Pt–M (M = Au and Tl) Dative Bonds Using Bis(cyclometalated)platinum(II) Complexes

Symmetrical and unsymmetrical biscyclometalated platinum(II) complexes [Pt(ptpy) 2 ], 1, and [Pt(ptpy)(bppy)], 2, in which ptpy = deprotonated 2-(p-tolyl)pyridine and bppy = deprotonated 2-(3-bromophenyl)pyridine, have been prepared from the reaction between tris(pentafluorophenyl)borane, B(C 6 F 5 ) 3 and 1 equiv of monocyclometalated complexes [PtMe(ptpy)(ptpyH)], B, and [PtMe(ptpy)(bppyH)], C, respectively. The solid-state structures of 1 and 2 have been determined by X-ray crystallography. The reaction of 1 with 1 equiv of TlPF 6 or [Au(PPh 3 )]OTF resulted in the production of heteronuclear complexes [Pt(ptpy) 2 Tl]PF 6 , 3 and {Pt(ptpy) 2 [Au(PPh 3 )]}OTF, 4, respectively. X-ray diffraction data showed that in solid state, complex 4 exists as a mixture of supported and unsupported Pt II -Au I -bonded structures, whereas complex 3 consists of an infinite helical chain structure built up by unsupported Pt-Tl dative bonds. Absorption, emission, and NMR spectroscopy data showed that both Pt-Tl and Pt-Au bonds in 3 and 4 have dynamic behavior. The low-temperature 1 H, 31 P{ 1 H}, and exchange spectroscopy NMR of 4 revealed two dynamic behaviors involving the rupture of the Au-C ipso bond as well as the dissociation-association of the [Au(PPh 3 )] + and Pt(ptpy) 2 fragments. All complexes displayed bright emission in the solid state, and their absorption and emission properties have been investigated both experimentally and by time-dependent density functional theory calculations