Synthesis and large crystal growth of a family of mixed-anionic methanesulfonate salts by anionic site-substitution: Na5(SO3CH3)4(X) (X = BF4−, ClO4−, PF6−, I−)†

Abstract

Four new mixed-anionic sodium methanesulfonate compounds were synthesized – Na₅(SO₃CH₃)₄(X) (X = (I) BF₄⁻, (II) ClO₄⁻, (III) PF₆⁻, and (IV) I⁻). Compounds I–III were grown as centimeter-size crystals under ambient conditions. Metal methanesulfonates (i.e., MSO₃CH₃ or M(SO₃CH₃)₂) are proposed as potential high-performance nonlinear optical materials owing to their large calculated bandgaps, local anisotropy, and large polarization. However, there are few experimental reports in the literature. The present study involves using anionic substitution as a structure building strategy to discover new complex metal methanesulfonates. The new compounds, Na₅(SO₃CH₃)₄(X), where X = (I) [BF₄]⁻, (II) [ClO₄]⁻, (III) [PF₆]⁻, and (IV) [I]⁻ crystallize in the monoclinic space groups P2/n or I2/m, and are prepared as (I–III) high-quality and centimeter-sized crystals grown at ambient conditions, whereas millimeter-sized crystals of I, II, and IV could be prepared in high yields by hydrothermal synthesis. I–III have wide optical transparency from 400–1100 nm and λ_abs of ≤210 nm. I–III are each highly soluble in water, air stable for several months, and thermally stable below 350 °C. These data suggest that ionic-substitution is a viable method of discovering new and complex metal methanesulfonate salts with diverse properties.