Rhenium(V) oxide complexes. Crystal and molecular structures of ReOI 2(PPh 3) 2(OReO 3) and of ReOI 2(PPh 3)(OPPh 3)(OReO 3)·0.5C 6H 6 obtained from the reaction of ReO 2I(PPh 3) 2 with oxygen

Abstract

The oxygenation reaction of the five-coordinated violet species ReO 2I(PPh 3) 2 leads to isolation of two crystalline compounds, both characterized by X-ray diffraction analysis: the dark-red ReOI 2(PPh 3) 2(OReO 3) (1), which is the main product, and the yellow ReOI 2(PPh 3)(OPPh 3)(OReO 3)·0.5C 6H 6 (2). Compound 1 gives monoclinic crystals, space group C2/ c, with a = 25.033(8), b = 16.944(5), c = 19.495(8) Å, β = 116.13(3)°, Z = 8. Compound 2 is monoclinic, space group P 1/ n, with a = 9.498(4), b = 25.048(8), c = 17.148(5) Å, β = 92.47(3)°, Z = 4. The structures of 1 and 2 were solved by Patterson and Fourier methods and refined by full-matrix least-squares, on the basis of 4229 ( 1) and 2672 ( 2) significant counter data ( I > 3σ( I)), respectively. The final values of the conventional agreement indices R and R w were 0.050 and 0.070 ( 1) and 0.033 and 0.039 (2), respectively. Both species contain a previously unexpected coordinated perrhenato ligand. The geometry of the two complexes is distorted octahedral: compound 1 contains two trans phosphine ligands (mean ReP= 2.513 Å) and two trans iodides (mean ReI 2.730 Å), the other two trans coordination sites being occupied by the oxide (ReO = 1.670(7) Å) and the perrhenate. Compound 2 shows a similar coordination geometry, with one of the phosphine ligands replaced by a phosphine oxide. The main bond parameters in 2 are: ReP 2.453(4) Å, ReI (mean) 2.727 Å, ReO(OPPh 3) 2.075(9) Å, ReO (oxide) 1.639(9) Å. The interactions Re(V)-perrhenate are similar in the two complexes, with Re(V)O bonds of 2.031(6) Å ( 1) and 2.079(9) Å ( 2). The ReORe angles show some difference: 164.3(4)° ( 1) and 153.5(5)° ( 2). Within the perrhenates, the ReO bond involving the bridging oxygen atom is somewhat longer than the other ReO bonds.