The Influence of Substituents at C2 Carbon of Thiosemicarbazones on the Bonding Pattern of Bis(diphenylphopshano)alkanes in Palladium(II) Complexes

Abstract

AbstractReactions of trans‐PdCl2(PPh3)2 with acetone thiosemicarbazone (Hactsc) and benzaldehyde thiosemicarbazone (Hbtsc) in a 1:1 molar ratio in the presence of Et3N yielded the neutral complexes [Pd(η2‐N3,S‐actsc)(PPh3)Cl] (1) and [Pd(η2‐N3,S‐btsc)(PPh3)Cl] (2) respectively. In contrast, reactions of cis‐PdCl2(dppe) (dppe = bis(diphenylphosphanyl)ethane) and cis‐PdCl2(dppp) (dppp = bis(diphenylphosphanyl)propane) with Hbtsc gave the ionic complexes [Pd(η2‐N2,S‐btsc)(η2‐dppe)]Cl (3) and [Pd(η2‐N3,S‐btsc)(η2‐dppp)]Cl (4) because of the chelation effect. The reaction of salicylaldehyde thiosemicarbazone (H2stsc) with cis‐PdCl2(dppm) (dppm = bis(diphenylphosphanyl)methane)and cis‐PdCl2(dppp) yielded the dinuclear complexes [Pd2(η3‐O,N3,S‐stsc)2(μ‐dppm)] (5) and [Pd2(η3‐O,N3,S‐stsc)2(μ‐dppp)] (6). Complexes 1–6 were characterized with spectroscopic techniques [IR, 1H, 31P{1H} NMR], and single‐crystal X‐ray crystallography. The ligands are negative bidentate in complexes 1–4 and dinegative tridentate (O, N3, S) in complexes 5 and 6. Diphosphanes exhibited both chelating (η2; 3, 4) as well as bridging (μ; 5, 6) modes.