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

• Published in: Journal of coordination chemistry 2014-09, Vol.67 (18), p.3042-3053
• Main Authors: Naktode, Kishor, Kottalanka, Ravi K., Adimulam, Harinath, Panda, Tarun K.
• Format: Article
• Language: English
• Subjects: Backbone; Chlorides; Cobalt; Coordination compounds; Copper; Copper(I); Diffraction; Ligands; Methyl alcohol; P-N-P ligand; P-O-P ligand; P-P bond; Synthesis; tetra-nuclear
• ISSN: 0095-8972; 1029-0389
• DOI: 10.1080/00958972.2014.953071

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 2 C 6 H 3 N(PPh 2 ) 2 )} 2 ] (2), [Cu 4 (μ 3 -Cl) 2 (μ 2 -Cl) 2 {μ 2 -(Ph 2 POPPh 2 )} 2 ] (4), and [Cu 2 (μ 2 -Cl) 2 (μ 2 -PPh 2 OPPh 2 )(η 1 -Ph 2 PP(=O)Ph 2 )(PPh 3 )] (5), and one cobalt complex, [(CoCl 2 ){μ 2 -2,6-Me 2 C 6 H 3 N(PPh 2 ) 2 } 2 ][CoCl 3 NH 2 (2,6-Me 2 Ph)] (3). Tetra-nuclear copper complex 2 was prepared in good yield by the reaction of bis(diphenylphosphino)-2,6-dimethylaniline [2,6-Me 2 C 6 H 3 N(PPh 2 ) 2 ] (1) with copper(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{ 1 H} NMR study, we observed the conversion of 2, with P-N-P backbone, to 4, with P-O-P backbone. Tetra-nuclear copper(I) complexes, [Cu 4 (μ 3 -Cl) 2 (μ 2 -Cl) 2 {μ 2 -(2,6-Me 2 C 6 H 3 N(PPh 2 ) 2 )} 2 ] (2), were obtained from [2,6-Me 2 C 6 H 3 N(PPh 2 ) 2 ] (1) and copper(I) chloride in the presence of triphenylphosphine. The mixed cobalt(II)/(III) complex [(CoCl 2 ){μ 2 -2,6-Me 2 C 6 H 3 N(PPh 2 ) 2 } 2 ][CoCl 3 NH 2 (2,6-Me 2 Ph)] (3) was obtained by the analogous reaction of 1 and CoCl 2 in methanol.