Selected platinum(II) and palladium(II) complexes react with 4-(difluorophosphino)-2,5-dimethyl-2H-1,2,3 sigma(2)-diazaphosphole (L-F) to form the expected X2M(L-F)(2) complexes; In some cases, redox processes yield stable, solid, M-0(L-F)(4) complexes; thus Pd(cod)Cl-2 with L-F gave a mixture of the Pd-0 and Pd-II complexes whereas Pt(cod)Cl-2 gave only the Pt(LF)(2)Cl-2 complex, With limited L-F, (cod)Pt(Me)Cl gave the expected (L-F)(2)Pt(Me)Cl complex, but when the reaction was carried out with excess L-F, Pt-II was reduced to Pt-0 to form the Pt-0(L-F)(4) complex. This complex was structurally characterized. Crystal data for C16H28F8N8O2P8Pt: tetragonal, I (4) over bar 2m (No. 121), a = 11.961(2) Angstrom, c = 15.034(3) Angstrom, V = 2150.8(6) Angstrom(3), Z = 2. Final indices: GOF = 1.299 [F-o(2) greater than or equal to -3 sigma-(F-o(2))] and R-1 = 0.0381, wR(2) = 0.1180 (for F-o(2)) 2 sigma(F-o(2))) and R-1 = 0.0395, wR(2) = 0.1188 for all data. The structure around the Pt-0 atom was revealed as a slightly squashed tetrahedron surrounded by four phospholylphosphine ligands coordinated through the exocyclic phosphine. The Pt-P distance is 2.237(3) Angstrom. The Pd(L-F)(4) analogue was also isolated in pure form from the reaction of L-F with Pd-2(dba)(3). The related 4-(bis(dimethylamino))2,5-dimethyl-2H-1,2,3 sigma(2)-diazaphosphole (L-N) displaced cod from M(cod)Cl-2 (M = Pd, Pt) to give only the (L-N)(2)-MCl2 complexes (M = Pd and Pt) with no evidence for reduction of the metal center. The larger steric bulk of L-N is presumably also the reason this ligand forms the trans complex instead of the cis complexes which were formed by L-F from the same precursors in analogous reactions. The reaction of L-N With (cod)Pt(Me)Cl produced only cis-(L-N)(2)Pt(Me)Cl; there was no evidence of reduction to Pt-0 in contrast to the behavior of L-F. With L-F, the stereochemistry of the final product was the same as that of the starting material. The third Ligand, 4-(bis(trifluoroethoxy)phosphino)-2,5-dimethyl-2H-1,2,3 sigma(2)-diazaphosphole (L-o) gave the expected platinum cis complex (L-o)(2)MCl2 from the (cod)MCl2 precursor, but palladium rearranged during the complexation reaction to form the trans complex. Again, no evidence for reduction of either Pt or Pd was observed with L-o.