Synthesis and Crystal Structures of (C₅H₇N₃Br)₃CuBr₄ and (C₅H₈N₃)CuBr₂: An Isolated Tetrahedral CuBr₄³^- Anion

Abstract

Two complexes of monomeric (C5H7N3Br)3CuBr4, 1, and polymeric (C5H8N3)CuBr2, 2, were crystallized from the reaction mixture prepared by adding CuBr2·6H2O to the HBr solution of 2,6-diaminopyridine. Complex 1 contains a unique, isolated tetrahedral CuBr43- anion, which is stabilized by extensive N−H···Br and C−H···Br hydrogen bonding. The structure of 2 consists of anionic chains of doubly edge sharing copper(I) metal centers through bromide atoms. The {[CuBr2]n}2n- linear chains are linked into two-dimensional molecular sheets through the N−H···Br interactions (2.582−2.951 Å).