N,N',N''-Triphenylguanidinate(-1) complexes of ruthenium, osmium and iridium: Synthesis and X-ray crystal structures

Article abstract of DOI:10.1016/S0020-1693(00)00046-3

N,N',N'-Triphenylguanidine (TpgH) reacts with [Ru(H)₂(CO)(PPh₃)₃] in refluxing toluene and with [Os(H)₂(CO)(PPh₃)₃] in refluxing o-xylene to yield the guanidinate(-1) complexes [RuH(Tpg)(CO)(PPh₃)₂] (1) and [Os(Tpg)₂(CO)(PPh₃)] (2), respectively. The reaction of TpgH with [RuCl₂(PPh₃)₃] in refluxing toluene affords a new route to the known complex [Ru(Tpg)₂(CO)(PPh₃)] (3). Finally the reaction of mer-[Ir(H)₃(PPh₃)₃] with TpgH in refluxing toluene yields the iridium(III) dihydride complex [Ir(H)₂(Tpg)(PPh₃)₂] (4). X-ray crystal structure determinations are reported for (1) and (4). (C) 2000 Elsevier Science S.A.

Full text of DOI:10.1016/S0020-1693(00)00046-3

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Inorganica Chimica Acta 303 (2000) 265–270
N,N%,N¦-Triphenylguanidinate(−1) complexes of ruthenium,
osmium and iridium: synthesis and X-ray crystal structuresꢀ
Stephen D. Robinson *, Arvind Sahajpal, Jonathan Steed
Department of Chemistry, King’s College London, Strand, London WC2R 2LS, UK
Received 27 August 1999; accepted 29 November 1999
Abstract
N,N%,N¦-Triphenylguanidine (TpgH) reacts with [Ru(H)2(CO)(PPh3)3] in refluxing toluene and with [Os(H)2(CO)(PPh3)3] in
refluxing o-xylene to yield the guanidinate(−1) complexes [RuH(Tpg)(CO)(PPh3)2] (1) and [Os(Tpg)2(CO)(PPh3)] (2), respectively.
The reaction of TpgH with [RuCl2(PPh3)3] in refluxing toluene affords a new route to the known complex [Ru(Tpg)2(CO)(PPh3)]
(3). Finally the reaction of mer-[Ir(H)3(PPh3)3] with TpgH in refluxing toluene yields the iridium(III) dihydride complex
[Ir(H)2(Tpg)(PPh3)2] (4). X-ray crystal structure determinations are reported for (1) and (4). © 2000 Elsevier Science S.A. All
rights reserved.
Keywords: Guanidinato complexes; Ruthenium complexes; Osmium complexes; Iridium complexes; Crystal structures
1. Introduction
2. Experimental
Transition metal complexes containing mono- or di-
anionic guanidinate ligands, though first reported many
years ago [2,3], have only recently begun to attract
significant attention. A small but rapidly growing num-
ber of such complexes containing chelate and/or bridg-
ing guanidinate(−1) ligands are now known [1,2,4–13]
including several synthesised in our laboratory [1,4]. In
addition complexes containing guanidinate(−2) lig-
ands have been reported for iron [3], platinum [14] and,
most recently niobium and tantalum [12]. In continua-
tion of our previous work [1,4] in this active field we
now report the synthesis of new N,N%,N¦-triphenyl-
guanidinate(−1) complexes of ruthenium, osmium and
iridium by a direct route from metal hydride precursors
and free guanidines. We also describe a new route to
the previously reported [1] complex [Ru(Tpg)2(CO)-
(PPh3)]. X-ray crystal structures are presented for two
of the new complexes, [RuH(Tpg)(CO)(PPh3)2] (1) and
[Ir(H)2(Tpg)(PPh3)2] (4)
2.1. General procedures
N,N%,N¦-Triphenylguanidine was obtained from Av-
ocado Research Chemicals, the platinum metal precur-
sors [Ru(H)2(CO)(PPh3)3], [Os(H)2(CO)(PPh3)3], [Ru-
Cl2(PPh3)3] and mer-[Ir(H)3(PPh3)3] were prepared by
literature methods [15]. Other reagents, experimental
techniques and instrumentation were as described in a
previous paper [16]. Infrared and NMR spectroscopic
data are presented in Table 1.
