(2-Pyridyloxy)arsines as ligands in transition metal chemistry: a stepwise As(iii) → As(ii) → As(i) reduction

Abstract

Neutral inherently tri- and tetradentate ligands of the type Ph_3−xAs(PyO)_x (x = 2 (1), 3 (2)) have been synthesized and characterized. Reaction of 1 with [RuCl₂(PPh₃)₃] affords complex [PhAs(μ-PyO)₂RuCl₂(PPh₃)] (3), whereas 2 and [RuCl₂(PPh₃)₃] react with formation of [As(μ-PyO)₂RuCl(PPh₃)₂] (5) and [Ph₃P(PyO)]Cl (6). Treatment of complex 5 with [AuCl(tht)] (tht = tetrahydrothiophene) results in liberation of tht and formation of [AuCl(As(PyO)₂)RuCl(PPh₃)₂] (7), featuring an (Au–As–Ru) core. For compounds 3, 5, and 7 the As–Ru and As–Au bond situation has been investigated using NBO, AIM and ELF analysis, allowing the assignment of pronounced canonical forms of σ-(As^III→Ru^II) to 3, σ-(As^II–Ru^I) to 5 and σ-(Au^I←As^I→Ru^II) to 7.