cis-Dicarbonyl-cis-dichlorido-trans-bis-(triphenyl-phosphine-kP) iridium(III) tetra-fluorido-borate, formed by reaction of (cyclo-octa-1,5-diene) bis-(triphenyl-phosphine)iridium tetrafluoridoborate with carbonyl fluoride in dichloro-methane solution

Article abstract of DOI:10.1107/S0108270107025358

The reaction between carbonyl fluoride and [Ir(COD)(PPh3)2]BF4 (COD is cyclo-octa-1,5-diene) in dichloro-methane solution affords the novel title iridium salt, [IrCl2(C18H15P)2(CO)2]BF4. The cation lies across a twofold rotation axis in the space group P21212 and its structure confirms the presence in a cis relationship of two metal-bound chlorides, while the phosphine ligands occupy a trans pair of sites. The anion also lies across a twofold rotation axis, and the F atoms are disordered over two sets of sites. International Union of Crystallography 2007.

Full text of DOI:10.1107/S0108270107025358

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
Carbonyl ¯uoride, on reaction at room temperature with a
stirred solution of [Ir(COD)(PPh3)2]BF4 in dichloromethane,
generated a signi®cant amount of precipitate. Removal of all
volatiles in vacuo yielded an air-sensitive solid, and isolation
and puri®cation of this afforded the product, [IrCl2(PPh3)2-
(CO)2]BF4, (I). Each of the ions lies across a twofold rotation
axis. The coordination environment of the iridium is essen-
tially octahedral (Fig. 1), with two cis-Cl ligands each trans to a
CO ligand, so that the two phosphone ligands are trans to one
another. The tetra¯uoridoborate counter-ion exhibits sub-
stantial disorder. The absence of a metal-bound ¯uoride in (I)
is surprising and suggests that, if a ¯uoro complex was initially
formed, the fate of the metal-bound ¯uoride lay in halide
exchange with the chlorinated solvent. NMR studies of the
crude reaction mixture lends credence to this, with a number
of resonances ascribed to varying degrees of solvent ¯uor-
ination being observed. However, it should be stressed that no
spectroscopic evidence for a metal-bound ¯uoride was
observed; the 31P{1H} NMR spectrum of the crude reaction
mixture indicated quantitative formation of (I).
ISSN 0108-2701
cis-Dicarbonyl-cis-dichlorido-trans-
bis(triphenylphosphine-jP)iridium(III)-
tetrafluoridoborate, formed by
reaction of (cycloocta-1,5-diene)-
bis(triphenylphosphine)iridium tetra-
fluoridoborate with carbonyl fluoride
in dichloromethane solution
Duncan A. J. Harding, Eric G. Hope,* Gregory A. Solan
and John Fawcett
Department of Chemistry, University of Leicester, Leicester LE1 7RH, England
Correspondence e-mail: egh1@le.ac.uk
Received 22 May 2007
Accepted 24 May 2007
Online 23 June 2007
Although (I) is isoelectronic and isostructural with the well
known complexes [OsCl2(CO)2L2] (L = phosphine), little
work involving either cationic iridium halide or hydride
complexes has been reported. Indeed, (I) represents the ®rst
iridium carbonyl phosphine chloride complex to be crystal-
lographically characterized, and is one of only a handful of
charged iridium halide complexes employing both PPh3 and
CO that have been isolated. Complexes similar to (I) have,
however, been observed in iridium hydride chemistry; it has
been reported (Malatesta et al., 1974) that reaction of
The reaction between carbonyl ¯uoride and [Ir(COD)-
(PPh3)2]BF4 (COD is cycloocta-1,5-diene) in dichloromethane
solution affords the novel title iridium salt, [IrCl2(C18H15P)2-
(CO)2]BF4. The cation lies across a twofold rotation axis in the
space group P21212 and its structure con®rms the presence in a
cis relationship of two metal-bound chlorides, while the
phosphine ligands occupy a trans pair of sites. The anion also
lies across a twofold rotation axis, and the F atoms are
disordered over two sets of sites.
Comment
Late transition metal complexes are increasingly being
exploited in carbon±¯uorine bond cleavages, and the resulting
metal±¯uoro complexes often exhibit interesting reactivities.
Much research has focused on the use of nickel-containing
systems (Cornin et al., 1997; Schaub & Radius, 2005), as these
have been shown to exhibit remarkable chemoselectivity
(Sladek et al., 2002). The viability of homogeneous rhodium-
catalysed carbon±¯uorine bond activation is well established
(Aizenberg & Milstein, 1994, 1995), and carbon±¯uorine bond
scission using iridium is not unprecedented (Kulawiec et al.,
1987). Theoretical studies indicate that carbon±¯uorine bond
activation at IrI should be facile (Su & Chu, 1997), and many
examples of carbon±¯uorine bond activation using other
platinum group metals now exist (Braun et al., 2002; Garratt et
al., 2005; Torrens, 2005). As part of our ongoing studies into
low-valent metal±¯uoro complexes, we investigated carbon±
¯uorine bond activation using [Ir(COD)(PPh3)2]BF4. Herein,
we report the reaction between carbonyl ¯uoride and
[Ir(COD)(PPh3)2]BF4.
Figure 1
View of the components of (I), shown with 50% probability ellipsoids. H
atoms have been omitted for clarity. [Symmetry code: (i) 1 x, 1 y, z.]
Acta Cryst. (2007). C63, m321±m322
DOI: 10.1107/S0108270107025358
# 2007 International Union of Crystallography m321

