Assembly and Autochirogenesis of a Chiral Inorganic Polythioanion Möbius Strip via Symmetry Breaking

Using [Mo2S2O2(H2O)6]2+ and squarate dianion, we synthesized
the thiometalate
ring compounds [(Mo2S2O2)x(OH)y(C4O4)z(Mo2O8)o(H2O)p]n−, where [x,y,z,o,p,n] = [7,14,2,0,2,4] for 1, [6,8,2,2,4,8] for 2, and [4,6,1,1,0,4] for both 3a and 3b, which are chiral and nonchiral isomers,
respectively. Not only do the four thiometalate clusters show decreasing
symmetry at the molecular level across the series, but the incorporation
of the “addendum” {Mo2O8}o unit also allows the thiometalate ring to
twist. The reaction initially yields the chiral molecule 3a with a twisted ring, which undergoes spontaneous resolution upon
crystallization; the reaction mixture later yields the intrinsically
nonchiral isomer 3b with a nontwisted ring. In addition,
the compounds are able to promote the electrocatalytic evolution of
hydrogen.

本研究以[Mo₂S₂O₂(H₂O)₆]²+与方酸二阴离子为起始原料，合成了硫代金属酸盐环类化合物[(Mo₂S₂O₂)ₓ(OH)ᵧ(C₄O₄)_z(Mo₂O₈)_o(H₂O)_p]ⁿ⁻。其中化合物1的[x,y,z,o,p,n]取值为[7,14,2,0,2,4]，化合物2的取值为[6,8,2,2,4,8]；3a与3b的取值均为[4,6,1,1,0,4]，二者分别为手性异构体与非手性异构体。该系列的四个硫代金属酸盐团簇在分子层面对称性依次降低，且引入{Mo₂O₈}附加单元可使硫代金属酸盐环发生扭转。反应初始阶段生成带有扭转环结构的手性分子3a，该分子在结晶过程中发生自发拆分；后续反应体系则生成带有非扭转环结构的固有非手性异构体3b。此外，上述化合物均具有电催化析氢性能。