Synthesis, molecular structures and ESI-mass studies of copper(I) complexes with ligands incorporating N, S and P donor atoms

Abstract

Equimolar reaction of copper(I) bromide with 2-thiouracil (tucH2) in acetonitrile-methanol formed a light yellow solid which on subsequent treatment with a mole of triphenyl phosphine (PPh3) in chloroform has yielded a sulfur-bridged dinuclear complex, [Cu2Br2(μ-S-tucH2)2(PPh3)2] ⋅2CHCl3 1. A reaction of copper(I) bromide with two moles of 2,4-dithiouracil (dtucH2) in acetonitrile-methanol followed by addition of two moles of PPh3, designed to form [Cu(μ-S,S-dtuc)2(PPh3)4Cu] 2a, instead resulted in the formation of previously reported polymer, {CuBr(μ-S,S-dtucH2)(PPh3)}n 2. Reaction of copper(I) iodide with 2-thiouracil (tucH2) and PPh3 in 1:1:2 molar ratio (Cu:H2tuc:PPh3) as well as that of copper(I) thiocyanate with pyridine-2-thione (pySH) or pyrimidine-2-thione (pymSH) and PPh3 in similar ratio, yielded an iodo-bridged unsymmetrical dimer, [(PPh3)2(μ-I)2Cu(PPh3)] 3 and thiocyanate bridged symmetrical dimer, [(PPh3)2Cu(μ-N,S- SCN)2Cu(PPh3)2] 4, respectively. In both the latter reactions, thio-ligands which initially bind to Cu metal center, are de-ligated by PPh3 ligand. Crystal data: 1, P21/c: 173(2) K, monoclinic, a, 13.4900(6); b, 17.1639(5); c, 12.1860(5) Å; β, 111.807(5) ∘; R, 5.10%; 2, Pbca: 296(2) K, orthorhombic, a, 10.859(3); b, 17.718(4); c, 23.713(6) Å; α=β=γ, 90 ∘; R, 4.60%; 3, P21: 173(2) K, monoclinic, a, 10.4208(7); b, 20.6402(12); c, 11.7260(7) Å; β, 105.601(7)∘; R, 3.97%; 4, P-1: 173(2) K, triclinic, a, 10.2035(4); b, 13.0192(5); c, 13.3586(6) Å; α, 114.856(4); β, 92.872(4)∘; γ, 100.720(4)∘; R, 3.71%. ESI-mass studies reveal different fragments of complexes. Sulfur-bridged dimer [Cu2Br2(μ-S-tucH2)2(PPh3)2]·2CHCl3 1 is the first example of a dinuclear complex of 2-thiouracil/ 2,4-dithiouracil class of ligands.