Synthesis and characterisation of some iridium-carbonyl-fluoride complexes. Crystal structures of [IrF(CO){P(C6H4-2-CH 3)3}2] and [IrF2(COD)py 2][BF4]

Article abstract of DOI:10.1039/c0dt00066c

Two routes to iridium(iii) fluorocomplexes are described. The direct reaction of tetrairidium dodecacarbonyl with elemental fluorine in aHF offers a clean, convenient, large scale route to [IrF₃(CO)₃]; addition of phosphines to [IrF₃(CO)₃] in THF affords mer-[IrF₃(CO)L₂] or [IrF(CO)L₂]. Alternatively, cationic [IrF₂(COD)L₂]⁺ and [IrF ₂(CO)₂L₂]⁺ (L = phosphine, pyridine; L₂ = α-diimine) are accessible via the oxidation of the iridium(i) precursors with xenon difluoride. The Royal Society of Chemistry 2010.

Full text of DOI:10.1039/c0dt00066c

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Synthesis and characterisation of some iridium-carbonyl-fluoride complexes.
Crystal structures of [IrF(CO){P(C6H4-2-CH3)3}2] and
[IrF2(COD)py2][BF4]†
John Fawcett, Duncan A. J. Harding and Eric G. Hope*
Received 3rd March 2010, Accepted 16th April 2010
First published as an Advance Article on the web 25th May 2010
DOI: 10.1039/c0dt00066c
Two routes to iridium(III) fluorocomplexes are described. The direct reaction of tetrairidium
dodecacarbonyl with elemental fluorine in aHF offers a clean, convenient, large scale route to
[IrF3(CO)3]; addition of phosphines to [IrF3(CO)3] in THF affords mer-[IrF3(CO)L2] or [IrF(CO)L2].
Alternatively, cationic [IrF2(COD)L2]+ and [IrF2(CO)2L2]+ (L = phosphine, pyridine; L2 = a-diimine)
are accessible via the oxidation of the iridium(I) precursors with xenon difluoride.
report of the synthesis of [IrF2(dppe)2]+[BF4]-,11 generated by
Introduction
the low temperature oxidation of [Ir(dppe)2]+[BF4]- with XeF2 in
Although the number of coordination or organometallic com-
DCM, to a range of iridium(III) difluorocations.
plexes of the platinum group metals with fluoride ligands is much
smaller than those containing the heavier halides, the synthetic
challenges and potential applications, such as in aryl-F bond
formation, of such metal fluoride complexes have resulted in
Results and discussion
Previously, [IrF3(CO)3] (1) had been prepared by us by the low
temperature oxidation of tetrairidium dodecacarbonyl with xenon
difluoride in anhydrous HF,21 but (1) is sensitive to over oxidation
in the presence of excess XeF2 and this is not a particularly
attractive synthetic route since it generates large volumes of waste
xenon. We have now found that (1) can be prepared on a large scale
(5–10 g) using elemental fluorine as the oxidant for Ir4(CO)12 in
HF solution by adapting our previously described procedure for
the synthesis of [MF2(CO)3]4 (M = Ru, Os).22 It is straightforward
to monitor the oxidation tensimetrically through the uptake of
fluorine gas, since there are no side products generated, and to
establish when the reaction is finished since, at room temperature
in aHF, (1) is stable to further reaction even under prolonged
(weeks) exposure to fluorine gas.
growing interest in this field. Recent notable examples include
palladium(II) {trans-[PdF2py2],1 [PdF2(t-Bubpy)]2 and [PdF(4-
C6H4F)(t-Bubpy)]3} and platinum(II) {[PtF2(PR3)2]4,5} complexes
prepared by halide exchange with AgF, ruthenium(II) {[Ru2(m-
F)3(PEt3)6]+6} and rhodium(I) {[RhF(PR3)3]7,8} complexes pre-
pared by protonation with TREAT-HF, the iridium(I) species
{[IrF(PPh3)(COD)]9} formed by protonation with HF, and the
platinum(IV) complex {[PtF2(Ph)2(PPh3)2]5} and the palladium(IV)
complexes {[PdF2(benzoquinolinyl)(pyridyl-sulfonamide)]10 and
[PdF2(FHF)(4-C6H4F)(t-Bubpy)]3} prepared by oxidation with
XeF2.
