Cd(NH2SO3)2•xH2O (x=0, 2): new sulfamates with a unique coordination environment and reversible phase transitions

초록

Two new cadmium sulfamates, namely, centrosymmetric Cd(NH2SO3)(2)center dot 2H(2)O and noncentrosymmetric Cd(NH2SO3)(2) have been successfully synthesized. Crystals of Cd(NH2SO3)(2)center dot 2H(2)O grown using an aqua-solution method reveal an infinite chain structure consisting of trans-[CdO2(H2O)(2)(NH2)(2)] octahedra and [NH2SO3] units. Crystals of Cd(NH2SO3)(2) obtained during the process of dehydration of Cd(NH2SO3)(2)center dot 2H(2)O exhibit a 3D framework composed of cis-[CdO4(NH2)(2)] octahedra and [NH2SO3] tetrahedra. Temperature- and humidity-induced reversible phase transitions of the title compounds are observed, which is confirmed by TGA and PXRD. Cd(NH2SO3)(2) exhibits a phase-matchable SHG response of ca. 0.15 x KDP. Interestingly, nitrogen-containing [CdO4N2] octahedra are found in the metal sulfamates for the first time. The unique arrangement is discussed with the hard-and-soft acids and bases theory and further compared with other existing [MO6] (M = Na, Mg) octahedra in sulfamates. In addition, the discovery would provide a new perspective to design new materials by adjusting the structural arrangement for polar anionic groups.

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