Mixed-metal cluster chemistry XII: Isocyanide derivatives of [CpWIr3(CO)11]; X-ray crystal structure of [CpWIr3(CO)9(CNC6H3Me 2-2,6)2]

Article abstract of DOI:10.1016/S0022-328X(98)01200-5

Reactions of [CpWIr₃(CO)₁₁] (1) with stoichiometric amounts of isocyanides afford the clusters [CpWIr₃(CO)_11-n(CNR)_n] [R = Xy (C₆H₃Me₂-2,6), n = 1 (2), 2 (3), 3 (4); R = ^tBu, n = 1 (5), 2 (6), 3 (7)] in good to excellent yields (47-63%). The products exhibit ligand fluxionality in solution, with the ¹³C-NMR spectra of 4-6 revealing that the carbonyls are undergoing fast exchange at 143 K. A single-crystal X-ray study of [CpWIr₃(CO)₉(CNXy)₂] (3) reveals that the coordination sphere of the cluster has an all-terminal ligand geometry, the first for a ligand substituted derivative of 1. The two iridium-ligated 2,6-dimethylphenylisocyanide ligands are coordinated to the same iridium vertex, the second example of this coordination geometry for a transition metal cluster.

Full text of DOI:10.1016/S0022-328X(98)01200-5

Journal of Organometallic Chemistry 579 (1999) 75–82
Mixed-metal cluster chemistry XII: isocyanide derivatives of
[CpWIr3(CO)11]; X-ray crystal structure of
[CpWIr3(CO)9(CNC6H3Me2-2,6)2]ꢀ
Susan M. Waterman a, Mark G. Humphrey a,*, David C.R. Hockless b
a Department of Chemistry, Australian National Uni6ersity, Canberra, A.C.T. 0200, Australia
b Research School of Chemistry, Australian National Uni6ersity, Canberra, A.C.T. 0200, Australia
Received 12 October 1998
Abstract
Reactions of [CpWIr3(CO)11] (1) with stoichiometric amounts of isocyanides afford the clusters [CpWIr3(CO)11−n(CNR)n]
[R=Xy (C6H3Me2-2,6), n=1 (2), 2 (3), 3 (4); R=tBu, n=1 (5), 2 (6), 3 (7)] in good to excellent yields (47–63%). The products
exhibit ligand fluxionality in solution, with the 13C-NMR spectra of 4-6 revealing that the carbonyls are undergoing fast exchange
at 143 K. A single-crystal X-ray study of [CpWIr3(CO)9(CNXy)2] (3) reveals that the coordination sphere of the cluster has an
all-terminal ligand geometry, the first for a ligand substituted derivative of 1. The two iridium-ligated 2,6-dimethylphenyliso-
cyanide ligands are coordinated to the same iridium vertex, the second example of this coordination geometry for a transition
metal cluster. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Tungsten; Iridium carbonyl; Isocyanide; Fluxionality
[11–24] and the isolobally-related [CpWIr3(CO)11] (1)
[5,6,9] usually results in the carbonyl ligand geometry in
the ground state shifting from all-terminal to one in
which the three edges of one face of the tetrahedral core
are spanned by bridging carbonyls. This affords three
different ligation sites with respect to the M3(m-CO)3
plane, namely radial, axial and apical (Fig. 1), all
potentially available for incoming ligands. The X-ray
structurally characterized examples are consistent with
substitution proceeding in a stepwise fashion at unsub-
stituted Ir(CO)3 vertices, to afford the coordination
geometries shown in Table 1. The sites of substitution
in the P-ligand substituted clusters are readily rational-
ized from a combination of steric and electronic factors
[25].
1. Introduction
The ligand substitution chemistry of homometallic
clusters has been studied intensively [2,3], but ligand
replacement at heterometallic clusters has been the
subject of comparatively few reports. Incorporation of
a heterometal into a cluster core affords the possibility
of not only metalloselectivity upon ligand substitution,
but also site selectivity due to a decrease in molecular
symmetry. With these ideas in mind, we have been
examining the effect of replacing the Ir(CO)3 vertices in
the tetrahedral [Ir4(CO)12] by isolobal CpM(CO)2 (M=
Mo, W) units upon phosphine reactivity, alkyne reac-
tivity, and ligand fluxionality [1,4–10]. The replacement
of carbonyl by P-donor ligands in both [Ir4(CO)12]
Isocyanide substitution at homometallic clusters has
also been of significant interest [34–42]. The cone an-
gles of isocyanides CNR are small for a wide range of
R substituents, substantially decreasing the importance
of steric requirements in controlling product distribu-
ꢀ For part XI see Ref. [1].
* Corresponding author. Tel.: +61-2-6249-2927; fax: +61-2-6249-
0760.
