Reactions of heterometallic tungsten-iridium and tungsten-rhodium complexes containing C4 chains

Article abstract of DOI:10.1016/S0022-328X(00)00309-0

Modified syntheses of {Cp(OC)₃W} C≡CC≡C{M(CO)(PPh₃)₂} (M = Rh, Ir) from W(C≡CC≡CH)(CO)₃Cp and M(OTf)(CO)-(PPh₃)₂ are described. The Group 9 metal centre is the most electron-rich site, read

Full text of DOI:10.1016/S0022-328X(00)00309-0

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Journal of Organometallic Chemistry 607 (2000) 137–145
Reactions of heterometallic tungsten–iridium and
tungsten–rhodium complexes containing C4 chains
Michael I. Bruce a,*, Benjamin G. Ellis a, Brian W. Skelton b, Allan H. White b
a Department of Chemistry, Uni6ersity of Adelaide, Adelaide, South Australia 5005, Australia
b Department of Chemistry, Uni6ersity of Western Australia, Nedlands, Western Australia 6907, Australia
Received 6 March 2000; accepted 8 May 2000
Dedicated with best wishes to Professor Martin Bennett, a valued friend and colleague, on the occasion of his retirement.
Abstract
Modified syntheses of {Cp(OC)3W}CꢀCCꢀC{M(CO)(PPh3)2} (M=Rh, Ir) from W(CꢀCCꢀCH)(CO)3Cp and M(OTf)(CO)-
(PPh3)2 are described. The Group 9 metal centre is the most electron-rich site, readily adding MeI or C2(CN)4. Reactions with iron
carbonyls give successively {Cp(OC)3W}CꢀCC2{Fe2M(CO)8(PPh3)} and {Cp(OC)8Fe2W}C2C2{Fe2M(CO)8(PPh3)}, in which
Fe2(CO)6 moieties add to a CꢀC group and the adjacent metal centre. X-ray structures of {Cp(OC)3W}CꢀCCꢀC{Rh(CO)[h-
C2(CN)4](PPh3)2}, {Cp(OC)3W}CꢀCC2{Fe2Rh(CO)8(PPh3)} and {Cp(OC)8Fe2W}C2C2{Fe2Ir(CO)8(PPh3)} have been determined.
© 2000 Elsevier Science S.A. All rights reserved.
Keywords: Tungsten; Rhodium; C4 chains; Heterometallic
1. Introduction
Several examples are known where electronic communi-
cation between the capping metal centres has been
demonstrated, usually via cyclic voltammetry [4]. In the
limit, they may approach one-dimensional carbon al-
lotropes (‘carbyne’) [5].
The unusual electronic, magnetic and optical proper-
ties and reasonable non-linear optical properties that
have been demonstrated for some metal complexes
containing alkynyl, diynyl and higher poly-ynyl ligands
We have been interested in examples of these com-
has encouraged much of the contemporary interest in
plexes in which the carbon chain is capped by two
these species [1,2]. The potential of these compounds as
different metal fragments and have recently described
molecular wires [3] has resulted in an increasing knowl-
systems containing tungsten attached to metals of
edge of their electronic structures, which may incorpo-
rate either alternating carbonꢁcarbon single and triple
bonds (A) and (B) or the cumulenic structure (C). The
MꢁC single bonds or MꢀC triple bonds in forms A and
B may become important if the metal centre(s) is(are)
redox-active.
Groups 6–12 [6]. As far as we are aware, the only other
heterometallic systems are those of Gladysz, who cou-
pled his rhenium systems with palladium or rhodium in
{Cp*(Ph3P)(NO)Re}(CꢀC)n{MLn} [n=1, 2; MLn=
PdCl(PEt3)2, Rh(CO)(PPh3)2] [7]. Complexes containing
the same metals with different ligands attached have
been reported by Lapinte, who described the synthesis
and redox properties of {Cp*(dppe)Fe}CꢀCCꢀC-
{Fe(CO)2Cp*} [4b]. In the present paper we describe
modified syntheses of {Cp(OC)3W}CꢀCCꢀC{M(CO)-
(PPh3)2} (M=Rh, Ir) and some of their reactions,
which illustrate the varying electronic properties of the
WꢁC4ꢁM chain.
Mꢁ(CꢀC)nꢁM Mꢁ(CꢀC)nꢁCꢀM Mꢂ(CꢂC)nꢂM
(A)
(B)
(C)
* Corresponding author. Fax: +61-88-3035939; fax: +61-88-
3034358.
E-mail address: michael.bruce@adelaide.edu.au (M.I. Bruce).
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00309-0

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M.I. Bruce et al. / Journal of Organometallic Chemistry 607 (2000) 137–145
2. Results and discussion
2017 cm−1, which was assigned to the w(CO) absorp-
tion of the iridium(III) centre, together with the w(OO)
2.1. Syntheses of
{Cp(OC)3W}CꢀCCꢀC{M(CO)(PPh3)2} (M=Ir, Rh)
band at 832 cm−1
.
1
The H-NMR spectra of 1 and 2 show singlet Cp
resonances at l 5.55 (Ir), 5.47 (Rh) and multiplets at l
7.39–7.75 assigned to the Ph protons. The 13C-NMR
spectra contain resonances at l 91.59 (Cp), between l
128.1 and 134.9 (Ph) and three singlets at ca. l 211,
231.6 (WꢁCO) and 240 (Ir/RhꢁCO). Resonances of the
carbon atoms of the chain in these and related com-
plexes were not observed even with long delay and
accumulation times.
The conditions under which our previous syntheses
of {Cp(OC)3W}CꢀCCꢀC{Ir(CO)(PPh3)2} and its
rhodium analogue were carried out resulted in the
ready formation of the dioxygen adducts, of which the
iridium derivative was crystallographically character-
ised, as a result of ready oxidative addition of O2 to the
Group 9 metal centres [6]. In the present work, we
sought a more efficient coupling of W(CꢀCCꢀCH)-
(CO)3Cp to the iridium or rhodium centres and exam-
ined the reactions of M(OTf)(CO)(PPh3)2 (M=Rh, Ir)
[8]. Accordingly, reactions of W(CꢀCCꢀCH)(CO)3Cp
[9] with M(OTf)(CO)(PPh3)2, made in situ [10], in the
presence of diethylamine, were performed in the strict
absence of oxygen using standard Schlenk techniques to
give the desired compounds {Cp(OC)3W)CꢀCCꢀC-
{M(CO)(PPh3)2} [M=Ir (1), Rh (2)] in high yield.
