6533b82dfe1ef96bd1291e58

RESEARCH PRODUCT

Magneto-structural correlations in discrete $Mn^{II}‐W^V$ cyano‐bridged assemblies with polyimine ligands

subject

description

We present the magneto-structural correlations for two novel discrete cyano-bridged assemblies based on cationic complexes of manganese(II) with diimine ligands and octacyanotungstate(V) ions. The crystal structure of [Mn II (terpy)(dmf)-(H 2 O) 2 ][Mn II (terpy)(H 2 O)(dmf)(μ-NC)W V (CN) 7 ] 2· 6H 2 O (1) (terpy = 2,2';6',2"-terpyridine, dmf = dimethylformamide) contains dinuclear {Mn II W V } - cyano-bridged anions, while the crystal structure of [Mn II (phen) 3 ] 2 [MnII(phen) 2 (μ-NC) 2 -W V (CN) 6 ] 2 (ClO 4 ) 2 ·9H 2 O (2) (phen = 1,10-phenanthroline) is built of tetranuclear {Mn II 2 W V 2} 2- square anions. Intramolecular Mn-W magnetic interactions through the cyano bridges are represented by magnetic coupling constants J = -39 cm -1 for the {Mn II W V }- unit in 1 and J 1 = -25.7 and J 2 = -16.7 cm -1 for the {Mn II 2 W V 2 } 2- unit in 2. J and J 1 represent relatively strong W-CN-Mn interactions and are ascribed to the bridges in b positions of TPRS-8 (trigonal prism square-face bicapped) of [W(CN) 8 ] 3- polyhedra, favoring the strongest electronic interactions between the d z2 -d x2-y2 orbital of W and the π* orbitals of CN - , whereas J 2 is related to the m vertex of [W(CN) 8 ] 3- . The magnetic properties of 1 and 2 are compared with reference compounds and discussed in the context of the type of coordination polyhedra of [W(CN) 8 ] 3- as well as the metric parameters of cyano-bridged W-CN-Mn linkages. We found the type of coordination polyhedra and bridging mode of [W(CN) 8 ] 3- to be the most important factors influencing the magnitude of the Mn-W magnetic interaction.