In comparison, however, relatively few Ir(III) fluoro-
complexes have been reported. Sporadic reports on the
oxidative addition chemistry of trans-[IrF(CO)(PPh3)2] have
afforded a modest number of such species,11,12 the oxidative
addition of NSF3, SF4, SeF4 or TeF4 to [IrCl(CO)(PEt3)2]
On reaction of (1) with two equivalents of triphenylphos-
phine in dry thf carbon monoxide is evolved and the new air-
sensitive iridium(III) carbonyl phosphine fluoride complex, mer-
[IrF3(CO)(PPh3)2] (2) is formed in high yield. The complex is
readily characterised in solution by NMR spectroscopy: The 19F
NMR spectrum consists of two mutually-coupled resonances, a
doublet of triplets at d -451.2 and a lower field triplet of triplets
at d -280.9. The high field resonance is typical of an F-trans-
F interaction across Ir(III)13,21 and is, therefore, assigned to the
two trans fluorines (FA; Scheme 1). The remaining resonance is
typical of an F-trans-CO moiety across Ir(III) (FB).15,21,23,24 The
generates
a
number of iridium(III) monofluorides,13,14 the
related [IrF(COF)(CO)2(PEt3)2][BF4] is formed in the reaction
of XeF2 with the iridium(I) salt [Ir(CO)3(PEt3)2][BF4]15
and
[Ir(H)2F(PtBu2Ph)2],16
[Ir(H)(F)(bq-NH2)(PPh3)2],17
[Ir(F)(Cp*)(Ph)(PMe3)]18 and [Ir(F)(Cp*)(Rf)(PMe3)] {Rf =
CF3, CF2CF3, CF2CF2CF3, CF(CF3)2, CF(CF3)(CF2CF3)}19 have
been reported more recently. Herein, we describe two strategies for
the synthesis of iridium(III) centres with more than one fluoride
ligand. Route 1 extends our synthetic strategy20 for the synthesis
of ruthenium and osmium ternary fluorides, whereby the fluorine
originates from the metal complex not from any additional
fluorine-containing reagent, to mer-[IrF3(CO)L2], including an
improved synthesis of [IrF3(CO)3] (1). Route 2 extends the brief
1
31P{ H} NMR spectrum exhibited a doublet of triplets at d -5.9
which exhibited mutual coupling to the resonances in the 19F
NMR spectrum. Comparable in situ spectroscopic data (Table 1)
were obtained for the products mer-[IrF3(CO)(PR3)2] {PR3
=
PMe3 (3), PEt3 (4), PMe2Ph (5), PMePh2 (6), PEtPh2 (7), PCy3
(8)} from the reaction of (1) with a range of other monodentate
ligands (Scheme 1). In contrast to our previously reported air- and
moisture-stable ruthenium(II) and osmium(II) carbonyl phosphine
fluoride complexes,20 these iridium(III) complexes are extremely
Department of Chemistry, University of Leicester, Leicester, UK LE1 7RH.
E-mail: egh1@le.ac.uk; Fax: + 44 116 252 3789
† CCDC reference numbers 720281 and 720282. For crystallographic data
in CIF or other electronic format see DOI: 10.1039/c0dt00066c
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1
Table 1 19F and 31P{ H} NMR data for mer-[IrF3(CO)L2]
crude reaction mixture reveal a doublet at d 26.2 and a mutually-
coupled triplet in the 19F NMR spectrum at d -253.2 that
indicate reduction of the iridium(III) centre and formation of trans-
[IrF(CO){P(C6H4-2-CH3)3}2] (9). In addition, resonances in the
NMR spectra that can be assigned to tris-o-tolylphosphineoxide
and HF that arise from oxidation of the ligand and reaction
with adventitious water. The phosphine oxide is readily removed
by recrystallization from methanol. It is assumed that the steric
demands made by the bulkier P(C6H4-2-CH3)3 prevent formation
of the expected Ir(III) complex. Confirmation of this assignment
comes from a single crystal structure determination; the molecular
structure and selected bond distances and angles are shown in
Fig. 1. The geometry around the metal centre is approximately
square planar, with little deviation from ideality [C(1)–Ir(1)–P(1)
87.89(6)◦]. There is scrambling between the F and CO sites.
The disorder could not be resolved and the data was modelled
d(FA)a/ d(FB)b/ d(P)/ 2J(FAFB)/ 2J(PFA)/ 2J(PFB)/
L
ppm
ppm
ppm
Hz
Hz
Hz
PPh3
PMe3
PEt3
-451.2 -280.9 -5.9
97
20
23
21
20
19
22
14
29
38
31
36
32
37
27
-470.6 -285.0 -12.0 97
-470.1 -286.8 -8.6
99
99
101
PMePh2 -460.2 -283.9 -9.5
PEtPh2 -454.6 -282.0 -1.4
PMe2Ph -463.2 -280.6 -11.9 98
Pcy3 -458.4 -281.1 -7.4 98
a F-trans-F. b F-trans-CO.
˚
˚
to give Ir–F = 2.028(9) A and Ir–C = 1.749(15) A distances.
Similar X/CO disorder has been observed previously in the related
complex trans-[IrCl(CO){P(C6H4-2-CH3)3}2].25
Fig. 1 Molecular structure of (9) with 50% displacement ellipsoids. H
atoms are omitted for clarity. The Ir atom is located on a centre of symmetry
and primed atoms are generated by 1-x, 1-y, -z. The CO and F sites
indicate 50 : 50 disorder of these positions. The disordered site of the C1 and
F1 could not be resolved and was modelled. The disorder is assumed from
the oxidation state of the Ir and the electron density of the C/F site with
respect to the carbonyl oxygen site (~2 : 1). Ir(1)–F(1), 2.028(9), Ir(1)–P(1),
2.3334(17), Ir(1)–C(1), 1.749(15), C(1)–O(1), 1.156(15), C(1)–Ir(1)–P(1),
93.6(16), P(1)–Ir(1)–F(1), 86.1(6).
Scheme 1
air- and moisture-sensitive. In addition, although these complexes
are stable in thf, even in the presence of excess ligand, on the
addition of chlorinated solvents, there is rapid decomposition
with the generation of a number of iridium-fluoride-phosphine
species. It is tempting to presume that these products arise from
halide exchange with the solvent, as reported previously for
iridium(III) carbonyl phosphine fluoride complexes,13 but these
decomposition reactions were never reproducible and we were
unable to definitively identify the reaction products.
