Platin(II)-Chromophore mit σ-gebundenen Ligatoratomen

Platinum(II) Chromophores with σ-Bonded Ligating Atoms The absorption spectra of the platinum(II) complexes PtL_xL′_4?x (L = NH₃, amine, hydride, alkyl; L′ = trialkylphosphine) consist of three band systems: (i) ligand-field bands, partially of fully screened by more intensive absorptions; (ii) at least three comparatively sharp bands of low to intermediate intensity (? = 400–10000), which are assigned to Rydberg transitions from 5d(Pt) to a linear combination of the (n+1)s-orbitals of the ligands (with a contribution of metal 6s- or 6p-orbitals, respectively); (iii) (only in the case of chromophores with two phosphorus ligands in trans-position) one high intensity band (? = 20000–50000), presumably due to a transition from the asymmetric linear combination of the trans-lying phosphorus lone-pairs to 5d_x2?y2(Pt). There is no evidence of low-lying π-combinations of phorphorus 3d-orbitals in the absorption spectra.