Synthesis of Cp* iridium and rhodium complexes containing bidentate sp2-N-donor ligands and counter-anions [Cp*MCl 3]-

Article abstract of DOI:10.1002/ejic.200600735

Complexes of the type [Cp*MCl(N-N)][X] (M = Rh and Ir) have been synthesised, where N-N is a series of bidentate ligands with sp² N-donors: bis(pyrazol-1-yl)methane (bpm), bis(1-methylimidazol-2-yl)methane (bim), bis(3,5-dimethylpyrazol-1-yl)methane (dmbpm), bis(1-methylimidazol-2-yl) ketone (bik), bis(2,4,6-trimethylphenylimino)acenapthene (mesBIAN), 2,4,6-trimethylphenylimino-(1-methyl-2-imidazolyl)methane (mesim-mim), and X = Cl^-, BF₄^- and the unusual anion [Cp*MCl₃]^-. All of these complexes were synthesised by treatment of [Cp*MCl₂]₂ with 2 equivalents of ligand and were isolated as air stable solids. The solid-state structures of [Cp*MCl(bpm)][Cp*MCl₃] (M = Rh and Ir) and [Cp*IrCl(bim)][Cp*IrCl₃] have been determined by single-crystal X-ray diffraction analysis. All of the structures of the bimetallic species displayed a "piano stool" configuration about the both the anionic and cationic metal centre. The solid-state structures of the monometallic iridium species [Cp*IrCl(N-N)][BF₄], where N-N = him, mesBIAN, and mesim-mim, were also determined using single-crystal X-ray diffraction analysis. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

Full text of DOI:10.1002/ejic.200600735

FULL PAPER
DOI: 10.1002/ejic.200600735
Synthesis of Cp* Iridium and Rhodium Complexes Containing Bidentate
sp2-N-Donor Ligands and Counter-Anions [Cp*MCl3]–
Danielle F. Kennedy,[a] Barbara A. Messerle,*[a] and Matthew K. Smith[b]
Keywords: Iridium(III) / Rhodium(III) / N-donor ligands / Cyclopentadienyl ligands
Complexes of the type [Cp*MCl(N–N)][X] (M = Rh and Ir)
have been synthesised, where N–N is a series of bidentate
ligands with sp2 N-donors: bis(pyrazol-1-yl)methane (bpm),
bis(1-methylimidazol-2-yl)methane (bim), bis(3,5-dimeth-
ylpyrazol-1-yl)methane (dmbpm), bis(1-methylimidazol-2-yl)
ketone (bik), bis(2,4,6-trimethylphenylimino)acenapthene
structures of [Cp*MCl(bpm)][Cp*MCl3] (M = Rh and Ir) and
[Cp*IrCl(bim)][Cp*IrCl3] have been determined by single-
crystal X-ray diffraction analysis. All of the structures of the
bimetallic species displayed a “piano stool” configuration
about the both the anionic and cationic metal centre. The
solid-state structures of the monometallic iridium species
[Cp*IrCl(N–N)][BF4], where N–N = bim, mesBIAN, and me-
sim-mim, were also determined using single-crystal X-ray
diffraction analysis.
(mesBIAN),
2,4,6-trimethylphenylimino-(1-methyl-2-imid-
–
azolyl)methane (mesim–mim), and X = Cl–, BF4 and the un-
usual anion [Cp*MCl3]–. All of these complexes were synthe-
sised by treatment of [Cp*MCl2]2 with 2 equivalents of li-
gand and were isolated as air stable solids. The solid-state
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
carbon bond formation,[21] and [Cp*RhCl2]2 has been
shown to effect transfer dehydrochlorination of aryl chlo-
rides.[22]
Introduction
Complexes containing rhodium(I) and iridium(I) metal
centres have found wide application in homogeneous cataly-
sis. Reactions catalysed by these complexes include the
hydrosilylation of imines,[1,2] the hydroamination and hy-
droalkoxylation of alkynes,[3–9] the hydroamination and hy-
droaminomethylation of olefins,[10,11] and the Pauson–
Khand reaction.[12,13] Increasingly, metal complexes con-
taining IrIII and RhIII metal centres are being investigated
as catalysts for a variety of transformations. Unlike IrI and
RhI catalysts, IrIII and RhIII complexes can not promote
reactions which require the initial oxidative addition of a
substrate. However, IrIII and RhIII metal centres are reactive
and have the potential to catalyse a range of other transfor-
mations not reliant on oxidative addition. Work by
Bergmann et al. with the complexes Cp*(PMe3)Ir(CH3)-
(OTf), and TpMe2(PMe3)Ir(CH3)(OTf) illustrated the ability
of IrIII complexes to effect C–H activation.[14,15] Recent
work by Crabtree et al. has utilised an IrIII hydride complex
to catalyse the intramolecular hydroamination and hydro-
alkoxylation of alkynes.[16] [Cp*IrCl2]2 is effective as a cata-
lyst for the hydroborylation of styryl sulfonamides,[17] the
N-alkylation of amines with alcohols[18] and also the trans-
fer hydrogenation of ketones[19] and quinolines.[20] RhIII
complexes are known to be effective in catalysing carbon–
1,2,3,4,5-Pentamethylcyclopentadienyl (Cp*) is ubiqui-
tous as a ligand in organometallic complexes. Many com-
plexes incorporating this ligand are important as active cat-
alysts, largely due to the electron-rich nature of the Cp*
group and also the ability of Cp* to completely block one
face of the complex, imparting steric bulk and structural
rigidity. IrIII and RhIII complexes incorporating both the
Cp* ligand and bidentate sp2-nitrogen donor ligands have
been synthesised previously.[23–31] In particular, the complex
[Cp*Ir(bipy)(H2O)]SO4 (bipy = 2,2Ј-bipyridine) was found
to be active as a catalyst for the hydration of phenylacetyl-
ene in water,[32] and the complex [Cp*Rh(iPr-pymox)]2+
(pymox = pyridyloxazoline) was found to promote the
enantioselective Diels–Alder reaction of methacrolein with
cyclopentadiene.[27]
In the course of the study of both IrIII and RhIII com-
plexes as potential catalysts we have synthesised a series of
1,2,3,4,5-pentamethylcyclopentadienyl complexes incorpo-
rating bidentate N donor ligands. Here, we report the syn-
thesis and characterisation of Rh/IrIII complexes of the type
[Cp*MCl(N–N)][X] (M = Rh and Ir), where N–N is a series
of bidentate ligands with sp2 N-donors: bis(pyrazol-1-yl)-
methane (bpm), bis(1-methylimidazol-2-yl)methane (bim),
bis(3,5-dimethylpyrazol-1-yl)methane (dmbpm), bis(1-
methylimidazol-2-yl) ketone (bik), bis(2,4,6-trimethylphen-
ylimino)acenapthene (mesBIAN), 2,4,6-trimethylphen-
[a] School of Chemistry, University of New South Wales,
Sydney, NSW 2052, Australia
Fax: +61-2-9385-6141
E-mail: b.messerle@unsw.edu.au
ylimino-(1-methyl-2-imidazolyl)methane
(mesim–mim),
[b] Research School of Chemistry, Australian National University,
Canberra, Australia
and X = Cl–, BF4– and the unusual anion [Cp*MCl3]– (Fig-
80
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Cp* Iridium and Rhodium Complexes Containing Bidentate Ligands
FULL PAPER
ure 1). The solid-state structures of the complexes 1c, 2b,
2c, 3c, 7b and 8b have been determined by single-crystal X-
ray diffraction analysis. The complexes 1c, 2c incorporate
the novel anion [Cp*IrCl3]–, and complex 3c incorporates
the rare anion [Cp*RhCl3]–.
Scheme 1.
1
The H NMR spectra of complexes 1c–3c showed the
presence of two molar equivalents of bound Cp* per mol
1
of ligand. H NOESY NMR spectrum confirmed that for
each of the complexes 1c–3c the sharper singlet occurring
slightly downfield at δ = 1.66, 1.61 and 1.69 ppm, respec-
tively, was due to the CH3 protons of the Cp* moiety bound
1
to the cationic fragment (Table 1). The H NMR spectra
also show that the two bridging methylene backbone pro-
tons of the N–N ligands, Ha and Hb, are in magnetically
distinct environments for each of the complexes 1c, 2c and
3c. For all of the complexes, the resonances due to Ha and
Hb occur as doublets. The assignment of these resonances
was established using 1H NOESY NMR, and the reso-
nances due to Ha were consistently shifted significantly
downfield relative to the resonances due to Hb (Table 1).
