Substituent effects in pyridyl-functionalized pyrylium salts, pyridines and λ,σ-phosphinines: a fundamental and systematic study.

A series of substituted, pyridyl-functionalized 2,4,6-triarylpyrylium salts were prepared and investigated for their light absorption and emission properties. After reaction with P(SiMe3)3, the corresponding λ3-phosphinines were obtained, which carry on the 4- or 6-aryl ring ±I and ±M substituents. Supported by DFT calculations, a systematic evaluation of the σ-donor and π-donor as well as π-acceptor properties of these low-coordinate P,N-hybrid ligands was performed.

Functional polyoxometalates from solvothermal reactions of VOSO with tripodal alkoxides - a study on the reactivity of different "tris" derivatives.

We report a study on the structure directing effects of functional groups and counterions. The aim was to find a facile and high yielding synthetic procedure to obtain polyoxometalate (POM) building blocks for post-functionalisation. Therefore, solvothermal reactions of VOSO with various tris(hydroxymethyl)methane derivatives in alkaline methanolic solutions were investigated.

Pyridyl-functionalised 3H-1,2,3,4-triazaphospholes: synthesis, coordination chemistry and photophysical properties of low-coordinate phosphorus compounds.

Novel conjugated, pyridyl-functionalised triazaphospholes with either tBu or SiMe3 substituents at the 5-position of the N3 PC heterocycle have been prepared by a [3+2] cycloaddition reaction and compared with structurally related, triazole-based systems. Photoexcitation of the 2-pyridyl-substituted triazaphosphole gives rise to a significant fluorescence emission with a quantum yield of up to 12 %. In contrast, the all-nitrogen triazole analogue shows no emission at all.

Bis-N-heterocyclic Carbene Aminopincer Ligands Enable High Activity in Ru-Catalyzed Ester Hydrogenation.

Bis-N-heterocyclic carbene (NHC) aminopincer ligands were successfully applied for the first time in the catalytic hydrogenation of esters. We have isolated and characterized a well-defined catalyst precursor as a dimeric [Ru2(L)2Cl3]PF6 complex and studied its reactivity and catalytic performance. Remarkable initial activities up to 283,000 h(-1) were achieved in the hydrogenation of ethyl hexanoate at only 12.

Synthesis and photoluminescence properties of an unprecedented phosphinine-Cu₄Br₄ cluster.

A hitherto unprecedented polynuclear phosphinine-Cu(I) complex has been prepared and crystallographically characterized. The molecular structure in the crystal verifies the presence of the heterocubane-type tetrameric cluster [LCuBr]4 (L = 2,4-diphenyl-5-methyl-6-(2,3-dimethylphenyl)phosphinine), which unexpectedly shows in the solid state temperature-independent orange phosphorescence solely from an (3)XMLCT state, in clear contrast to the well-established dual-emissive-state model for luminescent Cu4X4L4 clusters.

Tuning the electronic effects of aromatic phosphorus heterocycles: an unprecedented phosphinine with significant P(π)-donor properties.

A hitherto unprecedented electronic situation has been observed for a substituted, pyridyl-functionalized phosphinine. In contrast to previous studies, this compound shows considerable π-donor properties as the result of the rather strong +M effect of the CH3S-substituent, changing the electronic properties of this low-coordinate and aromatic phosphorus heterocycle substantially.

2,4,6-Triarylphosphinines versus 2,4,6-triarylpyridines: an investigation of the differences in reactivity between structurally related aromatic phosphorus and nitrogen heterocycles.

The novel atropisomeric pyridine derivative rac-10 has been synthesized and structurally characterized. In contrast to its phosphorus analogue 3, axially chiral 10 has a considerably lower rotational barrier as estimated by DFT calculations. However, the presence of the two enantiomers could be confirmed by means of chiral analytical HPLC analysis and by protonation experiments with a chiral acid.