Both complexes were isolated as bright yellow solids,
which are sensitive to air, heat and light. All attempts
to recrystallise these materials afforded mixtures with
the dioxygen adducts described previously.
Electrospray (ES) mass spectra of 1 show M+ at m/z
1126, together with fragment ions at m/z 1098 ([M−
CO]+) and 745 ([Ir(CO)(PPh)2]+). For 2, addition of
NaOMe was necessary to enhance the spectrum [12]
and resulted in the formation of an ion at m/z 1059
([M+Na]+), while in the negative ion spectrum [M+
OMe]− was observed at m/z 1067.
2.2. Reactions of 1 and 2
Complexes 1 and 2 contain four potential sites of
electrophilic attack, namely the two metal atoms and
the two CꢀC triple bonds. To probe their reactivity, we
The infrared spectrum of a dioxygen-free sample of 1
shows two peaks in the carbonyl region at 2037 and
1952 cm−1 corresponding to the w(CO) bands of the
W(CO)3 group. The Irꢁw(CO) peak in 1, predicted to be
at ca. 1955 cm−1 by comparison with that in
Ir(CꢀCPh)(CO)(PPh3)2 [11], is overlapped by the broad
lower energy Wꢁw(CO) band at 1952 cm−1. The corre-
have examined the reactions of 1 and 2 with
iodomethane, tetracyanoethene (tcne) and iron car-
bonyl. The reaction with dioxygen suggested that the
Group 9 metal is electron-rich, but other experiences
with ethynylmetal complexes have shown that Cb is also
a potential site for electrophilic attack [13]. Thus, while
Vaska’s complex readily adds iodomethane to give
IrMeClI(CO)(PPh3)2 [14], the complex Ru(CꢀCPh)-
(PPh3)2Cp can be methylated to give the vinylidene
[Ru(ꢂCꢂCMePh)(PPh3)2Cp]+ [15]. Reactions of
Ir(CꢀCPh)(CO)(PPh3)2 also occur at the iridium centre
[11].
Similarly, addition of tetracyanoethene to Vaska’s
complex results in IrCl(CO){h-C2(CN)4}(PPh3)2 [16], in
which the iridium centre is formally oxidised to Ir(III),
with w(CO) at 2060 cm−1. In contrast, tcne reacts with
Ru(CꢀCPh)(PPh3)2Cp to give the butadienyl complex
Ru{C[ꢂC(CN)2]ꢂCPhC(CN)2}(PPh3)2Cp, which readily
loses PPh3 to give Ru{h3-C(CN)2CPhCꢂC(CN)2-
}(PPh3)Cp, the initial reaction occurring by addition of
the electron-deficient olefin to the s-bonded alkynyl
group [17]. With Rh(CꢀCPh)(CO)(PPh3)2, addition oc-
curs to the metal centre [18], while with W(CꢀCCꢀCH)-
(CO)3Cp, addition occurs at the CꢀC triple bond fur-
ther from the tungsten atom [9].
sponding bands in 2 are found at 2037 and 1952 cm−1
,
but in this case the Rhꢁw(CO) band is found at 1973
cm−1. For 1, the w(CC) absorption occurs at 2115
cm−1. The formation of the dioxygen adduct of 1 upon
attempts at further purification was shown by the ap-
pearance of a new w(CO) band in the IR spectrum at

M.I. Bruce et al. / Journal of Organometallic Chemistry 607 (2000) 137–145
139
1
2.3. Reaction of 1 with iodomethane
The H-NMR spectra of 4 and 5 contain singlets at l
ca. 5.5 (Cp) and multiplets between l 7.26 and 7.52
(Ph), while the 13C-NMR spectra have multiplets be-
tween l 128.32 and 134.26 (Ph), with three singlets at l
ca. 230.7, 211.1 (WꢁCO) and 170.0 (IrꢁCO; the RhꢁCO
resonance was not observed). The low-field signal found
for the latter again confirms the presence of an oxidised
iridium centre. Singlet CN resonances were found at l
112.6 and 116.9.
The reaction between 1 and MeI was carried out in
thf and afforded {Cp(OC)3W}CꢀCCꢀC{IrMeI(CO)-
(PPh3)2} (3) in 76% yield. This complex was identified
spectroscopically and from elemental analysis. In partic-
ular, addition at Ir confirmed by the shift in the Ir
w(CO) band to 2047 cm−1, indicating a change in the
formal oxidation state at the iridium centre from +l to
+3. The 1H-NMR spectrum of 3 contains a triplet
resonance at l 0.68 (Me) and a singlet at 5.54 (Cp) in
addition to the Ph multiplet between l 7.32 and 8.03.
The 13C-NMR spectrum contained resonances at l 1.11
(Me), 91.64 (Cp) and a multiplet between l 127.63 and
131.72 (Ph). Two WꢁCO resonances were at l 230.76
and 210.89 ppm, while the IrꢁCO resonance at l 169.15
also confirms the presence of the Ir(III) centre, removal
of electron density from the metal causing an upfield
shift of ca. 70 ppm. The stereochemistry of the product
however could not be deduced unequivocally. In this
regard, we note that it was recently reported that
addition of H2 or HCꢀCPh to Ir(CꢀCPh)(CO)(PPh3)2
affords the cis,trans isomer of IrH(X)(CꢀCPh)(CO)-
(PPh3)2 (X=H or CꢀCPh) (corresponding to 3b) by
rapid intramolecular rearrangement of the first-formed
cis,cis isomer (corresponding to 3c) [19].
2.5. Molecular structure of
{Cp(OC)3W}CꢀCCꢀC{Rh(CO)[p-C2(CN)4](PPh3)2} (5)
Fig.