E-mail address: mark.humphrey@anu.edu.au (M.G. Humphrey)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01200-5

76
S.M. Waterman et al. / Journal of Organometallic Chemistry 579 (1999) 75–82
report herein the reactivity of 1 toward one, two or
three equivalents of XyNC (Xy=C6H3Me2-2,6) or
tBuNC, the characterization by a single-crystal X-ray
study of [CpWIr3(CO)9(CNXy)2] (3), the thermolyses of
the clusters 5–7, and a comparison of our results to
those obtained with the [Ir4(CO)12] system.
2. Results and discussion
Fig. 1. Carbonyl locations in tetrahedral clusters.
2.1. Syntheses and characterization of 2–7
tion. As a result, different coordination geometries
from those obtained with phosphines are frequently
observed [e.g. phosphine substitution at [Ru3(CO)12]
proceeds to afford sterically-driven equatorially-ligated
products (with respect to the Ru3 plane), whereas iso-
cyanide substitution affords electronically-preferred ax-
ially-coordinated derivatives [43]]. Despite comp-
rehensive investigations with homometallic clusters, the
reactivity of isocyanides with mixed-metal carbonyl
clusters has been comparatively less well studied. We
The reactions of [CpWIr3(CO)11] (1) with n equiva-
lents of 2,6-dimethylphenylisocyanide (CNXy) or t-
butylisocyanide (n=1–3) proceed in dichloromethane
at room temperature (r.t.) to afford the clusters
[CpWIr3(CO)11−n(CNXy)n] [n=1 (2), 2 (3) or 3 (4)] or
[CpWIr3(CO)11−n(CNBut)n] [n=1 (5), 2 (6) or 3 (7)],
respectively, as the major or sole reaction products in
good to excellent yields (Scheme 1). The clusters 2–7
1
have been characterized by a combination of IR, H-
Table 1
X-ray crystallographically verified coordination geometries for P-ligand derivatives of [Ir4(CO)12] and [CpWIr3(CO)11
]
Cluster
Type
Sites of substitution c
Ref.
[Ir4(CO)11{h1-[Fe(h5-P3C2But2)(h5-P2C3Bu3t )}]
A
A
A
B
B
B
B
B
B
B
B
B
B
B
B
B
A
B
B
B
L1 (M1=Ir)
[26]
[27]
[28,29]
[14,30]
[23]
[31]
[22]
[9]
[9]
[5]
[32]
[9]
[6]
[10]
[10]
[10]
[20]
[16,33]
[19]
[21]
[Ir4(CO)11{P(OCH2)3CEt}]
L1 (M1=Ir)
[CpWIr3(CO)11
]
L1 (M1=W)
[Ir4(m-CO)3(CO)7(PPh3)2]
[Ir4(m-CO)3(m-dmpe)(CO)7]
[Ir4(m-CO)3(m-dppb)(CO)7]
L2%, L3 (M1=Ir)
L2, L3 (M1=Ir)
L2, L3 (M1=Ir)
[Ir4(m-CO)3(m-dppee)(CO)7] a
[CpWIr3(m-CO)3(CO)7(PPh3)]
[CpWIr3(m-CO)3(CO)7(PMe3)]
[CpWIr3(m-CO)3(CO)7(PMe2Ph)]
[Ir4(m-CO)3(CO)6(PPh2pyl)3] b
[CpWIr3(m-CO)3(CO)6(PPh3)2]
[CpWIr3(m-CO)3(CO)6{P(Oph)3}2]
[CpWIr3(m-CO)3(m-dppm)(CO)6]
[CpWIr3(m-CO)3(m-dppe)(CO)6]
[CpWIr3(m-CO)3(m-dppa)(CO)6]
[Ir4{m3-HC(PPh2)3}(CO)9]
L2, L3 (M1=Ir)
L4%, L2 (M2=W)
L1, L2 (M1=W)
L1, L2 (M1=W)
L2%, L3%, L4 (M1=Ir)
L2%, L3, L4 (M3=W)
L2%, L3, L4 (M3=W)
L1, L2, L3 (M1=W)
L1, L2, L3 (M1=W)
L1, L2, L4 (M1=W)
L1, L2, L3 (M1=Ir)
L%, L2, L3, L4 (M1=Ir)
L1, L2, L3, L4 (M1=Ir)
L1, L2%, L3, L4 (M1=Ir)
[Ir4(m-CO)3(CO)5(PMe3)4]
[Ir4(m-CO)3(CO)5(PMe2Ph)4]
[Ir4(m-CO)3(m-dppm)2(CO)5]
a dppee, 1,2-cis-Bis(diphenylphosphino)ethene.
b PPh2pyl, diphenyl-2-pyridylphosphine.
c Unless otherwise indicated MꢀIr.

