This issue is dedicated to Allan White on the occasion of his 75th birthday. It celebrates his contribution to Australian chemistry through his achievements in inorganic chemistry, and his extensive collaborations.

The chemistry and reactivity of ethyne-1,2-diyl compounds, L_nM–CC–ML_n, is reviewed. These complexes are simple analogues of organic alkynes, or dimetalloalkynes. Reactivity patterns mimic those of simple organic alkynes but have reactive M–C(sp) bonds that sometimes participate in the formation of multimetallic compounds with metal electrophiles.

Reactions of aniline with a copper(ii) sulfate, chloride, or bromide in aqueous solution, yield copper(ii)-aniline complexes, in contrast to previously reported studies, which claimed the formation of copper-polyaniline composites.

Analysis of the lattice contacts of pendent amine, ammonio, and hydroxy groups provides a means of assessing the influence of a proximal metal cation centre on their nucleophilicity and electrophilicity.

Rubidium and caesium orthanilates form chemically stable two-dimensional layered coordination polymeric structures based on stereochemically variable metal centres: six-, seven-, eight- and ten-coordinate in the rubidium complex and seven-coordinate in the caesium complex, these compounds representing rare examples of structurally characterized metal complexes with orthanilic acid.

A multi-component bi-layer complex involving 1,4-bis(triethylammoniomethyl)benzene cation, p-sulfonatocalix[4]arene anion and phosphonium cation shows the preferential binding of the bis-triethylammonium cation in the cavity of two geometrically opposed calixarenes with the same molecular capsules persisting in solution.

Organometallics with various donor–bridge–acceptor arrangements allow investigation of the key factors affecting the properties of these multifunctional molecular systems. Herein, reactions of 7,7,8,8-tetracyanoquinodimethane (TCNQ) with Fe(C≡CR)(dppe)Cp* and Ru(C≡CR)(PPh₃)₂Cp (R = H, Ph) are described. Formed are the mono-cation (by oxidation in the iron series), zwitterionic complexes, and complexes formed by regioselective [2 + 2]-cycloaddition and subsequent ring-opening reactions; elimination of HCN (in the ruthenium series) was also observed.

Reaction of the labile cluster [Os₃(CO)₁₀(NCMe)₂] with 2,2′-benzothiazyl disulfide has been studied. Three new triosmium clusters have been synthesized and structurally characterized from this study.

An X-ray crystallographic study using two different radiation wavelengths was performed on 7-diethylamino-[1',3′,3′-trimethyl-4-((1,3,3-trimethyl-1,3-dihydro-2H-indole-2-ylidene)methyl)-1',3,3′,4-tetrahydrospiro[chromene-2,2'-indole]] crystals obtained from the condensation of two molecules of Fischer’s base with 4-(dimethylamino)salicylaldehyde. No significant deviations between the final models were observed.

Geometry, electron density, and electron localizability properties are used to clarify the nature of unusual hydrogen bonding to the siloxane linkage in a computational study. It is described how the basicity of the siloxane linkage can be significantly increased through variation of the Si–O–Si bond angle and how this is reflected in corresponding indicators of hydrogen bonding.

Reactions of Group 7 dinuclear complexes [M₂(CO)₆(μ-pyS)₂] (M = Mn, Re) with (Ph₃P)₂Ni(CO)₂ have been investigated.

A range of alkaline earth and lanthanoid complexes involving new substituted pyrazolates of the type [M(pz)_x(solv)_y] were prepared. They were structurally and spectroscopically characterized. Also, the first transoid lanthanoid iodo pyrazolate complex, [Ln^II(pz)I(thf)₄], was isolated.

The 2 : 1 tetrahedral complexes of the bidentate diphosphine ligands cis-bis(diphenylphosphino)ethene (dppey), cis-bis(diphenylphosphino)ethane (dppe), and cis-bis(diphenylphosphino)propane (dppp) with copper(i), silver(i), and gold(i) have been synthesized as tetraphenylborate salts and characterized by NMR spectroscopy, electrospray mass spectrometry, and single crystal X-ray structure determinations at 200 K.

Lanthanoid complexes of 5-(2′-pyridyl)tetrazole are unexpectedly isolated as hydrates, despite being crystallized in the presence of dimethyl sulfoxide.

