MM parameters for phosphorus(V) halides

Hello, everybody!
 Does anybody know where to take from MM parameters for calculating P(V)
 halides (with mixed P(V) surrounding, e.g. PF3Cl2) and, if possible, the
 (ED, IR or MW) structures of these molecules.
 Thanks in advance.
 Michael G. Razumov, Postgraduate Student of
 Kurnakov Institute of General and Inorganic Chemistry
 and Lomonosov Moscow State University
 E-Mail: michraz #*at*# michael #*at*#
 ICQ UIN: 25169010