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 P1̄ with a=13.463(2) Å, b=13.618(3) Å, c=20.151(4) Å, α=73.59(2), β=74.56(3), γ=65.82(2)° 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) Å, respectively. The absorption spectra of [Pt(tpy)(Me)]+(BPh4)− in acetonitrile show bands assigned to π–π* 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 (Kd=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.