metal-organic compounds
Table 1
Selected geometric parameters (A, ).
[Ir(CO)3(PPh3)]2 with HClO4 resulted in the formation of the
cation [IrH2(CO)2(PPh3)2]+, while a range of complexes of the
type [IrH2L2(CO)2]+ (L = phosphine) have also been isolated
(Mays et al., 1970). The formation of [IrI2(CO)2(PPh3)2]+ has
been inferred (Malatesta et al., 1970), but it could not be
puri®ed. Arguably the closest crystallographically character-
ized comparators to (I) are [IrCl2(CO)(PEt3)2(SOCl)] (Blake
et al., 1992), and the isostructural complex [OsCl2(CO)2-
(PEt3)2] (Clark et al., 1999). As expected, the metal±
phosphine bond lengths in [IrCl2(CO)(PEt3)2(SOCl)]
ꢁ
Ê
Ir1ÐC1
Ir1ÐCl1
Ir1ÐP1
1.911 (4)
2.3629 (8)
2.4258 (8)
C1ÐO1
B1ÐF1
B1ÐF2
1.116 (4)
1.318 (8)
1.361 (7)
C1ÐIr1ÐC1i
Cl1ÐIr1ÐCl1i
C1ÐIr1ÐP1
97.9 (2)
94.77 (5)
90.08 (9)
Cl1ÐIr1ÐP1
O1ÐC1ÐIr1
87.52 (3)
173.8 (3)
Symmetry code: (i) x ‡ 1; y ‡ 1; z.
Ê
Ê
[2.4257 (8) A] and [OsCl2(CO)2(PEt3)2] [2.4048 (11) A] are
At the end of the re®nement, the largest residual electron-density
Ê
peak in the Fourier difference map was located 0.97 A from Ir1.
Ê
close to those observed in (I) [2.4258 (8) A]. The metal±
chloride bond lengths of (I) are, however, slightly shorter
Ê
[2.3629 (8) A] than those of the isoelectronic [OsCl2(CO)2-
Ê
(PEt3)2] complex [2.444 (1) A], indicating a slightly stronger
metal±chloride interaction in (I), as expected from the cationic
nature of the complex.
Data collection: SMART (Bruker, 1998); cell re®nement: SMART;
data reduction: SAINT (Bruker, 1998); program(s) used to solve
structure: SHELXS97 (Sheldrick, 1997); program(s) used to re®ne
structure: SHELXL97 (Sheldrick, 1997); molecular graphics:
ORTEP-3 (Farrugia, 1997); software used to prepare material for
publication: SHELXL97, PLATON (Spek, 2003), WinGX (Farrugia,
1999) and enCIFer (Allen et al., 2004).
Experimental
[Ir(COD)(PPh3)2]BF4 (100 mg, 0.110 mmol) dissolved in dichloro-
methane (4 ml) was cooled to 195 K and placed under 1100 Torr
(1 Torr = 133.322 Pa) of COF2. The solution was warmed to room
temperature and stirred for 3 d whilst the uptake of COF2 was
measured tensimetrically. After removal of the volatiles in vacuo, the
resulting dark solid was washed twice with cold THF (0.5 ml, 258 K),
and the dark solution carefully decanted at 258 K, to afford the
product [IrCl2(CO)2(PPh3)2]BF4, (I), as an air-sensitive white solid in
32% yield. m/z (+ FAB): 815 ([M ± BF4 ± CO]+), 787 ([M ± BF4
2CO]+), 751([M ± BF4 2CO Cl]+), 715 ([M ± BF4 2CO 2Cl]+).
1H (CD2Cl2): ꢀ 7.91±7.40 (m, 30H, ArH); 19F{1H} NMR (CD2Cl2): ꢀ
149.7 (s); 31P{1H} (CD2Cl2): ꢀ 16.2 (s). ꢁmax/cm±1 (solid): 2016 (s,
CO), 1483 (s), 1432 (s), 1070 (s, [BF4] ), 683 (s). Single crystals of (I)
suitable for X-ray diffraction were grown by slow vapour diffusion of
hexane into a saturated dichloromethane solution of (I).
The authors thank the EPSRC for ®nancial support and Dr
Joseph Wright for assistance in the preparation of this
manuscript.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: GD3114). Services for accessing these data are
described at the back of the journal.
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Crystal data
3
Ê
[IrCl2(C18H15P)2(CO)2]BF4
Mr = 930.47
Orthorhombic, P21212
a = 11.2488 (5) A
b = 14.6091 (7) A
Ê
c = 10.6711 (5) A
V = 1753.63 (14) A
Z = 2
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1
Ê
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15288 measured re¯ections
4021 independent re¯ections
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4021 re¯ections
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H-atom parameters constrained
Áꢅmax = 1.47 e A
3
Ê
3
Ê
0.50 e A
Áꢅmin
=
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È
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1.2U (C). The Fatoms of the tetra¯uoridoborate ion, which lies across
eq
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®nal occupancies of 0.50 (3) for each, in the positions shown in Fig. 1.
ꢀ
m322 Harding et al. [IrCl2(C18H15P)2(CO)2]BF4
Acta Cryst. (2007). C63, m321±m322