Facile Transformation of Isolated Fragments to Infinite Chains in Rhenium Chalcocyanide Clusters: Synthesis and Structure of (Pr4N)2M(H2O)5 [Re6X8(CN)6]·H2O and (Pr4N)2M(H2O)4[Re6S8(CN)6] (X=S, Se; M=Mn, Ni)

Abstract

In this paper we report the synthesis of new compounds containing cluster anions [Re6S8(CN)6]4− and [Re6Se8(CN)6]4−. Interaction of aqueous solutions of anions with transition metal cations in presence of Pr4N+ gives two type of compounds: (Pr4N)2M(H2O)5[Re6X8(CN)6]·H2O, X=S, Se (orthorhombic phase) and (Pr4N)2M(H2O)4[Re6S8(CN)6] (tetragonal phase), X=S, Se, M=Mn, Ni. The structures of (Pr4N)2Mn(H2O)5 [Re6Se8(CN)6]·H2O (space group: P212121, a=18.286(2) Å, b=18.345(2) Å, c=16.568(2) Å, V=5558(1) Å3, Z=4, R1=0.0387, wR2=0.0624), (Pr4N)2Mn(H2O)4[Re6S8(CN)6] (space group: I4/m, a=13.255(2) Å, c=14.432(3) Å, V=2535.6(8) Å3, R1=0.0369, wR2=0.0960) and (Pr4N)2Ni(H2O)4[Re6S8(CN)6] (space group: I4/m, a=13.247(4) Å, c=14.246(6) Å, V=2500(2) Å3, R1=0.0414, wR2=0.1004) were determined by X-ray single crystal analysis. The structure of (Pr4N)2Mn(H2O)5[Re6Se8(CN)6]·H2O contains isolated fragments {Mn(H2O)5[Re6Se8(CN)6]}2−. The structures of (Pr4N)2M(H2O)4[Re6S8(CN)6] (M=Mn, Ni) contain {-Mn(H2O)4-[Re6S8(CN)6]-}2−∞ infinite chains. When heated the (Pr4N)2M(H2O)5[Re6S8(CN)6]·H2O compounds transform into (Pr4N)2M(H2O)4[Re6S8(CN)6], the reaction conditions depending on the nature of the metal. The formation and conversion of the compounds are discussed in terms of substitution of water molecules in coordination sphere of transition metal cations. It is shown that the orthorhombic structure can be considered as a superstructure in respect to the tetragonal one.