Investigation of structures of mono- and diorgano-substituted oligosiloxanes containing transition metal atoms

Oligomeric linear copper-containing diorganosiloxanes with a variable Cu : Si ratio and branched Cu- and Ni-containing organosiloxanes containing the gamma -aminopropyl group at the Si atom were investigated. IR spectroscopic studies demonstrated that the distribution of metal atoms throughout the m etallosiloxane chain in compounds with a high metal content (M : Si greater than or equal to 2) is rather uniform. According to the data from electron ic spectroscopy, compounds under study are complexes of metal ions characte rized by d-d transitions and an octahedral configuration of the coordinatio n units. The Cu-II and Ni-II ions are coordinated by the NH, groups primari ly through interchain interactions. ESR spectroscopic studies demonstrated that the Cu-II ions are located predominantly in the main chain to form -O- Cu-O- fragments. The coordination polyhedron changes from a nearly planar s quare tin the solid phase) to an elongated tetragonal bipyramid tin solutio n). The spectral parameters of the Cu-containing oligomer containing the ga mma -aminopropyl group at the Si atom indicate that the N atoms of the amin o groups are located in the equatorial plane of the Cu-containing coordinat ion polyhedron.