2.2. [Ru(H){PhNC(NHPh)NPh}(CO)(PPh3)2] (1)
Carbonyldihydridotris(triphenylphosphine)ruthenium
(0.6 g, 0.65 mmol) and N,N%,N¦-triphenylguanidine
(0.90 g, 3.14 mmol) were heated together under reflux
in toluene (40 cm3) for 8 h to give a dark green
solution. Concentration under reduced pressure left
an oil which on crystallisation from CH2Cl2–MeOH
afforded pale yellow crystals (0.48 g, 79%), m.p.
196–198°C (Found: C, 70.85; H, 4.95; N, 4.35. Anal.
Calc. for C56H47N3OP2Ru: C, 71.45; H, 5.05; N,
4.45%).
ꢀ Complexes of the platinum metals. Part 51 [1].
* Corresponding author. Tel.: +44-171-836 5454; fax: +44-171-
873 2810.
E-mail address: stephen.robinson@ukgateway.net (S.D. Robinson)
0020-1693/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(00)00046-3

266
S.D. Robinson et al. / Inorganica Chimica Acta 303 (2000) 265–270
Table 1
Infrared a and NMR b spectroscopic data
Complex
w(NꢀH)
w(MꢀH)
w(CꢁO)
l(MH)
2JHP
l(PPh3)
[RuH(Tpg)(CO)(PPh3)2] (1)
[Os(Tpg)2(CO)(PPh3)] (2)
[Ru(Tpg)2(CO)(PPh3)] (3)
3391
1971
1909
1894
1918
1930
−13.20(t)
21
46.43(s)
10.22 (s)
52.59 (s)
3389
3400
3377
[Ir(H)2(Tpg)(PPh3)2] (4)
2190
2157
−22.84(t)
17.6
20.25 (s)
a Nujol mulls/cm−1
.
b CDCl3 solutions, J in Hz, s=singlet, t=triplet.
,
2.3. [Os{PhNC(NHPh)NPh}2(CO)(PPh3)] (2)
(u=0.71073 A). For (1) a total of 360 oscillation
frames of 60 s exposure time with 0.5° rotation in q
were recorded with a crystal detector distance of 35
mm, resulting in data complete to 2q=42.5°. The
available software did not allow the collection of addi-
tional high-resolution data without extensive peak over-
lap. For (4) a total of 90 oscillation frames each of
width 2° in q and 30 s exposure time were recorded
with a crystal detector distance of 25 mm. Crystals were
indexed from the first ten frames using the DENZO
package [17] and positional data were refined along
with diffractometer constants to give the final cell
parameters. Integration and scaling (DENZO Scalepack
[17]) resulted in unique data sets corrected for Lorentz
and polarisation effects, and for the effects of crystal
decay and absorption, by a combination of averaging
of equivalent reflections and an overall volume and
scaling correction. Crystallographic data are recorded
in Table 2. The structures were solved using SHELXS-97
[18] and developed via alternating least squares cycles
and difference Fourier synthesis (SHELXL-97 [18]) with
the aid of the programme RES2INS [19]. All non-hydro-
gen atoms were modelled anisotropically while hydro-
gen atoms were assigned an isotropic thermal
parameter 1.2 times that of the parent atom (1.5 for
terminal atoms) and allowed to ride except hydride
ligands. In the case of (1) phenyl groups C(3)ꢀC(8) and
C(51)ꢀC(56) exhibited elongated thermal ellipsoids,
however attempts to model two alternate sets of posi-
tions for these rings were unsuccessful. A final differ-
ence Fourier maps for both compounds revealed the
locations of the hydride ligands which were included in
the model and their positional and thermal parameters
refined freely. All calculations were carried out with
either a Silicon graphics Indy R5000 work station or an
IBM compatible PC.
Carbonyldihydridotris(triphenylphosphine)osmium
(0.40 g, 0.39 mmol) and N,N%,N¦-triphenylguanidine
(0.68 g, 2.37 mmol) were heated together under reflux
in o-xylene (40 cm3) for 24 h to give a yellow–brown
solution. Evaporation under reduced pressure left an oil
which was crystallised from CH2Cl2–MeOH as lime-
yellow crystals (0.23 g, 56%) (Found: C, 63.75; H, 4.3;
N, 7.1. Anal. Calc. for C57H47N6POOs C, 65.0; H, 4.5;
N, 7.95%).
