Complexes of copper(I) thiocyanate with monodentate phosphine and pyridine ligands and the P(,N)-donor diphenyl(2-pyridyl)phosphine

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Copper(I) thiocyanate derivatives were prepared by the reaction of CuNCS with pyridine (py) and tertiary monophosphine ligands [PR3 in general; in detail: PPh3, triphenylphosphine, P(4-FPh)3, tris(4-fluorophenyl)phosphine)], as well as the potentially bidentate ligand diphenyl(2-pyridyl)phosphine (PPh2py). Mechanochemical methods were used in some cases to investigate stoichieometries that were not easily accessible by conventional solution syntheses. Three forms of the resulting adducts of CuNCS/PR3/py-base (1:3-n:n) stoichiometry-all containing four-coordinate copper(I) atoms and monodentate N-thiocyanate groups-were confirmed crystallographically. Mononuclear arrays are defined for [(PPh2py)3-n(py)nCuNCS], n = 0, 1, 2, the monodentate thiocyanate being N-coordinated in all; two polymorphs are observed for the n = 2 complex, both crystallizing in monoclinic P21 (Z = 2) cells with similar cell dimensions, but with aromatic components eclipsed about the Cu-P bond in the PPh3 complex, and staggered in the PPh2py complex. Bridging thiocyanate groups are found in the 1:1:1 CuNCS/PPh2py/2-methylpyridine (mpy) and P(4-FPh)3/mpy complexes, wherein centrosymmetric dimers with eight-membered central rings are obtained: [(R3P)(mpy)Cu(NCS)2Cu(PR3)(mpy)], as is also the case in the parent 1:2 CuNCS/PPh2py adduct [(pyPh2P)2Cu(NCS)2Cu(PPh2py)2]. For the 1:1:1 CuNCS/P(4-FPh)3/py and PPh3/Brmpy (Brmpy = 3-bromo-4-methylpyridine) adducts, and, likely, CuNCS/PPh2py/py (1:1:1), single-stranded polymers of the form [⋯Cu(NCS)(PR3)(py-base)(Cu)⋯](∞|∞) with linearly bridging NCS ligands were obtained. Some derivatives, representative of all forms, display medium to strong green to blue luminescence when excited with radiation at 365 nm. The 31P CPMAS NMR spectroscopic data clearly differentiate the inequivalent phosphorus positions within each system, showing a wide range of 1J(31P,63/65Cu) values ranging from 965 Hz for [Cu(NCS)(PPh2py)3] to 1540 Hz for dimeric [(4-FPh)3P(mpy)Cu(NCS)2Cu(P(4-FPh)3)(mpy)], reflecting the large variations in the Cu-P bond length.