Figure 1. The general structure of complexes 1a–8b and 1a–3c
where N–N = bpm = bis(pyrazol-1-yl)methane; bim = bis(1-meth-
ylimidazol-2-yl)methane; dmbpm = bis(3,5-dimethylpyrazol-1-yl)-
methane; bik = bis(1-methylimidazol-2-yl) ketone; mesBIAN =
bis(2,4,6-trimethylphenylimino)acenapthene; mesim–mim = (2,4,6-
trimethylphenyl)imino-(1-methylimidazol-2-yl)methane.
Table 1. Selected chemical shifts for complexes 1c–3c.
Compound
δ (ppm)
Cp* in
cation
Cp* in
anion
Ha
Hb
[Cp*Ir(bpm)Cl][Cp*IrCl3] (1c)
[Cp*Ir(bim)Cl][Cp*IrCl3] (2c)
[Cp*Rh(bpm)Cl][Cp*RhCl3] (3c) 8.07
8.35
5.01
5.67
4.73
5.84
1.66 (s) 1.58 (br. s)
1.61 (s) 1.54 (br. s)
1.69 (s) 1.61 (br. s)
Results and Discussion
The complexes 1c and 2c contain the novel anion
[Cp*IrCl3]–. Complex 3c contains the analogous anion
[Cp*RhCl3]– which has been reported recently by Severin
Synthesis of Complexes [Cp*MCl(N–N)][Cp*MCl3] 1c, 2c,
and 3c
Toluene suspensions of the metal precursors [Cp*IrCl2]2 et al.[33] as the anion in the ruthenium complex
and [Cp*RhCl2]2 were treated with two molar equivalents [Cp*Ru(C6H6)][Cp*RhCl3].[33] The [Cp*RhCl3]– anion has
of the bidentate nitrogen donor ligands bpm and bim also been observed in equilibrium in solution with the hy-
(Scheme 1) to generate the ion pairs [Cp*IrCl(bpm)]- drazine-bridged dimer [(Cp*RhCl2)2(µ-NH2NHMe)] by
[Cp*IrCl3] (1c), [Cp*IrCl(bim)][Cp*IrCl3] (2c), and Maitlis et al.[34]
[Cp*RhCl(bpm)][Cp*RhCl3] (3c) (Scheme 1). Using the
The relative binding strengths of the N-donor ligands
same approach, 2c was obtained in low yield as the minor correlates to the nature of the products formed on reaction
product, with [Cp*IrCl(bim)]Cl (2a) being formed as the with the dimeric Ir/Rh starting materials. The strongly co-
major product. Complexes 1c, 2c, and 3c were thermally ordinating bim ligand brings about the complete dissoci-
and air stable over extended periods. The sterically hindered ation of the metal precursor dimer ([Cp*IrCl2]2) and pri-
ligand mesBIAN failed to bind to [IrCp*Cl2]2.
marily formation of the product monomer, [Cp*IrCl-
Eur. J. Inorg. Chem. 2007, 80–89
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81

D. F. Kennedy, B. A. Messerle, M. K. Smith
FULL PAPER
(bim)]+Cl, 2a. The more weakly coordinating bpm ligand
leads to the formation of bimetallic ion pairs,
[Cp*MCl(bpm)][Cp*MCl3] 1c and 3c. The mesBIAN li-
gand is unable to bind to Ir with sufficient strength to split
the iridium precursor dimer, due to both the weaker binding
ability of the imine N-donors and the large steric bulk im-
parted by the mesityl groups. The complexes 1c–3c, which
contain bimetallic pairs, are of interest from the perspective
of coordination chemistry. For the purposes of catalysis, the
fact that molecules 1c–3c contain two metal centres makes
them inefficient in terms of the proportion of metal in-
volved, as only the cationic fragment of the metal complex
is catalytically active. To increase the efficiency of the syn-
thesis with respect to the quantity of metal used, the com-
–
plexes incorporating the alternate counterion BF4 were
synthesised.
Solid-State Structures of 1c, 2c and 3c
The solid-state structures of 1c, 2c and 3c with thermal
ellipsoids at the 50% probability level are shown in Fig-
ure 2. Selected bond lengths and angles for 1c, 2c and 3c
are presented in Table 2 and crystal structure and refine-
ment data are given in Table 5.
The cationic fragments of 1c, 2c and 3c have very similar
structures. The metal centres of 1c, 2c and 3c exist in the
piano-stool conformation with the six-membered metall-
ocycle formed by coordination of the bidentate ligands to
the metal centres in each case existing in the boat configura-
tion. The N–M–N angles for 1c, 2c and 3c are between
83.8(2)° and 85.25(9)°, which is significantly larger than the
values for related [IrCp*Cl(N–N)][X] complexes reported in
the literature, where the N–N ligand defines a five-mem-
bered metallocycle (values of between 75.6 and 77.5° have
been reported previously).[32,23,27,31] The N–M–N bite
angles are, however, similar to those reported for other Ir
complexes containing the bim and bpm ligand (values of
85.9° and 86.8°).[35,36] N–M–Cl angles of between
85.06(15)° and 88.56(7)° for 1c, 2c and 3c are consistent
with literature values of between 83.1° and 91.9° for similar
complexes.[32,23,27] The M–N distances in each of the com-
plexes are also comparable to those previously reported in
the literature with M–N(pyrazole) distances of 2.107(4) and
2.114(2) Å for 1c and 3c respectively and a slightly shorter
Ir–N(imidazole) distance of 2.089(5) Å for 2c. Literature
values range from 2.028 and 2.230 Å depending on the na-
ture of the N-donor ligand.[15,23,24,26]
Figure 2. ORTEP depiction of (a) [Cp*IrCl(bpm)][Cp*IrCl3] (1c);
(b) [Cp*IrCl(bim)][Cp*IrCl3] (2c); and (c) [Cp*RhCl(bpm)]-
[Cp*RhCl3] (3c) at 50% thermal ellipsoids for the non-hydrogen
atoms.
2.434 Å, which are comparable to the M–Cl bond lengths
of between 2.4100(16) and 2.4335(7) Å for the anions of
complexes 1c–3c.
Synthesis of Complexes [Cp*MCl(N–N)][BF4] 1b, 2b, 3b,
4b, 5b, 6b, 7b and 8b
In all of the solid-state structures for 1c–3c, the anions
[Cp*MCl3]– have the same piano-stool geometry described
Treatment of toluene suspensions of [MCp*Cl2]2 with
by the three chloride atoms and the η5-Cp* ligand around two molar equivalents of a bidentate nitrogen donor ligand
the iridium(III) or rhodium(III) metal centres. The piano- (N–N) and two molar equivalents of NaBF4 in MeOH at
stool geometry is frequently reported for Cp* iridium(III) room temperature resulted in the formation of the com-
or rhodium(III) complexes.[24,26,37] The equivalent confor- plexes [Cp*IrCl(N–N)]BF4, [N–N = bpm (1b), bim (2b) and
mation was also previously observed for the anion of the dmbpm (5b), bik (6b), mesBIAN (7b) and mesim-mim (8b)]
complex [Cp*Ru(C6H6)][Cp*RhCl3].[33] The M–Cl bond and [Cp*RhCl(N–N)]BF4, [N–N = bpm (3b), bim (4b)] in
lengths reported for this complex were between 2.409 and good to moderate yields (Scheme 2). Selected 1H NMR
82
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Cp* Iridium and Rhodium Complexes Containing Bidentate Ligands
FULL PAPER
Table 2. Selected bond lengths [Å] and bond angles [°][a] for the inner coordination sphere of 1c, 2c and 3c.
