metal-organic compounds
μ-Oxido-bis[hydridotris(trimethylphosphane-κP)iridium(III)](Ir—Ir) bis(tetrafluoridoborate) dihydrate
aDepartment of Chemistry, Virginia Tech, Blacksburg, VA 24061, USA
*Correspondence e-mail: jmerola@vt.edu
The title compound, [Ir2H2O(C3H9P)6](BF4)2·2H2O, was isolated from the reaction between [Ir(COD)(PMe3)3]BF4 and H2 in water (COD is cycloocta-1,5-diene). The consists of one IrIII atom bonded to three PMe3 groups, one hydride ligand and half an oxide ligand, in addition to a BF4− counter-ion and one water molecule of hydration. The single oxide ligand bridging two IrIII atoms is disordered across an inversion center with each O atom having a 50% site occupancy. Each IrIII atom has three PMe3 groups occupying facial positions, with the half-occupancy O atoms, a hydride ligand and an Ir—Ir bond completing the coordination sphere. The Ir—Ir distance is 2.8614 (12) Å, comparable to other iridium(III) metal–metal bonds. Two water molecules hydrogen bond to two BF4− anions in the unit cell.
CCDC reference: 988922
Related literature
For previous work on the aqueous chemistry of Ir(H)2(Cl)(PMe3)3, see: Merola et al. (2012). For the synthesis of [Ir(COD)(PMe3)3]BF4, see: Frazier & Merola (1992). For an Ir—Ir bond bridged only by an oxide, see: McGhee et al. (1988). For Ir—Ir bonds bridged by hydroxide and methoxide ligands, see: Fujita et al. (2000) (CCDC deposition numbers 146417–146418). For an Ir—Ir bond bridged by a phenoxide group, see: Lee et al. (2009) (CCDC deposition number 729562). For an Ir—Ir bond bridged by an oxide and a phenylimido group, see: Dobbs & Bergman (1994) (CCDC deposition number 645882). For a classic discussion of the trans effect and trans influence, see: Hartley (1973). For a description of the Cambridge Crystallographic Database, see: Groom & Allen (2014).
Experimental
Crystal data
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Data collection: XSCANS (Siemens, 1996); cell XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2.
Supporting information
CCDC reference: 988922
10.1107/S160053681400453X/pk2518sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S160053681400453X/pk2518Isup2.hkl
Supporting information file. DOI: 10.1107/S160053681400453X/pk2518Isup3.mol
[Ir(COD)(PMe3)3][BF4] (0.100 g) (Frazier & Merola, 1992) was dissolved in 10 ml of degassed, distilled H2O and heated to reflux while bubbling H2 through the solution. At the end of 2 h reflux, the reaction mixture was a yellow, homogeneous solution. Removal of the solvent under reduced pressure yielded 0.062 g of a yellow powder with complicated NMR spectra indicating the presence of multiple products. Dissolving the yellow powder in water and allowing for the slow evaporation of the solution yielded a few crystals suitable for X-ray diffraction. Screening 3 of the dozen or so crytals all showed the same unit cell.
Trimethylphosphine H atoms were placed at calculated positions and refined using a model in which the H atoms ride on the carbon atom to which it is attached with Uiso(H) = 1.5Ueq(C). The metal hydride hydrogen atoms were placed based on electron density from a difference map, the distance fixed to 1.55 Å and Uiso(H)=1.5Ueq(Ir) but the coordinates were allowed to refine. Hydrogen atoms on water were placed based on hydrogen-bonding vectors, Uiso(H) = 1.5Ueq(O) and the water was treated as a rigid group in refinement.
