Influence of anions and crystallisation conditions on the solid-state structure of some binuclear silver(I) complexes supported by triazolopyrimidine bridges

Abstract

The reaction of silver salts AgX (X = NO₃ or ½SO₄) with [1,2,4]triazolo[1,5-a]pyrimidine (tp) in aqueous media afforded the silver(I) binuclear complexes [Ag₂(NO₃)₂(µ-tp-N ³,N ⁴)₂] 1, [Ag₂(SO₄)(µ-tp-N ³,N ⁴)₂(H₂O)]·H₂O 2, [Ag₂(SO₄)(µ-tp-N ³,N ⁴)₃(H₂O)]·3H₂O 3 and [Ag₂(SO₄)₂(Htp)₂] 4. The compounds have been structurally characterised by spectroscopic methods (IR, ¹H, ¹³C NMR) and X-ray crystallography (1, 2 and 3). The X-ray results show that the complexes comprise dimeric units in which the silver atoms are bridged by two (1, 2) or three (3) tp ligands, giving rise to intermetallic contacts of 3.117(1), 3.127(1) and 3.089(1) Å respectively for 1, 2 and 3. The crystallisation conditions and/or the nature of the anion appear to play an important role in the stereochemistry of the silver centres. The NMR studies in D₂O suggest that the ligand exhibits in solution the same co-ordination mode as found in the solid state.