1 is a representation of a molecule of
{Cp(OC)3W}CꢀCCꢀC{Rh(CO)[h-C2(CN)4](PPh3)2] (5)
and significant bond parameters are collected in Table 1.
As can be seen, the acetylenic hydrogen in
W(CꢀCCꢀCH)(CO)3Cp has been replaced by a rhodium
,
[RhꢁC(4) 2.00(1) A], to which are attached the CO
,
group [RhꢁCO 1.86(1) A], two PPh3 ligands [RhꢁP
,
2.380, 2.393(4) A], and the tetracyanoethene ligand. The
latter is bonded to Rh via C(10) and C(20) in the usual
side-on h mode [RhꢁC(10, 20) 2.15, 2.16(1) A]. The
2
,
geometry is very similar to that of the same ligand in
Rh(CꢀCPh){h-C2(CN)4}(NCMe)(PPh3)2 [18] or Ir-
Br(CO)(AsPh3)2{h-C2(CN)4} [20]. The coordination ge-
ometry about rhodium is trigonal bipyramidal
(considering the tcne ligand to occupy one site), the two
PPh3 ligands occupying equatorial sites [P(1)ꢁRhꢁP(2)
110.2(1)°, cf. 107.43(6)° in the Ir complex]. The
,
,
C(10)ꢁC(20) bond [1.49(2) A, cf. 1.447(23) A in the Ir
2.4. Reactions with tetracyanoethene (tcne)
,
complex] is ca. 0.15 A longer than that found in free
,
tcne [1.344(3) A] [21]. Distortion of the tcne ligand from
The reactions of 1 or 2 with one equivalent of tcne in
THF gave {Cp(OC)3W}CꢀCCꢀC{M(CO)[h-C2(CN)4]-
(PPh3)2] [M=Ir (4), Rh (5)] as yellow and orange
crystalline solids, respectively. Attempts to add a second
tcne molecule to 4 proved unsuccessful. The formulas of
4 and 5 were established by elemental microanalysis and
spectroscopically and confirmed by a single-crystal X-
ray structure determination of 5. The IR spectrum of 4
contained w(CN) at 2227 cm−1 and three w(CO) bands
at 2058, 2039 and 1952 cm−1. Of these, the bands at
2039 and 1952 cm−1 can be assigned to the W(CO)3Cp
group, while that at 2058 cm−1 arises from the IrꢁCO
ligand, reflecting the presence of the formal Ir(III)
centre. For 5, these absorptions were found at 2224
[w(CN)] 2078, 2039 and 1953 cm−1 [w(CO)]; addition-
planarity also occurred as expected, with the four CN
substituents bent away from the metal, as found in other
examples of complexes containing this ligand [18,20,22].
Comparison of the tungsten moiety also reveals little
difference from related compounds. The C4 bridge is
non-linear, with angles at C(1,2,3,4) ranging between
170 and 178(1)°. The MꢁC bond lengths are 2.10(1) (W)
,
and 2.00(1) A (Rh) [cf. 2.148(4) in W(CꢀCCꢀCH)-
(CO)3Cp [23], 1.94(2) A in Rh(CꢀCPh){h-C2(CN)4}-
,
(NCMe)(PPh3)2] [18].
2.6. Reactions with Fe2(CO)9
Iron carbonyls readily form mixed-metal cluster com-
plexes, such as Fe2W(m3-C2R)(CO)8Cp (R=Ph [24], tol
[25]) with W(CꢀCR)(CO)3Cp, and Fe2M(m3-C2R)(CO)8-
(PPh3) (M=Ir, Rh) in reactions with Group 9 alkynyls
[26]. The reactions of 1 and 2 with Fe2(CO)9 were
carried out to determine the site(s) of addition to these
mixed-metal diyndiyl systems. Two major products were
isolated from reactions of 1 or 2 with an excess of
ally, the w(CC) absorption was found at 2142 cm−1
.

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M.I. Bruce et al. / Journal of Organometallic Chemistry 607 (2000) 137–145
Fe2(CO)9, which could be separated by preparative
TLC. They were characterised by elemental analyses
and spectroscopic methods as {Cp(OC)3W}CꢀCC2-
{Fe2M(CO)8(PPh3)} [M=Ir (6), Rh (7)] and
{Cp(OC)8Fe2W}C2C2{Fe2M(CO)8(PPh)3} [M=Ir (8),
Rh (9)], the structures being confirmed by single-crystal
structural determinations for 7 and 8.
For 6 and 7, the IR spectra contained similar com-
plex w(CO) patterns between 1950 and 2068 cm−1. The
1H-NMR spectra of the two complexes contained sin-
glet resonances at l 5.62 and 5.49 (Cp) and multiplets
between l 7.26 and 7.50 (Ph). The relative intensities of
the latter confirmed that one PPh3 ligand has been lost
from the Group 9 metal centre, probably in combina-
tion with an Fe(CO)4 fragment. In the 13C-NMR spec-
tra, singlets at l ca. 88.4 or 91.72 (Cp) and phenyl
multiplets between l 128.8 and 134.2 were found. At
low field, only signals at ca. l 218.5 (WꢁCO) and 212.0
(FeꢁCO) were observed, with a singlet at l 167.7 being
assigned to the RhꢁCO resonance, the IrꢁCO signal not
being found. In the ES mass spectra of solutions of 6
and 7 containing NaOMe, the base peak is [M+
OMe]−, at m/z 1202 and 1084, respectively.
The second product isolated from each reaction has
the formula {Cp(OC)8Fe2W}C2C2{Fe2M(CO)8(PPh3)}
[M=Ir (8), Rh (9)]. The rhodium complex was ob-
tained in very low yield, possibly because of the thermal
instability of 2. As for 6 and 7, the IR w(CO) spectra
of 8 and 9 are complex. The 1H-NMR spectrum of
8 contains a singlet resonance for the Cp protons at
l 5.63, with a Ph multiplet at l ca. 7.34–7.70, the latter
signal arising from only one PPh3 ligand. The 13C-
NMR spectrum of 8 contains a Cp singlet resonance
at l 91.94 and a Ph multiplet at l ca. 128.57–133.74.
