Heterobimetallic Oxalate‐Bridged M II Re IV (M = Zn, Cu, Ni, Co and Mn) Complexes Incorporating Bis(3,5‐dimethylpyrazol‐1‐yl)methane: Synthesis and Magneto‐Structural Studies

Five oxalato‐bridged heterobimetallic compounds of general formula [ReCl 4 (ox)M(bdmpzm) 2 ] · 2MeCN [ox = oxalate, bdmpzm = bis(3,5‐dimethylpyrazol‐1‐yl)methane, M = Zn ( 1 ), Cu ( 2 ), Ni ( 3 ), Co ( 4 ) and Mn ( 5 )] have been successfully synthesized in the self‐assembly reactions of the [ReCl 4 (ox)] 2– metalloligand with the coordinatively unsaturated [M(bdmpzm) 2 ] 2+ complex generated in situ by the reaction of the appropriate metal(II) salt with the bdmpzm ligand. Complexes 1 – 5 are isostructural compounds the crystal structures of which consist of neutral heterodinuclear [ReCl 4 (ox)M(bdmpzm) 2 ] units and free acetonitrile molecules. The magnetic properties of 1 – 5 were investigated in the temperature range 2.0–300 K. Compound 1 behaves as a magnetically isolated Re IV complex with a large zero‐field splitting (zfs) of this metal ion [ D Re = 54.7(8) cm –1 ]. Important ferromagnetic interactions between the Re IV and either Cu II in 2 [ J = +6.60(2) cm –1 , ground spin state S = 2] or Ni II in 3 [ J = +13.7(1) cm –1 , ground spin state S = 5/2] occur through the oxalate bridge, the orthogonality between the magnetic orbitals involved accounting for these ferromagnetic couplings. A thorough analysis of the magnetic data of 4 , in which spin–orbit coupling and zfs effects coexist with the magnetic coupling, also reveals the occurrence of a ferromagnetic interaction between Re IV and the high‐spin Co II [ J = +3.79(2) cm –1 , ground spin state S = 3]. Finally, a relatively weak intramolecular antiferromagnetic interaction is observed in 5 [ J = –0.995(5) cm –1 , ground spin state S = 1]. The nature and trend of the magnetic interactions in 2 – 4 are discussed in the light of the number and symmetry of the magnetic orbitals involved and compared with those reported in previous magneto‐structural studies in which [ReCl 4 (ox)] 2– was used as a metalloligand for first‐row transition‐metal ions.