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(CCPh)2]PF6·H2O (dppm = Ph2PCH2PPh2) has been determined: triclinic, space group P, Z= 2, a= 11.146(4), b= 14.512(2), c= 20.322(3)A, α= 81.55(1), β= 101.27(2), γ= 109.35(2)°. The complex cation consists of a square-planar P–Pt(CCPh)2–P and a linear P–Au–P moiety and the measured intramolecular Pt–Au separation is 2.910(1)A. The absorption and emission spectra of the complex and of [AgPt(dppm)2(CCPh)2]PF6 and trans-[Pt(dppm)2(CCPh)2] have been measured. Both dinuclear complexes possess low-energy intense electronic absorption bands {[AuPt(dppm)2(CCPh)2]PF6, λmax= 387 nm, Iµmax= 1.11 × 104 dm3 mol–1 cm–1; [AgPt(dppm)2(CCPh)2]PF6, λmax= 368, Iµmax= 1.63 × 104 dm3 mol–1 cm–1} which are red-shifted from that of trans-[Pt(dppm)2(CCPh)2]. In solid form, all three complexes exhibit photoluminescence at room temperature. Extended-Huckel molecular orbital calculations have been performed on the model complexes [AuPt(dmpm)2(CCPh)2]+ and trans-[Pt(dmpm)2(CCPh)2](dmpm = Me2PCH2PMe2).