Peaks at l 212.39 and 210.54 arise from FeꢁCO ligands
on the two different iron clusters. The IrꢁCO ligands
give a singlet at l 174.80 and the WꢁCO groups
are found at l 227.94. There does not appear to be
any intermetal exchange for these CO ligands. ES
mass spectra (negative ion mode with NaOMe) of 8
have as the base peak [M+OMe]+ at m/z 1454. An
MS/MS experiment showed fragmentation to [(M+
OMe)−nCO]− (n=4, 8 and 11). In the ES mass
spectrum of 9, the highest ion at m/z 1335 corresponds
to [M+H]+; an MS–MS experiment on this ion
showed fragmentation by loss of CO, PPh3 and
Fe2(CO)4 groups.
Addition of Fe2(CO)9 to both 6 and 7 resulted in
their conversion to the di-cluster complexes 8 and 9,
respectively, suggesting that the mono-cluster com-
pounds are in fact intermediates in the formation of the
di-cluster complexes 8 and 9.
Fig. 1. Plot of a molecule of {Cp(OC)3W}CꢀCCꢀC{Rh(CO)[h-C2(CN)4](PPh3)2} (5), showing atom numbering scheme. In this and subsequent
,
figures, non-hydrogen atoms are shown as 20% thermal ellipsoids; hydrogen atoms have arbitrary radii of 0.1 A.

M.I. Bruce et al. / Journal of Organometallic Chemistry 607 (2000) 137–145
141
2.7. Molecular structures of
{Cp(OC)3W}CꢀCC2{Fe2Rh(CO)8(PPh3)} (7) and
{Cp(OC)8Fe2W}C2C2{Fe2Ir(CO)8(PPh3)} (8)
Table 1
,
Selected bond distances (A) and bond angles (°) in complexes 5, 7 and
8
Bond
5
7
8
Figs. 2 and 3 contain plots of molecules of 7 and 8,
respectively, with important bond parameters being
summarised in Table 1. Direct comparisons can be
made with the previously described cluster complexes
Fe2W(m3-C2R)(CO)8Cp [24,25] and Fe2Ir(m3-C2Ph)-
(CO)8(PPh3) [26]. In 7, addition of an Fe2(CO)6 unit to
the rhodium centre formed an Fe2Rh cluster, which
carries eight CO groups and the remaining PPh3 ligand.
Two carbons of the C4 chain interact with this cluster in
the usual 2s,p mode, with C(4) being s-bonded to Fe
rather than Rh, as in precursor 2. Such rearrangement
is not unexpected, being the result of the ready mobility
of alkynyl groups (although not found here) around
a
Bond distances
WꢁC(Cp)
(av.)
WꢁCO
(av.)
WꢁC(1)
FeꢁCO
(av.)
Fe(3)ꢁFe(4)
Fe(5)ꢁFe(6)
Fe(3)ꢁM
Fe(4)ꢁM
Fe(5)ꢁM
Fe(6)ꢁM
MꢁP(1)
2.30–2.39(1)
2.33
1.94–2.05(2)
1.99
2.304–2.376(4) 2.296–2.330(10)
2.34 2.31
2.002–2.012(4) 1.982, 2.01(1)
2.006
1.996
1.978(7)
2.10(1)
2.125(3)
1.786–1.816(4)
1.799
2.6369(6)
2.530(2)
2.495(2)
2.5727(6) (Rh) 2.875(1) (W)
2.7119(5) (Rh) 2.8456(9) (W)
2.726(1) (Ir)
2.6787(9) (Ir)
2.380(3) (Rh)
2.393(4) (Rh)
1.86(1) (Rh)
2.4152(9) (Rh) 2.340(2) (Ir)
MꢁP(2)
MꢁC(2n)
1.912, 1.934(2) 1.917, 1.907(9)
(Rh)
(Ir)
MꢁC(3)
MꢁC(4)
2.223(2) (Rh)
2.160(3) (Rh)
2.00(1) (Rh)
1.929(7) (Ir)
2.028(8)
2.111(8)
Fe(3)ꢁC(1)
Fe(3)ꢁC(2)
Fe(3)ꢁC(3)
Fe(3)ꢁC(4)
Fe(4)ꢁC(I)
Fe(4)ꢁC(2)
Fe(4)ꢁC(4)
Fe(5)ꢁC(3)
Fe(5)ꢁC(4)
Fe(6)ꢁC(3)
Fe(6)ꢁC(4)
C(1)ꢁC(2)
C(2)ꢁC(3)
C(3)ꢁC(4)
2.105(3)
2.008(3)
2.038(6)
2.036(7)
1.812(2)
2.113(8)
2.018(7)
2.085(7)
2.076(6)
1.313(8)
1.42(1)
1.23(2)
1.38(2)
1.20(2)
1.218(3)
1.394(3)
1.323(3)
1.309(8)
b
Bond angles
c(1)ꢁWꢁC(11)
C(1)ꢁWꢁC(12) 131.1(6)
C(1)ꢁWꢁC(13)
P(1)ꢁRhꢁP(2)
74.6(6)
121.8(3)
96.0(3)
Fig. 2. Plot of a molecule of {Cp(OC)3W}CꢀCC2{Fe2Rh(CO)8-
(PPh3)} (7), showing atom numbering scheme.
