The first lead cobalt phosphite, PbCo(HPO).

Single crystals of a new lead cobalt phosphite, PbCo(HPO), have been synthesized using mild hydrothermal techniques and characterized by X-ray diffraction analysis, SQUID magnetic measurements, IR spectroscopy, UV/vis spectroscopy, thermogravimetric analysis, and scanning electron microscopy. PbCo(HPO) crystallizes in the non-centrosymmetric (NCS) R3m space group, a = 5.3145(15) Å, c = 25.494(7) Å, V = 623.6(4) Å. The crystal structure of PbCo(HPO) is based upon 2D heteropolyhedral blocks built up from CoO octahedral dimers and HPO pseudo-tetrahedra. Lead cations reside in the interlayer space of the structure. Here, the NCS character results reasonably from the cooperative Pb lone electron pair arrangements, by analogy to the centrosymmetric compound (NH)Co(HPO) with similar but disordered blocks. A local twisting of specific HPO groups arises due to unreasonably short HH contacts between two phosphite oxoanions. In terms of the magnetic behavior, the new PbCo(HPO) phase demonstrates weak antiferromagnetic interactions inside the CoO dimers between cobalt ions as expected from the phosphite μ-O bridges.