S.M. Waterman et al. / Journal of Organometallic Chemistry 579 (1999) 75–82
77
t
Scheme 1. Reactions of [CpWIr3(CO)11] (1) with RNC (R=C6H3Me2-2,6, Bu). Reaction conditions: CH2Cl2, r.t., 16 h.
and 13C-NMR (for 5–7) spectroscopies, mass spec-
trometry and, in the case of 2, 3, 5 and 6, satisfactory
microanalyses (the tris-substituted derivatives 4 and 7
proved unstable in solution over a period of time,
precluding successful recrystallization. We have previ-
ously noted a similar instability with [CpWIr3(m-
CO)3(CO)5(PMe3)3] [9] and [CpWIr3(m-CO)3(CO)5-
{P(OPh)3}3] [6]). IR spectra suggest the presence of
edge-bridging carbonyl ligands in the more highly sub-
stituted clusters 3, 4, 6 and 7 [w(CO) 1847–1816 cm−1].
In combination with the X-ray structural results de-
tailed below, the number of bands in the terminal
carbonyl ligand w(CO) regions of the IR spectra of 3, 4,
6 and 7 are indicative of the presence of isomers.
Complexes 2 and 5 have IR absorptions consistent with
the presence of terminal carbonyls only, suggesting a
ligands. The WIr3 core distances [W–Ir 2.781(1),
2.8282(9), 2.8502(1); Ir–Ir 2.682(1), 2.695(1), 2.7229(8)
˚
A] are similar to those of 1 [W–Ir 2.7920(10),
2.8151(10), 2.8648(10); Ir–Ir 2.6967(9), 2.6985(10),
˚
2.7018(9) A]. The longest W–Ir distance for 3 is effec-
tively trans to the Cp group. Ir–CO(terminal) [1.88(2)–
˚
˚
1.94(2) A] and W–CO interactions [1.96(1), 1.98(2) A]
for 3 are unexceptional. The Ir–CN [1.96(2), 2.01(1)],
IrC–N [1.13(2), 1.14(2)] and N–C(aryl) [1.39(2), 1.40(2)
˚
A] distances and Ir–C–N [174(1), 176(1)°] and C–N–
C(aryl) [174(2), 168(2)°] angles are consistent with the
expected valence bond structure Ir–CꢀN–Xy. The Ir–
CN linkages are (on average) longer than the Ir–CO
distances, consistent with the enhanced Ir“CO p*
backbonding of the carbonyl ligand. Ir(1) is in a unique
environment, being linked to one terminal carbonyl
ligand and two terminal 2,6-dimethylphenylisocyanide
ligands. The isocyanide ligands are trans to Ir–Ir link-
ages, and the unique carbonyl ligand at Ir(1) is trans to
the W–Ir linkage. This site selection may be determined
1
ligand disposition similar to the precursor 1. The H-
NMR spectra contain signals assigned to cyclopentadi-
enyl, phenyl and methyl groups for 2-4 and
cyclopentadienyl and methyl groups for 5-7, in the
appropriate ratios. The mass spectra of complexes 2-7
contain molecular ions, and all spectra contain frag-
ment ions corresponding to stepwise loss of carbonyls;
in all cases, the base peak is [M−3CO]+. Isotope
patterns are consistent with the presence of three irid-
ium atoms and one tungsten atom.
Table 2
Crystallographic data for 3
Empirical formula
Formula weight
Space group
C32H23Ir3N2O9W
1340.05
P21/n (No.14)
Monoclinic
Crystal system
Unit cell dimensions
2.2. X-ray structural study of 3
˚
a (A)
14.339(4)
12.772(4)
18.399(5)
96.62(2)
3347(2)
2.659
˚
b (A)
˚
The molecular structure of 3 as determined by a
single-crystal X-ray study is consistent with the formu-
lation given above and defines the substitution sites of
the isocyanides. A summary of crystal and refinement
data is found in Table 2, and selected bond distances
and angles are listed in Table 3. An ORTEP plot show-
ing the molecular geometry and atomic numbering
scheme is shown in Fig. 2.
Complex 3 has the WIr3 pseudotetrahedral frame-
work of the precursor cluster 1 and possesses an h5-cy-
clopentadienyl group, nine terminal carbonyl ligands,
and two iridium-ligated 2,6-dimethylphenylisocyanide
c (A)
i (°)
3
˚
V (A )
Dcalc. (g cm−3
)
Z
4
15.4
v (mm−1
)
Specimen size (mm3)
0.48×0.37×0.24
0.45, 1.00
50.1
6224
3832
A (min., max.)