1c
2c
3c
Atomic distance [Å]
Ir(1)–N(11)
Ir(1)–N(21)
Ir(1)–Cl(1)
Ir(1)–C(31)
Ir(1)–C(32)
Ir(1)–C(33)
Ir(1)–C(34)
Ir(1)–C(35)
Ir(2)–Cl(2)
Ir(2)–Cl(3)
Ir(2)–Cl(4)
2.107(4)
2.105(4)
2.4076(16)
2.170(5)
2.176(4)
2.144(5)
2.152(5)
2.169(5)
Ir(1)–N(11)
Ir(1)–N(21)
Ir(1)–Cl(1)
Ir(1)–C(31)
Ir(1)–C(32)
Ir(1)–C(33)
Ir(1)–C(34)
Ir(1)–C(35)
Ir(2)–Cl(2)
Ir(2)–Cl(3)
Ir(2)–Cl(4)
2.089(5)
2.090(5)
2.4012(18)
2.143(6)
2.158(6)
2.149(6)
2.156(6)
2.160(6)
Rh(1)–N(11)
Rh(1)–N(21)
Rh(1)–Cl(1)
Rh(1)–C(31)
Rh(1)–C(32)
Rh(1)–C(33)
Rh(1)–C(34)
Rh(1)–C(35)
Rh(2)–Cl(2)
Rh(2)–Cl(3)
Rh(2)–Cl(4)
2.114(2)
2.113(2)
2.4174(8)
2.170(3)
2.161(3)
2.170(3)
2.147(3)
2.142(3)
2.4090(8)
2.4126(7)
2.4335(7)
2.4130(13)
2.4322(13)
2.4111(17)
2.4163(19)
2.4100(16)
2.4158(18)
Bond angle [°]
N(21)–Ir(1)–N(11)
N(11)–Ir(1)–Cl(1)
N(21)–Ir(1)–Cl(1)
N(22)–C(1)–N(12)
N(11)–N(12)–C(1)
N(21)–N(22)–C(1)
N(12)–N(11)–Ir(1)
N(22)–N(21)–Ir(1)
83.95(17)
87.09(12)
86.77(12)
109.5(4)
119.8(4)
120.5(4)
123.7(3)
123.3(3)
N(11)–Ir(1)–N(21)
N(11)–Ir(1)–Cl(1)
N(21)–Ir(1)–Cl(1)
C(11)–C(1)–C(21)
N(11)–C(11)–C(1)
N(12)–C(11)–C(1)
C(11)–N(11)–Ir(1)
C(21)–N(21)–Ir(1)
83.8(2)
N(21)–Rh(1)–N(11) 85.25(9)
85.06(15)
85.67(15)
109.6(6)
125.0(5)
125.6(6)
124.9(4)
125.3(4)
N(11)–Rh(1)–Cl(1)
N(21)–Rh(1)–Cl(1)
N(22)–C(1)–N(12)
N(11)–N(12)–C(1)
N(21)–N(22)–C(1)
88.56(7)
88.41(7)
109.8(2)
120.1(2)
120.5(2)
N(12)–N(11)–Rh(1) 122.88(17)
N(22)–N(21)–Rh(1) 122.87(17)
[a] Estimated standard deviation in the least significant figure are given in parentheses.
chemical shifts for these complexes are presented in Table 3. plexes 1b–5b), which lie between 1.53 and 1.59 ppm, most
As already observed for the complexes 1c–3c, the two meth- likely a result of ring current effects due to the mesityl sub-
ylene protons (Ha and Hb) of the bridging carbon atoms of stituents on the mesim-mim ligand.
the bidentate ligands of the complexes 1b–5b exist in very
1
different magnetic environments, with the H NMR chemi-
Table 3. Selected chemical shifts for complexes 1b–8b.
cal shifts for Ha protons being significantly deshielded. The
1H chemical shift of the resonance due to the -CH3 groups
Compound
δ (ppm)
Ha
Hb
Cp*
of the Cp* ligand of complex 7b (at δ = 1.27 ppm) is shifted
significantly relative to that of the corresponding reso- [Cp*Ir(bpm)Cl]BF4 (1b)
7.03
4.52
7.28
4.47
6.48
–
5.68
4.14
6.00
4.16
5.67
–
1.56 (br. s)
1.59 (s)
1.71 (br. s)
1.60 (s)
1.56 (s)
1.53 (s)
[Cp*Ir(bim)Cl]BF4 (2b)
nances of the other iridium complexes in this series (com-
[Cp*Rh(bpm)Cl]BF4 (3b)
[Cp*Rh(bim)Cl]BF4 (4b)
[Cp*Ir(dmbpm)Cl]BF4 (5b)
[Cp*Ir(bik)Cl]BF4 (6b)
[Cp*Ir(mesBIAN)Cl]BF4 (7b)
[Cp*Ir(mesim-mim)Cl]BF4 (8b)
–
–
–
–
1.27 (s)
1.49 (s)
The [Cp*IrCl(N–N)]BF4 complex 7b (N–N = mesBIAN)
was made in good yield, however, the synthesis of the corre-
sponding rhodium complex was unsuccessful. This was at-
tributed to the steric bulk of the mesityl groups on this li-
gand, which may hinder binding of the ligand to the rho-
dium metal centre.
The interconversion of the bimetallic ion pair 1c to 1b,
–
the analogous BF4 salt, was investigated. A toluene solu-
tion of 1c, 1 equivalent of bpm and 1 equivalent of NaBF4
with a small amount of MeOH was stirred at room tem-
perature. 1b was isolated from the reaction mixture as the
1
only product and its identity was confirmed using H and
13C NMR spectroscopy. The addition of MeOH to the reac-
tion is necessary for the conversion of [IrCp*Cl3]– and
–
anion exchange to occur as both BF4 and Cl– are poorly
Scheme 2.
solubilised by toluene.
Eur. J. Inorg. Chem. 2007, 80–89
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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83

D. F. Kennedy, B. A. Messerle, M. K. Smith
FULL PAPER
Solid-State Structures of 2b, 7b and 8b
The two Ir–N bond lengths of 7b are 2.122(5) Å. The Ir–N
bond lengths for complex 8b are 2.100(5) and 2.121(4) Å
for the Ir–N(imidazole) and Ir–N(imine) bonds, respec-
tively. These are comparable to the Ir–N(imidazole) and Ir–
N(imine) bond lengths in complexes 2b and 7b, respectively.
All of the Ir–N bond lengths are comparable to the dis-
tances found in the literature for similar complexes (values
between 2.076 and 2.128 Å).[23,24,26]
Crystals suitable for X-ray structure determination were
obtained for 2b, 7b and 8b and ORTEP depictions of their
solid-state structures are depicted in Figure 3. Selected
bond lengths and angles for 2b, 7b and 8b are presented in
Table 4, and crystal structure and refinement data are given
in Table 6.
The length of the Ir–Cp* bond was dependent on the
nature of the cation as well as the nature of the ligand. The
Cp*–Ir bond lengths are slightly larger on average for the
BF4– salt 2b (2.144–2.181 Å), compared with the equivalent
bond lengths in the bimetallic ion pair 2c (2.143–2.160 Å).
The Cp*–Ir bond length in the solid-state structure of 7b is
significantly longer than in 2b and 2c (2.171–2.193 Å) due
to the high degree of steric hindrance caused by the bulky
mesBIAN ligand. The Cp*–Ir bond lengths for complex 8b
(2.158–2.189 Å) containing the hybrid mesitylimine-imid-
azole ligand are midway between those of complexes 2b
containing the imidazolium ligand, and 7b which contains
the bulky mesBIAN ligand. The Cp*–Ir bond lengths for
all of these complexes are within the range previously de-
scribed in the literature (2.110–2.195 Å).[23,24]
Conclusions
Complexes of the type [Cp*MCl(N–N)][X] were synthe-
sised (M = Rh/IrIII), with a series of bidentate N-donor
ligands. Where N–N was bpm or bim and there was no
alternate counterion present, bimetallic complexes formed
containing the counterion X = [Cp*MCl3]–. In the case of
the sterically hindered N-donor ligands, these bimetallic
complexes did not form. In the presence of the counterion
–
–
BF4 , the complexes where X = BF4 were synthesised suc-
cessfully.
The three dimensional solid-state structures of the cat-
ionic fragments of the bimetallic complexes 1c, 2c and 3c
were all very similar. Changing the counterion from the
–
[Cp*MCl3]– fragment to the smaller BF4 anion, did not
significantly change the structure of the cationic fragment.
