Structural trends in a series of bulky dialkylbiarylphosphane complexes of Cu.

Cu complexes containing the bulky dialkylbiarylphosphane 2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl (BuXPhos, L) and an ancillary ligand (Cl, Br, I, MeCN, ClO or SCN) have been structurally characterized, namely, chlorido[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I), [CuCl(CHP)], 1, bromido[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I), [CuBr(CHP)], 2, [2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]iodidocopper(I), [CuI(CHP)], 3, (acetonitrile-κN)[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I) hexafluoridophosphate, [Cu(CHCN)(CHP)]PF, 4, 2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κPcopper(I), [Cu(ClO)(CHP)], 5, and di-μ-thiocyanato-κS:N;κN:S-bis{[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I)}, [Cu(NCS)(CHP)], 6. Iodide complex 3 shows significant Cu-arene interactions, in contrast to its chloride 1 and bromide 2 counterparts, which is attributed to the weaker interaction between the iodide ion and the Cu centre. When replacing iodide with an acetonitrile (in 4) or perchlorate (in 5) ligand, the reduced interaction between the Cu atom and the ancillary ligand results in stronger Cu-arene interactions. No Cu-arene interactions are observed in dimer 6, due to the tricoordinated Cu centre having sufficient electron density from the coordinated ligands.