A reexamination of the magnetic susceptibility of the coordination complex μ4-oxohexa-μ-chlorotetrakis-(triphenylphosphine oxide) copper(II), Cu4OCl6(TPPO)4

High purity samples of Cu4OCl6 (triphenylphosphine oxide)4 have been prepared for a reexamination of the χ vs T behavior of this compound. EPR studies on single crystals of the compound have revealed the ground state to be S′=0 and an observed spectrum from an excited S′=2 manifold with a g factor of 2.10±0.01. The ordering of the energies of the spin manifolds is proposed to be S′=0, S′=2, S′=1. On this basis, experimentally determined χ vs T data were fitted to a modified Heisenberg exchange model for g=2.10, E(S′=1)−E(S′=0)=85±13 cm−1, E(S′=2)−E(S′=0)=10±1 cm−1, and z′J′=0±1 cm−1. Magnetic susceptibility measurements were also made on samples prepared by ‘‘doping’’ the tetramer into the pores of a crosslinked polymer.