Influence of sterically demanding groups on the structure and stability inthe solid and solution state of (acylpyrazolonate)bis(phosphine)copper(I) derivatives

New neutral derivatives [Cu(L)(PR3)(2)] (LH = 1-phenyl-3-methyl-4-R-1 (C=O) -pyrazol-5-one, in detail (LH)-H-1, R-1 = C6H5; (LH)-H-2, R-1 = CH3; (LH)-H -3, R-1 = CF3; (LH)-H-4, R-1 = C6H11; (LH)-H-5, R-1 = C6H5CH2; (LH)-H-6, R- 1 = (C6H5)(2)CH; R = C6H5, p-CH3C6H4, C6H5CH2 or C6H11) and [Cu(L)(2)] (L = L-4, L-5 and L-6) have been synthesised and characterised by analytical an d spectroscopic techniques. The X-ray crystal and molecular structures of [ Cu(L-1)(PCy3)(2)], [Cu(L-5)(PPh3)(2)] and [Cu(L-6)(PPh3)(2)] have been reso lved, in which the copper atom is found in a strongly distorted tetrahedral CuO2P2 environment. The interbond angles P-Cu-P, P-Cu-O and O-Cu-O are str ongly influenced by the steric properties of PR, and also to a lesser degre e by the 4-acyl moiety of the L donor. [Cu(L)(PR3)(2)] derivatives undergo partial dissociation in chloroform solution through breaking of Cu-P and, w hen R = Cy, also of Cu-O bonds. [Cu(L-4)(PPh3)(2)] reacts with 1-methylimid azolin-2-thione (Hmimt), with 1,10-phenanthroline (Phen), with 2,9-dimethyl -1,10-phenanthroline (Cupr) and with bis(diphenylphosphino)propane (DPPP), yielding the mixed-ligand compounds [Cu(PPh3)(Hmimt)(3)](L-4), [Cu(L-4)(PPh 3)(Phen)], [Cu(Cupr)(2)](L-4) and [Cu(DPPP)(2)](L-4), respectively. (C) 200 0 Elsevier Science S.A. All rights reserved.