Synthetic, spectroscopic and X-ray crystallographic studies on phenylcyanamidocopper(I) complexes

Abstract

The preparations of phenylcyanamidocopper(I) complexes of the types [Cu2(dppe)3L2]粍e2CO [dppe = 1,2-bis(diphenylphosphino)ethane, L = a phenylcyanamide ion] and [{Cu(PPh3)2L}2] are described. The crystal structures of two of the complexes, namely [Cu2(dppe)3(4-ClC6H4NCN)2]粍e2CO (4-ClC6H4NCN = 4-chlorophenylcyanamide) and [{Cu(PPh3)2(4-MeC6H4NCN)}2](4-MeC6H4NCN = 4-methylphenylcyanamide) have been determined by X-ray diffraction techniques. Crystals of [Cu2(dppe)3(4-ClC6H4NCN)2]粍e2CO are orthorhombic, space group Pbca, with a= 22.397(14), b= 18.970(7), c= 20.341(5)Šand Z= 4. The complex contains centrosymmetric dppe-bridged dinuclear molecules. Each copper atom has a distorted tetrahedral geometry with the cyano nitrogen from a terminally bound [4-ClC6H4NCN]- ligand [Cu-N 1.967(5)ŝ, two phosphorus atoms from a chelating dppe and one from the bridging dppe making up the co-ordination sphere. Crystals of [{Cu(PPh3)2(4-MeC6H4NCN)}2] are monoclinic, space group P21/n, with a= 15.003(2), b= 13.844(2), c= 18.711(2)Ŭ = 101.22(1)ࠡnd Z= 2. This complex is a centrosymmetric dimer with the [4-MeC6H4NCN]- ligands bridging in a 孱,3 fashion. Each copper atom has a distorted tetrahedral geometry, being bound to two PPh3 phosphorus atoms, a terminal cyano nitrogen atom from a [4-MeC6H4NCN]- ligand [Cu-N 2.045(2)ŝ and an amido nitrogen from the centrosymmetrically related [4-MeC6H4NCN]- ligand [Cu-N 2.095(2)ŝ. The v(CN) stretching vibration for the co-ordinated phenylcyanamides occurs in the 2125-2175 cm-1 range. Solid-state cross-polarisation magic-angle-spinning (CP-MAS)31P NMR spectra at 121.47 MHz for the complexes [{Cu(PPh3)2L}2](L = XC6H4NCN; X = 4-Me, 4-Cl or H) consist of two well resolved quartets of doublets arising from each of the crystallographically independent phosphorus nuclei. The doublet structure is a consequence of homonuclear phosphorus-phosphorus two-bond coupling [2J(P1-P2)= 120 Hz]. Available structural data for phenylcyanamidocopper complexes are summarised and comparison made with related pseudohalide complexes.