Hf5.08Mo0.92P3, a new mixed transition-metal phosphide: Structure, bonding, and site preferences

A new structure type which is similar to that of many known binary early transition-metal phosphides, sulfides, and selenides has been found in the ternary Hf-Mo-P system. The compound Hf5.08Mo0.92P3 has been synthesized by high-temperature techniques and characterized by single-crystal X-ray diffraction. The space group is Pnma (no. 62) with lattice parameters a = 18.231(7), b = 3.537(1), c = 9.695(5), Z = 4. The strength of the metal-metal and metal-phosphorus bonding in different metal sites in Hf2P and Hf5.08Mo0.92P3 has been determined by both Pauling bond orders (PBO) and Mulliken overlap populations (MOP) from extended Huckel tight-band calculations. Site preferences of the two metals in Hf5.08Mo0.92P3 are evaluated by MOP analysis. (C) 1996 Academic Press, Inc.