Data collection: XSCANS (Siemens, 1996); cell
XSCANS (Siemens, 1996); data reduction: XSCANS (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).[Ir2H2O(C3H9P)6](BF4)2·2H2O | Z = 1 |
Mr = 1068.50 | F(000) = 518 |
Triclinic, P1 | Dx = 1.841 Mg m−3 |
a = 9.2686 (19) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 9.6491 (19) Å | Cell parameters from 35 reflections |
c = 11.082 (2) Å | θ = 2–22° |
α = 96.48 (3)° | µ = 7.21 mm−1 |
β = 97.81 (3)° | T = 298 K |
γ = 97.97 (3)° | Prism, clear light yellow |
V = 963.6 (3) Å3 | 0.5 × 0.3 × 0.2 mm |
Siemens P4 diffractometer | 3949 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube, Siemens P4 | Rint = 0.015 |
Graphite monochromator | θmax = 27.5°, θmin = 1.9° |
ω scans | h = 0→12 |
Absorption correction: ψ scan (North et al., 1968) | k = −12→12 |
Tmin = 0.293, Tmax = 0.420 | l = −14→14 |
4707 measured reflections | 3 standard reflections every 300 reflections |
4430 independent reflections | intensity decay: 0.0(1) |
Refinement on F2 | Primary atom site location: heavy-atom method |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.034 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.086 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.10 | w = 1/[σ2(Fo2) + (0.0449P)2 + 1.2979P] where P = (Fo2 + 2Fc2)/3 |
4430 reflections | (Δ/σ)max < 0.001 |
196 parameters | Δρmax = 1.04 e Å−3 |
1 restraint | Δρmin = −1.45 e Å−3 |
[Ir2H2O(C3H9P)6](BF4)2·2H2O | γ = 97.97 (3)° |
Mr = 1068.50 | V = 963.6 (3) Å3 |
Triclinic, P1 | Z = 1 |
a = 9.2686 (19) Å | Mo Kα radiation |
b = 9.6491 (19) Å | µ = 7.21 mm−1 |
c = 11.082 (2) Å | T = 298 K |
α = 96.48 (3)° | 0.5 × 0.3 × 0.2 mm |
β = 97.81 (3)° |
Siemens P4 diffractometer | 3949 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.015 |
Tmin = 0.293, Tmax = 0.420 | 3 standard reflections every 300 reflections |
4707 measured reflections | intensity decay: 0.0(1) |
4430 independent reflections |
R[F2 > 2σ(F2)] = 0.034 | 1 restraint |
wR(F2) = 0.086 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.10 | Δρmax = 1.04 e Å−3 |
4430 reflections | Δρmin = −1.45 e Å−3 |
196 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Ir1 | 0.44635 (2) | 0.39247 (2) | 0.397713 (19) | 0.04330 (8) | |
H | 0.502 (7) | 0.285 (6) | 0.477 (5) | 0.065* | |
P1 | 0.30869 (19) | 0.54619 (17) | 0.29012 (15) | 0.0545 (4) | |
