Substitution of Azaheterocarboxylate Ligand in a Heteroleptic Silver(I) Complex with closo-Decaborate Anion in the Presence of Neutral Ligands

The substitution of the azaheterocarboxylate ligand (2-quinoxalinecarboxylate, Qox–) in the heteroleptic silver(I) coordination polymer {Ag6[B10H10]Qox4}n was studied in the presence of neutral ligands 2,2'-bipyridyl (bipy) and triphenylphosphine (Ph3P). It was found that dissolution of the starting polymer in dimethylformamide results in its dissociation, and the subsequent addition of neutral ligands leads to the complete displacement of the Qox– anion from the silver coordination sphere. The structures of the resulting molecular complex [Ag2(bipy)2[B10H10]] (1) and polymeric complex [Ag2(Ph3P)2[B10H10]]n (2) were determined by elemental analysis, IR spectroscopy, and X-ray diffraction. In the structure of complex 1, the boron cluster anion is coordinated along a face and an edge, forming a molecular compound. The structure of compound 2 is known: the closo-decaborate anion acts as a µ4-bridging ligand, forming a one-dimensional polymer chain. The obtained results demonstrate that neutral ligands effectively compete with the anionic azaheterocarboxylate ligand for coordination sites on silver(I) under conditions of dissociation of the starting polymer in DMF.