Platinum-Modified Nucleobase Pairs in the Solid State: A Theoretical Study

We present a theoretical study of a mixed adenine−thymine crystal complex of trans - a 2 Pt(II) ( a = CH 3 NH 2 ) with Watson−Crick orientation of the bases, experimentally studied by Krizanovic et al. ( J . Am . Chem . Soc . 1993, 115, 5538). Calculations are based on density functional theory with gradient-corrected exchange-correlation functionals. The results for the structural parameters compare well with X-ray data. The electronic structure near the gap exhibits the characteristic features of a square planar platinum(II) complex with π-acceptor ligands. Comparison with parallel calculations of the nonmetalated base pair helps clarify the role of the trans - a 2 Pt(II) moiety.