In contrast to the synthesis of (2–8), reaction between
[IrF3(CO)3] and bulky phosphines {e.g. trisnaphthylphosphine
or tris-o-tolylphosphine} did not afford mer-[IrF3(CO)2L2]. For
trisnaphthylphosphine, the starting materials were recovered un-
changed. For tris-o-tolylphosphine, NMR experiments on the
An alternative route to iridium(III) fluorides is oxidation. A
series of [Ir(COD)L2]+[BF4]- complexes (L = PPh3, PPh2CCPh,
PPh2Et) have been prepared following a literature procedure.26
The addition of one aliquot of XeF2 to deep red solutions of these
◦
species in dry dichloromethane, even at -80 C, liberated xenon
gas and the solutions changed to a pale straw yellow colour. The
colour change was sufficiently dramatic that it was possible to
5828 | Dalton Trans., 2010, 39, 5827–5832
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Table 2 Selected 19F and 31P NMR data for iridium difluoride cations
trans-,cis-[IrF2L2(COD)]+ trans-[IrF2L2(CO)2]+
cis-,trans-[IrF2L2(CO)2]+
L
d(F)/ppm
d(P)/ppm
2J(PF)/Hz
d(F)/ppm
d(P)/ppm
2J(PF)/Hz
d(F)/ppm
d(P)/ppm
2J(PF)/Hz
PPh3
-501.0
-491.1
-496.5
-483.4
-378.5
-28.1
-31.0
-28.2
-11.7
—
12
21
18
15
—
-508.0
-514.1
-510.6
-12.6
-25.3
-33.0
18
—
—
-343.3
-331.2
-304.0
-3.3
5.2
-19.9
31
32
38
PPh2CCPh
PMePh2
PEtPh2
py
L2
py/PCy3
RNCHCHNRa
RNCHCHNRb
-448.3
-433.4
-427.6
-10.3
—
—
14
—
—
-460.0
-456.5
—
—
—
—
a R = 2,4,6-Me3C6H2. b R = 2,6-iPr2C6H3.
judge accurately the end point of the reaction by sequentially
subliming small aliquots of XeF2 into the solutions. Confirmation
of the identities of the products was obtained by multinuclear
a saturated dichloromethane solution at 0 ◦C; the molecular
structure, which confirms the geometry suggested from the
spectroscopic data, in particular the F-trans-F arrangement,
is shown in Fig. 2 and selected bond lengths and bond angles
are reported in Table 3. This represents the first structurally
characterised iridium complex containing two fluoride ligands
and only the second structurally characterised iridium-COD
◦
NMR spectroscopic studies, recorded at -60 C, which revealed
mutually-coupled triplets in both the 19F and 31P spectra (Table 2).
The 19F NMR resonances, at ca. d -500, are in the region
diagnostic of F-trans-F on iridium(III) centres,13,21 which confirm
the formulation of the products as trans-,cis-[IrF2L2(COD)]+[BF4]-
(10–12; Scheme 1). As expected for such a conformation, the four
olefinic resonances on the COD ligand are equivalent, but at ca. d
5.6 are substantially shifted from those for the iridium(I) starting
materials (ca. d 4.2) in line with the greater Lewis acidity of the
iridium(III) metal centre. Extremely air- and moisture-sensitive
orange solids were obtained on removal of the solvent, which were
further characterised by mass spectrometry, infrared spectroscopy
and, for selected examples, elemental analysis. Unfortunately, the
products were also temperature sensitive and decomposed rapidly
in the solid state or in solution above -60 ◦C. In marked contrast,
no colour change occurred on the addition of XeF2 to a solution of
[Ir(COD)(PPh2Me)2]+[BF4]- at low temperature and NMR spectra
revealed only resonances associated with the starting materials.
However, slow reaction did occur at room temperature, with
xenon evolution, and the NMR spectra for the product, trans-,cis-
[IrF2(PPh2Me)2(COD)]+[BF4]- (13) (Table 2), were comparable
to those obtained for the other iridium(III) cations, whilst the
orange product, was thermally stable and could be stored at room
temperature without evidence of decomposition. The reason for
the anomalous behaviour in this particular reaction is unclear, but
others have reported the resistance of complexes incorporating the
PPh2Me ligand to undergo oxidation with XeF2.23
fluoride complex.9 The Ir–F bond lengths (2.003(6) A) are
˚
towards the lower end of the range of reported Ir(III)–F bond
lengths {1.998(3)15 to 2.143(4)17 A}, consistent with the presence
˚
Fig. 2 Molecular structure of the cation of (15) with 50% displacement
ellipsoids. H-atoms and the counter-ion (BF4-) are omitted for clarity.
Symmetry transformation used to generate equivalent atoms: -x+1/2,
y, -z.
