Crystal Structure of Hg2PCl2and Electronic Structure of Its Main "Building Unit"––The (P2Hg6) Octahedron

The crystal structure of Hg2PCl2(I) has been determined based on single crystal diffraction data. I crystallizes in a monoclinic space groupI2/m(No. 12, a nonstandard setting),a=7.643(6) ?,b=7.977(2) ?,c=8.539(6) ?,BETA=115.23(3)°,Z=4,R= 0.0526,wR2=0.1345. Its crystal structure is based on the (P2Hg6) octahedron. Such octahedra share four corners out of six, forming a layer. The arrangement of the layers follows that of the K2NiF4structure type. Relations of the structure of I to the structures of similar cadmium and mercury pnictidehalides are discussed. Some details of the electronic structure of I are discussed based on the molecular orbital calculations performed on a model (P2Hg6)8+cation.