). Compound 1 reacts with HCl forming the 2,2-diphenylcyclopropyl complex, OsCl[C₃H₃(Ph-2)₂](CO)₂(PPh₃)₂ (3). Reaction of either 1 or 3 with excess HCl leads to reversible formation of the hydroxycarbene complex, OsCl₂[{double bond, long}C(OH)C₃H₃(Ph-2)₂](CO)(PPh₃)₂ (4), through protonation of the acyl group formed by a migratory insertion reaction involving a carbonyl ligand and the σ-bound 2,2-diphenylcyclopropanyl ligand. An X-ray crystal structure determination of 2 is reported.

Full text of DOI:10.1016/j.jorganchem.2006.08.022

Journal of Organometallic Chemistry 691 (2006) 4901–4908
www.elsevier.com/locate/jorganchem
C–H Activation of 3,3-diphenylcyclopropene in the reaction
with Os(CO)2(PPh3)3: 3,3-diphenylcyclopropenyl,
2,2-diphenylcyclopropyl, and 3-phenylindenyl
complexes of osmium(II)
*
*
George R. Clark, Warren R. Roper , Deborah M. Tonei, L. James Wright
Department of Chemistry, The University of Auckland, Private Bag 92019, 23 Symonds Street, Auckland, New Zealand
Received 30 June 2006; received in revised form 7 August 2006; accepted 11 August 2006
Available online 22 August 2006
Abstract
Reaction between Os(CO)2(PPh3)3 and 3,3-diphenylcyclopropene under quartz–halogen irradiation leads to C(sp2)–H bond activa-
tion and the formation of the 3,3-diphenylcyclopropenyl complex, OsH[C3H(Ph-2)2](CO)2(PPh3)2 (1). When complex 1 is heated there
is ring-opening of the cyclopropene ring and rearrangement to the 3-phenylindenyl complex, OsH[C9H6(Ph-3)](CO)2(PPh3)2 (2). Com-
pound 1 reacts with HCl forming the 2,2-diphenylcyclopropyl complex, OsCl[C3H3(Ph-2)2](CO)2(PPh3)2 (3). Reaction of either 1 or 3
with excess HCl leads to reversible formation of the hydroxycarbene complex, OsCl2[@C(OH)C3H3(Ph-2)2](CO)(PPh3)2 (4), through
protonation of the acyl group formed by a migratory insertion reaction involving a carbonyl ligand and the r-bound 2,2-diphenylcyclo-
propanyl ligand. An X-ray crystal structure determination of 2 is reported.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: C–H Activation; Osmium; X-ray crystal structure; 3,3-Diphenylcyclopropenyl; 2,2-Diphenylcyclopropenyl; 3-Phenylindenyl
1. Introduction
stituents on the cyclopropene. More complex products aris-
ing from oxidative cyclisations with two molecules of
cyclopropene at a single metal centre have also been
reported [2].
The interaction of cyclopropene and substituted cyclo-
propenes with transition metals is a contemporary area of
research that has proved relevant to organometallic, bioin-
organic, and organic chemistry. The major product classes
formed through these interactions are presented in Chart 1.
Two main types of reactivity have been recognised, either
g2-coordination of the intact cyclopropene ligand to form
a p-adduct (illustrated by A in Chart 1), or ring-opening
reactions that can give rise to either vinyl alkylidene species
(B in Chart 1) or metallacyclobutenes (C in Chart 1) [1].
The type of product that forms depends upon the nature
of the transition metal, the ancillary ligands, and the sub-
The metal–cyclopropene interaction in the g2-bound
cyclopropene complexes ranges from relatively weak (best
described as an g2-olefin complex) to strong as depicted
by A in Chart 1 which is really a metallabicyclo-
[1.1.0]butane. By analogy with complexes of simple
alkenes, the weaker interaction would be expected for tran-
sition metals in higher oxidation states, where the alkene
acts principally as a r-donor. In this case there would be
expected to be minimal change to the length of the C@C
bond and the internal angles in the cyclopropene ring. By
contrast, the stronger interaction exemplified by the metal-
labicyclo[1.1.0]butane structure (A) is characterised by sig-
nificant lengthening of the C@C bond and bond angles at
these carbon atoms become more consistent with sp3
*
Corresponding authors. Tel.: +64 9 373 7999x8320; fax: +64 9 373
7422 (W.R. Roper).
E-mail address: w.roper@auckland.ac.nz (W.R. Roper).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.08.022

4902
G.R. Clark et al. / Journal of Organometallic Chemistry 691 (2006) 4901–4908
rhodabenzvalene complexes have been reported [14–17].
A related structure has been reported for molybdenum(II),
where the cyclopropene is tethered to the metal by a car-
boxylate group [18].
In contrast to all the above complexes which retained
an intact cyclopropene ring, it is also possible to have
products resulting from ring-opening forming either vinyl
alkylidene complexes (type B in Chart 1) or metallacyclo-
butenes (type C in Chart 1). Of the ring-opened struc-
tures the vinyl alkylidene complexes of type B,
particularly ruthenium(II) alkylidene complexes which
have found wide application as metathesis catalysts
[19], are better known than the metallacyclobutenes.
