Luminescent heterobimetallic complexes. Electronic structure and spectroscopy of [MPt(dppm)2(C≡CPh)2]PF6 (M = Au or Ag) and crystal structure of [AuPt(dppm)2(C≡CPh)2]PF6 (dppm = Ph2PCH2PPh2)

Abstract

The crystal structure of [AuPt(dppm)2(C≡CPh)2]PF6·H 2O (dppm = Ph2PCH2PPh2) has been determined: triclinic, space group P1, Z = 2, a = 11.146(4), b = 14.512(2), c = 20.322(3) Å, α = 81.55(1), β = 101.27(2), γ = 109.35(2)°. The complex cation consists of a square-planar P-Pt(C≡CPh)2-P and a linear P-Au-P moiety and the measured intramolecular Pt-Au separation is 2.910(1) Å. The absorption and emission spectra of the complex and of [AgPt(dppm)2(C≡CPh)2]PF6 and trans-[Pt(dppm)2(C≡CPh)2] have been measured. Both dinuclear complexes possess low-energy intense electronic absorption bands {[AuPt(dppm)2(C≡CPh)2]PF6, λmax = 387 nm, εmax = 1.11 × 104 dm3 mol-1 cm-1; [AgPt(dppm)2(C≡CPh)2]PF6, λmax = 368, εmax = 1.63 × 104 dm3 mol-1 cm-1} which are red-shifted from that of trans-[Pt(dppm)2(C≡CPh)2]. In solid form, all three complexes exhibit photoluminescence at room temperature. Extended-Hückel molecular orbital calculations have been performed on the model complexes [AuPt(dmpm)2(C≡CPh)2]+ and trans-[Pt(dmpm)2(C≡CPh)2] (dmpm = Me2PCH2PMe2).