Theoretical study of the exchange coupling substituting MoV with WV in four cyano-bridged M′9M6 (M′ = MnII or NiII; M = MoV or WV) systems

Abstract

Magnetic properties of four high-spin molecules [M′{M′(MeOH)₃}₈(μ-CN)₃₀{M(CN)₃}₆] (M′ = Mn^II and M = Mo^V for A; M′ = Mn^II and M = W^V for B; M′ = Ni^II and M = Mo^V for C; M′ = Ni^II and M = W^V for D) have been investigated using hybrid density functional theory (DFT) B3LYP with LANL2DZ basis set. Our calculations suggest that models [M′(μ-CN)₆{M(CN)₇}₆]¹⁶⁻ (M′ = Mn^II and M = Mo^V for A⁶; M′ = Mn^II and M = W^V for B⁶; M′ = Ni^II and M = Mo^V for C⁶; M′ = Ni^II and M = W^V for D⁶) and [M′(MeOH)₃(μ-CN)₃{M(CN)₇}₃]⁷⁻ (M′ = Mn^II and M = Mo^V for A³; M′ = Mn^II and M = W^V for B³; M′ = Ni^II and M = Mo^V for C³; M′ = Ni^II and M = W^V for D³) are good candidates to model the complete molecular structures of A, B, C and D. For all complexes and models, the antiferromagnetic or ferromagnetic exchange interactions through equatorial cyanides are all stronger than those through apical cyanides. In Mn₉M₆ (A and B) systems, substituting Mo with W always enhances the antiferromagnetic interactions for the apical and equatorial cyanides and the different C_brid–N_brid–Mn angles, but the behavior is more complicated for Ni₉M₆ (C and D). Moreover, the calculated Δ_xy values of a series of binuclear models according to Kahn–Briat model were used to confirm our conclusions.