Structural Diversity and Rare η 1 Cu-C Interactions in Cu I Complexes of 1,2,3-Triazole-Functionalized Bisphosphines.

This manuscript describes the synthesis of copper complexes of 1,2,3-triazolyl-phosphines: o -Ph 2 P(C 6 H 4 ){1,2,3-N 3 CC 6 H 5 )C(PPh 2 )} ( L1 ), (C 6 H 5 ){1,2,3-N 3 C(C 6 H 4 ( o -PPh 2 ))-C(PPh 2 )} ( L2 ), 3-Ph 2 P(C 5 H 3 N){1,2,3-N 3 C(C 6 H 5 )C(PPh 2 )} ( L3 ), o -Ph 2 P(C 6 H 4 ){1,2,3-N 3 C(C 5 H 5 N)C(PPh 2 )} ( L4 ), and {(3,5-Ph 2 PC 6 H 4 - o ) 2 1,2,3-N 3 CCH} ( L5 ). The reactions of L1 - L3 with Cu I salts afforded dimeric complexes having the general formula [Cu 2 (μ -X) 2 L 2 ] (L = L1 , X = Cl, Br and I: 1 - 3 ; L= L2 , X = Cl, Br and I: 4 - 6 ; L = L3 ; X = Cl, Br, and I: 7 - 9 ). The reaction of L4 with CuI in a 1:2 molar ratio afforded 1D-coordination polymer [{(CuI) 2 { o -Ph 2 P(C 6 H 4 ){1,2,3-N 3 C(C 5 H 5 N)C(PPh 2 )} -μ- (( k 1 - N )( k 2 - P,P ))}}] n ( 10 ). The reaction of L5 with cuprous halides (CuX) (X = Br, I) yielded mononuclear complexes [CuX{(3,5-Ph 2 PC 6 H 4 - o ) 2 1,2,3-N 3 CCH}-κ 2 P , P ] (X = Br, 12 ; I, 13 ). Crystal structures of complexes 12 and 13 showed close interactions between Cu I and the triazole C7 carbon. These relatively short Cu···C7 separations may be due to the η 1 -C interaction ( d π - p π bond) between the triazolic carbon atom ( via p z orbital) and Cu I or three-centered two-electron interaction between Cu I and the triazolic C-H bond. The existence of the Cu···C interaction was further evinced by the QTAIM analysis in compounds 12 and 13 .