The original ruthenium(II) alkylidene complex reported
by Grubbs and co-workers was formed by reaction of
either RuCl2(PPh3)3 or RuCl2(PPh3)4 with 3,3-diphenyl-
cyclopropene [20], the same cyclopropene employed in
the current study. 3,3-Diphenylcyclopropene also forms
alkylidene complexes with rhenium [21] and tantalum
[22]. Ring-opening to give metallacyclobutenes has been
observed in reactions between fluorine-substituted
cyclopropenes with complexes of platinum(0) [23] and
iridium(I) [24]. Metallacyclobutene complexes have also
been identified as the rearrangement products of the
g2-1,2-diphenylcyclopropene complexes of titanium and
zirconium described above [12], whereas alkylidene
complexes of titanium and zirconium have been
prepared from titanocene and zirconocene with 3,3-
dimethyl-, 3,3-diphenyl- and 3,3-methyl-3-phenylcyclo-
propene [25].
Chart 1. Different structure types from the interaction of cyclopropenes
with low oxidation state metal centres, including a new structure type (D)
from a C–H activation pathway.
hybridisation. This results in significant relief of ring strain
for the three-membered ring.
Cyclopropene complexes have been investigated in
nitrogenase reactivity modeling studies, since cycloprop-
enes have been shown to be potential nitrogenase sub-
strates, being reduced by transition metal complexes to
generate cyclopropane and propene [3]. The main focus
on nitrogenase model chemistry has focussed on complexes
formed with platinum(0) [4–6] with X-ray crystal structures
published for three platinum complexes, [Pt(1,2-Me2C3H2)-
(PPh3)2] [4], [Pt(3,3-Ph2C3H2)(PPh3)2] and [Pt(1,2-
Ph2C3H2)(PPh3)2] [6]. Nickel complexes have also been
synthesised [7] and recently the first crystal structure of
nickel(0) with a completely substituted cyclopropene,
[Ni(3-Me-3-tert-butyl-1,2-(CO2Me)2C3], was reported [8].
Iridium complexes of 3,3-diphenylcyclopropene have also
been prepared, with an X-ray crystal structure reported
for [IrCl(CO)(PMe3)2(3,3-Ph2C3H2)] [9]. As would be
expected for complexes of low oxidation state metals, all
of these complexes can be described as structural type A
[5,6,8,9].
The diverse reactivity of cyclopropenes upon interaction
with low oxidation state complexes prompted us to exam-
ine the interaction of 3,3-diphenylcyclopropene with the
low oxidation state complexes, OsCl(NO)(PPh3)3 and
Os(CO)2(PPh3)3. We have already described that with
OsCl(NO)(PPh3)3
a
regular g2-coordinated complex,
Os(g2-3,3-diphenylcyclopropene)Cl(NO)(PPh3)2, is formed
and that this complex upon treatment with HCl ring-opens
and rearranges, via a hydride migration, to the r-diphenyl-
allyl complex, Os(CH2CH@CPh2)Cl2(NO)(PPh3)2 [26]. We
now report that the reaction of 3,3-diphenylcyclopropene
with Os(CO)2(PPh3)3 follows a previously unobserved
pathway which involves sp2 C–H activation and leads to
a 3,3-diphenylcyclopropenyl, hydride complex as illus-
trated by D in Chart 1.
Complexes involving Group 6 transition metals are
typified by W(g2-3,3-diphenylcyclopropene)Cl2(NPh)-
[P(OMe)3]2 for which a crystal structure determination also
reveals bonding consistent with type A coordination [10].
Other examples involving earlier transition metals, which
have only been characterised spectroscopically, are
[(Cp)2Nb(C3H4)] [11], as well as complexes of g2-coordi-
nated 1,2-diphenylcyclopropene with titanocene and zirc-
onocene, and g2-coordinated 4,8-dioxaspiro[2.5]oct-1-ene
with titanocene [12].
Herein, we report (i) the formation of the 3,3-diphenyl-
cyclopropenyl complex, OsH[C3H(Ph-2)2](CO)2(PPh3)2
(1), when solutions of Os(CO)2(PPh3)3 and 3,3-diphenylcy-
clopropene are placed under quartz–halogen irradiation,
(ii) the thermal rearrangement of 1 to the 3-phenylindenyl
complex, OsH[C9H6(Ph-3)](CO)2(PPh3)2 (2), the structure
of which is confirmed by X-ray crystal structure determina-
tion, (iii) the reaction of 1 with excess HCl to give the
hydroxycarbene complex, OsCl2[@C(OH)C3H3(Ph-2)2]-
(CO)(PPh3)2 (4), and (iv) the deprotonation of 4 to give
the 2,2-diphenylcyclopropyl complex, OsCl[C3H3(Ph-2)2]-
(CO)2(PPh3)2 (3).
A special case of an g2-coordinated cyclopropene is
where the cyclopropene is tethered to the metal in the met-
allabenzvalenes, studied by Haley and co-workers [13].