P2 | 0.26109 (19) | 0.20850 (19) | 0.36625 (17) | 0.0573 (4) | |
P3 | 0.5672 (2) | 0.3085 (2) | 0.24848 (19) | 0.0650 (5) | |
O1 | 0.6514 (12) | 0.5458 (12) | 0.4336 (9) | 0.071 (3) | 0.50 |
C11 | 0.1914 (11) | 0.4787 (10) | 0.1441 (8) | 0.091 (3) | |
H11A | 0.2482 | 0.4349 | 0.0888 | 0.137* | |
H11B | 0.1530 | 0.5552 | 0.1092 | 0.137* | |
H11C | 0.1113 | 0.4104 | 0.1572 | 0.137* | |
C12 | 0.4183 (10) | 0.6996 (8) | 0.2485 (7) | 0.077 (2) | |
H12A | 0.4619 | 0.7628 | 0.3215 | 0.115* | |
H12B | 0.3563 | 0.7471 | 0.1960 | 0.115* | |
H12C | 0.4947 | 0.6699 | 0.2059 | 0.115* | |
C13 | 0.1780 (9) | 0.6263 (9) | 0.3741 (8) | 0.076 (2) | |
H13A | 0.1068 | 0.5534 | 0.3938 | 0.114* | |
H13B | 0.1284 | 0.6857 | 0.3241 | 0.114* | |
H13C | 0.2300 | 0.6819 | 0.4486 | 0.114* | |
C21 | 0.2986 (10) | 0.0608 (9) | 0.4459 (10) | 0.089 (3) | |
H21A | 0.3734 | 0.0170 | 0.4114 | 0.133* | |
H21B | 0.2101 | −0.0068 | 0.4370 | 0.133* | |
H21C | 0.3321 | 0.0936 | 0.5315 | 0.133* | |
C22 | 0.0959 (11) | 0.2463 (12) | 0.4220 (15) | 0.133 (5) | |
H22A | 0.1169 | 0.2749 | 0.5092 | 0.200* | |
H22B | 0.0224 | 0.1633 | 0.4043 | 0.200* | |
H22C | 0.0600 | 0.3210 | 0.3823 | 0.200* | |
C23 | 0.1925 (15) | 0.1187 (14) | 0.2126 (10) | 0.153 (6) | |
H23A | 0.1346 | 0.1767 | 0.1678 | 0.230* | |
H23B | 0.1325 | 0.0306 | 0.2172 | 0.230* | |
H23C | 0.2741 | 0.1012 | 0.1713 | 0.230* | |
C31 | 0.6143 (17) | 0.1367 (12) | 0.2590 (11) | 0.136 (6) | |
H31A | 0.6139 | 0.1158 | 0.3416 | 0.203* | |
H31B | 0.7107 | 0.1338 | 0.2372 | 0.203* | |
H31C | 0.5435 | 0.0681 | 0.2038 | 0.203* | |
C32 | 0.7546 (11) | 0.4063 (16) | 0.2693 (13) | 0.139 (5) | |
H32A | 0.7517 | 0.5056 | 0.2861 | 0.208* | |
H32B | 0.7968 | 0.3878 | 0.1958 | 0.208* | |
H32C | 0.8137 | 0.3769 | 0.3369 | 0.208* | |
C33 | 0.5107 (14) | 0.3194 (16) | 0.0923 (9) | 0.129 (5) | |
H33A | 0.4247 | 0.2506 | 0.0615 | 0.194* | |
H33B | 0.5886 | 0.3015 | 0.0466 | 0.194* | |
H33C | 0.4881 | 0.4122 | 0.0834 | 0.194* | |
F1 | 0.1765 (12) | 0.0878 (10) | 0.8932 (9) | 0.183 (4) | |
F2 | 0.0995 (18) | 0.1122 (13) | 0.7112 (9) | 0.239 (6) | |
F3 | 0.2533 (12) | 0.2732 (13) | 0.8167 (16) | 0.276 (8) | |
F4 | 0.0302 (11) | 0.2307 (12) | 0.8445 (11) | 0.195 (5) | |
B1 | 0.1475 (12) | 0.1797 (12) | 0.8151 (11) | 0.082 (3) | |
O2 | 0.8397 (15) | 0.1785 (12) | 0.0159 (12) | 0.152 (4) | |
