Nucleophylic attack of amine and hidroxide to platinum-dichlorobenzonitrile. Crystal structure of [Pt(NH=CPhNButCH2CH2NHBut)Cl(NHCOPh)], 2, and cis [Pt(NH=CPhNButCH2CH2NHBut)Cl2(NCPh)], 3

The trans and cis isomers of [PtCl2(NCPh)2] react with N,N′-di-tert-butylethylenediamine (t-Bu2en) under normal conditions to give [Pt(NH=CPhN-t-BuCH2CH2NH-t-Bu)Cl(NCPh)]Cl (1) and cis-[Pt(NH=CPhN-t-BuCH2CH2NH-t-Bu)Cl2(NCPh)] (3), respectively. In both cases one end of t-Bu2en adds to benzonitrile forming an amino-amidine ligand which is chelated in 1 (forming a seven-membered metallacycle) and monocoordinated in 3. The residual benzonitrile in the cationic complex 1 readily reacts with base to give a benzamidate species, [Pt(NH=CPhN-t-BuCH2CH2NH-t-Bu)Cl-(NHCOPh)] (2). Compound 3 exhibits, in solution, isomerization about the azomethine double bond (Δ‡223 = 10.8 ± 0.3 kcal mol-1) and more slowly undergoes an internal rearrangement with substitution of the residual benzonitrile by the uncoordinate end of the diamine and formation of [Pt(NH=CPhN-t-BuCH2CH2NH-t-Bu)Cl2] (4). The structures of 2 and 3 have been solved by single-crystal diffraction. Compound 2 crystallizes as methanol solvate (1:1) in the monoclinic space group P21/n with a = 25.374 (13) Å, b = 11.351 (8) Å, c = 9.338 (5) Å, β = 92.03 (4)°, and Z = 4. Compound 3 crystallizes as toluene solvate (2:1) in the monoclinic space group P21/a with a = 18.090 (10) Å, b = 9.376 (4) Å, c = 17.297 (7) Å, β = 91.76 (4)°, and Z = 4. Both compounds contain a strong intramolecular hydrogen bond which involves the oxygen atom of the benzamidate anion and the cis amine group of the chelate amino-amidine ligand in 2, the free and coordinate ends of the monocoordinate amino-amidine ligand, so forming a pseudo-seven-membered ring, in 3