Crystal structures for several of these iridabenzvalene and

G.R. Clark et al. / Journal of Organometallic Chemistry 691 (2006) 4901–4908
4903
2. Results and discussion
In view of the fact that the zerovalent complex, OsCl-
(NO)(PPh3)3, forms a regular g2-complex with 3,3-diphe-
nylcyclopropene [26] and also that both C2H4 [28] and
2.1. Reaction between 3,3-diphenylcyclopropene and
Os(CO)2(PPh3)3 to give the 3,3-diphenylcyclopropenyl
complex, OsH[C3H(Ph-2)2](CO)2(PPh3)2 (1)
maleic
anhydride
[29]
form
g2-adducts
with
Os(CO)2(PPh3)3, it is quite remarkable that 3,3-diphenylcy-
clopropene undergoes a C–H activation reaction with
Os(CO)2(PPh3)3. The situation is reminiscent of that exist-
ing in the interaction of ethylene with low oxidation state
iridium centres where the hydrido-, vinyl-product is some-
times more stable than the g2-ethylene adduct [30,31]. The
only other example of a cyclopropenyl ligand bound to a
transition metal through one of the alkene carbon of which
we are aware was derived from the reaction of
As depicted in Scheme 1, reaction between Os(CO)2-
(PPh3)3 and 3,3-diphenylcyclopropene under quartz–halo-
gen tungsten lamp irradiation (pyrex filtered) at room
temperature leads to fading of the yellow colour of
Os(CO)2(PPh3)3 to an almost colourless solution over a
period of 15 min. The cyclopropenyl-, hydride-complex,
OsH[C3H(Ph-2)2](CO)2(PPh3)2 (1), can be isolated in mod-
erate yield. The IR spectrum of 1 shows two strong m(CO)
bands at 2016 and 1981 cmꢀ1 indicating mutually cis CO
ligands. In the 13C NMR spectrum two signals are seen
for the CO ligands at 181.1 (2JCP = 7.4 Hz) and 181.9
(2JCP = 7.9 Hz) ppm, each signal being a triplet through
coupling to two equivalent phosphorus nuclei. Consistent
with this there is only one singlet resonance in the 31P
NMR spectrum for the two equivalent phosphorus ligands
and therefore the geometry of 1 is unambiguously defined
Pt(C2H4)(PPh3)2
with
3-chloromethyl-1,2-dichloro-
3-methycyclopropene. The product is claimed to arise
through oxidative addition involving one of the chlorines
originally at the double bond [6].
2.2. Thermal rearrangement of OsH[C3H(Ph-2)2]-
(CO)2(PPh3)2 (1) to the 3-phenylindenyl complex,
OsH[C9H6(Ph-3)](CO)2(PPh3)2 (2) and the crystal
structure of 2
1
as drawn in Scheme 1. The H NMR spectrum of 1 shows
a high-field triplet resonance at ꢀ5.78 (2JHP = 20.47 Hz)
ppm for the hydride ligand. The hydrogen on the cyclop-
ropenyl ring appears as a singlet at 6.29 ppm. The three
cyclopropenyl ring carbon atoms appear at 113.1 (t,
2JCP = 14.3 Hz) ppm for the osmium-bound carbon atom,
at 121.0 (t, 2JCP = 5.0 Hz) ppm for the @CH carbon atom,
and at 32.7 ppm for the saturated CPh2 carbon atom. It
can be noted that related complexes containing acyclic
vinyl ligands also show coupling of the b-carbon atom to
phosphorus [27].
OsH[C3H(Ph-2)2](CO)2(PPh3)2 (1) rearranges slowly in
toluene solution at 60 ꢁC over 2.5 h to give another colour-
less material identified as the 3-phenylindenyl complex,
OsH[C9H6(Ph-3)](CO)2(PPh3)2 (2) in high yield. The IR
spectrum of 2 shows two strong m(CO) bands at 2021 and
1958 cmꢀ1, positions similar to that of complex 1 and
indicative of a cis arrangement of the CO ligands. The
transformation of 1 to 2 is most conveniently monitored
by observing the 31P NMR spectrum since complex 1 has
a singlet resonance while complex 2 shows two doublet res-
onances at 10.93 (2JPP = 249.7 Hz) ppm and 7.97
(2JPP = 249.7 Hz) ppm. The large phosphorus–phosphorus
coupling is indicative of mutually trans and inequivalent
phosphorus atoms [32,33]. This fixes the geometry of the
complex as depicted in Scheme 1 and this was confirmed
by an X-ray crystal structure determination (see below).
The non-equivalence of the phosphorus atoms arises
because of the osmium-bound chiral carbon atom of the
3-phenylindenyl ligand. Note that in complex 1 the
osmium-bound carbon atom from the 3,3-diphenylcyclop-
ropenyl ligand is not chiral. The hydride ligand on osmium
appears in the 1H NMR spectrum as an apparent triplet at
ꢀ5.15 ppm. The hydrogen on the osmium-bound carbon
atom also has the appearance of an apparent triplet at
4.10 ppm. Similarly, in the 13C NMR spectrum the
osmium-bound carbon atom appears at 19.7 ppm as an
apparent triplet as do the two CO carbon atoms at 179.8
and 186.0 ppm.
The molecular geometry of complex 2 is shown in Fig. 1,
with crystal data collected in Table 1. Selected bond lengths
and angles are presented in Table 2. The structure confirms
the geometry deduced from spectroscopic data above, i.e.,
octahedral coordination about osmium with mutually trans
triphenylphosphine ligands and mutually cis CO ligands.