H2A | 0.8300 | 0.0897 | 0.0167 | 0.227* | |
H2B | 0.9030 | 0.2028 | −0.0295 | 0.227* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ir1 | 0.04201 (12) | 0.03886 (12) | 0.04581 (13) | 0.01001 (8) | −0.00422 (8) | 0.00061 (8) |
P1 | 0.0565 (9) | 0.0488 (8) | 0.0551 (9) | 0.0168 (7) | −0.0087 (7) | 0.0040 (7) |
P2 | 0.0473 (8) | 0.0595 (9) | 0.0631 (10) | 0.0015 (7) | 0.0047 (7) | 0.0133 (8) |
P3 | 0.0593 (10) | 0.0768 (12) | 0.0724 (11) | 0.0272 (9) | 0.0252 (9) | 0.0294 (9) |
O1 | 0.073 (6) | 0.078 (7) | 0.054 (5) | 0.013 (5) | −0.004 (5) | −0.001 (5) |
C11 | 0.091 (6) | 0.092 (6) | 0.080 (5) | 0.032 (5) | −0.034 (5) | −0.003 (5) |
C12 | 0.087 (6) | 0.072 (5) | 0.069 (5) | 0.014 (4) | −0.005 (4) | 0.019 (4) |
C13 | 0.061 (4) | 0.081 (5) | 0.088 (5) | 0.033 (4) | 0.000 (4) | 0.008 (4) |
C21 | 0.083 (6) | 0.062 (5) | 0.122 (8) | 0.005 (4) | 0.009 (5) | 0.031 (5) |
C22 | 0.069 (6) | 0.111 (8) | 0.252 (17) | 0.032 (6) | 0.075 (8) | 0.078 (10) |
C23 | 0.159 (12) | 0.161 (11) | 0.088 (7) | −0.101 (10) | −0.029 (7) | 0.012 (7) |
C31 | 0.215 (15) | 0.115 (8) | 0.129 (9) | 0.105 (10) | 0.103 (10) | 0.044 (7) |
C32 | 0.065 (6) | 0.221 (16) | 0.147 (11) | 0.021 (8) | 0.041 (7) | 0.066 (11) |
C33 | 0.139 (10) | 0.215 (14) | 0.064 (5) | 0.094 (10) | 0.036 (6) | 0.040 (7) |
F1 | 0.223 (10) | 0.145 (7) | 0.182 (8) | 0.062 (7) | −0.027 (7) | 0.050 (6) |
F2 | 0.349 (18) | 0.228 (12) | 0.105 (6) | −0.025 (12) | 0.014 (8) | −0.015 (7) |
F3 | 0.136 (8) | 0.222 (12) | 0.46 (2) | −0.071 (8) | 0.055 (11) | 0.102 (14) |
F4 | 0.173 (8) | 0.227 (11) | 0.245 (11) | 0.118 (8) | 0.097 (8) | 0.110 (9) |
B1 | 0.077 (6) | 0.080 (6) | 0.086 (7) | 0.003 (5) | 0.013 (5) | 0.003 (5) |
O2 | 0.179 (10) | 0.139 (8) | 0.165 (9) | 0.073 (8) | 0.071 (7) | 0.027 (7) |
Ir1—Ir1i | 2.8614 (12) | C13—H13C | 0.9600 |
Ir1—H | 1.53 (2) | C21—H21A | 0.9600 |
Ir1—P1 | 2.4000 (17) | C21—H21B | 0.9600 |
Ir1—P2 | 2.2524 (19) | C21—H21C | 0.9600 |
Ir1—P3 | 2.258 (2) | C22—H22A | 0.9600 |
Ir1—O1i | 2.242 (10) | C22—H22B | 0.9600 |
Ir1—O1 | 2.200 (11) | C22—H22C | 0.9600 |
P1—C11 | 1.820 (8) | C23—H23A | 0.9600 |
P1—C12 | 1.817 (8) | C23—H23B | 0.9600 |
P1—C13 | 1.827 (8) | C23—H23C | 0.9600 |
P2—C21 | 1.808 (8) | C31—H31A | 0.9600 |
P2—C22 | 1.794 (9) | C31—H31B | 0.9600 |
P2—C23 | 1.809 (11) | C31—H31C | 0.9600 |
P3—C31 | 1.784 (9) | C32—H32A | 0.9600 |
