Lattice effects on the electron resonance of halopentaamminechromium(III) complexes

Lattice effects on the electron resonance of halopentaamminechromium(III) complexes. Temperature dependence

“…Previously, it was found that changes in the size of the counterion give a corresponding change in the lattice dimensions. 1 In other words, substituting a larger counterion into the lattice caused it to expand. Two mechanisms were necessary to explain the effect of this expansion on the zero-field splitting parameters.…”

“…It has been reported1 that triphenylphosphine abstracts an oxo group from dioxobis(A,Ar-dialkyldithiocarbamato)molybdenum(VI) [MoC>2(S2(S2CNR2)2] yielding OMo-(S2CNR2)2 and triphenylphosphine oxide. This reaction, together with the recently discovered1•2 equilibrium (eq 1), was Mo2D3(S2CNR2)4 ;tMo02(S2CNR2)2 + OMo(S2CNR2)2 (1) used in the design1 of a system for the catalytic aerial oxidation of phosphines. Because of our continuing interest in the chemistry of oxomolybdenum species as possible models for molybdoenzymes,2-5 we have utilized and extended this type of oxo abstraction reaction to provide a convenient method of synthesis for a variety of oxomolybdenum(V) and -(IV) complexes.…”

“…The effects of nearest-neighbor counterions on the electron resonance spectra of halopentaamminechromium complexes were examined in a previous study. 1 It was shown that at least two separate mechanisms were necessary to account for the variations in the zero-field splitting tensors of [Cr(NH3)5X] Y2 (X = Cl, Br; Y~= Cl™, Br™, I™, NO3™) which were substituted into the isomorphous series of analogous cobalt hosts. The primary effect, a decrease of the axial parameter D with increased counterion size, was attributed to a variation of the orientation of repulsive forces between the counterions and the bound halide, which protrudes through the face of the roughly eightfold cubic arrangement of counterions.…”

Lattice effects on electron resonance of chromium(III) complexes. Second-neighbor effects

“…We have studied lattice effects on the electron resonance spectra of molecular ions in crystals by a variety of comparisons albeit inadvertently at times. [1][2][3][4][5][6] The primary effect appears in the zero-field splitting tensor for d3 and d5 ions with only small g-tensor variations. high-temperature regimes and the dominant effects for the two parameters have not been shown to correspond.…”