The metathesis reaction of LiP(SiR 3 )Ar* (R = iPr and Ph; Ar* = Mes and Tipp) with Ph 2 POCl yields Ar*(R 3 Si)P−P(O)Ph 2 . These diphosphane monoxides can be observed by NMR spectroscopy. However, they are intrinsically instable, and 1,3-trihydrylsilyl migration leads to the formation of 1λ 5 -diphosphenes of the type Ar*PP(OSiR 3 )Ph 2 with very large characteristic 1 J(P,P) coupling constants. A very short PP bond has been observed for the 1λ 5 -diphosphene TippPP(OSiPh 3 )Ph 2 . These 1λ 5 -diphosphenes are only stable in the crystalline state but degrade in solution to Ph 2 P−O−SiR 3 via elimination of the Ar*P: phosphinidenes which form secondary degradation products such as triaryl-cyclotriphosphanes. Formation of the 1λ 5 -diphosphene TippPP(OSiPh 3 )Ph 2 via 1,3-trihydrylsilyl migration from P to O and the fate due to PP bond cleavage has been verified by theoretical studies.

The reaction of LiP(H)Tipp (2a) and KP(H)Tipp (2b, Tipp = C6H2‐2,4,6‐iPr3), which are accessible via metalation of Tipp‐PH2 (1), with bis(4‐tert‐butylphenyl)phosphinic chloride yields Tipp‐P=P(OM)Ar2 [M = Li (3a) and K (3b)]. These complexes show characteristic chemical 31P shifts and large 1JPP coupling constants. These compounds degrade with elimination of the phosphinidene Tipp‐P: and the alkali metal diarylphosphinites M–O–PAr2 [M = Li (4a) and K (4b)]. The phosphinidene forms secondary degradation products (like the meso and R,R/S,S‐isomers of diphosphane Tipp‐P(H)–P(H)Tipp (5) via insertion into a P–H bond of newly formed Tipp‐PH2), whereas the crystallization of [Tipp‐P=P(OLi)Ar2·LiOPAr2·LiCl·2Et2O]2 (i.e. [3a·4a·LiCl·2Et2O]2) succeeds from diethyl ether. The metathesis reactions of LiP(SiiPr3)Tipp and LiP(SiiPr3)Mes (Mes = C6H2‐2,4,6‐Me3) with Ar2P(O)Cl yield Ar*‐P=P(OSiiPr3)Ar2 (Ar* = Mes, Tipp) which degrade to Ar2POSiiPr3 and other secondary products.

A pair of visible laser beams self-trap and spiral about each other as they propagate through polymer gels undergoing two different photochemical reactions. When launched into gels that undergo photopolymerization of methacrylate substituents or photo-oxidation of iodide anion, two non-coplanar (skewed) Gaussian beams collide and spiral about each other as they advance through the evolving medium. In the absence of chemical reactions, the linearly polarized beams broaden naturally and propagate along their original, straight-pathed trajectories. By contrast, refractive index gradients generated by the photochemical reactions elicit self-trapping and introduce an attractive interaction between the self-trapped beams. The self-trapped beams spiral about each other when this mutual attraction perfectly counterbalances their original tendency to diverge away from each other. These findings show that the photochemically mediated interactions of incident optical fields within the gel medium impart a helical trajectory and angular velocity to the self-trapped beam pair.

Potassiation of amidines and triazenes yields the corresponding potassium amidinates and triazenides. The favored configuration of the amidinate ligands is the (syn-E)-form whereas all known triazenides adopt this isomeric form. Extremely bulky groups at the amidinate ligands enforce the anticonfiguration stabilized by π-interactions between potassium and N-bound aryl groups. A special case has been observed for N′-bound 2-pyridylethyl substituents. In moderately strained [a]