Structures and spectroscopy of some adducts of coinage metal(I) cyanides with 'tetrahedral'-unidentate-N-bases

Crystallization of copper(I) cyanide from piperidine ('pip') solution yields an adduct of CuCN:pip (3:4) ratio, as established by a single crystal X-ray structure determination, which also shows the complex to have a single-stranded center dot center dot center dot Cu(CN)Cu(CN)center dot center dot center dot spine (C,N scrambled), one-third of the copper atoms carrying a pair of pip ligands, the others only one. Crystallization of silver(I) cyanide from piperidine ('pip') or cyclohexylamine ('CyNH2') solutions yields adducts of the unusual AgX:unidentate-N-base (1:2) stoichiometry. The CyNH2 adduct is, unusually for cyanide complexes of this type, mononuclear with a trigonal planar silver atom, [(NC)Ag(H2NCY)(2)], the AgCN component lying along the intersection of two crystallographic mirror planes which bisect and relate the H2NCy ligands (Ag-C, N 2.067(3), 2.335(2)angstrom; N-Ag-N, C 80-80(6), 139.60(4)degrees). In the pip adduct, the immediate silver atom environment is also three-coordinate (Ag-C; N, N 2.080(1); 2.288, 2.443(1)angstrom; N-Ag-N 88-34(4), N-Ag-C 144.47(4), 125.07(4), (Sigma 357(center dot 9)degrees) perturbed toward two-coordination, but the silver atom environment geometry is further perturbed from planarity by the parallel approach of an inversion-related molecule (Ag center dot center dot center dot C' 2.926(1)angstrom (Ag center dot center dot center dot Ag' 3.1842(2)degrees) forming a loose, albeit still discrete, dimer. Key features in the IR spectra of the above compounds and of AgCN:pip (1:1) and CuCN: CyNH2 (2: 3) are assigned and discussed in terms of the structures or of proposed structures in the case of the latter two adducts. The structure of [ClAg(PiP)(3)], adventitiously obtained, is also described (Ag-Cl 2.471(3); Ag-N 2.147(13), 2.188(7) (x2) angstrom; Cl-Ag-N 96.1(3), 98.5(2), N-Ag-N 116.3(2) (x2), 122.1(3)degrees).