The reaction of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson's Reagent) with two different Grignard reagents gave the corresponding dithiophosphinic acids (DTPA), CH3OC6H4-(R)P(S)SH; [R = iso-butyl (HL1) and sec-butyl (HL2)]. HL1 and HL2 were treated with dry ammonia to convert them to the ammonium salts, NH4L1 and NH4L2. Ni(II) and Co(II) complexes of L-1 and L-2 - [Ni(L-1)(2)], [Ni(L-2)(2)]; [Co(L-1)(2)](2) and [Co(L-2)(2)](2)-were obtained by the reaction of NH4L1 and NH4L2 with NiCl2 center dot 6H(2)O and CoCl2 center dot 6H(2)O, respectively, in ethanol. Square-planar nickel complexes [Ni(L-1)(2)] and [Ni(L-2)(2)] were further reacted with pyridine (Py) to obtain the octahedral complexes, [Ni(Py)(2)(L-1)(2)] and [Ni(Py)(2)(L-2)(2)]. The compounds were characterized by elemental analysis, FTIR, APCI/ESI-MS and H-1, C-13, and P-31 NMR spectroscopies. The novel nickel(II) complex [Ni(L-2)(2)] was characterized by X-ray crystallography.