2.4. [Ru{PhNC(NHPh)NPh}2(CO)(PPh3)] (3)
Dichlorotris(triphenylphosphine)ruthenium (0.6 g,
0.63 mmol) and N,N%,N¦-triphenylguanidine (0.92 g,
3.2 mmol) were heated together under reflux in toluene
(40 cm3) for approximately 4.5 h to give a dark green–
brown solution. Concentration under reduced pressure
followed by crystallisation of the residue from CH2Cl2–
MeOH afforded a few milligrams of an unidentified
purple solid which was removed by filtration, followed
by a main crop of lemon-yellow crystals (0.3 g, 50%)
identical to an authentic sample prepared as previously
described.
2.5. [Ir(H)2{PhNC(NHPh)NPh}(PPh3)2] (4)
mer-Trihydridotris(triphenylphosphine)iridium (0.4
g, 0.51 mmol) and N,N%,N¦-triphenylguanidine (0.74 g,
2.57 mmol) were heated together under reflux in
toluene (40 cm3) for approximately 18 h. to give a dark
yellow–brown solution. Concentration under reduced
pressure left an oil which on crystallisation from
CH2Cl2–MeOH gave pale yellow crystals (0.28 g, 55%),
m.p. 202–204°C (Found: C, 65.35; H, 4.6; N, 3.9. Anal.
Calc. for C55H48N3P2Ir: C, 65.7; H, 4.8; N, 4.15%).
2.6. X-ray crystallography
3. Results and discussion
Crystals were mounted on thin glass fibres using a
fast setting epoxy resin, data were collected on a Non-
ius Kappa CCD diffractometer using Mo Ka radiation
The reaction of [Ru(H)2(CO)(PPh3)3] with N,N%,N¦-
triphenylguanidine in refluxing toluene afforded the
pale yellow air stable complex [RuH(Tpg)(CO)(PPh3)2]

S.D. Robinson et al. / Inorganica Chimica Acta 303 (2000) 265–270
267
Table 2
Crystallographic data for complexes 1 and 4
Complex
1
4
Molecular formula
Molecular weight
Temperature (K)
C
940.98
293(2)
56H47N3OP2Ru
C55H48IrN3P2
1005.10
293(2)
,
Wavelength (A)
0.71073
orthorhombic
Pbca
0.71073
monoclinic
P21/a
Crystal system
Space group
,
a (A)
11.9120(2)
18.8830(3)
41.5780(7)
20.5315(2)
10.8110(2)
21.0185(4)
105.725(1)
4490.78(13)
4
1.487
3.086
2024
,
b (A)
,
c (A)
i (°)
V (A )
3
,
9352.3(3)
8
1.337
0.447
3888
Z
Calculated density (g cm−3
)
Absorption coefficient (mm−1
F(000)
)
Crystal size (mm)
q Range for data collection (°)
0.6×0.2×0.15
2.50 to 21.26
0.5×0.4×0.1
3.13 to 25.00
Index ranges
h
0 to 12
0 to 22
k
0 to 19
0 to 12
l
0 to 42
−24 to 23
Reflections collected/unique
Rint
119,805/5038
0.032
31294/7600
0.0450
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R Indices [I\2|(I)]
R indices (all data)
full-matrix least-squares on F2
5027/0/572
full-matrix least-squares on F2
7600/0/563
1.307
1.081
R1=0.0524, wR2=0.1402
R1=0.0627, wR2=0.2173
0.292 and −0.330
R1=0.0298, wR2=0.0741
R1=0.0345, wR2=0.0777
0.746 and −1.464
−3
,
Largest difference peak and hole (e A
)
(1) in good yield. The infrared and NMR data are very
similar to those previously recorded for the analogous
amidinate
complexes
[RuH{PhNC(R)NPh}(CO)-
(PPh3)2] [20] and established the trans phosphines stere-
ochemistry. However, in order to learn more about the
geometry of the chelated guanidinate ligand an X-ray
crystal structure determination was undertaken. The
molecular structure of (1) is shown in Fig. 1, selected
bond length and angle data are collated in Table 3. The
molecules are essentially octahedral with hydride, car-
bonyl, trans phosphines and chelate guanidinate(−1)
ligands. However, the octahedral coordination sphere
is distorted by the small bite angle [ÚNꢀRuꢀN=
59.6(2)°] of the guanidinate ligand. The ruthe-
niumꢀnitrogen, -phosphorus and -carbon bond lengths
are typical for octahedral ruthenium(II) and merit no
further comment other than to note that the RuꢀN
,
bond trans to hydride [2.229(4) A] is, as expected,
significantly longer than that trans to carbonyl [2.164(5)
,
A]. The hydride ligand was located at a distance of 1.59
,
A from the ruthenium. The planarity of the guanidinate
ligand N2CN skeleton is established by the sum of the
angles subtended at the central carbon atom which
equals 360.0°. As in previously reported N,N%,N¦-
triphenylguanidinate complexes of ruthenium(II) [1,7]
Fig. 1. Molecular structure of [RuH(Tpg)(CO)(PPh3)2] (1) (ellipsoids
drawn at 30% level, non-hydridic hydrogen atoms omitted for clar-
ity).

