Structural properties of the metallointercalator cationic complex (2,2 ': 6 ',2 ''-terpyridine)methylplatinum(II) ion

The complex [Pt(tpy)(Me)](+) (BPh4)(-) (tpy = 2,2':6',2 "-terpyridine) crystallizes in the triclinic space group <P(1)over bar> with a = 13.463(2) Angstrom, b = 13.618(3) Angstrom, c = 20.151(4) Angstrom, alpha = 73.59(2), beta = 74.56(3), gamma = 65.82(2)degrees and Z = 4. The final conventional R factor is 0.035. In the unit cell a couple of weakly interacting dimers are formed by stack of two [Pt(tpy)(Me)](+) cations in a head-to-tail fashion with intermolecular Pt ... Pt distances of 4.437(1) and 4.931(1) Angstrom, respectively. The absorption spectra of [Pt(tpy)(Me)](+) (BPh4)(-) in acetonitrile show bands assigned to pi-pi* and to MLCT transitions. The analysis of the dependence of the spectra on complex concentration gives a fairly low value for the dimerization equilibrium constant (K-d = 180 +/- 52 M-1 at 298 K). These fluid solutions are not emissive. The room-temperature solid-state emission spectra of the salts [Pt(tpy)(Me)]X are strongly dependent on the counterion (X = BPh4-, Cl-, PF6-, ClO4-, CF3SO3-). The cationic complex shows a considerable stability upon acidification and carbonilation in water.