Electronic absorption and MCD spectra for Pt(AuPPh3)8(2+) and Au(AuPPh3)8(3+) cluster complexes in poly(methyl methacrylate) thin films at 295 and 10 K

Electronic absorption and 8 T magnetic circular dichroism (MCD) spectra are reported for nitrate salts of Pt(AuPPh3)8(2+) and Au(AuPPh3)8(3+) in poly(methyl methacrylate) (PMM) thin films at 295 and 10 K in the vis-UV region from 1.6 to 3.6 microm(-1) (1 microm(-1) = 10(4) cm(-1). Enhanced resolution is observed at low temperature, especially for Pt(AuPPh3)8(2+), which emphasizes the differences in the nature of the low-energy excited configurations and states between Pt(AuPPh3)8(2+) and Au(AuPPh3)8(3+). The absorption and MCD spectra for Pt(AuPPh3)8(2+) are interpreted in terms of a combination of excitations from filled Pt 5d orbitals to empty Au framework 6s orbitals and intraframework Au8(2+) (IF) transitions, whereas the spectra for Au(AuPPh3)8(3+) are ascribed entirely to Au IF transitions.