Metal–thiosemicarbazone interactions. Synthesis of an iodo-bridged dinuclear [diiodobis(pyrrole-2-carbaldehydethiosemicarbazone)dicopper(I)] complex

Abstract

Reaction of copper(I) iodide with pyrrole-2-carbaldehydethiosemicarbazone (Hptsc) in a 1:1 mole ratio in MeCN, followed by addition of one mole of Ph3P, yielded a complex of empirical formula, CuI(Hptsc)(Ph3P), whose X-ray structure determination has shown that it exists as an iodo-bridged dinuclear copper(I) complex, [Cu2(μ-I)2(μ1-S-Hptsc)2(PPh3)2](1). The central kernel, Cu(μ-I)2Cu forms a parallelogram with unequal Cu—I distances {Cu—I, 2.644(2), 2.707(2)A} and bond angles {Cu—I—Cu, 70.72(7), I—Cu—I, 109.28(7)°}. Each Cu atom is further bonded to one S atom of Hptsc and one P atom of Ph3P, thus completing tetracoordination. The Cu...Cu⋆ separation of 3.097(4)A is close to the sum of the van der Waals radius of the Cu atom, 2.80 A. Compound (1) involves relatively strong inter-dimer hydrogen bonding via hydrazinic and pyrrole ring hydrogens with sulfur and iodine atoms respectively of the adjacent dimer {N(1)H...S#2, 2.50 A; N(4)H...I#3, 2.91 A}. The complex represents the first report of a copper(I) dimer with a thiosemicarbazone.