268
S.D. Robinson et al. / Inorganica Chimica Acta 303 (2000) 265–270
Table 3
study we observed that the reaction of [RuCl2(PPh3)3]
with various amidines in refluxing toluene also gave fair
yields of carbonyl containing products [20]. It appears
that [RuCl2(PPh3)3] and certain related ruthenium(II)
complexes in the presence of amidines and guanidines,
have a particularly high affinity for carbonyl ligands.
As in the case of the amidine reactions it appears
probable that traces of alcohol or similar CO sources
present in the toluene are responsible for the
carbonylation.
Abstraction of hydride and carbonyl ligands from
alcohols in the presence of base is a long established
feature of ruthenium chemistry [21,22]. Therefore, given
that amidines and, in particular, guanidines are strong
organic bases a reaction of this nature seems entirely
feasible in the present instance.
The reaction of [Os(H)2(CO)(PPh3)3] with N,N%,N¦-
triphenylguanidine in refluxing toluene did not give a
clean product. However, a similar reaction in refluxing
o-xylene afforded the bis(guanidinate) complex
[Os(Tpg)2(CO)(PPh3)] (2) in fair yield as air stable lime
yellow crystals. Apart from the expected small shift in
the w(CO) frequency, the infrared spectra of the os-
mium complex 2 and its ruthenium analogue 3 are
essentially identical. It is probable that complex 2 has
the same cis CO–PPh3 stereochemistry as complex 3,
and the available spectroscopic evidence (Table 1) ap-
pears consistent with this view. The bis(guanidinate)
complex isolated from the present reaction contrasts
with the hydrido(guanidinate) complex obtained from
the same osmium precursor and N,N%-diphenyl-
guanidine [4]. However, the difference can be attributed
,
Selected bond lengths (A) and angles and torsion angles (°) for
[RuH(Tpg)(CO)(PPh3)2] (1)
RuꢀC(1)
RuꢀN(1)
RuꢀN(2)
RuꢀP(2)
RuꢀP(1)
O(1)ꢀC(1)
1.818(6)
2.164(5)
2.229(4)
2.328(2)
2.384(2)
1.168(7)
N(1)ꢀC(2)
N(1)ꢀC(9)
N(2)ꢀC(2)
N(2)ꢀC(15)
N(3)ꢀC(2)
N(3)ꢀC(3)
N(3)ꢀH(N3)
1.336(7)
1.403(7)
1.315(7)
1.413(8)
1.385(7)
1.399(8)
0.86
C(1)ꢀRuꢀN(1)
C(1)ꢀRuꢀN(2)
N(1)ꢀRuꢀN(2)
C(1)ꢀRuꢀP(2)
N(1)ꢀRuꢀP(2)
N(2)ꢀRuꢀP(2)
C(1)ꢀRuꢀP(1)
N(1)ꢀRuꢀP(1)
N(2)ꢀRuꢀP(1)
P(2)ꢀRuꢀP(1)
C(2)ꢀN(1)ꢀC(9)
C(2)ꢀN(1)ꢀRu
167.2(2)
108.0(2)
59.6(2)
86.1(2)
92.45(13) C(2)ꢀN(3)ꢀC(3)
98.26(13) C(2)ꢀN(3)ꢀH(N3)
90.9(2)
92.54(13) O(1)ꢀC(1)ꢀRu
91.74(13) N(2)ꢀC(2)ꢀN(1)
170.00(5) N(2)ꢀC(2)ꢀN(3)
126.9(5)
95.8(3)
C(9)ꢀN(1)ꢀRu
C(2)ꢀN(2)ꢀC(15)
C(2)ꢀN(2)ꢀRu
C(15)ꢀN(2)ꢀRu
137.1(4)
126.0(5)
93.4(3)
134.4(4)
128.1(5)
116
C(3)ꢀN(3)ꢀH(N3)
116
175.8(5)
111.0(5)
126.7(5)
122.3(5)
N(1)ꢀC(2)ꢀN(3)
N(1)ꢀRuꢀN(2)ꢀC(2)
2.5(3)
the dihedral angle between the N2CN plane and the
NꢀRuꢀN plane is small [2.5(3)°] indicating very little
folding of the chelate ring. The stereochemistry about
the non-coordinated nitrogen N(3) is more uncertain.