2qmax (°)
N
No
R
0.040
0.031
Rw

78
S.M. Waterman et al. / Journal of Organometallic Chemistry 579 (1999) 75–82
Table 3
CO(21) and CO(31), it is not clear why coordination at
CO(22) and CO(33) does not proceed.
˚
Selected bond lengths (A) and bond angles (°) for complex 3
˚
Bond lengths (A)
2.3. Solution structures
Ir(1)–Ir(2)
Ir(2)–Ir(3)
Ir(2)–W(1)
Ir(1)–C(11)
Ir(1)–C(13)
Ir(2)–C(22)
Ir(3)–C(31)
Ir(3)–C(33)
W(1)–C(02)
W(1)–C(04)
W(1)–C(06)
2.7229(8)
2.695(1)
2.8282(9)
1.86(2)
2.01(1)
1.90(2)
1.89(2)
1.95(2)
2.26(2)
2.36(2)
1.98(2)
Ir(1)–Ir(3)
2.682(1)
2.8502(8)
2.781(1)
1.96(2)
1.88(2)
1.94(2)
1.91(2)
2.36(2)
2.31(2)
2.35(2)
1.94(1)
Ir(1)–W(1)
Ir(3)–W(1)
Ir(1)–C(12)
Ir(2)–C(21)
Ir(2)–C(23)
Ir(3)–C(32)
W(1)–C(01)
W(1)–C(03)
W(1)–C(05)
W(1)–C(07)
As mentioned above, the IR spectra of the complexes
3, 4, 6 and 7 are indicative of the presence of isomers,
with the mono-(isocyanide) substituted derivatives dis-
playing carbonyl frequencies arising from terminal car-
bonyls only. For all the clusters 2-7, only IR
absorptions appropriate for terminal isocyanide ligands
are observed [w(CN) 2179–2155 cm−1] (this is not
unexpected; previous studies have revealed that the
electron withdrawing R=CF3 group is required to
encourage the CNR ligand to adopt an edge-bridging
coordination mode [44]). These results, in combination
with the structural characterization of 3, lead us to
postulate that the clusters 2 and 5 adopt structures with
all-terminal ligand coordination geometries, analogous
to the structurally characterized precursor cluster 1 [29],
and the ‘parent’ cluster [Ir4(CO)12] [45] and its mono-
(isocyanide) substituted derivative [Ir4(CO)11(CNBut)]
[46]. The complexity of the IR spectra of 3, 4, 6 and 7
indicates the presence of isomers, weak absorptions in
the bridging carbonyl region suggesting that the clusters
exist as mixtures of isomers with all-terminal ligand
geometries and isomers incorporating a plane of bridg-
ing carbonyls (Fig. 1). We have recently reported the
isomer distribution and ligand fluxionality at
[CpWIr3(m-CO)3(CO)11−n(L)n] [L=PPh3, PMe3; n=1,
2 [4]] and [CpWIr3(m-L)(m-CO)3(CO)6] [L=dppe, dppm
[5]]. The IR spectra of 2-7 and unusual solid-state
structure of 3 prompted us to investigate the isomer
distribution and fluxionality of 5-7. The 13C-NMR
spectra of 5-7 each display a single carbonyl resonance
at r.t. Cooling the samples to 143 K reveals broadened
resonances only, and solubility problems precluded a
study at lower temperatures. The variable-temperature
NMR results suggest that the carbonyls are undergoing
much faster exchange than that observed in their phos-
phine-ligated analogues [4,5] (for which low tempera-
ture limiting spectra were obtained in the range
163–193 K).
