Potassium(I)thallium(I) heterometallic 3D polymeric mixed-anions compound, succinate–nitrate [K2Tl(μ-C4H4O4)(μ-NO3)]n

A three-dimensional polymeric KITlI heterometallic compound [K2Tl(μ-C4H4O4)(μ-NO3)]n, with mixes succinate and nitrate ligands, has been synthesized and characterized. Its single-crystal X-ray structure shows two types of K+-ions with coordination numbers of seven and eight and one Tl+-ion with a coordination number of five. However, the arrangement of O-atoms for TlI suggests a gap or hole in the coordination geometry around this atom. This ‘hole’ is possibly occupied by a stereochemically ‘active’ electron lone pair of thallium atoms. Two hydrogen atoms of succinate situated 3.26 Å above the proposed site on the lone pair of TlI is oriented in such a way that it might be thought to be forming weak Tl-Lp⋯H–C hydrogen bond or agostic interactions, thus attaining of environment TlO5H2.