The attached hydrogen atom has been located but the
associated errors are such that only one angle sub-
tended at N(3) can be determined with precision
[ÚC(2)ꢀN(3)ꢀC(3)=128.1(5)°]. However, values of
116.0° obtained for each of the other two give a total of
360.1° and strongly support sp2 trigonal planar hybridi-
sation at N(3). The CꢀN bond lengths within the
,
guanidinate chelate ring [1.336(7) and 1.315(7) A] are
consistent with a delocalised system involving substan-
tial double bond character. However, the bond from
the central carbon to the non-coordinated nitrogen,
,
N(3), is considerably longer [1.385(7) A] suggesting that
there is relatively little delocalisation of the lone pair on
N(3) over the N2CN skeleton. Finally, the lengths of
,
the NꢀC(Ph) bonds [av. 1.405(7) A] indicate that there
is little delocalisation of nitrogen lone-pair electron
density out onto the attached phenyl rings. This conclu-
sion is supported by the observation that the phenyl
rings are rotated out of the N2CN plane by approxi-
mately 30°.
The reaction of [RuCl2(PPh3)3] with N,N%,N¦-
triphenylguanidine in refluxing toluene afforded an al-
ternative route to the known complex [Ru(Tpg)2(CO)-
(PPh3)] (3) in fair yield. Characterisation of 3 was
achieved by comparison with an authentic sample pre-
pared by the original method [1]. The presence of a
carbonyl ligand in the final product of the reaction is
unexpected since no obvious source of CO is to hand.
However, it is interesting to note that in an earlier
Fig. 2. Molecular structure of [Ir(H)2(Tpg)(PPh3)2] (4) (ellipsoids
drawn at 30% level not omitted).

S.D. Robinson et al. / Inorganica Chimica Acta 303 (2000) 265–270
269
to the use of a lower boiling solvent (toluene) in the
latter case.
values of 111.6 and 115.3° found for the other two give
a total of 355.9°, which though someway short of the
ideal (360°) suggests essentially sp2 hybridisation about
N(3). Bond length data for the guanidinate ligand point
to delocalisation with significant CꢀN double bond
character within the chelate ring [CꢀN 1.327(5) and
The reaction of mer-[Ir(H)3(PPh3)3] with N,N%,N¦-
triphenylguanidine in refluxing toluene affords the iridi-
um(III) dihydride complex [Ir(H)2(Tpg)(PPh3)2] (4) in
good yield as air stable, pale yellow crystals. Spectro-
scopic data establish the trans-phosphines stereochem-
istry previously reported for the corresponding
amidinate complexes [Ir(H)2{PhNC(R)NPh}(PPh3)2]
[20]. However, as in the case of the ruthenium complex
1 an X-ray crystal structure analysis was undertaken to
investigate the detailed geometry of the coordinated
guanidinate ligand. The molecular structure of complex
4 is shown in Fig. 2, selected bond length and angle
data are collated in Table 4. The complex is essentially
octahedral, albeit highly distorted by the presence of a
small ‘bite’ guanidinate ligand [ÚNꢀIrꢀN=59.49(12)°].
The iridium–phosphorus and –nitrogen bond lengths
are within the ranges expected for octahedral iridiu-
m(III), with the latter reflecting the strong trans influ-
ence of the hydride ligands. The cis pair of hydride
ligands have been located. The sum of the angles
subtended at the central carbon atom of the guanidi-
nate ligand [359.5°] establishes that, as in complex 1
and other previously reported guanidinate complexes
[1,7] the N2CN skeleton is rigorously planar. However,
the dihedral angle between the N2CN plane and the
NꢀIrꢀN plane [6.1(2)°] indicates folding of the chelate
ring similar in magnitude to that reported for the
rhodium(III) complex [RhCl(Tpg)(h-C5Me5)] [7] but
larger than that found for N,N%,N¦-triphenylguanidi-
nate ligands chelated to ruthenium(II) [1,7] or palladiu-
m(II) [1]. Although the hydrogen atom attached to N(3)
has been located the associated errors are such that
only one angle subtended at N(3) can be measured
accurately [ÚC(1)ꢀN(3)ꢀC(2)=129.0(4)°]. However,
,
1.330(5) A] but suggest that there is little delocalisation
of the N(3) lone pair over the N2CN skeleton
,
[C(1)ꢀN(3) 1.405(5) A]. Likewise the lengths of the
,
NꢀC(Ph) bonds [av. 1.399(5) A] indicate that delocali-
sation of nitrogen lone pairs out onto the phenyl rings
is minimal. This conclusion is supported by the obser-
vation that the phenyl rings are rotated out of the
N2CN skeletal plane by approximately 19–26°.
