Non-covalent O⋯O interactions among isopolyanions using a cis-{MoO2} moiety by the assistance of N-H⋯O hydrogen bonds

Abstract

An inorganic-organic hybrid material, [2-AmPH]4[Mo 8O26] (1) has been isolated by the reaction of Na 2MoO4·H2O with 2-aminopyrimidine (2-Amp) from an acidic aqueous medium. In this low pH synthesis, the organic molecule (2-Amp) gets mono-protonated (2-AmpH+) and acts as the cation in stabilizing the octamolybdate anion in 1. Compound 1 crystallizes in the triclinic space group P-1 with a = 9.925(3), b = 10.020(3), c = 10.414(3) Å, α= 88.811(4), β= 64.907(4), γ= 89.506(4)°, Z= 1. An interesting three-dimensional supramolecular structure, having well-defined channels, is formed through N-H⋯O and C-H⋯O hydrogen bonds, in which the protonated organic cation plays a significant role. The crystal structure also reveals an unusual cluster-cluster (non-covalent O⋯O) interaction using cis-(MoO2) moieties of the isopolyanion. N-H⋯O hydrogen bonds, originated from pyridimidinium cation and isopolyanion, are found to influence to attain such non-covalent O⋯O interactions among polyoxometalate anions. An interesting helical arrangement, formed from isopolyanion and organic cation, is observed. © Indian Academy of Sciences.