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The synthesis of C∧C∧P pre-ligands based on a dicyclohexylphosphine-substituted biphenyl framework is reported. The pre-ligands form the respective non-palindromic pincer complexes of Pt II and Pd II via double oxidative addition and subsequent comproportionation or C-H activation. The complexes of Pt II as well as Pd II emit similar green phosphorescence efficiently in the solid state, the former also in solution albeit with less intensity. The most fascinating photophysical feature, however, is a direct singlet-triplet (S 0 → T 1 ) excitation of this phosphorescence in the spectral window between the emission and the major singlet-singlet UV absorption. The S 0 → T 1 excitation spectra show a rich vibronic pattern, which is especially pronounced for the solid samples at cryogenic temperatures. The molar extinction of the lowest-energy singlet-triplet absorption band of the homologous Pt and Pd complexes as well as that of the Pt complex with a different (NHC) ancillary ligand were determined in tetrahydrofuran solutions. Quantum efficiencies of triplet formation (by intersystem crossing) via the "standard" excitation pathway S 0 → S n → T 1 were determined for the Pt complexes and found to be different in dependence of the ancillary ligand.

Orange, transparent crystals of [BMIm] 2 [Mn(CO) 3 (GeI 3 ) 3 ] (BMIm: 1-butyl-3-methylimidazolium) are obtained by reacting GeI 4 , [Mn(CO) 6 ][AlCl 4 ], and Ph 3 GeH in the ionic liquid [BMIm][NTf 2 ]. [Mn(CO) 6 ][AlCl 4 ] and triphenylgermane turn out to be essential as reactive carbonyl precursors and for the reduction of GeI 4 . According to X-ray structure analysis based on single crystals, the title compound exhibits a novel {MnGe 3 } cluster unit with Mn-Ge single bonds and surprisingly short distances (236-241 pm). Although sensitive to oxygen/moisture, the carbonyl compound is stable up to a temperature of 150 °C. Mass spectrometry (MS) shows [Mn(CO) 3 (GeI 3 ) 2 ] - , [Mn(CO) 3 (GeI 3 )I] - , and [GeI 3 ] - as decomposition fragments in the gas phase. In addition to crystal structure analysis and MS, the title compound is characterized by energy-dispersive X-ray spectroscopy (EDXS), thermogravimetry (TG), optical spectroscopy (UV-visible), infrared spectroscopy (FT-IR), and density functional theory (DFT) calculations.