SPECTROSCOPIC STUDIES OF CYCLO-METALATED PT(II) COMPLEXES - SPECTROSCOPIC EVIDENCE OF STRONG INTERCOMPLEX COUPLING IN SINGLE-CRYSTAL [PT(2,2'-BIPYRIMIDINE)(CN)2].DMF

The optical properties (polarized absorption and emission) of single crystal [Pt(bpm)(CN)2]·DMF under variation of temperature (1.9 K ≤T≤295 K) and homogeneous magnetic fields (0≤H≤ 6 T) are reported. When the magnetic field strength is raised from H=0 to 6 T, the low-temperature emission is blue shifted by 220 cm-1, the intensity increases by a factor of ∼27, and the lifetime is reduced from τ=1.8 ms to 15 μs. The spectroscopic results are explained on the basis of the crystal structure of [Pt(bpm)(CN)2]·DMF, which exhibits columns of [Pt(bpm)(CN)2] complexes with a nearly face-to-face arrangement and relatively short PtPt distances (∼3.28 Å), yielding a distinct inter-complex coupling. Crystallographic data for [Pt(bpm)(CN)2]·DMF: monoclinic, space group P21/m, a=10.702(2), b =6.518(1), c=10.700(2) Å,β=95.57(2)°, V=742.86 Å3, Z=2, Dc=2.14g cm-3, μ(Mo Kα)=95.5 cm-1, R=0.069, Rw=0.056 for 113 variables and 3497 reflexes with I > 3σ(I). © 1990.