The chemical shift of the resonance due to the -CH3 pro-
tons of the Cp* of the Ir complex containing the mesBIAN
ligand [Cp*IrCl(mesBIAN)]BF4 (7b) was significantly
shifted upfield relative to the same resonance of the remain-
ing Ir complexes, and this was attributed to the presence of
the aromatic rings of the mesBIAN ligand.
The catalytic activity of the complexes reported in this
paper is currently under investigation and will be reported
in a future paper.
Figure 3. ORTEP depiction of (a) [Cp*IrCl(bim)]+ (2b); (b)
[Cp*IrCl(mesBIAN)]+ (7b) and (c) [Cp*IrCl(mesim-mim)]+ (8b) at
50% thermal ellipsoids for the non-hydrogen atoms.
Experimental Section
General Procedures: All manipulations of metal complexes and air-
sensitive reagents were carried out using standard Schlenk tech-
niques or in a nitrogen- or argon-filled drybox. All solvents were
distilled under argon. n-Hexane, n-pentane and toluene were dis-
The solid-state structure of 2b is very similar to that of
2c with comparable N–Ir–N bite angles of 83.51(11)° and
83.8(2)°, respectively, and Ir–N bond lengths of 2.095(3)
and 2.101(3) Å for 2b and 2.089(5) and 2.090(5) Å for 2c. tilled from sodium benzophenone ketyl. Dichloromethane was dis-
84 Eur. J. Inorg. Chem. 2007, 80–89
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Cp* Iridium and Rhodium Complexes Containing Bidentate Ligands
FULL PAPER
Table 4. Selected bond lengths [Å] and bond angles [°][a] for the inner coordination sphere of 2b, 7b and 8b.
2b
7b
8b
Atomic distance [Å]
Ir(1)–N(111)
Ir(1)–N(121)
Ir(1)–C(131)
Ir(1)–C(132)
Ir(1)–C(133)
Ir(1)–C(134)
Ir(1)–C(135)
Ir(1)–Cl(1)
2.095(3)
2.101(3)
2.166(4)
2.181(3)
2.155(4)
2.144(4)
2.155(4)
2.4025(10)
Ir(1)–N(11)
Ir(1)–N(11)#1
Ir(1)–C(31)
Ir(1)–C(31)#1
Ir(1)–C(32)
Ir(1)–C(32)#1
Ir(1)–C(33)
Ir(1)–Cl(1)
2.122(5)
2.122(5)
2.171(6)
2.171(6)
2.193(7)
2.193(7)
2.187(9)
2.377(2)
Ir(1)–N(111)
Ir(1)–N(211)
Ir(1)–C(311)
Ir(1)–C(312)
Ir(1)–C(313)
Ir(1)–C(314)
Ir(1)–C(315)
Ir(1)–Cl(1)
2.100(5)
2.121(4)
2.178(5)
2.158(6)
2.175(5)
2.189(5)
2.176(6)
2.4009(17)
Bond angle [°]
N(111)–Ir(1)–N(121)
N(111)–Ir(1)–Cl(1)
N(121)–Ir(1)–Cl(1)
–N(111)–Ir(1)
C(112)–N(111)–Ir(1)
–C(111)–C(1)
83.51(11)
85.63(9)
87.71(9)
124.6(2)
127.6(2)
126.9(3)
123.9(3)
112.0(3)
N(11)–Ir(1)–N(11)#1
N(11)–Ir(1)–Cl(1)
N(11)#1–Ir(1)–Cl(1)
C(11)–N(11)–Ir(1)
C(21)–N(11)–Ir(1)
N(11)–C(11)–C(11)#1 116.9(3)
C(11)–N(11)–Ir(1) 113.4(4)
76.5(3)
N(111)–Ir(1)–N(211)
N(111)–Ir(1)–Cl(1)
–Ir(1)–Cl(1)
–N(111)–Ir(1)
–N(211)–Ir(1)
N(111)–C(111)–C(1)
N(211)–C(1)–C(111)
75.80(18)
84.05(13)
87.58(13)
114.0(4)
127.5(3)
117.4(5)
115.7(5)
85.51(13)
85.51(13)
113.4(4)
128.5(4)
N(112)–C(111)–C(1)
–C(1)–C(111)
[a] Estimated standard deviation in the least significant figure are given in parentheses.
1
3
tilled from calcium hydride. CD2Cl2 was dried with calcium hydride
and vacuum-distilled before use. 1,2,3,4,5-Pentamethylcyclopenta-
diene was purchased from Lancaster and used without further puri-
fication. Iridium(III) chloride hydrate and rhodium(III) chloride
hydrate were obtained from Precious Metals Online (PMO) and
were used without further purification. [IrCp*Cl2]2, [RhCp*-
Cl2]2,[37] bis(1-pyrazolyl)methane,[38] bis(1-methylimidazol-2-yl)-
methane,[39] bis(1-methylimidazol-2-yl) ketone,[40] bis(2,4,6-trimeth-
[Cp*IrCl]+. H NMR (CD2Cl2, 300 MHz): δ = 8.79 (d, JH5-H4
=
2
2.3 Hz, 2 H, H5), 8.35 (d, JHa-Hb = 15.1 Hz, 1 H, Ha), 7.60 (d,
3JH3-H4 = 2.3 Hz, 2 H, H3), 6.44 (m, 2 H, H4), 5.67 (d, JHa-Hb
=
2
15.1 Hz, 1 H, Hb), 1.66 [s, 15 H, CH3(Cp*)cation], 1.58 [s, 15 H,
CH3(Cp*)anion] ppm. 13C{1H} NMR (CD2Cl2, 75 MHz): δ = 143
(C5), 136 (C3), 107 (C4), 88 (Cp*), 84 (CH2), 8.8 [CH3(Cp*)], 8.6
[CH3(Cp*)] ppm.
Synthesis of [Cp*IrCl(bim)][Cp*IrCl3] (2c) and [Cp*IrCl(bim)]Cl
ylphenylimino)acenapthene[41,42]
and
2-formyl-1-methylimid-
(2a):
A toluene suspension (25 mL) of [IrCp*Cl2]2 (99 mg,
azole[43] were prepared following literature methods.
0.11 mmol) was stirred for 30 min. A toluene solution (10 mL) of
bis(1-methylimidazol-2-yl)methane, bim, (43 mg, 0.24 mmol) was
then added dropwise and the mixture was stirred for 45 min. The
yellow solid was collected by filtration, washed with toluene
(2 ϫ 5 mL) and recrystallised from dichloromethane and pentane.
A yellow powder was isolated by filtration and dried in vacuo. This
1H, 13C and 19F NMR spectra were recorded with Bruker DPX300
and DMX500 spectrometers. All spectra were recorded at 298 K
unless otherwise specified. 1H NMR and 13C NMR chemical shifts
were referenced internally to residual solvent resonances. 19F NMR
was referenced externally using α,α,α-trifluorotoluene in CDCl3.
Melting points were recorded using a Mel-Temp apparatus and are
uncorrected. IR spectra were recorded using an ATI Mattson Gen-
esis Series FT-IR spectrometer. Electrospray mass spectra were per-
formed by the Biomedical Mass Spectrometry Facility (BMSF) at
the University of New South Wales, Sydney, Australia. Elemental
analyses were performed by the Campbell Microanalytical Labora-
tory at the University of Otago, New Zealand. Single-crystal X-ray
structure analyses were obtained at the Research School of Chemis-
try at the Australian National University, Canberra, Australia.
crude compound was
a mixture of [Cp*IrCl(bim)]Cl and
[Cp*IrCl(bim)][Cp*IrCl3] and was recrystallised by slow diffusion
of petroleum into a CH2Cl2 solution of the complex. Two sets of
analytically pure crystals were obtained; microcrystalline yellow
[Cp*IrCl(bim)]Cl Yield: 28% (40 mg) and large red cubic crystals
of [Cp*IrCl(bim)][Cp*IrCl3]3. Yield: 17% (16 mg). The crystals of
2a and 2c were separated physically. The red cubic crystals of 2c
were suitable for X-ray crystal structure analysis.
