Synthesis, Characterization, Spectroscopic and Photophysical Properties of New [Cu(NCS){(L‐ N ) 2 or (L′‐ N N )}(PPh 3 )] Complexes (L‐ N , L′‐ N N = Aromatic Nitrogen Base)

The syntheses, spectroscopic characterization (IR, 1 H and 31 P NMR, ESI‐MS) and conductivity studies of the mixed N,P‐donor complexes of copper(I) thiocyanate: [Cu(NCS)(py) 2 (PPh 3 )], ( 2 ), [Cu(NCS)(Mepy)(PPh 3 )] 2 , ( 3 ), [Cu(NCS)(phen)(PPh 3 )], ( 4 ), [Cu(NCS)(bpy)(PPh 3 )], ( 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) Å for py 2 adduct 2 , cf. 2.1748(9)–2.200(1) and 2.071(2)–2.106(4) Å for the counterpart values for bidentate adducts 4 – 6 ]. However, Cu–N(CS) and Cu–N–C are 2.013(2) Å and 157.4(2)° for py 2 adduct 2 and 1.946(2)–1.981(8) Å and 166.7(2)–176.58(2)° for bidentate counterparts 4 – 6 . The change is attributed primarily to the closure in the N–Cu–N angle [99.58(8)° for py 2 2 ; 77.7(6)–80.5(3)° for N∧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 theformation of [(Ph 3 P)MepyCu( SCN NCS )Cu(Mepy)(PPh 3 )] 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 wereacquired. The 31 P 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.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)