ARCHITECTURE OF THE ORGANOMETALLIC ION-EXCHANGERS [(ME3SNIV)4MII(CN)6]INFINITY(M = FE, RU, OS) - A COMBINED MULTINUCLEAR SOLID-STATE MAGNETIC-RESONANCE AND INFRARED RAMAN-SPECTROSCOPIC STUDY

With extensive use of the N-15 isotopomer, 1a, of the organotin polymer [(Me3Sn)4Fe(CN)6]infinity (1) and of variable-temperature solid-state C-13 NMR studies, the CP MAS C-13, N-15, and Sn-119 NMR spectra of the coordination polymers [(Me3SnIV)4MII(CN)6]infinity with M = Fe (1), Ru (2), and Os (3) have been fully determined and optimally assessed. According to these measurements, the asymmetric unit involves three equally-abundant, nonequivalent CN ligands and two equally-abundant, nonequivalent Me3Sn groups with six crystallographically different methyl C atoms. A structural model is proposed in which one type of N atom is bonded to two Sn atoms. Below -20-degrees-C, each of the six CH3 groups gives rise to an individual, sharp 13C signal, while above room temperature rapid rotation of both Me3Sn groups leads to two resonances. The vibrational spectra in the nu(SnC) and nu(CN) absorption ranges suggest the exclusive presence of trigonal planar Me3Sn fragments and one significantly distorted (from O(h)), albeit still centrosymmetric, M(CN)6 unit (local symmetry: D4h from IR/Ra: D2h from NMR). From all spectroscopic findings, a three-dimensional network reminiscent of that of the polymeric acid [H4Fe(CN)6]infinity may be deduced. The preferred architecture, which also involves three-coordinate cyanide N atoms, -CNSn2, contrasts with the known structures of polymeric [(R3Sn)2CO3]infinity systems wherein both penta- and tetracoordinated Sn atoms coexist.