[Cp*IrCl(bim)]Cl (2a): M.p. 225–228 °C. IR (KBr disc): ν 3427 (br),
˜
3118 (m), 2918 (m), 1637 (w), 1508 (m), 1450 (m), 1412 (m), 1381
(w), 1279 (w), 1261 (w), 1150 (m), 1096 (m), 1032 (vs), 796 (m) 7,61
(m) cm–1. MS (ES+, CH2Cl2): m/z (%)= 539 (100) [M+], 540 (90),
537 (80), 541 (70), 503 (50). 1H NMR (CD2Cl2, 300 MHz): δ =
Synthesis of [Cp*IrCl(bpm)][Cp*IrCl3] (1c): A toluene suspension
(25 mL) of [IrCp*Cl2]2 (90 mg, 0.11 mmol) was stirred for 30 min
and a toluene solution (10 mL) of bis(pyrazolyl)methane, bpm
(38 mg, 0.25 mmol) was added dropwise. On addition of the ligand,
the suspension immediately changed colour from orange–red to
yellow. The mixture was stirred for a further 45 min. The yellow
solid was collected by filtration, washed with toluene (2 ϫ 5 mL)
and dried in vacuo to give the compound as a yellow air stable
solid. The solid was recrystallised by slow diffusion of pentane into
a CH2Cl2 solution of the complex to give 1c as small orange crys-
tals which were suitable for X-ray analysis. Yield: 31% (32 mg).
M.p. Ͼ 230 °C. C27H38Cl4Ir2N4 (944.9): calcd. C 34.32, H 4.05, N
2
7.00 (s, 4 H, H4 and H5), 5.36 (d, JHb-Ha = 18.8 Hz, 1 H, Ha),
2
4.52 (d, JHa-Hb = 19.2 Hz, 1 H, Hb), 4.10 (s, 6 H, N–CH3), 1.62
[s, 15 H, CH3(Cp*)] ppm. 13C{1H} NMR (CD2Cl2, 75 MHz): δ =
141.3 (C2), 128.7 (C4), 122.7 (C5), 86.9 (Cp*), 35.4 (N–CH3), 26.1
(CH2), 8.7 [CH3(Cp*)] ppm.
[Cp*IrCl(bim)][Cp*IrCl3] (2c): M.p. 270–275 °C. C29H42Cl4Ir2N4·
CH2Cl2 (1057.9): calcd. C 34.06, H 4.19, N 5.30; found C 33.76, H
4.17, N 5.03. IR (KBr disc): ν = 3466 (br), 3143 (m), 3117 (m),
˜
5.93; found C 34.23, H 4.14 N 5.30. IR (KBr): ν = 3475 (br), 3111
2977 (w), 2910 (m), 1635 (m), 1551 (w), 1514 (vs), 1452 (s), 1377
˜
(m), 2962 (w), 2915 (m), 2341 (w), 1635 (w), 1558 (w), 1421 (vs), (m), 1292 (w), 1178 (w), 1144 (w), 1081 (w), 1035 (s), 758 (s) cm–1.
1273 (vs), 1096 (m), 1067 (m), 1031 (m), 772 (m), 754 (m) cm–1. MS (ES+, CH2Cl2): m/z (%) = 539 (10) [Cp*IrCl(bim)]+), 503 (100).
MS (ES+, CH2Cl2): m/z (%) = 511 (10) [Cp*IrCl(bpm)]+, 363 (100)
1H NMR (CD2Cl2, 300 MHz): δ = 6.95 (s, 4 H, H4 and H5), 5.01
Eur. J. Inorg. Chem. 2007, 80–89
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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85

D. F. Kennedy, B. A. Messerle, M. K. Smith
FULL PAPER
(d, JHb-Ha = 19.2 Hz, 1 H, Ha), 4.73 (d, JHa-Hb = 19.2 Hz, 1 H,
Hb), 4.04 (s, 6 H, N–CH3), 1.61 [s, 15 H, CH3(Cp*)cation], 1.54 [s,
2
2
1
[Cp*IrCl(bim)]+, 537 (30). H NMR (CD2Cl2, 300 MHz): δ = 7.02
3
3
(d, JH4-H5 = 1.8 Hz, 2 H, H4 or H5), 6.99 (d, JH4-H5 = 1.8 Hz, 2
2
15 H, CH3(Cp*)anion] ppm. 13C{1H} NMR (CD2Cl2, 75 MHz): δ H, H4 or H5), 4.52 (d, JHb-Ha = 19.0 Hz, 1 H, Ha), 4.14 (d,
= 141.8 (C2), 128.1 (C4), 122.5 (C5), 86.9 (Cp), 35.9 (N–CH3), 25.2
(CH2), 8.8 [CH3(Cp*)] ppm.
2JHa-Hb = 19.0 Hz, 1 H, Hb), 3.86 (s, 6 H, N-CH3), 1.59 [s, 15 H,
CH3(Cp*)] ppm. 13C NMR (CD2Cl2, 75 MHz): δ = 141.1 (C2),
129.3 (C4), 123.7 (C5), 86.9 (Cp*), 35.9 (N–CH3), 25.2 (CH2), 8.8
Synthesis of [Cp*RhCl(bpm)][Cp*RhCl3] (3c): [RhCp*Cl2]2
(215 mg, 0.35 mmol) and bpm (383 mg, 2.5 mmol) were suspended
in toluene and stirred for 3 h. The orange-brown solid which
formed was collected by filtration and was recrystallised by layering
a CH2Cl2 solution of the compound with pentane. The product
crystallised both as large red plates and small orange crystals. Both
crystal forms were found to be analytically pure [Cp*RhCl-
(bpm)][Cp*RhCl3]. The red plates of [Cp*RhCl(bpm)][Cp*RhCl3]
[CH3(Cp*)] ppm. 19F NMR (CD2Cl2, 282.41 MHz):
δ =
–154.1 ppm.
Synthesis of [Cp*IrCl(dmbpm)]BF4 (5b): A toluene (10 mL) suspen-
sion of [IrCp*Cl2]2 (52.4 mg, 0.066 mmol) was stirred for 10 min
prior to the addition of a toluene solution (5 mL) of bis(3,5-di-
methylpyrazolyl)methane, dmbpm (24.1 mg, 0.139 mmol). The sus-
pension was stirred for 45 min before addition of a methanol solu-
were suitable for X-ray crystal structure analysis. Yield: 32% tion of NaBF4 (24.2 mg, 0.221 mmol). The orange solid dissolved
(105 mg). M.p. Ͼ 310 °C. IR (KBr disc): ν = 3409 (br), 3120 (w), producing a yellow solution which was stirred overnight. The vol-
˜
2965 (w), 1635 (m), 1522 (m), 1489 (m), 1458 (m), 1403 (s), 1375 ume of the solution was reduced in vacuo, filtered and was layered
(m), 1288 (s), 1264 (m), 1096 (s), 1058 (s), 1017 (s), 799 (s), 168 (s) with pentane. The precipitate was collected, washed with pentane
cm–1. 1H NMR (CD2Cl2, 300 MHz): δ = 8.76 (d, 3JH5-H4 = 2.5 Hz, and dried to give [Cp*IrCl(dmbpm)]BF4 as a yellow solid. Yield:
2
3
2 H, H5), 8.07 (d, JHb-Ha = 15.1 Hz, 1 H, Ha), 7.60 (d, JH3-H4
=
50% (42.5 mg). C21H31BClF4IrN4 (654.0): calcd. C 38.57, H 4.78,
2
2.3 Hz, 2 H, H3), 6.39 (m, 2 H, H4), 5.84 (d, JHa-Hb = 15.1 Hz, 1 N 8.57; found C 38.30, H 4.78., N 8.40%. IR (KBr disc): ν = 3448
˜
H, Hb), 1.69 [s, 15 H, CH3(Cp*)cation], 1.61 [br. s, 15 H, CH3-
(br), 3136 (w), 2986 (w), 1699 (w), 1652 (w), 1561 (s), 1490 (m),
(Cp*)anion] ppm. 13C{1H} NMR (CD2Cl2, 75 MHz): δ = 145.0 1472 (s), 1426 (s), 1396 (s), 1288 (vs), 1156 (vs), 843 (m), 806 (m),
1
(C5), 137.5 (C3), 108.3 (C4), 97.3 (d, JRh-Cp* = 8.7 Hz, Cp), 64.3
(CH2), 9.8 (Cp–CH3), 9.6 [CH3(Cp*)] ppm.