126.2(1)
73.8(1)
77.2(6)
110.2(1)
C(4)ꢁRhꢁC(21) 176.3(5)
P(1)ꢁRhꢁC(21) 95.7(4)
P(2)ꢁRhꢁC(21) 87.8(4)
P(1)ꢁRhꢁC(4)
P(2)ꢁRhꢁC(4)
Fe(3)ꢁMꢁP
Fe(5)ꢁMꢁP
WꢁC(1)ꢁC(2)
C(1)ꢁC(2)ꢁC(3) 173(1)
C(2)ꢁC(3)ꢁC(4) 176(1)
C(3)ꢁC(4)ꢁM
81.4(3)
91.2(3)
148.55(2) (Rh)
108.38(5) (Ir)
158.9(5)
146.1(6)
178(1)
177.4(3)
175.2(3)
150.1(2)
149.1(6)
170(1) (Rh)
156.4(2) [Fe(4)] 153.2(5) (Ir)
a Other distances. For 5: MꢁC(10), 2.15(1); MꢁC(20), 2.16(1);
C(10)ꢁC(20), 1.49(2); P(1)ꢁRhꢁC(10/20), 125.5(3); P(2)ꢁRhꢁC(10/20),
123.8(3).
b Other angles: Rh(2)ꢁC(10)ꢁC(101,102), 115.9(8), 116.7(9);
Rh(2)ꢁC(20)ꢁC(201,202), 120.0(8), 111.5(9)°. C(20)ꢁC(10)ꢁC(101,102)
are 120(1), 116(1); with C(101)ꢁC(10)ꢁC(102), 112(1) (S 348°);
C(10)ꢁC(20)ꢁC(201,202) are 117(1), 118(1); with C(201)ꢁC(20)ꢁ
C(202), 114(1)° (S 348°).
Fig. 3. Plot of a molecule of {Cp(OC)8Fe2W}C2C2{Fe2Ir(CO)8-
(PPh3)} (8), showing atom numbering scheme.

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M.I. Bruce et al. / Journal of Organometallic Chemistry 607 (2000) 137–145
clusters [27]. A homometallic example is found in
obtained from
Fe(CꢀCPh)(CO)2Cp and Fe2(CO)9, in which the C2Ph
and Cp groups are attached to different iron atoms [28].
environment with little decomposition occurring over
several months. The reactions of these complexes re-
vealed that the Group 9 metal was the most electron-
rich site in the molecule. Thus, oxidative addition
reactions with MeI and tcne have given complexes in
which the Group 9 metal is formally oxidised. Reac-
tions of 1 and 2 with Fe2(CO)9 result in addition of
Fe2(CO)6 moieties firstly to the CꢀC triple bond adja-
cent to the Group 9 metal, and then to the CꢀC triple
bond adjacent to the tungsten. From these reactions,
mixed-metal clusters incorporating either two or four
carbons of the C4 chain have been obtained, but it has
not been possible to attach all four carbons to a single
polymetallic cluster.
Fe3(m3-C2Ph)(m-CO)(CO)7Cp,
,
The FeꢁFe bond in 7 [2.6369(6) A] is similar to that
found in Fe2W{m3-C(tol)}{m-C2(SiMe3)2(m-CO)(CO)6Cp
[29], while the two FeꢁRh bonds differ significantly
,
[Fe(1,2)ꢁRh 2.5727(6), 2.7119(5) A], reflecting the dif-
ferent electron density at each iron, resulting from the
s or p coordination of the C2 unit. For comparison, the
FeꢁRh distances in Fe2Rh(m-H)(m3-COMe)(CO)7Cp are
,
2.634 and 2.652(1) A [30]. The alkynyl substituent in 7
is the ꢁCꢀCW(CO)3Cp group and is bent away from
the cluster [C(2)ꢁC(3)ꢁC(4) 150.1(2)°]; the correspond-
ing angle at C(4) is 156.4(2)°. The W(CO)3Cp group is
similar to that in 5, with angles along the chain at C(1)
and C(2) being 177.4(3) and 175.2(3)°, respectively.
In complex 8, addition of the second Fe2(CO)6 unit
occurred at tungsten to give an Fe2W cluster with loss
of a CO ligand. Metal–metal separations are 2.495(2),
2.530(2) (FeꢁFe), 2.6787(9), 2.726(1) (FeꢁIr), 2.8456(9)
4. Experimental
4.1. General reaction conditions
All reactions were carried out under dry, high purity
nitrogen using standard Schlenk techniques. Solvents
were dried, distilled and degassed before use. Elemental
analyses were by the Canadian Microanalytical Service,
Delta, BC. Preparative TLC was carried out on glass
plates (20×20 cm) coated with silica (Merck 60
GF254, 0.5 mm thick).
,
and 2.875(1) A (FeꢁW). The differences between the
various values can be ascribed to the differences in local
coordination, e.g. the two FeꢁFe distances are found in
different clusters, the two FeꢁIr distances are trans to
CO and PPh3, while the two FeꢁW bonds are trans to
CO and Cp, respectively. The FeꢁW distances are
longer than those found in Fe2W{m3(tol)}{m-
C2(SiMe3)2}(m-CO)(CO)6Cp [29] and Fe2W{m3-C(tol)}-
4.1.1. Instrumentation
,
(m-CO)(CO)8Cp [2.756, 2.805(2) A] [30]. The C4 chain is
IR: Perkin–Elmer FT-IR 1920X. Solution spectra
were obtained using a solution cell fitted with NaCl
windows (path length 0.5 mm). Nujol mull spectra were
collected from samples mounted between NaCl discs.
NMR: samples were dissolved in CDCl3 (Aldrich) using
5 mm sample tubes. Spectra were recorded using a
Varian Gemini 200 instrument (1H at 199.98 MHz, 13C
at 50.29 MHz). Electrospray (ES) mass spectra were
obtained by direct diffusion of solutions in MeOH
(unless otherwise indicated) into a Finnegan LCQ in-
strument. Nitrogen was used as the drying and nebulis-
ing gas. Chemical aids to ionisation are indicated where
used [12].
now complexed to both cluster cores, the two C2 units
both being attached in the 2s,p mode with the s bonds
,
between C(1) and W [1.978(7) A] and, in contrast with
,
7, between C(4) and Ir [1.929(7) A]. The C4 chains are
no longer linear, with angles at C(1,2,3,4) ranging
between 146.1(6) and 158.9(5)°, comparable with those
found in other examples of C2FeM (M=Ir, W) clusters
mentioned above. It is notable that the C2Fe2Ir and
C2Fe2W clusters are joined only by the C(2)ꢁC(3) bond
,
[1.42(1) A] as has been found before in the anion
[{Fe3(CO)9}(m-C2C2)]2−, in which the separation is
1.42(1) [31]. Similarly, the angles at the central carbons
are 146.1 and 149.1(6)° in 8, which may be compared
with the value of 148.0(6)° in the cluster dianion.
