Structural and magnetic properties of copper(II) dimers bridged by oxalate, azide, and cyanide ions; X-ray structures of [Cu2{EtN(CH2CH2NEt2)2}2(C2O4)][BPh4]2 and [Cu2{MeN(CH2CH2NMe2)2}2(N3)2][BPh4]2. The role of the transition-metal ion ground state in magnetic exchange interactions

Abstract

Variable-temperature (4·2–270K) magnetic susceptibility, e.s.r., and single-crystal X-ray crystallographic data are presented to show that a predominantly d_z2 Cu^II ground state can lead to appreciable magnetic exchange interactions via the extended bridges in [Cu₂(Et₅dien)₂(C₂O₄)][BPh₄]₂, [Cu₂(Me₅dien)₂(N₃)₂][BPh₄]₂, and [Cu₂(tren)₂(CN)][PF₆]₃[Et₅dien = EtN(CH₂CH₂NEt₂)₂, Me₅dien = MeN(CH₂CH₂NMe₂)₂, and tren = N(CH₂CH₂NH₂)₃].