Monometallic and Bimetallic Platinum Complexes with Fluorinated β-Diketiminate Ligands

Presented here are complexes of two different fluorinated beta-diketiminate (NacNac) ligands with cyclometalated platinum. Reaction of the cyclometalated platinum dimers [Pt(C(sic)N)(mu-X)](2) [C(sic)N = 2-phenylpyridine (ppy), 2-(2,4-difluorophenyl)pyridine (F(2)ppy); X = Cl, Br] with lithium salts of backbone-fluorinated beta-diketiminate ligands produces two structure types, depending on the temperature of the reaction. At milder temperatures (< 80 degrees C), the major product is an unusual halide-bridged diplatinum complex, demonstrating a unique NacNac binding mode bridging the two platinum centers. At higher temperatures (> 100 degrees C), the major species is a monoplatinum complex of the type Pt(C(sic)N)(NacNac). The complexes display reduction waves in their cyclic voltammograms at mild potentials, as well as intense visible absorption bands (lambda > 500 nm), that depend minimally on the identity of the C(sic)N ligand or, in the case of the bimetallic complexes, the identity of the bridging halide. In addition, the monoplatinum complexes exhibit structured luminescence in the red and near-infrared regions deriving a NacNac-centered triplet state. All of these observations suggest that the NacNac pi system contributes substantially to the frontier orbitals and motivates continued exploration of fluorinated beta-diketiminate ligands in the design of complexes with desirable ligand-based redox and optical properties.