NUCLEOPHILIC ATTACK OF AMINE AND HYDROXYDE TO PLATINUM DIBENZONITRILE DICHLORIDE. CRYSTAL STRUCTURE OF (2) AND cis-<Pt(NH=CPhN-t-BuCH2CH2NH-t-Bu)Cl2(NCPh)(3)

Article abstract of DOI:10.1021/ja00266a011

The trans and cis isomers of react with N,N'-di-tert-butylethylenediamine (t-Bu2en) under normal conditions to give (1) and cis- 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, (2).Compound 3 exhibits, in solution, isomerization about the azomethine double bond (ΔG₂₂₃^<*> = 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 (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) Angstroem, b = 11.351(8) Angstroem, c = 9.338(5) Angstroem, β = 92.03(4)deg, and Z = 4.Compound 3 crystallizes as toluene solvate (2:1) in the monoclinic space group P2₁/a with a = 18.090(10) Angstroem, b = 9.376(4) Angstroem c = 17.297(7) Angstroem, β = 91.76(4)deg, 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.