In both examples, the C4 chains adopt a transoid
geometry.
4.1.2. Reagents
The compounds W(CꢀCCꢀCH)(CO)3Cp [10], Ir-
Cl(CO)(PPh3)2 [32] and RhCl(CO)(PPh3)2 [33] were pre-
pared by the cited methods.
3. Conclusions
4.2. Preparation of
{Cp(OC)3W}CꢀCCꢀC{M(CO)(PPh3)2} (M=Ir, Rh)
The
complexes
{Cp(OC)3W}CꢀCCꢀC{M(CO)-
(PPh3)2} where M=Rh or Ir have been prepared suc-
cessfully by a new synthetic method involving reactions
of triflate derivatives with W(CꢀCCꢀCH)(CO)3Cp. Al-
though these complexes were light and air sensitive, it
was found that they can be stored in a cold and dark
4.2.1. M=Ir (1)
A solution of IrCl(CO)(PPh3)2 (200 mg, 0.25 mmol)
and AgOTf (66 mg, 0.25 mmol) in CH2Cl2 (20 ml) was
stirred at room temperature (r.t.) for 3 h. The yellow
solution was filtered under nitrogen into a Schlenk tube

M.I. Bruce et al. / Journal of Organometallic Chemistry 607 (2000) 137–145
143
and concentrated to 5 ml. NHEt2 (30 ml) was added,
followed by W(CꢀCCꢀCH)(CO)3Cp (98 mg, 0.25 mmol)
and the solution was stirred for 1 h. The bright yellow
precipitate of {Cp(OC)3W}CꢀCCꢀC{Ir(CO)(PPh3)2} (1)
(230 mg, 80%) was collected by vacuum filtration and
washed with hexane, with strict exclusion of air. Anal.
Found: C, 52.29; H, 3.45. Calc. for C49H35IrO4P2W: C,
52.28; H, 3.13%; M, 1126. IR (CH2Cl2): w(CO): 2037,
1952 cm−1. 1H-NMR: l 5.55 (s, 5H, Cp), 7.39–7.75 (m,
30H, Ph). 13C-NMR: l 91.59 (s, Cp), 128.13–134.92 (m,
Ph), 211.89 (s, WꢁCO), 231.62 (s, WꢁCO), 240.25 (s,
IrꢁCO). ES mass spectra (MeOH, m/z): 1126, M+;
1098, [M−CO]+; 745, [Ir(CO)(PPh3)2]+.
tcne (12 mg, 0.09 mmol) was added. The solution was
stirred in the dark at 4°C for 20 min. Purification by
preparative TLC (4:6 acetone–hexane, Rf 0.43)
{Cp(OC)3W}CꢀCCꢀC{Ir(CO)[h-C2(CN)4](PPh3)2} (4)
(87 mg, 78%). Anal. Found: C, 52.63; H 2.98; N, 4.50.
Calc. for C55H35N4IrO4P2W: C, 52.68; H, 2.8 1; N,
4.46%; M, 1254. IR (CH2Cl2): w(CN) 2227, w(CO) 2058,
1
2039, 1952 cm−1. H-NMR: l 5.53 (s, 511, Cp), 7.26–
7.52 (m, 30H, Ph). 13C-NMR: l 91.83 (s, Cp), 112.66,
116.95 (CN), 128.32–134.26 (m, Ph), 170.00 (s, IrꢁCO),
211.17 (s, WꢁCO), 230.63 (s, WꢁCO). ES mass spectrum
(MeOH, with NaOMe, m/z): 1277, [M+Na]+; 1149,
[(M+Na)−C2(CN)4]+.
4.2.2. M=Rh (2)
4.4.2. {Cp(OC)3W}CꢀCCꢀC{Rh(CO)[p-C2(CN)4]-
(PPh3)2} (5)
This complex was prepared in a similar manner to 1,
using RhCl(CO)(PPh3)2 (200 mg, 0.28 mmol), AgOTf
(74 mg, 0.28 mmol) and W(CꢀCCꢀCH)(CO)3Cp (110
mg, 0.28 mmol) in CH2Cl2 (20 ml) and NHEt2 (30 ml).
The yellow precipitate of {Cp(OC)3W}CꢀCCꢀC-
{Rh(CO)(PPh3)2} (2) (235 mg, 81%) was collected by
vacuum filtration and washed with hexane, again with
strict exclusion of air. Anal. Found: C, 56.95; H, 3.62.
Calc. for C49H35O4P2RhW: C, 56.78; H, 3.40%; M,
The colour of a solution of 2 (100 mg, 0.09 mmol) in
thf (20 ml) changed rapidly from yellow to orange when
tcne (12.3 mg, 0.09 mmol) was added. After stirring in
the dark at r.t. for 1 h, solvent was removed under
vacuum and the residue purified by preparative TLC
(4:3 acetone–hexane, Rf 0.35) which afforded
{Cp(OC)3W}CꢀCCꢀC{Rh(CO)[h-C2(CN)4](PPh3)2} (5)
as an orange crystalline solid (80 mg, 72%). Anal.
Found: C, 53.67; H, 3.02; N, 4.44. Calc. for
C55H35N4O4P2RhW·CH2Cl2: C, 53.82; H, 2.98; N,
4.48%; M, 1164. IR (CH2Cl2): w(CN), 2224; w(CC),
1036. IR (CH2Cl2): w(CO): 1952, 1973, 2037 cm−1
.
1H-NMR: l 5.47 (s, 5H, Cp), 7.40–7.75 (m, 30H, Ph).
13C-NMR: l 91.6 (s, Cp), 128.2–134.8 (m, Ph), 210.8 (s,
WꢁCO), 231.6 (s, WꢁCO), 239.8 (s, RhꢁCO). ES mass
spectrum (with NaOMe, m/z): (positive ion mode) 1059,
[M+Na]+; (negative ion mode) 1067, [M+OMe]−.
