Nuclear Quadrupole Resonance Study of Antimony Pentachloride and Its Phase Transition

Abstract

Abstract A phase transition was found in solid antimony pentachloride at 212°K by the nuclear quadrupole resonance and the differential thermal analysis. In the high temperature solid phase, five resonance lines were observed that were all assigned to antimony resonances and that were dependent on temperature only slightly. The quadrupole coupling constant of 121Sb was 84.54±0.01 MHz (asymmetry η=1.0±0.3%). Chlorine resonances were not detected above the transition point. In the low temperature phase, many resonance lines were observed due both to chlorine and antimony; the latter gave the coupling constant for 121Sb 186.43±0.03 MHz (η=79.54±0.02%) and 172.8±0.3 MHz (η=79.2±0.3%). There are two nonequivalent sites for antimony. The structure in the two solid phases was suggested as being trigonal bipyramidal above 212°K and a dimerized Sb2Cl10 bridged by two chlorine atoms with hexa-coordinated antimony atoms below 212°K.