Scheme 1. C–H activation in the reaction of 3,3-diphenylcyclopropene
with Os(CO)2(PPh3)3 and subsequent rearrangement of the r-bound 3,3-
diphenylcyclopropenyl complex (1) to the r-bound 3-phenylindenyl
complex (2).

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G.R. Clark et al. / Journal of Organometallic Chemistry 691 (2006) 4901–4908
Table 2
˚
Selected bond lengths (A) and angles (ꢁ) for 2
Bond lengths
Os–C(17)
Os–C(16)
Os–C(1)
1.892(8)
1.944(9)
2.290(7)
Os–P(2)
Os–P(1)
2.3767(19)
2.3864(19)
1.485(11)
1.489(11)
1.363(11)
1.448(11)
1.399(11)
1.421(11)
1.397(12)
1.392(12)
1.395(12)
1.406(11)
C(1)–C(9)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(4)–C(9)
C(5)–C(6)
C(6)–C(7)
C(7)–C(8)
C(8)–C(9)
Bond angles
C(17)–Os–C(16)
C(17)–Os–C(1)
C(16)–Os–C(1)
C(17)–Os–P(2)
C(16)–Os–P(2)
92.5(3)
176.2(3)
90.9(3)
87.2(2)
95.0(2)
Fig. 1. The crystal structure of complex 2 showing the atom labelling and
C(1)–Os–P(2)
90.9(2)
depicting the atoms as 50% probability displacement ellipsoids [47].
C(17)–Os–P(1)
C(16)–Os–P(1)
C(1)–Os–P(1)
90.1(2)
95.9(2)
91.2(2)
P(2)–Os–P(1)
168.88(7)
107.3(3)
101.1(4)
96.7(3)
Table 1
C(31)–P(1)–C(41)
C(31)–P(1)–C(21)
C(41)–P(1)–C(21)
C(31)–P(1)–Os
C(41)–P(1)–Os
C(21)–P(1)–Os
C(61)–P(2)–C(51)
C(61)–P(2)–C(71)
C(51)–P(2)–C(71)
C(61)–P(2)–Os
C(51)–P(2)–Os
C(71)–P(2)–Os
C(9)–C(1)–C(2)
C(9)–C(1)–Os
Data collection and processing parameters for 2
Compound
2 Æ 0.5CH2Cl2
C53.5H42ClO2OsP2
1004.46
114.3(2)
120.4(2)
114.1(3)
105.5(4)
100.9(4)
100.7(4)
115.2(3)
118.3(3)
113.9(3)
101.9(6)
118.4(5)
114.7(5)
112.4(7)
107.7(7)
119.6(7)
132.1(7)
108.3(7)
119.4(7)
131.1(7)
109.5(7)
Empirical formula
Molecular weight
Crystal system
Space group
Triclinic
ꢀ
P1
˚
a (A)
9.8165(1)
14.1863(2)
17.3840(2)
72.637(1)
86.346(1)
86.121(1)
2302.88(5)
85(2)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
C(2)–C(1)–Os
T (K)
C(3)–C(2)–C(1)
C(2)–C(3)–C(4)
C(5)–C(4)–C(9)
C(5)–C(4)–C(3)
C(9)–C(4)–C(3)
C(8)–C(9)–C(4)
C(8)–C(9)–C(1)
C(4)–C(9)–C(1)
Z
2
Dcalc (g cmꢀ3
F(000)
)
1.449
1004
2.936
l (mmꢀ1
)
Crystal size (mm)
h (Min–max) (ꢁ)
Independent reflections (I > 2rI)
0.20 · 0.08 · 0.08
2.21–25.72
8667 (Rint 0.0512)
0.7449, 0.8432
1.026
T (Min, max)
Goodness-of-fit on F2
R, wR2 (observed data)
R, wR2 (all data)
0.0557, 0.1331
0.0703, 0.1423
P
P
rings about P(1) adjusts to accommodate the bulk of the
3-phenylindenyl ligand. This is most obvious in that the
benzene ring C(41)–C(46) is pushed towards the ring
C(21)–C(26) such that the C(41)–P(1)–C(21) angle is
reduced to 96.7(3)ꢁ. The Os–C(1) distance to the 3-phenyl-
R = iFoj ꢀ jFci/ jFoj.
P
P
2
2
1=2
wR2 ¼ f ½wðF 2o ꢀ F c2Þ ꢁ= ½wðF 2oÞ ꢁg
.
The hydride ligand was not located. The two Os–P dis-
tances are significantly different (Os–P(1), 2.3864(19) and
Os–P(2), 2.3767(19) A) in keeping with the non-equivalence
evident from the spectroscopic data discussed above. The
presence of the 3-phenylindenyl ligand causes distortion
of the geometry at P(1) as the disposition of the phenyl
˚
indenyl ligand is 2.290(7) A. This is an extraordinarily long
˚
Os–C distance as can be seen by comparing the Os–CH3
˚
distance (2.209(4) A) in Os(Me)(SnMe2Cl)(CO)2(PPh3)2, a
related molecule which also has mutually trans triphenyl-
phosphine molecules and mutually cis CO ligands [34].