Bond angles (°)
Ir(2)–Ir(1)–Ir(3)
Ir(3)–Ir(1)–W(1)
Ir(1)–Ir(2)–W(1)
Ir(1)–Ir(3)–Ir(2)
Ir(2)–Ir(3)–W(1)
Ir(1)–W(1)–Ir(3)
Ir(2)–Ir(1)–C(11)
W(1)–Ir(1)–C(11)
Ir(2)–Ir(1)–C(13)
Ir(3)–Ir(1)–C(13)
W(1)–Ir(1)–C(13)
C(11)–Ir(1)–C(13)
59.81(2)
60.27(3)
61.75(2)
60.84(2)
62.16(3)
56.87(2)
89.6(5)
148.8(4)
105.2(4)
158.2(4)
99.2(4)
Ir(2)–Ir(1)–W(1)
Ir(1)–Ir(2)–Ir(3)
Ir(3)–Ir(2)–W(1)
Ir(1)–Ir(3)–W(1)
Ir(1)–W(1)–Ir(2)
Ir(2)–W(1)–Ir(3)
Ir(3)–Ir(1)–C(11)
Ir(2)–Ir(1)–C(12)
Ir(3)–Ir(1)–C(12)
W(1)–Ir(1)–C(12)
C(11)–Ir(1)–C(12)
C(12)–Ir(1)–C(13)
60.94(2)
59.35(2)
60.42(3)
62.86(3)
57.31(2)
57.42(2)
97.3(4)
155.4(4)
95.6(4)
109.4(4)
93.2(6)
93.8(6)
98.5(6)
Ir(1)–C(11)–O(11) 177(1)
Ir(1)–C(13)–N(13) 176(1)
Ir(1)–C(12)–N(12) 174(1)
by the nature of the trans-disposed ligand; the iso-
cyanides are trans to CO groups, and the CO ligand is
trans to the Cp ligand, both of which should maximize
back-bonding to the carbonyls, and are consistent with
the site selection being driven by electronic consider-
ations. It is perhaps surprising that both isocyanides
ligate the same iridium. Although steric considerations
may disfavor coordination at the site occupied by
2.4. Thermolyses of isocyanide-adducts of
[CpWIr3(CO)11]
Thermolyses of isocyanide-ligated transition metal
carbonyl clusters sometimes result in an increased
‘metal loading’ of the isocyanide ligand [47,48], and in
one instance led to cleavage of the CꢀNR bond [49].
With these results in mind, the thermolyses of 5 and 6
were investigated. However, rather than increasing the
‘loading’ of the isocyanide ligand, redistribution of
isocyanide ligands resulted, affording mixtures of 5 and
6 in each case.
Fig. 2. Molecular structure and atomic labeling scheme for
[CpWIr3(CO)9(CNXy)2] (3). 20% thermal envelopes are shown for the
˚
non-hydrogen atoms; hydrogen atoms have arbitrary radii of 0.1 A.

S.M. Waterman et al. / Journal of Organometallic Chemistry 579 (1999) 75–82
79
All other solvents were reagent grade, and used as
received. Petroleum ether refers to a fraction of boiling
point range 60–80°C. The products of thin-layer chro-
matography were separated on 20×20 cm glass plates
coated with Merck GF254 silica gel (0.5 mm).
[CpWIr3(CO)11] [28] was prepared by the published
procedure. 13CO-enriched samples were prepared from
13CO-enriched (65%) 1, itself obtained by stirring a
solution of the cluster in CH2Cl2 under 1.2 atm 13CO at
60°C for 48 h. t-Butylisocyanide (Aldrich) and 2,6-
dimethylphenylisocyanide (Fluka) were purchased com-
mercially and used as received.
IR spectra were recorded on a Perkin–Elmer System
2000 Fourier transform spectrophotometer with NaCl
optics. 1H-NMR spectra were recorded on a Varian
Gemini 300 spectrometer (300 MHz) and were run in
CDCl3 (Aldrich) or acetone-d6 (Aldrich). 13C-NMR
spectra were recorded on a Varian VXR300S spectrom-
eter (75 MHz) in acetone-d6 (Aldrich) or 4CS2:1CD2Cl2
(CS2: Univer; CD2Cl2: Aldrich) or on a Bruker DMX
500, spectrometer (125.7 MHz) in CDFCl2 [51]. Chemi-
cal shifts in ppm are referenced to internal residual
solvent.
Fig. 3. Ref. [42].
2.5. Discussion
Stuntz and Shapley have examined isocyanide substi-
tution at [Ir4(CO)12] [50]. Introduction of BuNC into
t
the tetrairidium cluster necessitates significantly more
forcing conditions (refluxing chlorobenzene or prior
activation with Me3NO · 2H2O) than are required to
effect substitution at [CpWIr3(CO)11] (1). We have
noted a similar rate enhancement for phosphine substi-
tution in proceeding from the homometallic to the
heterometallic system. IR and 13C-NMR spectra for
[Ir4(CO)12−n(CNR)n] are consistent with isomers with
terminal carbonyls only for n=1 or 2, and isomers
possessing bridging carbonyls for n=3 or 4. A similar
result is apparent for the tungsten–triiridium deriva-
tives if the Cp group is considered as the first incoming
ligand. Low temperature limiting spectra were achiev-
able for the tetrairidium system at 183 K, but could not
be obtained for the mixed-metal derivatives to 143 K,
consistent with significantly enhanced fluxionality from
the homometallic to the heterometallic system. The
Mass spectra were obtained at the Australian Na-
tional University on a VG ZAB 2SEQ instrument (30
kV Cs+ ions, current 1 mA, accelerating potential 8
kV, matrix 3-nitrobenzyl alcohol). Peaks are reported in
the form: m/z (assignment, relative intensity). Elemen-
tal microanalyses were performed by the Microanalysis
Service Unit in the Research School of Chemistry,
Australian National University.
structural study of [Ir4(CO)11(CNBut)] revealed
a
derivative with no bridging carbonyl ligands, as ex-
pected from the solution spectral data [46]. The struc-
tural study of [CpWIr3(CO)9(CNXy)2] (3) similarly
reveals an isomeric form with no bridging carbonyls,
although the spectral data for this derivative indicate
that other isomers with bridging carbonyls are also
present in solution.
