Tetra-nuclear copper complex having P-N-P ligand to P-O-P ligand - synthesis, structural, and mechanistic studies

摘要

Tetra-nuclear copper(I) complexes, [Cu_4(μ_3-Cl)_2(μ_2-Cl)_2{μ_2-(2,6-Me_2C_6H_3N(PPh_2)_2)}_2] (2), were obtained from [2,6-Me_2C_6H_3N(PPh_2)_2)] (1) and copper(I) chloride in the presence of triphenylphos-phine. The mixed cobalt(II)/(III) complex [(CoCl_2){μ_2-(2,6-Me_2C_6H_3N(PPh_2)_2)}_2][CoCl_3NH_2(2,6-Me_2Ph)] (3) was obtained by the analogous reaction of 1 and CoCl_2 in methanol. We report the synthesis and structures of three copper(I) complexes, [Cu_4(μ_3-Cl)_2(μ_2-Cl)_2{μ_2-(2,6-Me_2C_6H_3N(PPh_2)_2)}_2] (2), [Cu_4(μ_3-Cl)_2(μ_2-Cl)_2{μ_2-(Ph_2(PPh_2)}_2] (4), and [Cu_2(μ_2-Cl)_2(μ_2-PPh_2OPPh_2)(η~1-Ph_2PP(=O)Ph_2)(PPh_3)] (5), and one cobalt complex, [(CoCl_2){μ_2-2,6-Me_2C_6H_3N (PPh_2)_2}_2][CoCl_3NH_2(2,6-Me_2Ph)] (3). Tetra-nuclear copper complex 2 was prepared in good yield by the reaction of bis(diphenylphosphino)-2,6-dimethylaniline [2,6-Me_2C_6H_3N(PPh_2)_2] (1) with cop-per(I) chloride along with triphenylphosphine in methanol. Adding a calculated amount of water and dichloromethane mixture (1 : 10) to 2 produced a second tetra-nuclear copper(I) complex, 4, with a P-O-P backbone, along with a small amount of the unsymmetrical copper(I) complex 5. The cobalt complex 3 was obtained by reaction of 1 with cobalt(II) chloride. The solid-state structures of 2-5 were established by single-crystal X-ray diffraction analysis. In the solid state, both 2 and 4 form a tetra-nuclear copper core. In the ~(31)P{~1H} NMR study, we observed the conversion of 2, with P-N-P backbone, to 4, with P-O-P backbone.