Similarly, oxidation of the pyridine-substituted iridium(I)
cations {[Ir(py)(PCy3)(COD)]+[BF4]-, and [Ir(py)2(COD)]+-
[BF4]-} with XeF2 afforded the analogous trans-,cis-
[IrF2(py)(PCy3)(COD)]+[BF4]- (14) and [IrF2(py)2(COD)]+[BF4]-
(15), which were characterised by multinuclear NMR (Table 2),
mass spectrometry and elemental analysis. For the former,
inequivalence of the olefinic COD protons is clearly evident in
two 2H multiplets in the 1H NMR spectrum, whilst the high
frequency shift in the 19F NMR resonances (d -448 and -378
respectively) reflect the changes observed between phosphorus-
and nitrogen-donors in [RuF2(CO)2L2] complexes.20 Single
crystals of [IrF2(py)2(COD)]+[BF4]- (15) suitable for structural
characterisation were grown by slow diffusion of hexane into
◦
˚
Table 3 Selected bond lengths (A) and angles ( ) for bis(pyridine)(cyclo-
octa-1,5-diene)iridiumdifluoride tetrafluoroborate, [IrF2py2(COD)][BF4],
(15)
Ir(1)–F(1)
Ir(1)–N(1)
Ir(1)–C(4)
Ir(1)–C(1)
N(1)–C(9)
N(1)–C(5)
2.003(6)
2.124(9)
2.237(11)
2.242(11)
1.303(14)
1.344(14)
F(1)–Ir(1)–F(1¢)
F(1)–Ir(1)–N(1)
N(1)–Ir(1)–N(1¢)
F(1)–Ir(1)–C(4)
F(1)–Ir(1)–C(1)
C(5)–N(1)–Ir(1)
C(9)–N(1)–Ir(1)
167.0(3)
85.7(3)
88.6(4)
75.8(4)
77.4(4)
120.0(8)
119.7(8)
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of two fluoride ligands and a cationic metal centre. However, the
Ir–C distances associated with the coordinated COD ligand are
state at room temperature. Throughout, these iridium fluoride
complexes reveal highly diagnostic very low frequency resonances
in their 19F NMR spectra.
˚
unusually long (2.240 A) in comparison with those for the parent
26
˚
iridium(I) COD cation (2.120 A) or the recently characterised
[IrF(PPh3)(COD)] (2.135 A).
9
˚
Experimental
In a parallel study, we have prepared a couple of irid-
=
General remarks
ium(I) a-diimine cationic complexes, e.g. [Ir(COD)(RN CH–
+
-
CH NR)] [BF4] { R = 2,4,6-Me3C6H2, 2,6-iPr2C6H3},27 and
=
All reactions, unless otherwise stated, were carried out under
an atmosphere of dry, oxygen-freed nitrogen, using standard
Schlenk line or metal vacuum line techniques or in a nitrogen
purged dry box. Solvents were distilled under nitrogen from
appropriate drying agents and degassed prior to use.29 1H, 19F and
31P NMR spectroscopies were carried out on a Bruker DPX300
spectrometer at 300.14, 282.41 and 121.50 MHz respectively or a
Bruker DRX400 spectrometer at 400.13, 376.46 and 161.98 MHz
respectively and were referenced to external SiMe4 (1H), external
CFCl3 (19F) and to external H3PO4 (31P) using the high frequency
positive convention. Spectra were recorded at -60 ◦C, unless
otherwise stated. Abbreviations for NMR spectral multiplicities
are as follows: s = singlet, d = doublet, m = multiplet. J values are
given in Hz. Elemental analyses were performed by the Elemental
Analysis Service at the University of North London. Mass spectra
were recorded on a Kratos Concept 1H mass spectrometer. IR
spectra were recorded as solid samples on a Perkin Elmer Spectrum
One FT-IR spectrometer.
these can similarly be oxidised with XeF2 in solution to afford
+
-
=
=
[IrF2(COD)(RN CH-CH NR)] [BF4] (16,17; Scheme 1), which
have been characterised by multinuclear NMR spectroscopy, mass
spectrometry and elemental analysis. These are room temperature
stable examples of this group of difluoroiridium(III) cations and
the first a-diimine metal fluoride complexes. These species have
nCN stretches shifted to slightly lower frequencies than those for
the starting materials in keeping with the change in oxidation state
of the metal. The low frequency 19F NMR resonances for these
complexes (Table 2) are diagnostic of the F-trans-F arrangement
on iridium(III) centres and are observed at an intermediate field be-
tween those for [IrF2(py)2(COD)]+ and [IrF2(phosphine)2(COD)]+.
The potential applicability of these COD-derivatised irid-
ium(III) difluorocations is severely restricted by their limited
stability. It has been noted previously11 that the presence of
Lewis acidic co-ligands tends to increase the stability of the
M-F bond and, indeed, the majority of late transition metal
fluoride complexes contain CO or NO co-ligands. Displacement
of COD by CO in the iridium(I) starting materials described
above is facile and the resulting complexes [Ir(CO)2L2]+[BF4]-
(L = PPh3, PPh2Me, PPh2CCPh; L2 = RN CH-CH NR {R =
2,4,6-Me3C6H2, 2,6-iPr2C6H3})27,28 could be similarly oxidised
with XeF2 in dichloromethane at -80 ◦C. Significantly, in line
with our intentions, the products are stable in the solid state at
room temperature. Unfortunately, for the monodentate phosphine
complexes, the stereochemical rigidity of the COD-complexes is
lost such that the desired iridium(III) difluoride complexes were
formed as approximately 1 : 1 mixtures of the all-trans and cis-
difluoride complexes [IrF2(CO)2L2]+[BF4]- (18–20) (Scheme 1;
Table 2). For the all-trans isomers, the 19F NMR resonances occur
at substantially lower frequencies and the 2JPF coupling constants
are larger than those for the cis-difluoride isomers, as expected for
the F-trans-F and F-cis-F arrangements.13,21-24 In the oxidations of
the a-diimine complexes, the corresponding iridium(III) difluoride
cations are formed as the single F-trans-F isomers, trans-,cis-
[IrF2(CO)2(L-L)]+[BF4]- (21,22) (Scheme 1; Table 2), for which the
shifts in dF to low frequency, in comparison to those for the related
COD-complexes, mirror those for the related pairs of monodentate
phosphine complexes.