Cluster 3 is the first structurally characterized tetra-
hedral cluster with two terminal isocyanide groups lig-
ated to the same metal vertex, although a precedent
exists in trinuclear cluster chemistry: a structural char-
acterization of the triangular [Fe3(m-CO)2(CO)8-
(CNBut)2] reveals a related ligand disposition to 3 [42],
3.1. Reaction of [CpWIr3(CO)11] with one equi6alent of
XyNC
An orange solution of [CpWIr3(CO)11] (1) (20.0 mg,
0.0176 mmol) and XyNC (2.3 mg, 0.0176 mmol) in
CH2Cl2 (20 ml) was stirred at r.t. for 16 h. The dark
orange solution was then evaporated to dryness. The
resultant orange residue was dissolved in CH2Cl2 (ca. 1
ml) and chromatographed (2CH2Cl2:1 petroleum ether
eluant), affording two bands. The contents of the first
band were identified as 1 (2.6 mg, 12%) by solution IR
spectroscopy. Crystallization of the contents of the
second band, Rf 0.60, from CH2Cl2/MeOH afforded
orange crystals of [CpWIr3(CO)10(CNXy)] (2) (13.6 mg,
60%). Analytical data for 2: IR (c-C6H12): w(CꢀN)
2153m, w(CꢀO) 2067s, 2037vs, 2027m, 2014s, 2001w,
t
with two BuNC ligated to the same iron vertex, but
with two bridging carbonyls ligating the Fe–Fe bond
opposite the bis(isocyanide)-ligated iron vertex (Fig. 3).
3. Experimental
1987w, 1986m, 1972w, 1950w cm−1
;
1H-NMR
All reactions were performed under an atmosphere of
dry nitrogen (high-purity grade, CIG), although no
special precautions were taken to exclude air during
work-up. The reaction solvents were dried and distilled
under nitrogen using standard methods: CH2Cl2 over
CaH2, THF and toluene from sodium/benzophenone.
(CDCl3): l 7.17–7.09 (m, 3H, C6H3), 5.21 (s, 5H,
C5H5), 2.38 (s, 6H, Me); MS 1237 ([M]+, 10), 1209
([M−CO]+, 12), 1181 ([M−2CO]+, 25), 1153 ([M−
3CO]+, 100), 1125 ([M−4CO]+, 55), 1097 ([M−
5CO]+, 39), 1069 ([M−6CO]+, 45), 1041
([M−7CO]+, 52), 1013 ([M−8CO]+, 56), 985 ([M−

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S.M. Waterman et al. / Journal of Organometallic Chemistry 579 (1999) 75–82
9CO]+, 26). Anal. Calc.: C 23.31, H 1.14, N 1.13.
Found: C 24.22, H 1.08, N 1.26%.
chromatography (3CH2Cl2:2 petroleum ether eluant).
The contents of the first band were identified as 1 (1.8
mg, 9%) by solution IR spectroscopy. Crystallization of
the contents of the second band, Rf 0.78, from CH2Cl2/
3.2. Reaction of [CpWIr3(CO)11] with two equi6alents
of XyNC
MeOH
afforded
orange
crystals
of
[CpWIr3(CO)10(CNBut)] (5) (12.1 mg, 58%). Analytical
data for 5: IR (c-C6H12): w(CꢀN) 2178m, w(CꢀO) 2069s,
2036vs, 2026s, 2012s, 1999w, 1989sh, 1984m, 1964w
cm−1; 1H-NMR (acetone-d6): l 5.44 (s, 5H, C5H5), 1.52
(s, 9H, Me); 13C-NMR (acetone-d6): 180.4 (s, CO), 87.6
(s, C5H5), other signals not observed; MS 1189 ([M]+,
5), 1161 ([M−CO]+, 10), 1133 ([M−2CO]+, 20),
1105 ([M−3CO]+, 100), 1077 ([M−4CO]+, 55), 1049
([M−5CO]+, 30), 1021 ([M−6CO]+, 37), 993 ([M−
7CO]+, 35), 965 ([M−8CO]+, 22), 937 ([M−9CO]+,
13). Anal. Calc.: C 20.21 H 1.19, N 1.13. Found: C
21.14, H 1.42, N 1.32%.