G.R. Clark et al. / Journal of Organometallic Chemistry 691 (2006) 4901–4908
4905
Undoubtedly the steric bulk of the 3-phenylindenyl ligand
contributes to the long Os–C(1) distance.
carbene carbon atom, the saturated 2,2-diphenylcyclopro-
pyl group. A likely intermediate in this transformation is
labeled A in Scheme 2, i.e., a cationic cyclopropanylidene
complex from b-protonation of the cyclopropenyl ligand
in complex 1. The protonation of vinyl ligands to give car-
bene complexes is an established organometallic reaction
[39]. Hydride migration from osmium to the carbene car-
bon atom driven by chloride coordination gives the
2,2-diphenylcyclopropyl complex, OsCl[C3H3(Ph-2)2]-
(CO)2(PPh3)2 (3). Again there is ample precedent for this
type of transformation [40]. Finally, migration of the 2,2-
diphenylcyclopropyl onto an adjacent CO ligand accompa-
nied by protonation at the resulting acyl oxygen atom and
further chloride coordination gives the hydroxycarbene
complex, OsCl2[@C(OH)C3H3(Ph-2)2](CO)(PPh3)2 (4).
This final protonation is reversible and a convenient syn-
thesis of OsCl[C3H3(Ph-2)2](CO)2(PPh3)2 (3) involves addi-
tion of aqueous NaOH to OsCl2[@C(OH)C3H3(Ph-2)2]-
(CO)(PPh3)2 (4). There is precedent for the formation of
an hydroxycarbene complex on osmium by this same pro-
cess in that treatment of the closely related ethyl derivative,
Os(Et)Cl(CO)2(PPh3)2, with HCl gives OsCl2[@C(OH)Et]-
(CO)(PPh3)2 [28].
The facile rearrangement of the 3,3-diphenylcycloprope-
nyl ligand in complex 1 to the 3-phenylindenyl ligand in
complex 2 requires comment. It is well-known that phe-
nyl-substituted cyclopropenes can be induced to rearrange
to indenes, the reaction being promoted thermally, by acid
or by irradiation [2a]. A specific example is that molten
tetraphenylcyclopropene rearranges quantitatively to
1,2,3-triphenylindene [35a] and there are numerous other
examples of related rearrangements [35b–35m]. Clearly,
the ready isomerisation of the osmium-substituted cyclo-
propene ring in complex 1 to the osmium-substituted
indene in complex 2 is facilitated by the presence of the
osmium substituent. It can be noted that the isomerisation
of 1,2,3-triphenylcyclopropene to 1,2-diphenylindene has
been reported to be catalysed by platinum [36]. It may be
relevant that ruthenium complexes [37] and osmium com-
plexes [38] bearing the diphenylvinyl substituted carbyne
ligand rearrange to stable complexes bearing a 3-phenylin-
denylidene ligand. It is conceivable that ring-opening of the
cyclopropenyl ligand while bound to osmium in complex 1
could generate a diphenylvinyl substituted carbyne ligand
and after rearrangement of this to a 3-phenylindenylidene
ligand, hydride return from osmium to the carbene ligand
would produce the observed 3-phenylindenyl complex 2.
The IR spectrum of complex 3 shows two strong m(CO)
bands at 2025 and 1957 cmꢀ1 consistent with the presence
of two cis CO ligands. In the 31P NMR spectrum complex 3
shows two doublet resonances at ꢀ9.62 (2JPP = 308.0 Hz)
ppm and ꢀ14.02 (2JPP = 308.0 Hz) ppm. The large phos-
phorus-phosphorus coupling is indicative of mutually trans
and inequivalent phosphorus atoms [32,33] so fixing the
geometry of the complex as depicted in Scheme 2. Once
again the osmium-bound carbon atom of the 2,2-diphenyl-
cyclopropyl ligand is chiral, accounting for the non-equiv-
alence of the phosphorus atoms. The two hydrogen atoms
of the methylene group in the cyclopropyl ring are also
inequivalent for the same reason and as a consequence in
2.3. The reaction of OsH[C3H(Ph-2)2](CO)2(PPh3)2 (1)
with HCl to give initially the 2,2-diphenylcyclopropyl
complex, OsCl[C3H3(Ph-2)2](CO)2(PPh3)2 (3), and
further reversible reaction with HCl to give the
hydroxycarbene complex, OsCl2[@C(OH)C3H3(Ph-2)2]-
(CO)(PPh3)2 (4)
As depicted in Scheme 2, the addition of an excess of
HCl to OsH[C3H(Ph-2)2](CO)2(PPh3)2 (1) produces the
hydroxycarbene complex, OsCl2[@C(OH)C3H3(Ph-2)2]-
(CO)(PPh3)2 (4) which has as the other substituent on the
1
the H NMR spectrum of 3 two separate resonances are
observed, each a doublet of doublets, at 1.14 (2JHH
=
4.1 Hz; JHH = 10.2 Hz) ppm and 1.59 (2JHH = 4.3 Hz;
3JHH = 9.2 Hz) ppm. The proton on the osmium-bound
carbon atom appears as a broad apparent triplet at
1.94 ppm. In the 13C NMR spectrum of 3 the three satu-
rated cyclopropyl ring carbon atoms appear at 23.6
(OsCH), 35.8 (CH2), and 37.5 (CPh2) ppm while the two
CO ligands appear at 174.8 and 178.0 ppm.