705 (w), 686 (m), 658 (w), 624 (w), 520 (m), 456 (m) cm–1. MS
(ES+, CH2Cl2): m/z (%) = 568 (100) [Cp*IrCl(dmbpm)]+), 567 (90),
569 (80), 565 (60). 1H NMR (CD2Cl2, 300 MHz): δ = 6.48 (d,
Synthesis of [Cp*IrCl(bpm)]BF4 (1b): [IrCp*Cl2]2 (53 mg,
0.067 mmol) was suspended in toluene (10 mL) and stirred for
10 min. A toluene (5 mL) solution of bpm (23 mg, 0.16 mmol) was
added and the mixture was stirred for 30 min before a methanol
solution (5 mL) of NaBF4 (14 mg, 0.127 mmol) was added. The
solid dissolved to generate a yellow solution which was allowed to
stir overnight. The solvent volume was reduced to ca. 5 mL, filtered
and layered with pentane (10 mL). The resulting precipitate was
collected by filtration, washed with pentane (5 mL) and dried in
vacuo to give [Cp*IrCl(bpm)]BF4 as a yellow solid. Yield: 53%
(42 mg). M.p. 275–285 °C. C17H23Cl1BF4Ir1N1 (597.2): calcd. C
34.15, H 3.88, N 9.37; found C 34.18, H 3.91, N 9.14. IR (KBr
2
2JHb-Ha = 15.9 Hz, 1 H, Ha), 6.14 (s, 2 H, H4), 5.67 (d, JHb-Ha
=
15.9 Hz, 1 H, Hb), 2.54 (s, 6 H, CH3), 2.42 (s, 6 H, CH3), 1.56 [s,
15 H, CH3(Cp*)] ppm. 13C{1H} NMR (CD2Cl2, 75 MHz): δ =
155.1 (C3 or 5), 144.04 (C3 or 5), 109.51 (C4), 89.35 (Cp*), 58.4
(CH2), 15.2 (Me), 11.6 (Me), 9.7 [CH3(Cp*)] ppm. 19F NMR
(CD2Cl2, 282.41 MHz): δ = –152.5 ppm.
Synthesis of [Cp*IrCl(bik)]BF4 (6b): A toluene (10 mL) suspension
of [IrCp*Cl2]2 (46.3 mg, 0.058 mmol) was stirred for 30 min prior
to the addition of a MeOH solution (5 mL) of bis(1-methylimida-
zol-2-yl) ketone, bik, (44.1 mg, 0.231 mmol). The suspension was
stirred for 30 min before addition of a MeOH solution (5 mL) of
NaBF4 (24.2 mg, 0.221 mmol). The yellow solution was stirred for
2 h before the volume of the solution was reduced, filtered and
disc): ν = 3649 (w), 3427 (br), 3119 (m), 3081 (m), 2984 (w), 2913
˜
(w), 1636 (m), 1489 (w), 1456 (m), 1418 (s), 1288 (s), 1277 (m),
1084 (vs), 989 (vs), 764 (m) cm–1. MS (ES+, CH2Cl2): m/z (%) = was layered with pentane. The yellow solid obtained was collected,
511 (100) [Cp*IrCl(bpm)]+), 509 (80), 513 (80). 1H NMR (CD2Cl2,
washed with pentane and dried in vacuo to give [Cp*IrCl(bik)]BF4.
Yield: 31% (23 mg). M.p. 301–305 °C. C19H25BClF4IrN4O (639.9):
3
300 MHz): δ = 8.07 (d, JH5-H4 = 2.7 Hz, 2 H, H5), 7.58 (d,
2
3JH3-H4 = 2.5 Hz, 2 H, H3), 7.03 (d, JHb-Ha = 14.5 Hz, 1 H, Ha), calcd. C 35.66, H 3.94, N 8.76; found C 35.44, H 4.13, N 8.47. IR
3
3
6.43 (dd, JH5-H4 = 2.7 Hz, JH5-H4 = 2.5 Hz, 2 H, H4), 5.68 (d,
(KBr disc): ν = 3522 (br), 3442 (br), 3374 (br), 3153 (w), 3128 (w),
˜
2JHa-Hb = 14.5 Hz, 1 H, Hb), 1.56 [br. s, 15 H, CH3(Cp*)] ppm. 1634 (vs), 1558 (w), 1481 (w), 1421 (vs), 1386 (m), 1293 (m), 1189
13C{1H} NMR (CD2Cl2, 75 MHz): δ = 144.8 (C3), 135.0 (C5),
108.7 (C4), 88.8 (Cp*), 62.7 (CH2), 8.7 [CH3(Cp*)] ppm. 19F NMR
(CD2Cl2, 282.41 MHz): δ = –151.4 ppm.
(m), 1083 (m), 1032 (m), 904 (vs) cm–1. MS (ES+, CH2Cl2): m/z
(%) = 554 (100), 552 (95), 555 (92), 553 (90) [Cp*IrCl(bik)]+), 551
(50). 1H NMR (CD2Cl2, 300 MHz): δ = 7.52 (d, 3JH5-H4 = 1.10 Hz,
3
2 H, H4 or H5), 7.36 (d, JH5-H4 = 1.10 Hz, 2 H, H4 or H5), 4.23
Synthesis of [Cp*IrCl(bim)]BF4 (2b): [IrCp*Cl2]2 (58.8 mg,
0.073 mmol), bim (27.2 mg, 0.154 mmol) and NaBF4 (19.2 mg,
0.175 mmol) were dissolved in toluene (10 mL) and MeOH (5 mL)
and stirred for 2 h. The solution was reduced in volume, filtered
and layered with pentane. The product was allowed to precipitate
overnight, collected by filtration, washed with pentane and dried
in vacuo to isolate [Cp*IrCl(bim)]BF4 as a yellow powder. Yield:
73% (67.3 mg). Yellow crystals of [Cp*IrCl(bim)]BF4 obtained by
layering a CH2Cl2 solution of 2b with petroleum in air were suitable
(s, 6 H, N–Me) 1.53 [s, 15 H, CH3(Cp*)] ppm. 13C{1H} NMR
(CD2Cl2, 75 MHz): δ = 172.7 (C=O), 132.7 (C2), 129.9 (C4), 128.0
(C5), 88.5 (Cp*), 38.2 (N–Me), 8.3 [CH3(Cp*)] ppm. 19F NMR
(CD2Cl2, 282.41 MHz): δ = –153.9 ppm
Synthesis of [Cp*IrCl(mesBIAN)]BF4 (7b): A toluene (20 mL) sus-
pension of [IrCp*Cl2]2 (110.5 mg, 0.139 mmol) was stirred for
30 min prior to the addition of a toluene solution (5 mL) of 1,2-
bis(2,4,6-trimethylphenylimino)acenapthene, mesBIAN, (129.2 mg,
for X-ray crystal structure analysis. M.p. 273–278 °C. 0.310 mmol). The suspension was stirred for 30 min before drop
C19H27ClBF4IrN4·H2O (625.9): calcd. C 35.44, H 4.54, N 8.70;
wise addition of a MeOH/toluene solution (5 mL, 1: 4) of NaBF4
(34.1 mg, 0.310 mmol). The dark brown solution was stirred over-
night; the solvent was removed in vacuo to give a brown solid. The
solid was recrystallised from CH2Cl2, by slow diffusion of pentane.
