Colin L. Raston

Reaction of sodium p-sulfonatocalix[4]arene and yttrium or europium trichloride in aqueous solution at pH ca. 3 results in the formation of a skewed calixarene dimer that encapsulates solvent water molecules. Two aquated sodium atoms bridge between the calixarenes via sulfonate groups, and a terminal aquated rare earth is bound to another sulfonate group on each calixarene.

Kröhnke type pyridines are readily accessible via a sequential solventless aldol condensation and Michael addition involving solid NaOH, followed by treatment with ammonium acetate in acetic acid, as a one pot reaction, which enables both symmetrical and unsymmetrical 2,6-bisaryl substituted pyridines to be isolated in high yield, typically >75%.

Reaction of RECl₂ (R⁻ = C(SiMe₃)₂(6-Me-2-pyridyl)⁻, E = P or As) with LiAlH₄ in THF affords directly bonded aluminium hydride–pnictide hydride complexes as weakly associated hydride bridged dimers, [RE(H)–Al(H)₂]₂; a strong solvent dependency of these reactions, which had previously been observed with the formation of the disecondary diphosphane in Et₂O (E = P), is further confirmed by the formation of RAsH₂ from RAsCl₂ and LiAlH₄ in Et₂O.

The reaction of the dimeric diethyl ether solvated lithium amide, bis[{2-(6-methyl)pyridyl}trimethylsilylamidolithium dietherate], with two equivalents of arsenic(III) trichloride in diethyl ether affords the amido arsenic dichloride compound [{2-(6-Me)C₅H₃N}NSiMe₃(AsCl₂)] (1), while four equivalents of arsenic(III) trichloride in diethyl ether gives the complex [{2-(6-Me)C₅H₃N}N(AsCl₂)₂] (3) through the cleavage of the N–Si bond. This compound is also isolated from the redistribution reaction of the previously reported compound [{2-(6-Me)C₅H₃N}NAsCl]₂ (2) with two equivalents of AsCl₃ in toluene. The crystal structure of (3) shows it to be monomeric with two geminal AsCl₂ groups. One arsenic centre has pyramidal geometry with the other four-coordinate arsenic centre having distorted trigonal bipyramidal geometry with the putative lone pair of electrons occupying an equatorial position. Homoleptic triamido–antimony and –bismuth complexes are prepared from the 2∶3 stoichiometric reaction of MCl₃ (M = Sb, Bi) and dimeric lithium amide. The amide nitrogen centres are coordinated fac to the metal centre with each ligand chelating the metal giving it six-fold coordination. The M–N(amide) bonds are much shorter than the M–N(pyridyl) bonds, suggestive of a putative lone pair of electrons intersecting the [N(pyr)]₃ plane. This gives the molecule a distorted octahedral shape with a non-crystallographic C₃ axis.