Syntheses. fac-Iridiumtricarbonyltrifluoride (1)21. Tetrairidi-
umdodecacarbonyl (1 g, 0.9 mmol) was dissolved in aHF (2 cm3)
in a 10 mm O.D., 1.5 mm wall thickness pre-passivated FEP vessel
fitted with a PTFE valve. Aliquots of elemental fluorine were
metered into the reaction vessel, to a total pressure of 2 atm,
whilst cooling the solution to -78 ◦C. After each addition, the
reaction mixture was allowed to warm to room temperature and
stirred for 16 h. The reaction was judged to have finished when
fluorine stopped being consumed. The solvent was then removed
in vacuo and to give the product as a yellow solid (0.290 g, 96%),
which was stored in pre-passivated FEP containers in a dry box.
Bis(triphenylphosphine)carbonyliridiumtrifluoride (2). Triph-
enylphosphine (126 mg, 0.48 mmol) and fac-[IrF3(CO)3] (75 mg,
0.23 mmol) were stirred in dry thf (50 cm3) under nitrogen for
16 h. The solvent was removed in vacuo and the resulting powder
recrystallized from methanol to give the product as an air-sensitive
yellow powder (110 mg, 60%). Found: C, 55.6; H, 3.9. Calc.
for C37H30F3IrOP2: C, 55.4; H, 3.75%. nmax/cm-1 3924br, 3053br,
2966br, 2011 s, 1479 s, 1432 s, 1262 s, 1094 s, 797 s, 744 s, 685s. dH
(CDCl3) 7.40-7.20 (30H, m, Ph). dF (CDCl3) -451.2 (dt, 2JFF 97,
=
=
2JPF 20, IrF-trans-F), -280.9 (tt, JFF 97, JPF 29, IrF-trans-CO).
2
2
dP (CDCl3) -5.9 (dt, 2JPF 29, 2JPF 20, IrP2).
The other iridium(III) complexes (3–8) were prepared similarly
but not isolated and their NMR spectra recorded (Table 1).
Bis{tris(o-tolyl)phosphine}carbonyliridiumfluoride (9) was
prepared similarly and obtained as an air-sensitive yellow solid
(68 mg, 35%). m/z (FAB) 848 ([M]+), 829 ([M-F]+). nmax/cm-1
1936 s, 1561br, 1443br, 1273br, 1029 m, 747 s, 713s. dH (C6D6) 8.20
(3H, m, Ph), 7.20-7.08 (9H, m, Ph), 2.63 (9H, s, CH3). dF (C6D6)
-253.2 (t,2JPF 36, IrF). dP (C6D6) 26.2 (d, 2JPF 36, IrP2).
Conclusions
Tricarbonyliridium trifluoride, readily prepared by the treatment
of [Ir4(CO)12] in aHF with elemental fluorine, is a conve-
nient reagent for iridium(III) fluorine chemistry. Reaction with
phosphines affords highly reactive mer-[IrF3(CO)L2] or trans-
[IrF(CO)L2]. Alternatively, a range of cationic [IrF2(COD)L2]+,
[IrF2(COD)(L-L)]+, [IrF2(CO)2L2]+ or [IrF2(CO)2(L-L)]+ can be
prepared by reaction of iridium(I) precursors with XeF2. Although
the COD-derivatised complexes have limited solution and solid-
state stability, the CO-derivatised species can be stored in the solid-
Bis(triphenylphosphine)(cyclo - octa - 1,5 - diene)iridiumdifluo -
ride tetrafluoroborate (10). [Ir(PPh3)2(COD)][BF4] (50 mg,
0.055 mmol) and XeF2 (13 mg, 0.076 mmol) were loaded into
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separate, passivated, FEP reaction vessels (4 mm O.D., 3 mm I.D.)
linked via a T-union (PTFE, Production Techniques Ltd) in a
dry box and connected to an all-metal vacuum line via a PTFE
valve. The apparatus was evacuated, dichloromethane transferred
onto the solids by distillation at -196 ◦C and the vessels warmed
to ensure complete dissolution of the solids. The solution of
the iridium salt was refrozen at -196 ◦C and the XeF2 solution
added in a single aliquot. On warming, ca -80 ◦C, with agitation
and occasional venting to remove xenon gas, the solutions mixed
and the red solution slowly turned yellow. Once the reaction was
deemed complete, either the FEP vessel was heat-sealed for NMR
investigations (at -60 ◦C) or the solvent removed in vacuo to leave
the product as an air- and temperature-sensitive yellow powder
in quantitative yield (52 mg). Found: C, 52.6; H, 4.0. Calc. for
C44H42BF6IrP2·CH2Cl2: C, 52.2; H, 4.3%. m/z (FAB) 755 ([M-
COD-BF4]+). nmax/cm-1 3059br, 1483 s, 1432 s, 1048vs, 747 s, 688s.