Following the method of Section 3.1, [CpWIr3(CO)11]
(1) (20.0 mg, 0.0176 mmol) and XyNC (4.6 mg, 0.0352
mmol) in CH2Cl2 (20 ml) afforded two bands after
chromatography (2CH2Cl2:1 petroleum ether eluant).
The contents of the first band were identified as 2 (6.5
mg, 30%) by solution IR spectroscopy. Crystallization
of the contents of the second band, Rf 0.38, from
CH2Cl2/MeOH
afforded
orange
crystals
of
[CpWIr3(CO)9(CNXy)2] (3) (11.1 mg, 47%). Analytical
data for 3: IR (c-C6H12): w(CꢀN) 2152m, 2118m,
w(CꢀO) 2051s, 2046m, 2027vs, 2025vs, 2007s, 2001s,
1994m, 1991m, 1984m, 1978m, 1898w, 1847w cm−1
;
1H-NMR (CDCl3): l 7.30–7.03 (m, 6H, C6H3), 5.08 (s,
5H, C5H5), 2.35 (s, 12H, Me); MS 1340 ([M]+, 5), 1312
([M−CO]+, 6), 1284 ([M−2CO]+, 14), 1256 ([M−
3CO]+, 100), 1228 ([M−4CO]+, 58), 1200 ([M−
5CO]+, 42), 1172 ([M−6CO]+, 23), 1144
([M−7CO]+, 19), 1116 ([M−8CO]+, 16). Anal.
Calc.: C 28.68, H 1.73, N 2.09. Found: C 28.19, H 1.83,
N 2.04%.
3.5. Reaction of [CpWIr3(CO)11] with two equi6alents
of BuNC
t
Following the method of Section 3.1, [CpWIr3(CO)11]
t
(1) (20.0 mg, 0.0176 mmol) and BuNC (4 ml, 0.0352
mmol) in CH2Cl2 (20 ml) afforded two bands after
chromatography (3CH2Cl2:2 petroleum ether eluant).
The contents of the first band were identified as 5 (5.6
mg, 28%) by solution IR spectroscopy. Crystallization
of the contents of the second band, Rf 0.39, from
3.3. Reaction of [CpWIr3(CO)11] with three equi6alents
of XyNC
CH2Cl2/MeOH
afforded
orange
crystals
of
[CpWIr3(CO)9(CNBut)2] (6) (12.6 mg, 58%). Analytical
data for 6: IR (c-C6H12): w(CꢀN) 2177m, 2152m,
w(CꢀO) 2049s, 2045s, 2022vs, 2005s, 1996s, 1986s,
Following the method of Section 3.1, [CpWIr3(CO)11]
(1) (20.0 mg, 0.0176 mmol) and XyNC (7.0 mg, 0.0530
mmol) in CH2Cl2 (20 ml) afforded two bands after
chromatography (3 CH2Cl2:1 petroleum ether eluant).
The contents of the first band were identified as 3 (6.6
mg, 28%) by solution IR spectroscopy. Crystallization
of the contents of the second band, Rf 0.55, from
1974m, 1925w, 1890m, 1854w, 1838w cm−1; H-NMR
1
(acetone-d6): l 5.18 (s, 5H, C5H5), 1.49 (s, 18H, Me);
13C-NMR (CS2/CD2Cl2): 182.0 (s, CO), 86.2 (s, C5H5),
28.5 (s, Me), other signals not observed; MS 1244
([M]+, 5), 1216 ([M−CO]+, 7), 1188 ([M−2CO]+,
17), 1160 ([M−3CO]+, 100), 1132 ([M−4CO]+, 65),
1104 ([M−5CO]+, 47), 1076 ([M−6CO]+, 28), 1048
([M−7CO]+, 23), 1020 ([M−8CO]+, 21), 992 ([M−
9CO]+, 20). Anal. Calc.: C 23.17 H 1.86, N 2.25.
Found: C 23.51, H 1.98, N 2.00%.
CH2Cl2/MeOH
afforded
orange
crystals
of
[CpWIr3(CO)8(CNXy)3] (4) (16.0 mg, 63%). Analytical
data for 4: IR (c-C6H12): w(CꢀN) 2150s, 2131s, 2115s,
w(CꢀO) 2031s, 2022m, 2017m, 1995vs, 1986s, 1972m,
1898w, 1879m, 1840m cm−1 1H-NMR (CDCl3): l
;
7.12–7.00 (m, 9H, C6H3), 5.01 (s, 5H, C5H5), 2.31 (s,
18H, Me); MS 1443 ([M]+, 8), 1415 ([M−CO]+, 4),
1387 ([M−2CO]+, 10), 1359 ([M−3CO]+, 100), 1331
([M−4CO]+, 53), 1303 ([M−5CO]+, 69), 1275
([M−6CO]+, 13), 1247 ([M−7CO]+, 30). Satisfac-
tory microanalyses could not be obtained due to sample
decomposition in solution over days.