P3—C32 | 1.830 (11) | C32—H32B | 0.9600 |
P3—C33 | 1.759 (10) | C32—H32C | 0.9600 |
O1—Ir1i | 2.242 (10) | C33—H33A | 0.9600 |
C11—H11A | 0.9600 | C33—H33B | 0.9600 |
C11—H11B | 0.9600 | C33—H33C | 0.9600 |
C11—H11C | 0.9600 | F1—B1 | 1.336 (14) |
C12—H12A | 0.9600 | F2—B1 | 1.249 (14) |
C12—H12B | 0.9600 | F3—B1 | 1.234 (13) |
C12—H12C | 0.9600 | F4—B1 | 1.318 (13) |
C13—H13A | 0.9600 | O2—H2A | 0.8500 |
C13—H13B | 0.9600 | O2—H2B | 0.8499 |
Ir1i—Ir1—H | 88 (3) | H12B—C12—H12C | 109.5 |
P1—Ir1—Ir1i | 92.32 (5) | P1—C13—H13A | 109.5 |
P1—Ir1—H | 167 (3) | P1—C13—H13B | 109.5 |
P2—Ir1—Ir1i | 132.22 (5) | P1—C13—H13C | 109.5 |
P2—Ir1—H | 75 (3) | H13A—C13—H13B | 109.5 |
P2—Ir1—P1 | 95.38 (7) | H13A—C13—H13C | 109.5 |
P2—Ir1—P3 | 95.89 (8) | H13B—C13—H13C | 109.5 |
P3—Ir1—Ir1i | 128.86 (6) | P2—C21—H21A | 109.5 |
P3—Ir1—H | 89 (3) | P2—C21—H21B | 109.5 |
P3—Ir1—P1 | 100.31 (7) | P2—C21—H21C | 109.5 |
O1—Ir1—Ir1i | 50.6 (3) | H21A—C21—H21B | 109.5 |
O1i—Ir1—Ir1i | 49.2 (3) | H21A—C21—H21C | 109.5 |
O1i—Ir1—H | 81 (3) | H21B—C21—H21C | 109.5 |
O1—Ir1—H | 97 (3) | P2—C22—H22A | 109.5 |
O1—Ir1—P1 | 93.5 (3) | P2—C22—H22B | 109.5 |
O1i—Ir1—P1 | 89.5 (3) | P2—C22—H22C | 109.5 |
O1—Ir1—P2 | 170.5 (3) | H22A—C22—H22B | 109.5 |
O1i—Ir1—P2 | 83.7 (3) | H22A—C22—H22C | 109.5 |
O1i—Ir1—P3 | 170.2 (3) | H22B—C22—H22C | 109.5 |
O1—Ir1—P3 | 79.2 (3) | P2—C23—H23A | 109.5 |
O1—Ir1—O1i | 99.8 (4) | P2—C23—H23B | 109.5 |
C11—P1—Ir1 | 120.0 (3) | P2—C23—H23C | 109.5 |
C11—P1—C13 | 100.5 (4) | H23A—C23—H23B | 109.5 |
C12—P1—Ir1 | 115.3 (3) | H23A—C23—H23C | 109.5 |
C12—P1—C11 | 100.7 (4) | H23B—C23—H23C | 109.5 |
C12—P1—C13 | 102.1 (4) | P3—C31—H31A | 109.5 |
C13—P1—Ir1 | 115.4 (3) | P3—C31—H31B | 109.5 |
C21—P2—Ir1 | 114.9 (3) | P3—C31—H31C | 109.5 |
C21—P2—C23 | 100.6 (6) | H31A—C31—H31B | 109.5 |
C22—P2—Ir1 | 114.6 (4) | H31A—C31—H31C | 109.5 |
C22—P2—C21 | 100.8 (5) | H31B—C31—H31C | 109.5 |
C22—P2—C23 | 102.8 (7) | P3—C32—H32A | 109.5 |
C23—P2—Ir1 | 120.3 (4) | P3—C32—H32B | 109.5 |
C31—P3—Ir1 | 115.4 (3) | P3—C32—H32C | 109.5 |
C31—P3—C32 | 97.9 (7) | H32A—C32—H32B | 109.5 |
C32—P3—Ir1 | 109.8 (5) | H32A—C32—H32C | 109.5 |
C33—P3—Ir1 | 122.3 (4) | H32B—C32—H32C | 109.5 |
C33—P3—C31 | 107.5 (6) | P3—C33—H33A | 109.5 |
C33—P3—C32 | 100.0 (6) | P3—C33—H33B | 109.5 |
Ir1—O1—Ir1i | 80.2 (4) | P3—C33—H33C | 109.5 |
P1—C11—H11A | 109.5 | H33A—C33—H33B | 109.5 |