dH (CD2Cl2) 7.60-7.10 (30H, m, Ph), 5.65 (4H, br s, COD-CH),
2.40 (4H, m, COD-CH2), 2.15 (4H, m, COD-CH2). dF (CD2Cl2)
3125w, 1608 s, 1483 s, 1450 s, 1035vs, 762 s, 688s. dH (CD2Cl2) 8.89
3
(4H, m, NCHCH), 8.03 (2H, t, JHH = 14 Hz, 4-CH), 7.64 (4H,
m, NCH), 5.75 (4H, br s, COD-CH), 2.68 (4H, m, COD-CH2),
2.43 (4H, m, COD-CH2). dF (CD2Cl2) -153.4 (s, [BF4]-), -378.5
(s, IrF2).
Glyoxal-bis-(2,4,6-trimethylphenylimine)(cyclo-octa-1,5-di-
ene)iridiumdifluoride tetrafluoroborate (16) as a dark brown solid.
Found: C, 46.7; H, 4.95; N, 3.8. Calc. for C28H36BF6IrN2: C,
46.9; H, 5.0; N, 3.9%. m/z (FAB) 631 ([M-BF4]+). nmax/cm-1
2919w, 1606w, 1477w, 1020vs, 850s. dH (CD2Cl2) 8.58 (2H, br s,
NCHCHN), 7.18 (4H, br s, 3-CH), 5.65 (4H, br s, COD-CH),
2.50-1.80 (26H, m, COD-CH2 and CH3). dF (CD2Cl2) -153.0 (s,
[BF4]-), -433.4 (s, IrF2).
Glyoxal - bis - (2,6 - diisopropylphenylimine) (cyclo - octa - 1,5 -
diene)iridiumdifluoride tetrafluoroborate (17) as a deep red solid.
Found: C, 50.8; H, 6.0; N, 3.5. Calc. For C34H48BF6IrN2: C, 50.9;
H, 6.0; N, 3.5%. m/z (FAB) 715 (M-BF4]+), 695 ([M-HF-BF4]+),
677 ([M-2F-BF4]+). nmax/cm-1 2964w, 1595w, 1463br, 1032vs, 800 s,
752s. dH (CD2Cl2) 8.98 (2H, br s, NCHCHN), 7.40-7.10 (6H, m, 3-
CH and 4-CH), 5.50 (4H, br s, COD-CH), 2.50 (4H, m, CH3CH),
2.50-1.00 (32H, m, COD-CH2 and CH3). dF (CD2Cl2) -151.0 (s,
[BF4]-), -427.6 (s, IrF2).
2
-153.0 (s, [BF4]-), -501.0 (t, JPF 12, IrF2). dP (CD2Cl2) -28.1 (t,
2JPF 12, IrP2).
The other iridium difluorocations (11–22) were prepared simi-
larly in quantitative yields.
Bis(phenylethynyldiphenylphosphine)(cyclo-octa-1,5-diene)-
iridiumdifluoride tetrafluoroborate (11) as an orange powder.
Found: C, 57.55; H, 4.4. Calc. for C48H42BF6IrP2: C, 57.8; H,
4.2%. m/z (FAB) 911 ([M-BF4]+), 803 ([M-COD-BF4]+). nmax/cm-1
3095 s, 2941w, 2174 s, 1480 s, 1438 s, 1040vs, 752 s, 688s. dH
(CD2Cl2) 7.80-7.20 (30H, m, Ph), 5.67 (4H, br s, COD-CH), 2.50
(4H, m, COD-CH2), 2.32 (4H, m, COD-CH2). dF (CD2Cl2) -152.1
(s, [BF4]-), -491.1 (t, 2JPF 21 Hz, IrF2). dP (CD2Cl2) -31.0 (t, 2JPF
21, IrP2).
Bis(ethyldiphenylphosphine)(cyclo-octa-1,5-diene)iridiumdi-
fluoride tetrafluoroborate (12) as a yellow powder. m/z (FAB)
659 ([M-COD-BF4]+). nmax/cm-1 2941w, 1483w, 1432 s, 1025vs,
742 s, 691s. dH (CD2Cl2) 7.70-7.10 (20H, m, Ph), 5.76 (4H, br s,
COD-CH), 2.48 (4H, m, COD-CH2), 2.26 (4H, m, COD-CH2). dF
(CD2Cl2) -151.1 (s, [BF4]-), -483.4 (t, 2JPF 15, IrF2). dP (CD2Cl2)
-11.7 (t, 2JPF 15, IrP2).
