Van H. Crawford

Magnetic studies on μ4‐oxo‐hexa‐μ‐chlorotetrakis [(pyridine) ‐ copper (II)]

The magnetic susceptibility of μ4‐oxo‐hexa‐μ‐chlorotetrakis[(pyridine)copper(II)] has been measured in the temperature range 1.7−294°K. The data may be explained on the basis of simple Heisenberg exchange theory with J=7.65 cm−1, g=2.25, and zJ1 (the intercluster exchange parameter)=−4.0 cm−1.

Magnetic studies of vanadyl(IV) tartrate dimers

Abstract Temperature-dependent magnetic susceptibility data have been collected for solid sodium salts of the binuclearvanadyl(IV) complexes [(VO) 2 ( d -tart) 2 ] 4− , [(VO) 2 ( dl -tart) 2 ] 4− , [(VO) 2 ( dl -mmt) 2 ] 4− ,and [(VO) 2 ( dl -dmt) 2 ] 4− . (“tart” = tartrate(4−), “mmt” = monomethyl-tartrate(4−), “dmt” = dimethyltartrate(4−).) Ferromagnetic intradimer- and antiferromagnetic interdimer exchange is found; however, both interactions are small and similar in magnitude and reliable exchange constants cannot be extracted. The intradimer interaction probably occurs by a superexchange mechanism.

Near One‐Dimensional Antiferromagnetism in Oxovanadium Carboxylates VO(OOCR)2

The spin levels, the dependencies of the effective magnetic moments μeff, and the spin specific heat Cm as functions of kT/J for open linear Heisenberg chains with individual ion spins Si of 1/2 to 5/2 and length N≤11 have been calculated. A comparison of the results with other well known models has been made. The magnetic susceptibility and EPR spectra of oxovanadium carboxylates VO(OOCR)2 (R=CH3, CH2Cl, CHCl2, CCl3, C(CH3)3, C2H5, C3H7, iso‐C3H7, C4H9, and C6H13) have been studied, and the data have been interpreted in terms of the calculations. The results suggest that the chains contain approximately 50 monomeric subunits. The magnetic susceptibility data for all the compounds are consistent with the Heisenberg model for antiferromagnetic linear chains with a small antiferromagnetic interchain interaction and the presence of a small amount of monomeric impurities.

Chloro-bridged triplet ground-state copper(II) dimer

Magnetic susceptibility measurements on the dimer di-µ-chloro-bis[chloro(dimethylglyoxime)copper(II)] indicate a triplet ground state with a singlet–triplet splitting of 6·3 cm–1.