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Structural aspects of crystalline hydrated polyborate salts containing polyborate anions partnered with either cationic transition-metal complexes or non-metal (organic) cations are documented. The structures are described in terms of Christ and Clark's and Burns’ descriptors. The review, which concentrates on the period 2000–2015, also describes synthetic approaches (hydrothermal, solvothermal, flux methods) and physical and spectroscopic properties of the polyborate salts.

Single crystals of [Co(en)3][B5O6(OH)4] [B8O10(OH)6]·5H2O are prepared by addition of B(OH)3 to a H2O/MeOH solution of [Co(en)3][OH]3 (gentle warming, 3 h; 41% yield).

The title compound is synthesized by addition of en in MeOH to B(OH)3 in H2O (20 °C, 48 h, 6% yield).

The air/moisture-sensitive triarylborthiins, Ar3B3S3 (Ar = 4-MeC6H4, 3-MeC6H4, 2-MeC6H4, 4-EtC6H4, and 3,5-Me2C6H3), have been prepared by the reaction of ArBBr2 With HgS in benzene at reflux and have been characterized by 11B NMR and IR spectroscopy and mass spectrometry. The substituted aryl derivatives are less air-stable than Ph3B3S3, and in air significantly decompose to boron-oxygen species within minutes; the approximate order of air-stability is (Ar =) Ph > 3,5-Me2C6H3 > 4-EtC6H4 > 4-MeC6H4 > 3-MeC6H4 > 2-MeC6H4· ArBBr2 compounds have been prepared by the reaction of ArHgBr with BBr3; their 11B, 13C, and 1H NMR data are presented. NMR (13C, 1H) data are also reported for the ArHgBr species prepared by reaction of ArMgBr with HgBr2.

The synthesis and characterisation (m.p., elemental analysis, IR, NMR) of some previously unreported Me3B3O3. L adducts (L=piperidine, isobutylamine, morpholine, 3-picoline, benzylamine) are described. The crystal and molecular structure of (Me3B3O3NH2Bu)-Bu-i . MeB(OH)(2) has been determined by a single-crystal X-ray diffraction study. The structure reveals an unusual H-bond interaction between MeB(OH)(2) and a ring O atom of the six-membered B3O3 ring of the trimethylboroxine adduct, Me3B3O3. (NH2Bu)-Bu-i. The direction of the H-bond strongly suggests sp(2) hybridisation for this O atom. The Lewis acidity of Me3B3O3, Ph3B3O3, 1,3,5-Ph3B3N3Me3 and 1,3,5-Ph3C6H3 have been estimated by Gutmann's method and data interpreted in terms of relative K-bonding strength within these ring systems.

By screening a library of metalloenzyme inhibitors, the N-formyl-hydroxylamine derivative BB-3497 was identified as a potent inhibitor of Escherichia coli peptide deformylase with antibacterial activity both in vitro and in vivo. The homochiral synthesis of BB-3497, involving a novel asymmetric Michael addition reaction is described.

Stoichiometric reagents for the control of the absolute stereochemistry of new chiral centres produced during reactions involving carbon-carbon bond formation are described. Chiral iron acyl reagents act as chiral equivalents of a variety of carbonyl functionalities and their potential for asymmetric synthesis can be illustrated for pseudopeptides, amino acids, P-lactams, y-lactams and lactones. A simple methodology based on arene chromium tricarbonyl chemistry allows the elaboration of benzylic chiral centres with complete control over the absolute stereochemistry. This may be illustrated, for example, by the conversion of amphetamine derivatives into pseudoephedrines.

Te2Ph2 (II) reacts with the tetramers (Ia) and (Ib) to yield the binuclear compounds (III).

Thermolysis of [6,6,6-(PMe2Ph)3-6-H-nido-6-ReB9H12-9-(OEt)](1) in C2D2Cl4 solution gives the new, pale yellow air-stable compound [2,2,2-(PMe2Ph)3-2,2-H2-nido-2-ReB8H11](2) in 80% yield. Crystals of the CH2Cl2 hemisolvate of (2) are monoclinic, space group P21/c, with a= 1 130.0(3), b= 1 292.2(3), c= 2 424.0(5) pm, β= 94.15(2)°, and Z= 4; the molecular structure was refined to R= 0.0399, R′= 0.0454. The detailed n.m.r. behaviour of compound (2) together with data for previously reported rhodium and iridium analogues permits the location of the substituent site on previously unconfirmed [2-(CO)-2,2-(PMe3)2-nido-2-IrB8H10-3-Cl] and thence provides information on mechanistic pathways for the formation of these and related metallaboranes. Detailed n.m.r. data for the non-metalla analogues [B9H12]– and previously unassigned [3-ClB9H11]– provide information on their mechanism of formation and a comparison with the metallaborane analogues. The n.m.r. work includes extensive use of [11B–11B]-COSY and [1H–1H]-COSY experiments and establishes general points.

In urine, after oral doses of phendimetrazine to man, were found unchanged drug, the N-demethylated metabolite, phenmetrazine, and the N-oxide of phendimetrazine, but not N-hydroxyphenmetrazine; the metabolites were identified using t.l.c. and g.l.c. The stability of the drug and its metabolites in biological fluids and in ether was studied. A gas chromatographic procedure for the quantitative determination of unchanged drug, its N-oxide and phenmetrazine in urine, plasma and saliva was developed, the N-oxide being reduced before analysis.

Dimethyl(methylthio)arsine, AsMe2(SMe)(L), is a potentially ambidentate ligand with the possibility of arsine and/or sulphur co-ordination to a transition metal. We have investigated the reaction of the ligand for the scission of the tetrameric trimethylplatinum halides, and that for carbon monoxide displacement from the rhenium pentacarbonyl halides. In both of these reactions organic arsines and sulphides individually are known to be effective, producing well characterised stable products. Ligand L reacts with [(PtXMe3)4](X = Cl, Br, or I) and with [ReX(CO)5](X = Cl, Br, or I) to yield respectively fac-[PtXMe3L2] and fac-[ReX(CO)3L2] in good yield. Hydrogen-1 and 13C n.m.r. studies demonstrate that in all complexes the ligand behaves in a monodentate manner with exclusively arsenic–metal bonds. In solution the compounds give no indications of any fluxional behaviour in the temperature range –80 to +80°C. The fac structure of all of these complexes gives rise to the interesting observation that all three methyl groups in the co-ordinated ligand AsMe2(SMe) are non-equivalent.