Stereochemical Investigation of the Addition of Primary and Secondary Aliphatic Amines to the Nitrile Complexes Cis- and Trans-[Ptcl2(Ncme)(2)]. X-Ray Structures of the Amidine Complexes Trans-[Pt(Nh2Pri)(2){Z-N(H)=C(Nhpri)Me}]Cl-2 Center Dot 4H(2)O and Trans-[Ptcl2(Ncme){E-N(H)=C(Nmebut)Me}]