The divalent lanthanide borohydrides [Ln(BH(4))(2)(THF)(2)] (Ln = Eu, Yb) have been prepared in a straightforward approach. The europium compound shows blue luminescence in the solid state, having a quantum yield of 75%. Nonradiative deactivation of C-H and B-H oscillator groups could be excluded in the perdeuterated complex [Eu(BD(4))(2)(d(8)-THF)(2)], which showed a quantum yield of 93%. The monocationic species [Ln(BH(4))(THF)(5)][BPh(4)] and the bis(phosphinimino)methanides [{(Me(3)SiNPPh(2))(2)CH}Ln(BH(4))(THF)(2)] have been prepared from [Ln(BH(4))(2)(THF)(2)]. They show significantly lower or no luminescence. Using the diamagnetic compound [{(Me(3)SiNPPh(2))(2)CH}Yb(BH(4))(THF)(2)], we performed a 2D (31)P/(171)Yb HMQC experiment.

The [4+2] cycloaddition reaction between 2-pyrone and Me Si-C≡P gives the corresponding 2-(trimethylsilyl)-λ -phosphinine in good yields as a rather air and moisture stable, colorless oil. Insight into the regioselectivity of the pericyclic reaction was obtained with the help of deuterium-labeling experiments. The silyl-phosphinine acts as a ligand for the preparation of a Cu(I) and the first crystallographically characterized phosphinine-Ag(I) complex. The title compound was further used as a starting material for an alternative preparation of the parent phosphinine C H P by means of protodesilylation with HCl. C H P reacts with CuBr⋅S(CH ) to give an infinite Cu(I)Br coordination polymer. DFT calculations shed light on the influence of the -Si(CH ) group on the electronic properties of the aromatic phosphorus heterocycle.

This highlight review provides an overview of recent developments in the chemistry of pyridyl-functionalized λ 3 σ 2 -phosphinines and 3H-1,2,3,4-triazaphospholes. The access to novel chelating, low-coordinate phosphorus heterocycles can lead to a much broader scope for potential applications. New developments in areas such as homogeneous catalysis, molecular materials, and supramolecular chemistry can consequently be foreseen in the near future.

The facile access to 3-bromo-2-pyrone allows the preparation of 6-bromo-2-trimethylsilyl-phosphinine by a [4+2] cycloaddition with Me3 Si-C≡P for the first time. The regioselectivity of this reaction could be verified by means of single crystal X-ray diffraction of the corresponding W(0) complex. In the presence of ZnBr2 and dppp (1,3-bis(diphenylphosphino)propane) as a bidentate ligand, the bromo-phosphinine quantitatively undergoes a Negishi cross-coupling reaction with PhLi that selectively leads to 6-phenyl-2-trimethylsilyl-phosphinine. This heterocycle could again be characterized by means of X-ray diffraction as a W(0) complex. These results describe a new and convenient route to 2,6-disubstituted phosphinines that makes use of readily available starting materials.

Arsaalkynes can undergo regioselective and quantitative [3+2] cycloaddition reactions with organic azides to give hitherto unknown 3H-1,2,3,4-triazaarsole derivatives. The reaction product was obtained as a white, air- and moisture-stable solid, and the presence of a planar, five-membered arsenic heterocycle was unambiguously verified by means of X-ray crystallography. DFT calculations gave insight into the electronic structure of these novel compounds compared to tetrazoles and triazaphospholes. The coordination chemistry towards Re(I) was investigated and compared with the structurally related phosphorus-containing ligand. These preliminary investigations pave the way for a new class of arsenic heterocycles and fill the gap between the azaarsoles already known.