EPR and optical studies in pseudotetrahedral tetramethyl ammonium copper {II) bromide
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EPR studies of single crystal copper tetramethyl ammonium bromide, T2CuBr4(T = (CH3~4N] in the
temperature range 77-300 K indicate the largest covalency in this compound compared to similar
halogenated pseudotetrahedral copper compounds. The angle cos _,r between the c axis and the ionic g 11 axis
is 12' and 65' at 250 and 220 K, respectively. The change is continuous down to 200 K. The g shift between
300 and 200 K indicates an increase in the strength of the ligand field with lowering of temperature. The
magnetic susceptibility ellipsoid and the g -tensor ellipsoid do not coincide in this material. Optical spectra in
T2(Cu:Zn)Br4 have been assigned. The nonobservation of an EPR signal in T,(Cu:Zn)Br4 and Cs2CuBr4
indicates that ligand field properties in these pseudotetrahedral compounds are quite different from that of
T2CuBr4•
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QH301 Biology