1
2142; w(CO): 2078, 2039, 1953 cm−1. H-NMR: l 5.51
(s, 5H, Cp), 7.29–7.57 (m, 30H, Ph). 13C-NMR: l 91.64
(s, Cp), 112.71, 116.72 (CN), 128.26–134.15 (m, Ph),
211.11 (s, WꢁCO), 230.79 (s, WꢁCO). ES mass spectrum
(MeOH, m/z): 1036, [M−C2(CN)4]+.
4.3. Reaction with iodomethane
4.3.1. {Cp(OC)3W}CꢀCCꢀC[IrMeI(CO)(PPh3)2] (3)
Iodomethane (0.25 ml, 0.4 mmol) was added to a
solution of 1 (100 mg, 0.08 mmol) in thf (20 ml), and the
resulting solution was stirred in the dark for 1 h. The
solvent and any unreacted iodomethane were removed
under vacuum and the residue was purified by prepara-
tive TLC (4:6 acetone–hexane, Rf 0.47) to give
{Cp(OC)3W}CꢀCCꢀC{IrMeI(CO)(PPh3)2} (3) (85 mg,
76%). Anal. Found: C, 47.95; H, 3.3 1. Calc. for
C50H38IrO4P2W: C, 47.37; H, 3.02%; M, 1268. IR
4.5. Reactions with Fe2(CO)9
4.5.1. {Cp(OC)3W}CꢀCC2{Fe2Ir(CO)8(PPh3)} (6)
A suspension of 1 (100 mg, 0.089 mmol) and
Fe2(CO)9 (143 mg, 0.39 mmol) in thf (30 ml) was heated
at reflux point for 1 h. The solvent was removed under
vacuum and isolation of the product by preparative
TLC (4:6 CH2Cl2–hexane) gave a dark red band (Rf
0.43) that was recrystallised from CH2Cl2–hexane to
give {Cp(OC)3W}CꢀC2{Fe2Ir(CO)8(PPh3)} (6) as a red
crystalline solid (7 mg, 7%) which analysed consistently
for a 2CH2Cl2-solvate. Anal. Found: C, 35.91, 35.73; H,
1.52, 1.57. Calc. for C38H20Fe2IrO11PW·2CH2Cl2: C,
35.82; H, 1.80%; M, 1171. IR (cyclohexane): w(CO)
2068, 2054, 2029, 2021, 2014, 2003, 1986, 1965, 1951
cm−1. 1H-NMR: l 5.60 (s, 5H, Cp), 7.26–7.52 (m, 15H,
Ph). 13C-NMR: l 88.39 (s, Cp), 128.79–133.88 (m, Ph),
212.07 (s, FeꢁCO), 218.46 (s, WꢁCO). ES mass spec-
trum (MeOH, with NaOMe, m/z): 1202, [M+OMe]−;
1174–1062, [(M+OMe)−nCO]− (n=1–5); 940–854,
[(M+OMe)−nCO−PPh3]− (n=0–3).
1
(CH2Cl2): w(CO) 2047, 2037, 1950 cm−1. H-NMR: l
3
0.68 [t, J(HP)=5.4 Hz, 3H, Me], 5.54 (s, 5H, Cp),
7.32–8.03 (m, 30H, Ph). 13C-NMR: l 1.11 (s, Me), 91.64
(s, Cp), 127.63–131.72 (m, Ph), 169.15 (s, IrꢁCO),
210.80 (s, WꢁCO), 230.76 (s, WꢁCO). ES mass spectrum
(MeOH, with NaOMe, m/z): 1291, [M+Na]+; 1143,
[M−I]+.
4.4. Reactions with tetracyanoethene
4.4.1. {Cp(OC)3W}CꢀCCꢀC{Ir(CO)[p-C2(CN)4]-
(PPh3)2} (4)
To a solution of 1 (104 mg, 0.09 mmol) in thf (15 ml),

144
M.I. Bruce et al. / Journal of Organometallic Chemistry 607 (2000) 137–145
4.5.2. {Cp(OC)3W}CꢀCC2{Fe2Rh(CO)8(PPh3)} (7)
A suspension of 2 (100 mg, 0.09 mmol) and Fe2(CO)9
(174 mg, 0.48 mmol) in thf (20 ml) was heated at reflux
point for 2 h. The solvent was removed under vacuum
and the residue purified by preparative TLC (4:6
CH2Cl2–hexane, Rf 0.39) to give dark red crystals of
{Cp(OC)3W}CꢀCC2{Fe2Rh(CO)8(PPh3)} (7) (35 mg,
37%). IR (cyclohexane): w(CO) 2065, 2041, 2014, 1978,
ment, merged to unique sets after ‘empirical’ absorption
corrections (processing by proprietary software SMART
XPREP) [34]. Ntot data merged to N
unique (Rint, quoted), No with F\4|(F) being used in
the refinements. All data were measured using
,
SAINT, SADABS,
,
monochromatic MoꢁKa radiation, u=0.71073 A. In
the refinements, anisotropic thermal parameter forms
were used for the non-hydrogen atoms, (x, y, z, Uiso)
being constrained at estimated values. Conventional
residuals R, Rw on ꢀFꢀ are quoted, statistical weights
being employed. Neutral atom complex scattering fac-
tors were used; computation used the XTAL 3.4 pro-
gram system [35]. Pertinent results are given in the
figures (which show non-hydrogen atoms with 50%
probability amplitude displacement ellipsoids) and
tables.
1
1963, 1952 cm−1. H-NMR: l 5.49 (s, 5H, Cp), 7.30–
7.43 (m, 30H, Ph). 13C-NMR: l 91.72 (s, Cp), 128.35–
134.22 (m, Ph), 167.70 (s, RhꢁCO), 210.33 (s, WꢁCO),
212.52 (s, FeCO). ES mass spectrum (MeOH, with
NaOMe, m/z): 1084, [M+OMe]−.