Dark brown crystals of [Cp*IrCl(mesBIAN)]BF4 were collected,
found C 35.81, H 4.37, N 8.73%. IR (KBr disc): ν = 3432 (br),
˜
3108 (m), 1716 (w), 1699 (w), 1652 (m), 1655 (m), 1557 (w), 1514
(m), 1456 (w), 1413 (w), 1290 (w), 1084 (br. s), 1032 (vs), 820 (w),
758 (m) cm–1. MS (ES+, CH2Cl2): m/z (%)
= 539 (100)
86
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© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 80–89

Cp* Iridium and Rhodium Complexes Containing Bidentate Ligands
washed with pentane (2 5 mL) and dried. Yield: 54%
FULL PAPER
8.18 (s, 1 H, N=CH), 7.27 (s, 1 H, H5), 7.12 (s, 1 H, H4), 6.87 (s,
2 H, m-H), 4.14 (s, 3 H, N–Me), 2.23 (s, 3 H, p-Me), 2.11 (s, 6
H, o-Me) ppm. 13C{1H} NMR ([D6]acetone, 75 MHz): δ = 154.8
(N=CH), 148.4 (C7), 142.9 (C1), 129.4 (C4), 128.6 (p), 128.5 (o),
126.5 (o), 126.0 (C5), 35.0 (N–Me), 19.9 (p-Me), 17.6 (o-Me)
(129 mg). The dark brown crystals of 6b obtained were
suitable for X-ray crystal structure analysis. M.p. Ͼ 230 °C.
C40H43BClF4IrN2·H2O·CH2Cl2·CH3OH[44] (1001.3): calcd.
C
50.38, H 5.13, N 2.80; found C 50.07, H 4.75, N 2.80%. IR (KBr
disc): ν = 3629 (w), 3588 (w), 3433 (br), 2917 (w), 2361 (w), 1624 ppm.
˜
(w), 1064 (m),1473 (m) 1436 (m), 1417 (m), 1382 (m), 1302 (m),
Synthesis of [Cp*IrCl(mesim-mim)]BF4 (8b): [IrCp*Cl2]2 (75.6 mg,
1058 (vs), 1031 (vs), 778 (m) cm–1. MS (ES+, CH2Cl2): m/z (%) =
0.095 mmol) and 2,4,6-trimethylphenylimino-(1-methyl-2-imid-
azolyl)methane (7) (86.3 mg, 0.400 mmol) were dissolved in toluene
(10 mL) and stirred for 30 min prior to the addition of a methanol
solution (5 mL) of NaBF4 (24.2 mg, 0.221 mmol). The dark orange
solution was stirred for 2 h before the volume was reduced, filtered
and the solution was layered with pentane (10 mL). Orange crystals
of [Cp*IrCl(mesim-mim)]BF4 were collected in air and dried. Yield:
38% (49.1 mg) M.p. 283–288 °C. C24H32BClF4IrN3 (677.0): calcd.
C 42.58, H 4.76, N 6.21; found C 42.44, H 4.74, N 6.09. IR (KBr
1
782 (100) [Cp*IrCl(mesBIAN)]+), 783 (60), 784 (10), 743 (10). H
NMR (CD2Cl2, 300 MHz): δ = 8.19 (d, 3JH5-H4 = 8.4 Hz, 2 H, H5),
7.55 (m, 2 H, H4), 7.23 (s, 2 H, H10), 7.10 (s, 2 H, H12), 6.89 (d,
3JH3-H4 = 7.3 Hz, 2 H, H3), 2.48 (s, 6 H, o-Me), 2.46 (p, 6 H, p-
Me), 1.92 (s, 6 H, oЈ-Me), 1.27 [s, 15 H, CH3(Cp*)] ppm. 13C{1H}
NMR (CD2Cl2, 75 MHz): δ = 178.7 (C1), 145.0 (C7), 142.1 (C8),
139.9 (C11), 133.2 (C5), 132.0 (C6), 131.7 (C9), 131.5 (C10), 130.6
(C12), 130.0 (C4), 129.2 (C13), 126.8 (C2), 125.5 (C3), 93.5 (Cp*),
21.3 (p-Me), 20.5 (o-Me), 18.6 (oЈ-Me), 8.6 [CH3(Cp*)] ppm. 19F
NMR (CD2Cl2, 282.41 MHz): δ = –154.0 (br. s, BF4) ppm.
disc): ν = 3853 (w), 3736 (w), 3394 (br), 3153 (w), 2190 (m), 1584
˜
(m), 1488 (m), 1424 (s), 1386 (m), 1309 (m), 1298 (m), 1142 (m),
Synthesis of [(2,4,6-Trimethylphenyl)imino](1-methyl-2-imidazolyl)-
methane: 2-Formyl-1-methylimidazole (1.38 g, 12.5 mmol) and
2,4,6-trimethylaniline (4 mL, 26.5 mmol) were dissolved in ethanol
(12 mL) and heated to reflux for 3 h. The solvent was removed in
vacuo to give a brown oil which was purified by kugelrohr distil-
lation. The product [(2,4,6-trimethylphenyl)imino](1-methyl-2-
imidazolyl)methane was obtained as a viscous yellow oil. Yield:
25% (878 mg). C14H17N3 (227.3): calcd. C 73.98, H 7.54, N 18.49;
found C 73.49, H 7.88, N 17.73. MS (GC-EI, CH2Cl2): m/z (%) =
120 (100), 135 (90) [M+]. 1H NMR ([D6]acetone, 300 MHz): δ =
1061 (vs), 989 (m), 853 (m), 782 (m) cm–1.
MS (ES+, CH2Cl2): m/z (%) = 590 (100) [Cp*IrCl(mesim-mim)]+)
1
588 (80), 592 (50). H NMR (CD2Cl2, 300 MHz): δ = 8.57 (s, 1 H,
3
3
H6), 7.42 (d, JH5-H4 = 1.51 Hz, 1 H, H5) 7.32 (d, JH4-H5
=
1.51 Hz, 1 H, H4), 6.96 (s, 1 H, H10), 6.93 (s, 1 H, H12), 3.99 (s,
3 H, N–Me), 2.26 (s, 3 H, p-Me), 2.20 (s, 3 H, oЈ-Me), 2.00 (s, 3
H, o-Me), 1.49 [s, 15 H, CH3(Cp*)] ppm. 13C{1H} NMR (CD2Cl2,
75 MHz): δ = 156.6 (C6), 149.8 (C2), 144.7 (C8), 138.5 (C11), 131.9
(C13), 130.0 (C12), 129.9 (C9), 128.6 (C4), 128.3 (C5), 89.7
Table 5. Crystal structure and refinement data for 1c, 2c and 3c.
Compound
1c
2c
3c
Empirical formula
Formula weight
Temperature [K]
Wavelength [Å]
Crystal system
Space group
Crystal size [mm]
a [Å]
C27H38Cl4Ir2N4
944.81
200(2)
0.71073
monoclinic
P21/a
C31H46Cl8Ir2N4
1142.72
200(2)
0.71073
orthorhombic
P212121
C27H38Cl4N4Rh2
766.23
200(2)
0.71073
monoclinic
P21/a
0.19ϫ0.12ϫ0.11
14.626(3)
0.34ϫ0.31ϫ0.28
12.001(2)
0.51ϫ0.43ϫ0.12
14.596(2)
b [Å]
14.413(3)
15.082(3)
14.436(2)
c [Å]
14.918(3)
21.807(4)
14.876(2)
α [°]
90
90
90
β [°]
103.20(3)
90
3061.7(11)
4
2.05
90
90
103.1620(10)
90
3052.0(7)
γ [°]
V [Å3]
3947.0(14)
4
1.923
7.305
2200
Z
4
Dcalcd. [Mg/m3]
1.668
1.455
1544
µ [mm–1
F(000)
]
9.057
1800
θ Range for data collection [°]
Limiting indices
3.14–27.50
–18ՅhՅ18, –17ՅkՅ18,
–19ՅlՅ19
63766
3.11–27.49
–15ՅhՅ12, –19ՅkՅ19,
–28ՅlՅ28
55293
3.15–27.49
–18ՅhՅ18, –18ՅkՅ17,
–19ՅlՅ18
63992
Reflections collected
Independent reflections
Completeness to theta
Max. and min. transmission
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [IϾ2σ(I)]
7009 [Rint = 0.0820]
27.50°, 99.8%
0.451 and 0.285
full-matrix least squares on F2
7009/0/345
1.022
R1 = 0.0334,
wR2 = 0.0757
R1 = 0.0530,
wR2 = 0.0846
0.00088(6)
1.385 and –2.072
9054 [Rint = 0.1317]
27.49°, 99.8%
0.356 and 0.161
full-matrix least squares on F2
9054/0/418
1.01
R1 = 0.0346,
wR2 = 0.0752
R1 = 0.0464,
wR2 = 0.0796
–0.014(7)
6976 [Rint = 0.0685]
27.49°, 99.6%
0.921 and 0.719
full-matrix least squares on F2
6976/0/344
1.009
R1 = 0.0324,
wR2 = 0.0855
R1 = 0.0401,
wR2 = 0.0914
R indices (all data)
Extinction coefficient
Largest diff. peak and hole [e·Å
–3
]
0.936 and –1.096
1.521 and –0.932
Eur. J. Inorg. Chem. 2007, 80–89
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
87

D. F. Kennedy, B. A. Messerle, M. K. Smith
FULL PAPER
Table 6. Crystal structure and refinement data for 2b, 7b and 8b.
