Isolation of an Unusual Deprotonated Form of o-Aminobenzylidene: An Intermediate in the Template Condensation of o-Aminobenzaldehyde with Platinum(II)

Article abstract of DOI:10.1021/ja00534a026

The isolation and characterization of the platinum complex of the dimeric condensate of o-aminobenzaldehyde, an intermediate en route to the tetraaza macrocyclic ligand obtained from the teramerization of o-aminobenzaldehyde, are described.Deep purple cis-chloroplatinum, Pt(AAA)Cl, crystallizes in the space group P2₁/c with unit cell dimensions a = 15.771 (2) Angstroem, b = 6.950 (1) Angstroem, c = 18.718 (3) Angstroem, and β = 121.43 (1) deg.The immediate coordination sphere of the platinum consists of two nitrogens and the aldehyde oxygen from the dimerization of o-aminobenzaldehyde plus, at the fourth site, a chloride ion.Two different Pt-N bonds of 1.93 (2) and 1.99 (1) Angstroem are observed, the former associated with the terminal amine,along with Pt-O and Pt-Cl bonds of 2.01 (1) and 2.309 (5) Angstroem, respectively.Bonds length and angles are indicative of electron delocalisation within the inner chelate ring of the o-aminobenzylidene moiety, a result of the unexpected deprotonated terminal amine.Pt(AAA)Cl further reacts to give the fully closed teraaza macrocyclic complex.