3
The IR spectrum of complex 4 shows only one strong
m(CO) band at 1949 cmꢀ1 indicating the presence of one
terminal CO ligand. In the 31P NMR spectrum complex 4
shows two doublet resonances at ꢀ9.87 (2JPP = 293.1 Hz)
ppm and 0.56 (2JPP = 293.1 Hz) ppm. The large phospho-
rus–phosphorus coupling is again indicative of mutually
trans and inequivalent phosphorus atoms [32,33], consis-
tent with the geometry of the complex as depicted in
Scheme 2. Once again the carbon atom of the 2,2-diphenyl-
cyclopropyl substituent bound to the carbene carbon
ligand is chiral, accounting for the non-equivalence of the
phosphorus atoms. The 1H NMR spectrum reveals the
Scheme 2. Reactions of complex 1 with HCl, complex A marked with an
asterix is a postulated intermediate.

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G.R. Clark et al. / Journal of Organometallic Chemistry 691 (2006) 4901–4908
presence of the hydroxycarbene ligand by the singlet reso-
nance at 13.49 ppm attributable to the OH group. This
chemical shift is typical of hydroxyl carbene complexes,
e.g., Cr[@C(OH)Me](CO)5 has an OH resonance at
12.35 ppm [41]. Another characteristic feature of the
hydroxyl carbene ligand in complex 4 is the very low-field,
apparent triplet resonance that appears in the 13C NMR
spectrum at 269.8 ppm (2JCP = 6.1 Hz, Os@COH). The
three saturated cyclopropyl ring carbon atoms appear at
27.0 (s, CH2), 46.9 (s, CPh2), and 54.7 (s, CH) ppm while
the single CO ligand appears at 178.6 ppm.
Elemental analyses were obtained from the Microanalytical
Laboratory, University of Otago.
4.2. Preparation of OsH[C3H(Ph-2)2](CO)2(PPh3)2 (1)
Os(CO)2(PPh3)3 (0.465 g, 0.45 mmol) was dissolved/sus-
pended in deoxygenated benzene (50 mL) contained in a
250 mL Pyrex Schlenk tube and 3,3-diphenylcyclopropene
(0.200 mL, 1.15 mmol) was added. The resulting mixture
was irradiated with a quartz–halogen tungsten lamp
(1000 W) for 15 min with air-cooling of the vessel to ensure
the temperature did not rise above 30 ꢁC. During this time
all the material dissolved and the colour faded from the
bright yellow of Os(CO)2(PPh3)3 to a very pale yellow. This
solution was then stirred for 1 h without the lamp at room
temperature. The solvent was then removed under vacuum
to give a cream-coloured solid. This was purified by chro-
matography on silica gel, using dichloromethane as eluent.
The major colourless band eluted from the column was col-
lected (monitored by thin layer chromatography) and the
solvent removed. The resulting solid was washed with hex-
ane to give pure 1 as an almost colourless solid (0.194 g,
45%). m/z 964.22609 (M + H)+; C53H42O2OsP2 requires
964.22749. Anal. Calc. for C53H42O2OsP2: C, 66.10; H,
4.40. Found: C, 66.16; H, 4.65%. IR (cmꢀ1): 2016s, 1981s
m(CO); 1899 m m(OsH). 1H NMR (CDCl3, d): ꢀ5.78 (t,
3. Conclusions
A new pathway for the reaction of 3,3-diphenylcyclo-
propene with a low-valent metal complex has been demon-
strated. The reaction with Os(CO)2(PPh3)3 leads to a C–H
activation process producing the 3,3-diphenylcycloprope-
nyl complex, OsH[C3H(Ph-2)2](CO)2(PPh3)2 (1). This com-
plex is thermally unstable and readily rearranges to the
3-phenylindenyl complex, OsH[C9H6(Ph-3)](CO)2(PPh3)2
(2). A crystal structure determination of complex 2 reveals
a long Os–C distance to the r-bound 3-phenylindenyl
˚
ligand of 2.290(7) A. Reaction of complex 1 with HCl sat-
urates the 3,3-diphenylcyclopropenyl ligand to the 2,2-
diphenylcyclopropyl ligand. Under the acid conditions a
migratory insertion reaction ensues leading to the hydroxy
carbene complex, OsCl2[@C(OH)C3H3(Ph-2)2](CO)(PPh3)2
(4) which has the 2,2-diphenylcyclopropyl group as a car-
bene substituent. The migratory insertion reaction is
reversible and treatment of complex 4 with NaOH pro-
duces the dicarbonyl, 2,2-diphenylcyclopropyl complex,
OsCl[C3H3(Ph-2)2](CO)2(PPh3)2 (3).