Compound
2b
7b
8b
Empirical formula
Formula weight
Temperature [K]
Wavelength [Å]
Crystal system
Space group
Crystal size [mm]
a [Å]
C19H27BClF4IrN4
625.91
200(2)
0.71073
orthorhombic
Pcab
0.19ϫ0.17ϫ0.12
15.2650(10)
16.6330(10)
17.4210(10)
90
C42H51BCl5F4IrN2O2
1072.11
200(2)
0.71073
orthorhombic
Pbnm
0.20ϫ0.18ϫ0.18
15.265(3)
16.509(4)
17.182(3)
90
C25H34BCl3F4IrN3
761.91
200(2)
0.71073
triclinic
¯
P1
0.25ϫ0.10ϫ0.05
9.5200(19)
12.287(3)
13.418(3)
68.51(3)
b [Å]
c [Å]
α [°]
β [°]
90
90
4423.2(5)
8
1.88
6.204
90
90
85.49(3)
77.04(3)
1423.2(5)
2
1.778
5.019
γ [°]
V [Å3]
4330.0(15)
4
1.645
Z
Dcalcd. [Mg/m3]
µ [mm–1]
3.448
F(000)
2432
2144
748
θ Range for data collection [°]
Limiting indices
2.91–27.49
–19ՅhՅ19, –21ՅkՅ21,
–22ՅlՅ22
65229
2.94–27.47
–19ՅhՅ19, –21ՅkՅ21,
–22ՅlՅ22
81934
3.11–25.04
–11ՅhՅ10, –14ՅkՅ14,
–15ՅlՅ15
16560
Reflections collected
Independent reflections
Completeness to theta
Max. and min. transmission
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [IϾ2σ(I)]
5070 [Rint = 0.0948]
27.49°, 99.9%
0.512 and 0.336
full-matrix least squares on F2
5070/0/278
1.006
R1 = 0.0306,
wR2 = 0.0716
R1 = 0.0456,
wR2 = 0.0797
5091 [Rint = 0.1034]
27.50°, 99.3%
0.712 and 0.557
full-matrix least squares on F2
5091/47/308
1.007
R1 = 0.0514,
wR2 = 0.1398
R1 = 0.0680,
wR2 = 0.1520
0.765 and –0.640
5027 [Rint = 0.0709]
25.04°, 99.7%
0.805 and 0.478
full-matrix least squares on F2
5027/0/343
1.019
R1 = 0.0343,
wR2 = 0.0783
R1 = 0.0439,
wR2 = 0.0827
1.193 and –1.008
R indices (all data)
Largest diff. peak and hole [e·Å–3] 0.898 and –1.747
(1JRh-Cp = 8.7 Hz, Cp*), 35.5 (N–Me), 20.4 (p-Me), 19.6 (oЈ-Me),
IR (KBr disc): ν = 3129 (m), 2961 (w), 1621 (w), 1547 (m), 1515
˜
18.6 (o-Me), 8.3 [CH3(Cp*)] ppm. 19F NMR (CD2Cl2, (s), 1456 (m), 1417 (s), 1378 (m), 1288 (m), 1171 (w), 1143 (m),
282.41 MHz): δ = 153.7 ppm.
1057 (br. s), 819 (w), 762 (s), 618 (m), 521 (m), 436 (m), 409 (m)
cm–1. MS (ES+, CH2Cl2) m/z: 449 (M+, 100%), 451 (80%), 413
(70%). 1H NMR (CD2Cl2, 300 MHz): δ = 7.03 (d, 4 H, H4 and
Synthesis of [Cp*RhCl(bpm)]BF4 (3b): [RhCp*Cl2]2 (99 mg,
0.16 mmol), bpm (86 mg, 0.58 mmol) and NaBF4 (67 mg,
0.61 mmol) were suspended in toluene and stirred for 12 h at room
temp. The yellow-orange solid was collected in air by filtration and
2
2
H5), 4.47 (d, JHb-Ha = 19.0 Hz, 1 H, Ha), 4.16 (d, JHa-Hb
=
19.0 Hz, 1 H, Hb), 3.83 (s, 6 H, N–CH3), 1.60 [s, 15 H, CH3(Cp*)]
ppm. 13C NMR [CD2Cl2, 75 MHz]: δ = 142.0 (C2), 129.1 (C4 or
5), 123.8 (C5 or 4), 96.0 (1JRh-Cp = 8.0 Hz, Cp*), 34.9 (N–CH3),
22.8 (CH2), 9.4 [CH3(Cp*)] ppm. 19F NMR (CD2Cl2,
282.41 MHz): δ = –152.2 ppm.
was recrystallised from
a
CH2Cl2/hexane (1:1) mix.
[Cp*RhCl(bpm)]BF4 was obtained as an orange powder. Yield:
47% (77 mg). MP Ͼ 230 °C dec. C17H23BClF4N4Rh (508.55):
calcd. C 40.15, H 4.56, N 11.02; found C 39.97, H 4.77, N 10.94.
IR (KBr disc): ν = 3144 (m), 3117 (w), 3081 (w), 2959 (w), 2922
˜
X-ray Crystallography
(w), 1493 (m), 1457 (m), 1430 (m), 1403 (s), 1288 (vs), 1278 (s),
1098 (vs), 1038 (vs), 986 (m), 767 (s) cm–1. 1H NMR (CD2Cl2,
Details of the crystals and their refinements are given in Table 5
and Table 6. CCDC- 291178, -291179, -291180, -291478, -609638
and -609639 contain the supplementary crystallographic infor-
mation for 1c, 7b, 2c, 3c, 8b and 2b, respectively. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
3
300 MHz): δ = 8.27 (d, JH5-H4 = 2.64 Hz, 2 H, H5), 7.73 (d,
2
3JH3-H4 = 2.26 Hz, 2 H, H3), 7.28 (d, JHb-Ha = 14.7 Hz, 1 H, Ha),
3
3
6.50 (dd, JH5-H4 = 2.64 Hz, JH3-H4 = 2.26 Hz, 2 H, H4), 6.00 (d,
2JHa-Hb = 14.7 Hz, 1 H, Hb), 1.71 [br. s, 15 H, CH3(Cp*)] ppm.
13C{1H} NMR (CD2Cl2, 75 MHz): δ = 144.8 (C3), 135.0 (C5),
108.7 (C4), 88.8 (Cp*), 62.7 (CH2), 8.7 [CH3(Cp*)] ppm. 19F NMR
(CD2Cl2, 282.41 MHz): δ = –151.6 ppm.
Synthesis of [Cp*RhCl(bim)]BF4 (4b): [RhCp*Cl2]2 (104 mg,
0.17 mmol), bim (115 mg, 0.65 mmol) and NaBF4 were suspended
in toluene and stirred for 12 h at room temp. The orange solid was
collected via filtration and recrystallised from CH2Cl2: pentane.
Red cubic crystals of [Cp*RhCl(bim)]BF4 were obtained. Yield:
63% (115 mg). M.p. 290 °C (dec.). C19H27BClF4N4Rh (536.6):
calcd. C 42.53, H 5.07, N 10.44; found C 42.56, H 5.20, N 10.50.
Acknowledgments
We gratefully acknowledge financial support from The University
of New South Wales, The Australian Research Council and the
Australian government for an Australian Postgraduate Award
(D.F.K.). We acknowledge Bradley Man for assistance.
88
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Eur. J. Inorg. Chem. 2007, 80–89

Cp* Iridium and Rhodium Complexes Containing Bidentate Ligands
FULL PAPER
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Received: August 7, 2006
Published Online: November 14, 2006
Eur. J. Inorg. Chem. 2007, 80–89
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
89