| Abstract |
The reaction of CuBr with 3 equiv of CNR in CHCl3 at RT furnished the pure tris-isocyanide complexes [CuBr(CNR)(3)] [R = 2,6-Me2C6H3 (Xyl) (1), 2-Cl-6-MeC6H3 (2), 2-Naphthyl (3), C6H11 (Cy) (4)] in 85-99\% isolated yield. Compounds 1-4 were characterized by elemental analyses (C, H, N), high resolution ESI+-MS, IR, H-1 and C-13\H-1\ NMR spectroscopic techniques, and by single-crystal X-ray diffraction for 1 and 2. Coordination polyhedra of these two complexes are intermediate between tetrahedral and trigonal pyramidal with three isocyanide and one bromide ligands; the fragment M-C-N is bent [171.2(2)-175.6( 2)degrees]. The influence of crystal packing effects on the geometric parameters of 1 as well as nature of the coordination Cu-C bonds and bond order of the formal triple C equivalent to N bonds in this compound were also studied theoretically at the DFT level of theory. The crystal packing effects noticeably affect the values of the Cu-C-N angles and lead to a decrease of these angles approximately 10 degrees relative to the gas phase geometries. Results of the AIM, NBO, and CDA analyses reveal that the Cu-C coordination bonds are of the electrostatic nature. Electrostatic interaction, unlike the covalent one, has no orientation, and it is the reason of the curved shape of the metal-ligand fragment. (C) 2015 Elsevier B.V. All rights reserved. |
