Luminescent platinum(II) complexes. Electronic spectroscopy of platinum(II) complexes of 2,2′:6′,2″-terpyridine (terpy) and p-substituted phenylterpyridines and crystal structure of [pt(terpy)Cl][CF3SO3]

Abstract

The complexes [Pt(terpy)L′]n+ (terpy = 2,2′:6′,2″-terpyridine; L′ = Cl, Br, I, N3 or SCN-, n = 1; L′ = NH3, n = 2) have been prepared and their spectroscopic and emission properties studied. Absorption bands are found at 300-350 and at 370-450 nm, which are assigned to the intraligand and metal-to-ligand change-transfer (m.l.c.t.) transitions, respectively. The complexes [Pt(4′R-terpy)Cl]ClO4 (R′ = C6H4OMe-p,C6H4Me-p, C6H4Br-p or C6H4CN-p) were prepared by the reaction of K2[PtCl4] with 4′R-terpy in water-MeCN. Unlike [Pt(terpy)L′]n+ which show emission in the solid state only, [Pt(4′R-terpy)Cl]+ display 3m.l.c.t. emission in fluid solution at room temperature. The crystal structure of [Pt(terpy)Cl][CF3SO3] has been determined: monoclinic, space group P21/n, a = 13.808(4), b = 6.873(1), c = 19.477(5) Å, β = 105.54(2)°, and Z = 4. In the unit cell, two [Pt(terpy)Cl]+ cations stack in a head-to-tail fashion with an intermolecular Pt ⋯ Pt distance of 3.329(1) Å. The solid-state emission of [Pt(terpy)Cl][CF3SO3] is similar to that of the 3(dσ*πb) emission of the dinuclear complex [Pt2(terpy)2L][ClO4]3 (L = guadinate) having intramolecular Pt ⋯ Pt separations of 3.090(1) and 3.071(1) Å.