Spectroscopic Characterization of Platinum(IV) Terpyridyl Complexes.

Pt(tpy)X [X = Cl (), Br (); tpy = 2,2':6',2″-terpyridine] salts were prepared by the oxidative addition of Pt(tpy)X with X as originally reported by Morgan and Burstall in 1934. The complexes have been fully characterized by H NMR spectroscopy, elemental analysis, mass spectrometry, and X-ray crystallography. The electronic structures of and were investigated using absorption and emission spectroscopy, and the accumulated data are consistent with stabilization of the singlet ligand-centered and potentially singlet ligand field/singlet ligand-to-metal charge-transfer states for and compared to those for Pt(tpy)Cl () and Pt(tpy)Br (). The changes in the lowest-energy-absorbing state result in drastic differences in the emission behavior among -. Specifically, emits from a lowest-energy state that appears to have triplet ligand field/triplet ligand-to-metal charge-transfer character, whereas exhibits no appreciable emission between 400 and 800 nm.