P1—C11—H11B | 109.5 | H33A—C33—H33C | 109.5 |
P1—C11—H11C | 109.5 | H33B—C33—H33C | 109.5 |
H11A—C11—H11B | 109.5 | F2—B1—F1 | 108.4 (11) |
H11A—C11—H11C | 109.5 | F2—B1—F4 | 102.0 (12) |
H11B—C11—H11C | 109.5 | F3—B1—F1 | 112.7 (12) |
P1—C12—H12A | 109.5 | F3—B1—F2 | 114.0 (13) |
P1—C12—H12B | 109.5 | F3—B1—F4 | 112.5 (12) |
P1—C12—H12C | 109.5 | F4—B1—F1 | 106.4 (10) |
H12A—C12—H12B | 109.5 | H2A—O2—H2B | 109.5 |
H12A—C12—H12C | 109.5 | ||
Ir1i—Ir1—P1—C11 | −176.0 (4) | P2—Ir1—P3—C33 | 78.6 (6) |
Ir1i—Ir1—P1—C12 | 63.3 (3) | P3—Ir1—P1—C11 | 53.8 (4) |
Ir1i—Ir1—P1—C13 | −55.5 (3) | P3—Ir1—P1—C12 | −66.9 (3) |
Ir1i—Ir1—P2—C21 | −75.3 (4) | P3—Ir1—P1—C13 | 174.3 (3) |
Ir1i—Ir1—P2—C22 | 40.9 (5) | P3—Ir1—P2—C21 | 85.6 (4) |
Ir1i—Ir1—P2—C23 | 164.2 (7) | P3—Ir1—P2—C22 | −158.2 (5) |
Ir1i—Ir1—P3—C31 | 106.5 (6) | P3—Ir1—P2—C23 | −34.8 (7) |
Ir1i—Ir1—P3—C32 | −2.9 (5) | P3—Ir1—O1—Ir1i | −170.1 (3) |
Ir1i—Ir1—P3—C33 | −119.5 (6) | O1—Ir1—P1—C11 | 133.4 (5) |
P1—Ir1—P2—C21 | −173.4 (4) | O1i—Ir1—P1—C11 | −126.8 (5) |
P1—Ir1—P2—C22 | −57.2 (5) | O1i—Ir1—P1—C12 | 112.5 (4) |
P1—Ir1—P2—C23 | 66.2 (7) | O1—Ir1—P1—C12 | 12.7 (4) |
P1—Ir1—P3—C31 | −152.0 (6) | O1i—Ir1—P1—C13 | −6.3 (4) |
P1—Ir1—P3—C32 | 98.6 (5) | O1—Ir1—P1—C13 | −106.1 (4) |
P1—Ir1—P3—C33 | −18.0 (6) | O1i—Ir1—P2—C21 | −84.5 (5) |
P1—Ir1—O1—Ir1i | 90.1 (2) | O1i—Ir1—P2—C22 | 31.7 (6) |
P2—Ir1—P1—C11 | −43.2 (4) | O1i—Ir1—P2—C23 | 155.1 (7) |
P2—Ir1—P1—C12 | −163.9 (3) | O1—Ir1—P3—C31 | 116.3 (7) |
P2—Ir1—P1—C13 | 77.3 (3) | O1—Ir1—P3—C32 | 6.9 (5) |
P2—Ir1—P3—C31 | −55.4 (6) | O1—Ir1—P3—C33 | −109.6 (7) |
P2—Ir1—P3—C32 | −164.9 (5) | O1i—Ir1—O1—Ir1i | 0.0 |
Symmetry code: (i) −x+1, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2A···F1ii | 0.85 | 2.08 | 2.856 (15) | 152 |
O2—H2B···F4iii | 0.85 | 1.96 | 2.804 (18) | 170 |
Symmetry codes: (ii) −x+1, −y, −z+1; (iii) x+1, y, z−1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2A···F1i | 0.85 | 2.08 | 2.856 (15) | 152 |
O2—H2B···F4ii | 0.85 | 1.96 | 2.804 (18) | 170 |
Symmetry codes: (i) −x+1, −y, −z+1; (ii) x+1, y, z−1. |
Acknowledgements
Financial support for this work was provided by ACS–PRF (grant No. 23961-C1) and by the National Science Foundation (grant No. CHE-902244). The Virginia Tech Subvention Fund is gratefully acknowledged for covering the open-access fee.
