Synthesis, characterization, spectroscopic and photophysical properties of new [Cu(NCS){(L-N)2 or (L′-N∧N)}(PPh3)] complexes (L-N, L′-N∧N = aromatic nitrogen base)

The syntheses, spectroscopic characterization (IR, H-1 and P-31 NMR, ESI-MS) and conductivity studies of the mixed N,P-donor complexes of copper(I) thiocyanate: [Cu(NCS)(py)(2)-(PPh3)] (2), [Cu(NCS)(Mepy)(PPh3)](2), (3), [Cu(NCS)(phen)-(PPh3)], (4), [Cu(NCS)(bpy)(PPh3)], (5), [Cu(NCS)(bpy)-(PPh(2)py)], (6), [Cu(NCS)(py)(PPh(2)py)], (7), (py = pyridine; Mepy = 2-methylpyridine; phen = 1,10-phenanthroline, bpy = 2,2'-bipyridyl), together with single-crystal X-ray structural characterizations of 2, 3, 4 (new polymorph), 5 and 6 are reported, which provides an opportunity to study the effect of the introduction of a pair of nitrogen donors, both unidentate and chelate, on the bonding parameters of the Cu/NCS/P system. Cu-P and Cu-N-2(ar) are found to be similar [2.1974(5) and 2.091(2), 2.070(1) angstrom for py(2) adduct 2, cf. 2.1748(9)-2.200(1) and 2.071(2)-2.106(4) angstrom for the counterpart values for bidentate adducts 4-6]. However, Cu-N(CS) and Cu-N-C are 2.013(2) angstrom and 157.4(2)degrees for py(2) adduct 2 and 1.946(2)-1.981(8) angstrom and 166.7(2)-176.58(2)degrees for bidentate counterparts 4-6. The change is attributed primarily to the closure in the N-Cu-N angle [99.58(8)degrees for py(2) 2; 77.7(6)-80.5(3)degrees for N boolean AND N-bidentate donors 4-6]. In consequence of the increased steric profile of the Mepy ligand, we find the stoichiometry diminished to 1:1:1, which resulted in the CN formation of [(Ph3P)MepyCu(SCN NCS)Cu(Mepy)(PPh3)] dimers. TDDFT/CPCM calculations were used to clarify the type of transitions involved in the UV/Vis absorption spectra, and the corresponding experimental photoemission data were acquired. The P-31 CPMAS spectra of the copper derivatives exhibit distorted quartets that afford values for (1)J(Cu,p). Furthermore, the quadrupole-induced distortion factors were calculated, and in the cases of 2, 4 and 5, the quadrupole coupling constants were obtained, on the basis of the X-ray structures. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).