The scope and variety of sulfur-nitrolgen rings become more comprehensible on adopting the coordination number of sulfur as a classification principle. In compounds of two-coordinate sulfur (and nitrogen) the π-electrons are largely delocalized; the coordination number and bond length can be correlated in some compounds of sulfur with higher coordination number.

The design of entirely new syntheses, and the classification and documentation of structures, substructures, and reactons are examples of new applications of computers to chemistry. The starting point is a mathematical model of constitutional chemistry based on the extension of the concept of isomerism to ensembles of molecules.

The feasibility of simultaneous multielement determinations is one of the particular advantages of activation analysis. This trace analytical method can detect many elements and isotopes at concentrations below the ppb level.

Selective removal of an ester group from the completely protected nucleoside 3′-phosphate (2) by electrochemical reduction solves a serious problem of nucleotide synthesis. Reaction (2) → (3) requires a potential of −0.5 V; (2) → (1) can be accomplished by acid hydrolysis. At −1.2 V the remaining ester groups are removed from (1).

Lasalocid (X-537 A) (1), an ionophoric antibiotic, complexes both biogenic amines and inorganic cations. It has now been established that Na⁺ and serotonin bimaleate, 3-hydroxytyramine, or L-norepinephrine compete for binding to (1).

Two Pt and three H atoms, together with four PPh₃ groups, make up the cation of complex (1), RPh, which can be isolated as yellow, air-stable crystals. The remarkable structure was elucidated by NMR spectroscopy.

Aza-analogues of the antiaromatic cyclopentadienyl cations are present in the salts (1) and (2). The antiaromatic character of the azacations is weaker than that of the parent cation; the donor groups contribute to stabilization.

Cleavage of the CoCo bond in the complex is feasible without disrupting the binuclear structure. Thus a Lewis acid, e.g. CF₃COOH, and a Lewis base. e.g. PMe₃, can be added successively to (1).

Rotation within the linear group can be hindered by substituents; the first example is bis(dimethyltriptycenyl)ethyne (1), R_iR_aCH₃. Stuart-Briegleb space-filling models do not reproduce this effect.

The cyclopentacyclononene derivative (3). the first compound to contain this ring system and also the first stable cyclononatetraene not to have an annelated benzene ring, has been synthesized from the “ethanoazulene” (1). This synthesis is possible because azulene reacts readily with the ynamine (2), to give the tricyclic species (4). Although 4,6,8-methylazulene initially gives the desired ring system (5), immediate transannular bonding occurs. The bracket in (1) prevents this reaction.

The cyclopentacyclononene derivative (3). the first compound to contain this ring system and also the first stable cyclononatetraene not to have an annelated benzene ring, has been synthesized from the “ethanoazulene” (1). This synthesis is possible because azulene reacts readily with the ynamine (2), to give the tricyclic species (4). Although 4,6,8-methylazulene initially gives the desired ring system (5), immediate transannular bonding occurs. The bracket in (1) prevents this reaction.

A facile entry to cycloheptenones and cyclopentanones is provided by the new cyclization reagent (1). Examples are the synthesis of Karahanaenone (2) from isoprene, and of(±)-α-cuparenone (4), R = p-CH₃C₆H₄, from 1-isopropenyl-4-methylbenzene.

Liberation of aldehydes RCHO from dithiane oxides (1) can be accomplished by transformation into the salts (3) and their cleavage with water. The reaction sequence (1)→(3) → RCHO is milder than the usual cleavage of (1) with acid.

Dynamic bond switching at π-hypervalent sulfur has now been demonstrated. (1) and (2) rapidly equilibrate; this reaction involves the thiathiophtheneanalogous system (3).

An insight into the mode of reaction of nitrile ylides such as (1) has come from the study of their intramolecular cyloaddition to double bonds. The formation of (2a) and (2b) in the ratio 9:1 is assessed as indicating a synchronous mechanism (RpCL—C₆H₄).

Five different bonding states of sulfur are found in complex (1). It is a further example of the importance of S ligands in the stabilization of unusual coordination compounds of transition metals.

A new synthetic unit for phosphorus-carbon compounds has been discovered in the symmetrical “carbodiphosphorane” (2). It forms a 1:1 salt with HCL, and a dioxide (via elimination of RCL) with alcohols ROH.

The simplest dienylketene-phenol rearrangement has been achieved by vacuum flash thermolysis of sorboyl chloride at 6 × 10⁻⁵ torr/660°C. Other dienylketenes can also be generated under these conditions.