Bis(triphenylphosphine)(dicarbonyl)iridiumdifluoride tetraflu-
oroborate (18) as a buff solid. Found: C, 50.7; H, 3.5. Calc. for
C38H30BF6IrO2P2: C, 50.8; H, 3.3%. m/z (FAB) 792 ([M-F-BF4]+),
773 ([M-2F-BF4]+), 745 ([M-2F-CO-BF4]+). nmax/cm-1 3059 w,
1994 s, 1480 s, 1435 s, 1040vs, 747 s, 689vs. dH (CD2Cl2) 7.65-
7.25 (30H, m, Ph). dF (CD2Cl2) -152.4 (s, [BF4]-), -343.4 (t, 2JPF
2
31, IrF2 {F-trans-CO}), -508.0 (t, JPF 18, IrF2 {F-trans-F}). dP
(CD2Cl2) -3.3 (t, 2JPF 31, IrP2), -12.6 (t, 2JPF 18, IrP2).
Bis (methyldiphenylphosphine) (dicarbonyl) iridiumdifluoride
tetrafluoroborate (19) as a buff solid. Found: C, 43.5; H, 3.3. Calc.
for C28H26BF6IrO2P2: C, 43.5; H, 3.4%. m/z (FAB) 649 ([M-2F-
BF4]+), 621 ([M-2F-CO-BF4]+). nmax/cm-1 2930 w, 2034 s, 1435 s,
1038vs, 884 s, 739 s, 691vs. dH (CD2Cl2) 7.58-7.20 (20H, m, Ph),
2.25 (6H, m, CH3). dF (CD2Cl2) -151.5 (s, [BF4]-), -304.0 (t,
2JPF 38, IrF2 {F-trans-CO}), -510.6 (br s, IrF2 {F-trans-F}). dP
(CD2Cl2) -19.9 (t, 2JPF 38, IrP2), -33.0 (br s, IrP2).
Bis(methyldiphenylphosphine)(cyclo-octa-1,5-diene)iridiumdi-
fluoride tetrafluoroborate (13) was prepared as a yellow powder
on reaction at room temperature. Found: C, 49.4; H, 4.7. Calc.
for C34H38BF6IrP2: C, 49.45; H, 4.6%. m/z (FAB) 739 ([M-BF4]+),
631 ([M-COD-BF4]+). nmax/cm-1 3048br, 1477 s, 1432 s, 1046vs,
741 s, 691s. dH (CD2Cl2) 7.90-7.10 (20H, m, Ph), 5.74 (4H, br s,
COD-CH), 2.50-2.10 (11H, m, COD-CH2 and CH3). dF (CD2Cl2)
Bis(phenylethynyldiphenylphosphine)(dicarbonyl)iridiumdiflu-
oride tetrafluoroborate (20) as a buff powder. Found: C, 53.2; H,
3.1. Calc. for C42H30BF6IrO2P2: C, 53.3; H 3.2%. m/z (FAB) 793
([M-2F-CO-BF4]+). nmax/cm-1 3054w, 2164 s (CC), 2000br (CO),
1435 s, 1042 s (s, [BF4]-), 752 s, 686s. dH (CD2Cl2) 7.70-7.20 (m,
2
30H, Ph). dF (CD2Cl2) -149.8 (s, [BF4]-), -331.2 (t, JPF 32, IrF2
{F-trans-CO}); -514.1 (br s, IrF2 {F-trans-F}); dP (CD2Cl2) 5.2
(t, 2JPF 32, IrP2{F-trans-CO}), -25.3 (br s, IrP2 {F-trans-F}).
Glyoxal-bis-(2,4,6-trimethylphenylimine)(dicarbonyl)iridium-
difluoride tetrafluoroborate (21) as a dark brown powder. Found:
C, 39.6; H, 3.5; N, 4.1. Calc. for C22H24BF6IrN2O2: C, 39.7; H
3.6; N, 4.2%. m/z (FAB) 560 ([M-HF-BF4]+), 541 ([M-2F-BF4]+).
2
-152.1 (s, [BF4]-), -496.5 (t, JPF 18, IrF2). dP (CD2Cl2) -28.2 (t,
2JPF 18, IrP2).
Pyridine(tricyclohexylphosphine)(cyclo-octa-1,5-diene)iridi-
umdifluoride tetrafluoroborate (14) as an orange solid. m/z (FAB)
698 ([M-BF4]+), 599 ([M-py-HF-BF4]+). nmax/cm-1 2924br, 2852br,
1449 s, 1039vs, 763br, 699br. dH (CD2Cl2) 9.24 (2H, s, NCHCH),
n
max/cm-1 2924w, 2084 s (CO), 2028 s (CO), 1602br, 1474br, 1046vs
3
8.19 (1H, t, JHH 14, 4-CH), 7.85 (2H, m, NCH), 6.38 (2H, br s,
([BF4]-), 856s. dH (CD2Cl2) 9.02 (s, 2H, NCH), 6.95 (s, 4H, meta-
CH), 2.29 (s, 6H, para-CH3), 2.25 (s, 12H, ortho-CH3). dF (CD2Cl2)
-149.2 (s, [BF4]-), -460.0 (s, IrF2).
COD-CH), 5.69 (2H, br s, COD-CH), 2.50-1.00 (41H, m, COD-
2
CH2 and C6H11). dF (CD2Cl2) -151.2 (s, [BF4]-), -448.3 (d, JPF
14, IrF2). dP (CD2Cl2) -10.3 (t, 2JPF 14, IrP2).
