Steric Modification of Metal-Phosphorus Bond Lengths: the Preparation, Characterization and Crystal Structures of mer-trans-(PPri3)2(PMe2Ph)Cl-cis-H2IrIII and mer-trans-(PPri3)2(PMe2Ph)H3IrIII

Article abstract of DOI:10.1071/CH9951183

The syntheses and subsequent characterization of the complexes mer-trans-(PPrⁱ3)2(PMe2Ph)-Cl-cis-H2Ir^III (1) and mer-trans-(PPrⁱ3)2(PMe2Ph)H3Ir^III (2) by n.m.r. and by low temperature (153+/-5 K) X-ray diffraction analyses are reported.Crystals of (1) are monoclinic, space group P2₁/c with a 19.277(2), b 9.020(1), c 17.657(2) Angstroem, β 101.40(1) deg and Z 4.Crystals of (2) are orthorhombic, space group P2₁2₁2₁, with a 19.373(3), b 18.724(2), c 8.113(1) Angstroem and Z 4.Full-matrix least-squares analyses converged with R = 0.027 and wR = 0.031 for (1) (3243 reflections), and R = 0.030 and wR = 0.038 for (2) (2892 reflections).Consistent with previous observation, the unit increase in chloride content (in place of hydride) in (1) is accompanied by a global lengthening of 0.036 Angstroem (av.) in the Ir-P bond lenghts cf. those in (2).Also, because of increased steric crowding (two PPrⁱ3 ligands in place of two PMe2Ph), the Ir-PMe2Ph bond in (1) is 0.019(2) Angstroem longer than the chemically equivalent bond in mer-(PMe2Ph)3Cl-cis-H2Ir^III.In previously reported complexes in this series metrically similar increases in Ir-PMe2Ph distances result from the replacement of just one PMe2Ph ligand by PPrⁱ3.