In situ formed [M(CN)9] (M = W, Mo) as a building block for the construction of two nona-cyanometalate-bridged heterometallic coordination polymers

Abstract

Two interesting nona-cyanometalate-based coordination polymers (CPs) {[μ₄-M(CN)₉Mn₂(dpo)₂(DMF)₄]·DMF}_n (M = W 1, Mo 2) were obtained from the reaction of 2,5-di(4-pyridyl)-1,3,4-oxadiazole (dpo) and (Bu₃NH)₃[M(CN)₈] (M = W, Mo) with Mn(NO₃)₂·6H₂O in DMF. It is noteworthy that the in situ generated [M(CN)₉]⁴⁻ (M = W, Mo), the first nona-cyanometalate-based example of precursor, plays the roles of not only the charge-balancing counter anion but also the molecular building blocks in inducing the neutral structures of CPs 1 and 2. Single-crystal diffraction analysis reveals that CPs 1 and 2 crystallize in the tetragonal crystal system with the I4/m space group and possess the same 3D framework structure in a (4,4)-connected mot topology with the point symbol {6⁶}{6⁴·8²}₂. Variable-temperature magnetic susceptibility measurements in the temperature range of 2 to 300 K reveal that there are antiferromagnetic interactions between the M^V (M = W, Mo) of nona-cyanometalate [M(CN)₉]⁴⁻ and Mn^II spin centers in both CPs 1 and 2.