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}]Cl2.4H2O and trans-[PtCl2(NCMe)

The reactions of cis-[PtCl2(NCMe)2] with a 5-fold excess of the primary aliphatic amines RNH2 (R = Me, Et, Pri, But) in CH2Cl2 at 10 °C afford in high yield the bis-amidine complexes cis-[PtCl2{Z-N(H)=C(NHR)Me} 2], where both the amidine ligands assume the Z configuration. The corresponding reactions of trans-[PtCl2(NCMe)2] with RNH2 (R = Me, Et, But) give a mixture of the bis-amidine trans-[PtCl2{Z-N(H)=C(NHR)Me}2] and the mono-amidine trans-[PtCl2(NCMe){Z-N(H)=C(NHR)Me}] derivatives, which could be isolated as pure products operating with a platinum nitrile complex:amine molar ratio of 1:50 or 1:1, respectively. The reaction of trans-[PtCl2(NCMe)2] with a 50-molar excess of PriNH2 affords the bis- amidine bis-amine dicationic complex trans-[Pt(H2NPri)2{Z-N(H)=C(NHPri)Me} 2]Cl2, which has been characterized also by X-ray diffraction analysis. The reactions of cis- and trans-[PtCl2(NCMe)2] with the secondary aliphatic amines R'R NH yield the bis-amidine complexes cis- and trans- [PtCl2{E-N(H)=C(NR'R)Me}2] (R', R = Et) and/or cis- and trans-[PtCl(NCMe) {E-N(H)=C(NR'R)Me}2] (R', R = Et; R' = Me, R = But), where the amidine ligands have the E configuration. The compound trans-[PtCl2(NCMe){E-N(H)=C (NMeBut)Me}] has been characterized by single crystal X-ray diffraction. All the complexes have been characterized by IR, 1H and 13C NMR spectroscopies. The Z or E configuration of the amidine ligand can be readily deduced by 1H NMR data.