Crystal structures of mercury(II) chloride and bromide addition complexes of carbonylchlorobis(triphenylphosphine)iridium(I)

Abstract

The crystal structures of the oxidative-addition products of trans-[IrCl(CO)(PPh3)2] with HgCl2 and HgBr2 have been determined by X-ray diffraction. The structure of [IrCl2(HgCl) (CO)(PPh3)2] was refined by least squares to R 0.059 (3 430 observed reflections). Crystals are monoclinic, space group P21/n, a = 15.805(2), b = 21.734(3), c = 10.537(1) Å, β = 92.13(2)°, Z = 4. The two chlorines bonded to the pseudo-octahedral iridium are mutually cis [Ir-Cl, 2.453(5), 2.401 (4) Å]. while the two PPh3 ligands are trans [Ir-P, 2.387(4), 2.378(4) Å], with the HgCl group trans to the Ir-Cl bond [Ir-Hg, 2.570(1) Å]. The mercury atom lies close to a centre of symmetry and Ir-Hg-Cl is slightly perturbed from linearity by interaction of Hg with the chlorine of its inversion image [Hg-Cl, 2.366(5), Hg ⋯ Cl′, 3.148(5) Å; Ir-Hg-Cl, 172.2(1)°]. The structure of the isomorphous [IrBrCl(HgBr)(CO)(PPh3)2] [a = 16.021(7), b = 21.788(6), c = 10.568(4) Å, β = 93.11(3)°] indicates that the oxidative-addition reaction is predominantly trans in this instance: the partial bromine occupancy of the equatorial chlorine site is ca. 0.15; R was 0.072 for 3 810 observed reflections. Show more