Glyoxal-bis-(2,6-diisopropylphenylimine)(dicarbonyl)iridium-
difluoride tetrafluoroborate (22) as a dark brown powder. Found:
C, 43.0; H, 4.3; N, 3.5. Calc. for C28H36BF6IrN2O2·0.5DCM: C,
43.2; H 4.7; N, 3.5%. m/z (+ FAB) 643 ([M-HF-BF4]+), 625
([M-2F-BF4]+); nmax/cm-1 2969w, 2090 s (CO), 2034 s (CO), 1457br,
Bis(pyridine)(cyclo-octa-1,5-diene)iridiumdifluoride tetrafluo-
roborate (15) as yellow crystals. Found: C, 37.05; H, 3.6; N, 4.9.
Calc. for C18H22BF6IrN2: C, 37.05; H, 3.8; N, 4.8%. m/z (FAB) 497
([M-BF4]+), 459 ([M-2F-BF4]+), 398 ([M-py-HF-BF4]+). nmax/cm-1
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Dalton Trans., 2010, 39, 5827–5832 | 5831
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1365br, 1046vs ([BF4]-), 797 s, 752s. dH (CDCl3) 9.14 (s, 2H, NCH),
7.34 (m, 6H, ArH), 3.05 (sep, 4H, 3JHH 6.4, CH3CH), 1.19 (d, 12H,
3JHH 6.4, CH3CH), 1.14 (d, 12H, 3JHH 6.4, CH3CH). dF (CDCl3)
-149.6 (s, [BF4]-), -456.5 (s, IrF2).
Acknowledgements
We thank EPSRC for financial support and Dr Joseph Wright for
assistance with the structural studies.
Crystal data
References
˚
(9) C43H42FIrOP2, M = 847.91, monoclinic, a = 10.4725(15) A, b =
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3
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˚
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11.1807(16) A, c = 15.201(2) A, b = 92.106(3) , U = 1778.7(4) A ,
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-3
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Mo-Ka radiation, l = 0.71073 A, Z = 2, Dc = 1.583 g cm ,
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F(000) = 848, dimensions 0.18 ¥ 0.12 ¥ 0.08 mm3, m(Mo-Ka) =
3.882 mm-1, empirical absorption correction based on y scans,
maximum and minimum transmission factors of 0.733 and 0.498,
respectively, Bruker APEX 2000 CCD diffractometer structure, w
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-12 ≤ k ≤ 13, -18 ≤ l ≤ 18; 12187 reflections were measured, and
3499 were unique (Rint = 0.0579).
˚
(15) C18H22BF6IrN2, M = 583.39, tetragonal, a = 17.4108(15) A,
3
˚
˚
˚
b = 17.4108(15) A, c = 25.463(3) A, U = 7718.8(13) A , T =
150(2) K, space group I 41/a c d, graphite-monochromated Mo-
-3
˚
Ka radiation, l = 0.71073 A, Z = 16, Dc = 2.008 Mg m ,
F(000) = 4480, dimensions 0.37 ¥ 0.04 ¥ 0.03 mm3, m(Mo-Ka) =
6.981 mm-1, semi-empirical absorption correction, maximum and
minimum transmission factors of 0.811 and 0.413, respectively,
Bruker APEX 2000 CCD diffractometer structure, w scans, data
collection range 2.30 < q < 26.00◦, -21 ≤ h ≤ 21, -21 ≤ k ≤ 21,
-31 ≤ l ≤ 30; 23152 reflections were measured, 1904 were unique
(Rint = 0.1342)
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Structure solution and refinement
The structures were solved by direct methods. The structure
refinement on F2 employed SHELXTL VERSION 6.10 (SHELXTL,
an integrated system for solving, refining and displaying crystal
structures).30 Hydrogen atoms were included in calculated posi-
˚
tions (C–H = 0.96 A) riding on the bonded atom with isotropic
displacement parameters set to 1.2 Ueq(C). All non-H atoms were
refined with anisotropic displacement parameters.
(9) Final R1 = 0.0470 and wR2 = 0.0827 (R1 = 0.0715 and
wR2 = 0.0892, respectively, for all data) for 229 variables. The final
-3
˚
residual Fourier map showed peaks of 1.197 and -0.739 e A .
(15) Final R1 = 0.0553 and wR2 = 0.1223 (R1 = 0.0879 and
wR2 = 0.1353, respectively, for all data) for 125 variables. The final
-3
˚
residual Fourier map showed peaks of 1.887 and -2.214 e A .
Crystallographic data (excluding structure factors) for the struc-
tures in this paper have been deposited with the Cambridge Crys-
tallographic Data Centre as supplementary publication CCDC
reference numbers 720281 and 720282. Copies of the data can
be obtained, free of charge, on application to CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK, (fax: +44 1223 336033 or e-mail:
deposit@ccdc.cam.ac.uk).
27 J. Fawcett, D. A. J. Harding, and E. G. Hope, unpublished work.
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1977, 141, 205.
29 W. L. F. Armarego, D. D. Perrin, ‘Purification of Laboratory Chemicals’,
5th Ed., Butterworth-Heinemann, London, 2003.
30 G. M. Sheldrick, SHELXTL-NT Version 6.10, Madison, Siemens
Analytical Instruments, WI, USA, 2000.
5832 | Dalton Trans., 2010, 39, 5827–5832
This journal is
The Royal Society of Chemistry 2010
©