4.5.3. {Cp(OC)8Fe2W}C2C2{Fe2Ir(CO)8(PPh3)} (8)
A suspension of 1 (100 mg, 0.089 mmol) and
Fe2(CO)9 (143 mg, 0.39 mmol) in thf (30 ml) was heated
at reflux point for 1 h. The solvent was removed under
vacuum and isolation of the product by preparative
TLC (4/6 CH2Cl2–hexane) gave a dark red band (Rf
0.48) that was recrystallised from CH2Cl2–hexane to
give {Cp(OC)8Fe2W}C2C2{Fe2Ir(CO)8(PPh3)} (8) as a
red crystalline solid (28 mg, 22%). Anal. Found: C,
35.89; H, 1.49. Calc. for C43H20Fe4IrO16PW: C, 36.29;
H, 1.41%; M, 1423. IR (cyclohexane): w(CO) 2063,
5.1. Crystal and refinement data
5.1.1. {Cp(OC)3W}CꢀCCꢀC{Rh(CO)[p-C2(CN)4]-
(PPh3)2}·3CH2Cl2 (5)
(
C55H35N4O4P2RhW·3CH2Cl2: space group P1, a=
,
12.107(3), b=15.774(4), c=15.911(4) A, (h=
3
,
80.696(5), i=81.864(5), k=85.910(5)°, V=2965 A ,
1
2041, 2026, 2013, 1999, 1962, 1951 cm−1. H-NMR: l
Z=2. Dcalc=1.590 g cm−3; F(000)=1400. vMo=26
5.63 (s, 511, Cp), 7.34–7.50 (m, 1511, Ph). 13C-NMR: l
91.94 (s, Cp), 128.57–133.74 (m, Ph), 174.80 (s, IrꢁCO),
210.54 (s, FeꢁCO), 212.39 (s, FeꢁCO), 227.94 (s,
WꢁCO). ES mass spectrum (MeOH, with NaOMe,
m/z): 1454, [M+OMe]−; 1342, [(M+OMe)−4CO]−;
1228, [(M+OMe)−8CO]−; 1147, [(M+OMe)−
11CO]−.
cm−1; specimen: 0.28×0.14×0.05 mm; Tmin,max
=
0.69, 0.84. Ntot=22 496, N=10 384 (Rint=0.043),
No=4820, R=0.064, Rw=0.057. nv=678; ꢀDzꢀ=
−3
,
1.3(2) e A
.
Variata. Phenyl ring C(22n) was modelled as disor-
dered over two sets of sites, occupancy set at 0.5 for
each after trial refinement. A nearby void contained
residues modelled as dichloromethane (3) disordered
over two sets of sites with similar occupancy, possibly
concerted with the disorder of the phenyl ring.
4.5.4. {Cp(OC)8Fe2W}C2C2{Fe2Rh(CO)8(PPh3)} (9)
A suspension of 2 (100 mg, 0.09 mmol) and Fe2(CO)9
(174 mg, 0.48 mmol) in thf (20 ml) was heated at reflux
point for 2 h. The solvent was removed under vacuum
and the residue purified by preparative TLC (4/6
CH2Cl2–hexane, Rf 0.39) to give a red solid that was
recrystallised with CH2Cl2–hexane to give crystals of 6.
The mother liquor was further purified by preparative
TLC and crystallisation (CH2Cl2–hexane) to give
{Cp(OC)8Fe2W}C2C2{Fe2Rh(CO)8(PPh3)} (9) (5 mg,
6%). Anal. Found: C, 38.15; H, 1.51. Calc. for
C43H20Fe4O16PRhW: C, 38.72; H, 1.5 1%; M, 1334. IR
(CH2Cl2): w(CO) 2089, 2066, 2039, 2012, 1974, 1959,
1833 cm−1. ES mass spectrum (MeOH, m/z): 1335,
[M+H]+; 1307, [M−CO]+; 1113 [M−Fe2(CO)4]+;
1073, [M−PPh3]+; 1046, [M−CO−PPh3]+.
5.1.2. {Cp(OC)3W}CꢀCC2{Fe2Rh(CO)8(PPh3)} (7)
(
C38H20Fe2O11PRhW: triclinic, space group P1, a=
,
12.490(2), b=12.485(2), c=13.439(2) A, h=62.909(1),
3
,
i=72.647(1), k=75.881(1)°, V=1817 A , Z=2.
calc=1.977 g cm−3; F(000)=1044. vMo=45 cm−l
specimen: 0.40×0.22×0. 12 mm; Tmin,max=0.64, 0.93.
tot=20 883, N=8923 (Rint=0.022), No=7930, R=
D
;
N
−3
,
0.021, Rw=0.026. nv=487; ꢀDzꢀ=1.4(1) e A
.
5.1.3. {Cp(OC)8Fe2W}C2C2{Fe2Ir(CO)8(PPh3)} (8)
(
C43H20Fe4IrO16PW: triclinic, space group P1, a=
,
10.269(1), b=14.025(2), c=16.889(2) A, h=
3
,
109.808(2), i=96.566(2), k=100.671(2)°, V=2207 A ,
Z=2. Dcalc=2.141 g cm−3; F(000)=1352. vMo=70
5. Crystallography
cm−1; specimen: 0.20×0.10×0.06 mm; Tmin,max
=
0.67, 0.95. Ntot=25 318, N=10 635 (Rint=0.026),
No=8407, R=0.030, Rw=0.050. nv=596; ꢀDzꢀ=
Full spheres of data to 2q=58° were measured at ca.
153 K using a Bruker AXS CCD area-detector instru-
2.8(1) e A−3
.

M.I. Bruce et al. / Journal of Organometallic Chemistry 607 (2000) 137–145
145
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[10] W. Beck, H. Bauer, B. Olgemo¨ller, Inorg. Synth. 26 (1989) 120.
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6. Supplementary material
Crystallographic data for the structure determina-
tions have been deposited with the Cambridge Crystal-
lographic Data Centre as CCDC 140684–6 for
compounds 5, 7 and 8, respectively. 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).
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[14] R.F. Heck, J. Org. Chem. 28 (1963) 604.
Acknowledgements
[15] M.I. Bruce, R.C. Wallis, Aust. J. Chem. 32 (1979) 1471.
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[19] C.S. Chin, M. Oh, G. Won, H. Cho, D. Shin, Polyhedron 18
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We thank the Australian Research Council for sup-
port of this work and J.F. Krieg for some preliminary
experiments.
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