The solution behaviour of nickel complexes of bis(benzimidazolin-2-ylidene)pyridine pincer ligands suggests an equilibrium between four- and five-coordinate complexes.

Quadratic optical non-linearities of gold alkynyl complexes increase on π-system lengthening and on introduction of electron-releasing substituents on the π-bridge ring adjacent to the metal centre, while maximal values of the effective two-photon absorption cross-sections of 1,4-{(PCy₃)Au(C≡C)}₂C₆H₄ and {(PCy₃)Au(C≡C-4-C₆H₄C≡C)}₆C₆ increase non-linearly on proceeding from linear complex to 6-fold-symmetric complex.

2-(Di-2-pyridylamino)pyrimidine forms mononuclear trans-[Fe(NCS)₂(L)₂], [Cu(L)₂(H₂O)](BF₄)₂·H₂O and [PdCl₂(L)] complexes, a dinuclear [(PdCl₂)₂(L)]·¾H₂O complex, and a discrete [Ag₂(L)₄](PF₆)₂ metallomacrocycle. trans-[Fe(NCS)₂(L)₂] undergoes a temperature-dependent spin crossover, which was examined by magnetic and structural measurements.

The evolution of coordination geometries from pentagonal bipyramids to octahedra is caused by the modulation in (1 – x)Ta₂O₅·xAl₂O₃.

Eight square pyramidal copper complexes and four square planar palladium complexes with general structure [Cu(I_L)(A_L)H₂O]²⁺, were synthesised. The crystal structures of [Cu-PHENSS](ClO₄)₂·H₂O and [Cu-56MESS](ClO₄)₂·1.5H₂O are reported. The copper complexes display some anticancer and antibacterial activity. The palladium complexes all have IC₅₀ values of ~10 μM in the L1210 cell line and minimal antibacterial activity.

Members of a family of iron(II) complexes of a dipyridylamino-substituted triazine ligand (DTAC) of formula [Fe(DTAC)₂(anion)₂], display high-spin structural and magnetic features when anion = NCS and NCSe and spin-crossover behaviour when anion = N(CN)₂ and NCBH₃.

Six homo- and heteroleptic bismuth(iii) thiobenzoates of form Ph_3-nBiL_n (n = –3) have been synthesised by solvent-mediated and solvent-free methods. The structures of the compounds derived from thiobenzoic acid have been determined by X-ray crystallography. Bactericidal studies against three strains of Helicobacter pylori show a minimum inhibitory concentration of 6.25 µg mL^–1 for all compounds, indicating that the high activity is independent of ligand type and degree of substitution at the Bi(iii) centre.

Extreme weathering breaks ilmenite, FeTiO₃, into separate, surface-active oxyhydroxides that are prone to gather undesirable contaminants. However, in reduction kilns the most influential ‘contaminant’ may be water, which promotes reactivity and causes ilmenite grains to expand, sometimes to cenospheres. In complex ways, such ilmenite accumulates in unusable sinter.

Structures of oxime derivatives of varying reactivity reveal distortions of bond distances and angles consistent with the early stages of the Beckmann rearrangement.

Two novel trinuclear Cu^II complexes have been synthesised from the nucleophilic addition derivatives of the small nitrile anion, dicyanonitrosomethanide (dcnm).

Two new polyamine ligands, L¹ and L², incorporating pyridyl and aliphatic amine donor sites yield the mono- and binuclear complexes [Cu(L¹)](ClO₄)₂ (1) and [Cl₂Cu(L²)CuCl(H₂O)]ClO₄ (2), respectively, in which the copper ions each exhibit distorted square pyramidal coordination; in binuclear 2 non-equivalent coordination behaviour is present at the individual copper sites.

This communication describes the use of activators regenerated by electron-transfer atom-transfer radical polymerization to synthesize poly(2-hydroxyethyl methacrylate) sponges.

The reaction of N,N-dimethyl-d-proline-dimethylester (Pro(CH₃)₃⁺) with LiTCNQ (TCNQ = tetracyanoquinodimethane) in water resulted in a mixture of crystals, 1 : 1 [Pro(CH₃)₃TCNQ] and 2 : 3 ([(Pro(CH₃)₃)₂(TCNQ)₃]). Each crystal is analysed by X-ray, infrared, Raman and electrochemistry. The electrochemical method provides an exceptionally sensitive method of distinguishing differences in stoichiometry.