LOW-TEMPERATURE POLARIZED SINGLE-CRYSTAL RAMAN-SPECTRA OF THE BETA-ALUMS CSM(SO4)(2)CENTER-DOT-12H(2)O (M=MO OR RU) BETWEEN 275 AND 1200 CM(-1)

Low-temperature, polarized, single-crystal Raman spectra of the beta-a lums CsM(SO,), . 12H(2)O (M = Mo or Ru) and their deuterated analogues were recorded between 275 and 1200 cm(-1). The internal modes of sulp hate and [M(OH2)(6)](3+) and the external modes of water coordinated t o the mono- and tervalent cation were assigned. This allowed a compari son between the wavenumbers of the internal modes of second- and first -row transition metal hexaaquacations. The relationship between nu(1)( MO(6)) and the M(III)-O bond length is similar for the first-row trans ition and Group 13 metals, but is significantly different for the seco nd-row transition metals. This suggests a non-ionic contribution to th e metal-water bonding in the latter case. The relative intensities of the nu(1)(MO(6)) modes are highly dependent on the identity of the met al; however, the trend in this property is not simply related to eithe r the bond strength, the polarizing power of the cation or the covalen t interaction.