2
1H, OsH, JHP = 20.47 Hz), 6.29 (s, 1H, @CH), 6.45,
6.77 (m, 10H, C6H5 substituents on cyclopropenyl ligand),
7.21–749 (m, 30H, PPh3). 13C NMR (C6D6, d): 32.7 (s, qua-
2
ternary, CPh2), 113.1 (t, quaternary, JCP = 14.3 Hz, Os-
3
C), 121.0 (t, JCP = 5.0 Hz, @CH), 121.8, 125.5, 127.3,
149.4 (quaternary) (s, aromatic carbons from phenyl sub-
stituents on cyclopropenyl ligand), 126.5 (t0 [27],
2,4
J
= 9.9 Hz, o-C6H5), 128.5 (s, p-C6H5), 132.8 (m, i-
CP
3,5
4. Experimental
C6H5), 133.0 (t0,
J
= 11.2 Hz, m-C6H5), 181.1 (t,
CP
2JCP = 7.4 Hz, CO), 181.9 (t, JCP = 7.9 Hz, CO). 31P
2
4.1. General procedures and instruments
NMR (CDCl3, d): 8.96 (s, PPh3).
Standard laboratory procedures were followed as have
been described previously [27]. The compounds
Os(CO)2(PPh3)3 [42], and 3,3-diphenylcyclopropene [22],
were prepared by the literature methods.
4.3. Preparation of OsH[C9H6(Ph-3)](CO)2(PPh3)2 (2)
OsH[C3H(Ph-2)2](CO)2(PPh3)2 (1) (0.300 g, 0.31 mmol)
was dissolved/suspended in toluene (40 mL) under nitrogen
and the mixture heated to 50–60 ꢁC for 2.5 h. All material
dissolved and there was a slight darkening of the solution.
The transformation of compound 1 into compound 2 was
conveniently monitored by either 1H or 31P NMR spectros-
copy. Toluene was removed under vacuum to give an
almost colourless solid which was washed with hexane
and recrystallised from CH2Cl2/C2H5OH to pure 2 as a
colourless crystalline solid (0.250 g, 83%). Anal. Calc. for
C53H42O2OsP2 Æ 0.5CH2Cl2: C, 63.90; H, 4.31. Found: C,
64.43; H, 4.46%. The presence of the 0.5 equivalent of
CH2Cl2 was confirmed by the 1H NMR spectrum and
the crystal structure determination. IR (cmꢀ1): 2021s,
Infrared spectra (4000–400 cmꢀ1) were recorded as
Nujol mulls between KBr plates on a Perkin Elmer Para-
gon 1000 spectrometer. NMR spectra were obtained on
either a Bruker DRX 400 or a Bruker Avance 300 at
1
25 ꢁC. For the Bruker DRX 400, H, 13C and 31P NMR
spectra were obtained operating at 400.1 (1H), 100.6 (13C)
and 162.0 (31P) MHz, respectively. For the Bruker Avance
1
300, H, 13C, and 31P NMR spectra were obtained operat-
ing at 300.13 (1H), 75.48 (13C) MHz, and 121.50 (31P)
MHz, respectively. Resonances are quoted in ppm and
1H NMR spectra referenced to either tetramethylsilane
(0.00 ppm) or the proteo-impurity in the solvent
(7.25 ppm for CHCl3). 13C NMR spectra were referenced
to CDCl3 (77.00 ppm), and 31P NMR spectra to 85%
orthophosphoric acid (0.00 ppm) as an external standard.
1
1958s m(CO); 1910m m(OsH). H NMR (CDCl3, d): ꢀ5.15
2
(apparent t, 1H, OsH, JHP = 20.50 Hz), 4.10 (apparent t,
3
1H, OsCH, JHP = 9.40 Hz), 6.24 (broad s, 1H, Os–CH–

G.R. Clark et al. / Journal of Organometallic Chemistry 691 (2006) 4901–4908
4907
CH@), 6.36–7.63, (m, 39H, phenylindenyl protons and
PPh3). 13C NMR (CDCl3, d): 19.7 (apparent t,
2JCP = 5.2 Hz, Os–CH), 119.1, 121.7, 123.6, 125.3, 127.6–
128.2, 129.6, 129.9, 132.7 (quaternary), 133.7–134.9, 137.9
(quaternary), 141.6( quaternary), 157.7 (quaternary) (s,
aromatic carbons from phenylindenyl ligand and PPh3
ligands), 152.0 (s, Os–CH–CH@), 179.8 (apparent t,
PPh3), 13.49 (s, 1H, OH). 13C NMR (CDCl3, d): 27.0 (s,
CH2), 46.9 (s, CPh2), 54.7 (s, CH–CH2), 126.4, 126.5,
127.7, 127.8, 127.9, 128.4, 130.0, 130.1, 130.7, 131.2 (qua-
ternary), 131.5 (quaternary), 132.0 (quaternary), 134.4,
134.5, 134.6, 134.7, 139.1 (quaternary), 145.2 (quaternary)
(aromatic carbons from phenyl substituents and PPh3),
2
178.6 (apparent t, JCP = 8.5 Hz, CO), 269.8 (apparent t,
2JCP = 8.4 Hz, CO), 186.0 (apparent t, JCP = 6.1 Hz,
2JCP = 6.1 Hz, Os@COH). 31P NMR (CDCl3, d): ꢀ9.87
2
2
2
2
CO). 31P NMR (CDCl3, d): 10.93 (d, JPP = 249.7 Hz,
(d, JPP = 293.1 Hz, PPh3), 0.56 (d, JPP = 293.1 Hz,
PPh3).
