Stable cis-dichloro- and cis-dimethylplatinum(II) complexes bearing bulky primary phosphines, such as BbtPH(2) (Bbt = 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl) and TbtPH(2) (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl), were synthesized and isolated as stable compounds. The treatment of cis-[PtMe2)(PH(2)Bbt)(2)] with lithium diisopropylamide (LDA) followed by the addition of an alkyl halide afforded the corresponding alkylated complexes, cis-[PtMe2(PHRBbt)(PH(2)Bbt)] (R = Me, Et, Bu, etc.). The spectroscopic observation of the intermediacy of the lithiated complex, cis-[PtMe2(PHLiBbt)(PH(2)Bbt)], has been accomplished.