Binuclear platinum diphosphite complexes. Crystal structures of K4[Pt2(pop)4Br]·3H2O, a new linear chain semiconductor, and K4[Pt2(pop)4Cl2]·2H2O

Abstract

The structures of crystals of K4[Pt2(pop)4Br]·3H2O (pop = (HO2P)2O2-), "Pt2Br", and K4[Pt2(pop)4Cl2]·2H2O, "Pt2Cl2", have been determined. The structure of "Pt2Br" features a symmetric Pt-Br-Pt unit in an infinite linear chain (Pt-Pt-Br-Pt-Pt-Br-; σ∥ = ∼10-4-10-3 Ω-1 cm-1) with d(Pt-Pt) = 2.793 (1) and d(Pt-Br) = 2.699 (1) Å; "Pt2Cl2" is a discrete binuclear ion, with d(Pt-Pt) = 2.695 (1) and d(Pt-Cl) = 2.407 (2) Å. Both Pt-Pt distances are shorter than those (2.925 (1) Å) in K4[Pt2(pop)4]·2H2O, "Pt2"; the order d("Pt2") > d ("Pt2Br") > d("Pt2Cl2") accords with an electronic structural model in which "Pt2" is (dσ)2(dσ*)2 "Pt2Br" is (dσ)2 (dσ*)1, and "Pt2Cl2" is (dσ)2. © 1983 American Chemical Society.