The presence of a hydrogen atom on the exo-cyclic
(non-coordinated) nitrogen atoms in complexes 1 and 4
prevented the precise measurement of angles subtended
at these centres. Consequently our conclusions concern-
ing the geometry and electron distribution about these
exo-cyclic nitrogens are of necessity rather tenuous.
However recently reported X-ray crystal structure data
for [Ta{CyNC(NMe2)NCy}(NMe2)4] [23] do appear to
offer support for our findings. In the tantalum complex
the presence of two methyl groups on the exo-cyclic
nitrogen atom of each guanidinate ligand permits accu-
rate measurement of the angles subtended at this atom.
These total 351.0 and 352.3° indicating essentially pla-
nar coordination in each case. Moreover the NMe2
groups are twisted out of the guanidinate N2CN skele-
tal plane by an average of 80.7° and the N2CꢀNMe2
,
distances (av. 1.42 A) correspond to CꢀN single bonds.
Taken together these results clearly indicate that while
the exo-cyclic nitrogens are essentially sp2 hybridised,
their lone pair electron density is not significantly delo-
calised over the guanidinate skeleton. These conclusions
are essentially similar to those reached for complexes 1
and 4 in the present work.
Table 4
4. Supplementary material
,
Selected bond lengths (A) and angles and torsion angles (°) for
[Ir(H)2(Tpg)(PPh3)2] (4)
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Centre as supple-
mentary material publication nos. CCDC 141389 and
141390. 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.uk).
IrꢀN(1)
IrꢀN(2)
IrꢀP(2)
IrꢀP(1)
N(1)ꢀC(1)
N(1)ꢀC(8)
2.196(3)
2.217(3)
2.2862(9)
2.3062(10)
1.327(5)
1.407(5)
N(2)ꢀC(1)
N(2)ꢀC(14)
N(3)ꢀC(2)
N(3)ꢀC(1)
N(3)ꢀH(N3)
1.330(5)
1.395(5)
1.396(5)
1.405(5)
0.926
N(1)ꢀIrꢀN(2)
N(1)ꢀIrꢀP(2)
N(2)ꢀIrꢀP(2)
N(1)ꢀIrꢀP(1)
N(2)ꢀIrꢀP(1)
P(2)ꢀIrꢀP(1)
C(1)ꢀN(1)ꢀC(8)
C(1)ꢀN(1)ꢀIr
C(8)ꢀN(1)ꢀIr
59.49(12)
91.64(9)
96.27(9)
92.61(9)
91.85(9)
171.88(4)
128.5(3)
94.8(2)
C(1)ꢀN(2)ꢀC(14) 129.6(3)
C(1)ꢀN(2)ꢀIr
C(14)ꢀN(2)ꢀIr
C(2)ꢀN(3)ꢀC(1)
C(2)ꢀN(3)ꢀH(N3) 115.3
C(1)ꢀN(3)ꢀH(N3) 111.6
N(1)ꢀC(1)ꢀN(2)
N(1)ꢀC(1)ꢀN(3)
N(2)ꢀC(1)ꢀN(3)
93.7(2)
133.1(3)
129.0(4)
Acknowledgements
111.0(3)
121.2(4)
127.3(4)
We thank the Royal Society for the provision of
funds to purchase platinum metals, EPSRC and KCL
for funding for the diffractometer and the Nuffield
Foundation for provision of computing equipment.
136.8(3)
N(2)ꢀIrꢀN(1)ꢀC(1) 6.1(2)

270
S.D. Robinson et al. / Inorganica Chimica Acta 303 (2000) 265–270
[12] M.K.T. Tin, N. Thirupathi, G.P.A. Yap, D.S. Richeson, J.
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