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Our studies of the aqueous catalysis of iridium trimethylphosphine complexes led us to a detailed study of the solution behavior and catalytic chemistry of H2Ir(PMe3)3Cl in water (Merola et al., 2012). H2Ir(PMe3)3Cl is formed by the reaction between [Ir(COD)(PMe3)3]Cl and H2 in water (COD = 1,5-cyclooctadiene). The reaction of H2 with [Ir(COD)(PMe3)3][BF4] (Frazier & Merola, 1992) was investigated to see how a poorly coordinating anion will affect that system. The reaction of hydrogen gas with the BF4- salt did not lead to a clean product, but to a yellow solid that, according to its 1H NMR spectrum, is a very complex mixture of products. The hydride region of the spectrum was particularly complicated with many hydride resonances from δ -10 to -40 p.p.m.. Slow cooling of an aqueous solution of the reaction mixture produced a few crystals suitable for X-ray diffraction. The title compound is a dinuclear iridium complex with an iridium—iridium bond bridged by a single oxo bridge. Iridium hydride hydrogen atoms were located via a difference map and set at a fixed Ir—H distance of 1.55 Å with Uiso set at 1.5 the Ueq of iridium. The oxo bridge is disordered about the inversion center. The Ir—P bond distances are 2.2524 (19), 2.258 (2), and 2.4001 (17) Å with the longer bond length for P trans to H which has a large trans influence (Hartley, 1973). The dinuclear iridium fragment is a dication charge balanced by two BF4- ions that show the large thermal ellipsoids common for fluorinated anions. There are two waters of hydration in the crystal lattice that are hydrogen-bonded to the BF4- ions.
There were some issues with making correct assignments for the title compound in the absence of clear spectral identification. One must be cautious in the assignment of hydrogen attached to a heavy metal such as iridium, but the presence of iridium hydrides is consistent with one set of resonances found in the 1H NMR spectrum at δ -11 p.p.m. as a doublet of triplets due to coupling to the hydrogen from one trans P atom (larger doublet coupling) and two cis P atoms (smaller triplet coupling). The larger Ir—P bond distance for one of the PMe3 ligands is also consistent with a hydride ligand situated trans to it. That the bridging ligand is a single oxo bridge may be inferred by the fact that the iridium fragment is a dication - two oxo bridges would make the fragment neutral. Attempts were made to solve and refine the structure in P1 to try and resolve the issue of the disordered oxo group, but working in P1 led to a significantly poorer structure model. In addition, models with bridging hydroxides were attempted and also found to be unsatisfactory.
There are 783 structures in the CSD with Ir—Ir bonds, but when limited to those also bridged by oxygen, there are only 6 entries (Groom & Allen, 2014). Two of the structures contained bridging hydroxide and methoxide (Fujita et al., 2000) with Ir—Ir distances of 2.953 (1) and 2.933 (4) Å respectively. An Ir—Ir bond bridged by a phenoxide ligand had an Ir—Ir distance of 2.902 (4) Å (Lee et al., 2009). An Ir—Ir bond with a bridging oxide with no other bridging ligand displayed an Ir—Ir bond of 2.6172 (4) Å (McGhee et al., 1988) and two iridium atoms bridged with both an oxide and a phenylimido ligand showed an Ir—Ir distance of 2.7220 (2) Å (Dobbs & Bergman, 1994). The Ir—Ir distance in the title compound of 2.8614 (12) Å is consistent with a single metal-metal bond bridged by an oxide rather than an alkoxide or hydroxide.