3.6. Reaction of [CpWIr3(CO)11] with three equi6alents
of BuNC
t
Following the method of Section 3.1, [CpWIr3(CO)11]
t
(1) (20.0 mg, 0.0176 mmol) and BuNC (6 ml, 0.0530
mmol) in CH2Cl2 (20 ml) afforded two bands after
chromatography (2CH2Cl2:1 petroleum ether eluant).
The contents of the first band were identified as 6 (6.1
mg, 28%) by solution IR spectroscopy. Crystallization
of the contents of the second band, Rf 0.38, from
3.4. Reaction of [CpWIr3(CO)11] with one equi6alent of
tBuNC
Following the method of Section 3.1, [CpWIr3(CO)11]
(1) (20.0 mg, 0.0176 mmol) and BuNC (2 ml, 0.0176
mmol) in CH2Cl2 (20 ml) afforded two bands after
CH2Cl2/MeOH
afforded
orange
crystals
of
t
[CpWIr3(CO)8(CNBut)3] (7) (13.5 mg, 59%). Analytical
data for 7: IR (CH2Cl2): w(CꢀN) 2179m, 2155m,

S.M. Waterman et al. / Journal of Organometallic Chemistry 579 (1999) 75–82
81
w(CꢀO) 2056vw, 2021vs, 1982vs, 1867w, 1816m cm−1
;
limit (ꢀ–2q scan mode; monochromatic Mo–Ka radia-
tion (u=0.71073 A)), yielding N independent reflec-
1H-NMR (acetone-d6): l 4.99 (s, 5H, C5H5), 1.46 (s,
27H, Me); 13C-NMR (CS2/CD2Cl2) 182.6 (s, CO), 85.9
(s, C5H5), 29.0 (s, Me), other signals not observed; MS
1299 ([M]+, 10), 1271 ([M−CO]+, 6), 1243 ([M−
2CO]+, 13), 1215 ([M−3CO]+, 100), 1187 ([M−
4CO]+, 60), 1159 ([M−5CO]+, 75), 1131
([M−6CO]+, 18), 1103 ([M−7CO]+, 35), 1075
([M−8CO]+, 30). Satisfactory microanalyses could
not be obtained due to sample decomposition in solu-
tion over days.
˚
tions. No of these with I=3|(I) were considered
‘observed’ and used in the full matrix/large block least
squares refinements after empirical absorption correc-
tion. Anisotropic thermal parameters were refined for
the non-hydrogen atoms; (x, y, z, Uiso)H were included,
constrained at estimated values. Conventional residuals
R, Rw on ꢀFꢀ at convergence are given. Neutral atom
complex scattering factors were used, computation us-
ing teXsan [52]. Pertinent results are given in the figures
and tables.
3.7. Thermolysis of [CpWIr3(CO)10(CNBut)]
An orange solution of [CpWIr3(CO)10(CNBut)] (5)
(20.0 mg, 0.0168 mmol) in THF (15 ml) was slowly
heated to 60°C and refluxed for 30 h. A brown decom-
position product was noted in the resultant orange
solution. The solution was cooled and the solvent re-
moved in vacuo, leaving a brown residue. Subsequent
purification by thin layer chromatography (2CH2Cl2:1
petroleum ether eluant) afforded two bands, identified
4. Supplementary material
Atomic coordinates, bond lengths and angles, and
thermal parameters have been deposited with the Cam-
bridge Crystallographic Data Centre. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK (Fax: +44-1223-336-033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
by IR spectroscopy as
5 (3.3 mg, 15%) and
[CpWIr3(CO)9(CNBut)2] (6) (2.0 mg, 10%).
3.8. Thermolysis of [CpWIr3(CO)9(CNBut)2]
(method A)
Acknowledgements
An orange solution of [CpWIr3(CO)9(CNBut)2] 6
(20.0 mg, 0.0164 mmol) in THF (15 ml) was slowly
heated to 60°C and refluxed for 30 h. The green solu-
tion obtained was evaporated to dryness. Subsequent
purification by thin layer chromatography (2CH2Cl2:1
petroleum ether eluant) afforded two bands, identified
by IR spectroscopy as 5 (2.0 mg, 10%) and 6 (7 mg,
30%).
The authors thank the Australian Research Council
for support of this work and Johnson-Matthey Tech-
nology Center for the generous loan of IrCl3. Associate
Professor O.b. Shawkataly is thanked for the gift of
some 2,6-dimethylphenylisocyanide. MGH is an ARC
Australian Research Fellow.
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