2
PPh3), 7.97 (d, JPP = 249.7 Hz PPh3).
4.4. Preparation of OsCl[C3H3(Ph-2)2](CO)2(PPh3)2 (3)
4.6. X-ray crystal structure determination for complex 2
OsCl2[@C(OH)C3H3(Ph-2)2](CO)(PPh3)2 (4) (0.060 g,
0.0058 mmol) was dissolved in dichloromethane (15 mL),
aqueous NaOH (5 mL, 0.1 mol Lꢀ1) added, and the mix-
ture stirred for 20 min. The organic fraction was removed,
washed with water, dried with CaCl2, and addition of eth-
anol followed by removal of the dichloromethane under
vacuum gave pure 3 as a colourless microcrystalline solid
(0.052 g, 90%). Anal. Calc. for C53H43ClO2OsP2: C,
63.68; H, 4.34; Cl, 3.55. Found: C, 64.43; H, 4.46; Cl,
X-ray intensity data were recorded on a Siemens
SMART diffractometer with
a CCD area detector
using graphite monochromated Mo Ka radiation (k =
˚
0.71073 A) at 85 K. Data were integrated and corrected
for Lorentz and polarisation effects using SAINT [43].
Semi-empirical absorption corrections were applied based
on equivalent reflections using SADABS [44]. The structure
was solved by direct methods and refined by full-matrix
least-squares on F2 using programs SHELXS97 [45] and
SHELXL97 [46]. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were located geometri-
cally and refined using a riding model. The crystals con-
tain 0.5 molecules of dichloromethane of crystallisation.
The chlorine atoms of this dichloromethane could be
reliably located, but not the methylene group. The
diagram was produced using ORTEP3 [47]. Crystal data
and refinement details for the structure are given in
Table 1.
1
4.10%. IR (cmꢀ1): 2025s, 1957s m(CO). H NMR (CDCl3,
2
3
d): 1.14 (dd, 1H, JHH = 4.1 Hz, JHH = 10.2 Hz, –CH2–),
2
3
1.59 (dd, 1H, JHH = 4.3 Hz, JHH = 9.2 Hz, –CH2–),
3
1.94 (broad apparent t, 1H, JHH = 9.5 Hz, Os–CH–),
6.54–7.87 (m, 40H, phenyl substituents and PPh3). 13C
2
NMR (CDCl3, d): 23.6 (apparent t, JCP = 9.1 Hz, Os–
3
3
CH), 35.8 (dd, JCP = 3.6 Hz, JCP = 9.7 Hz, CH2), 37.5
(s (quaternary), CPh2), 123.5, 125.2, 125.6, 127.3, 127.6,
127.9, 128.0, 128.1, 128.3, 130.2, 130.4, 130.6, 131.6,
131.7, 132.0 (quaternary), 132.1 (quaternary), 132.6 (qua-
ternary), 133.0, 133.2, 133.3 (quaternary), 133.6 (quater-
nary), 133.7 (quaternary), 133.9 (quaternary), 134.4,
134.5, 134.6, 134.7, 145.0 (quaternary), 151.3 (quaternary),
(aromatic carbons from phenyl substituents and PPh3),
5. Supplementary material
Crystallographic data (excluding structure factors) for 2
have been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication No. CCDC
612721. Copies of this information can be obtained free
of charge from the Director, CCDC, 12 Union Road, Cam-
bridge, CB2 1EZ, UK (Fax: +44 1223 336 033; e-mail:
deposit@ccdc.cam.ac.uk or www: http://www.ccdc.
cam.ac.uk).
2
174.8 (apparent t, JCP = 6.9 Hz, CO), 178.0 (apparent t,
2JCP = 8.1 Hz, CO). 31P NMR (CDCl3, d): ꢀ 9.62
2
2
(d, JPP = 308.0 Hz PPh3), ꢀ14.02 (d, JPP = 308.0 Hz
PPh3).
4.5. Preparation of OsCl2[@C(OH)C3H3(Ph-2)2]
(CO)(PPh3)2 (4)
Acknowledgement
The 3,3-diphenylcyclopropenyl hydride complex
1
(0.134 g, 0.0139 mmol), was dissolved in dichloromethane
(ca. 30 mL). A solution of concd. HCl (12 drops, 32%) in
methanol (5 mL) was added and the reaction mixture was
stirred at room temperature for 25 min under nitrogen.
The solvent was then removed under reduced pressure.
The white residue thus obtained was recystallised from
dichloromethane/ethanol to give pure 4 as a colourless
microcrystalline solid (0.080 g, 56%). Anal. Calc. for
C53H44Cl2O2OsP2: C, 61.44; H, 4.28; Cl, 6.84. Found: C,
61.43; H, 4.40; Cl, 6.80%. IR (cmꢀ1): 1949s m(CO). 1H
NMR (CDCl3, d): 1.22 (m, 2H, –CH2–), 3.73 (m, 1H,
CH–CH2), 6.54–7.78 (m, 40H, phenyl substituents and
We thank the Foundation for Research, Science and
Technology for supporting this work through a post-doc-
toral fellowship to D.M.T.
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