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We report the solution and structural chemistry of nickel(ii) complexes of the phosphine-oxime Ph2PC6H4-2-CH=NOH (PCH=NOH). PCH=NOH invariably binds in a bidentate manner as illustrated by cis-Ni(PCH=NOH)2Cl2 and cis-[Ni(PCH=NOH)2]2+ (as its BF4− salt). Treatment of PCH=NOH with Ni(OAc)2(H2O)4 gave charge-neutral trans-[Ni(PCH=NO)2]0. Treatment of trans-[Ni(PCH=NO)2]0 with BF3 gave [Ni(PCH=NO)2BF2]BF4. The cation features a planar NiP2N2 center wherein the pair of oximate groups are linked by the difluoroboryl center. The 1 : 1 complexes of the oxime and the oximate are illustrated by [Ni(PCH=NOH)Cl2]2 and [Ni(C6F5)(PCH=NO)]2, which feature five- and four-coordinate Ni(ii) centers, respectively. All complexes in this series hydrolyze to give the trinickel oxo-phosphine-oximate complex [Ni3(PCH=NO)3O]+. One feature of the PCH=NOH ligand is its wide bite angle combined with its protic OH center. These aspects are manifested in the structures of Ni(PCH=NOH)2Cl2 and [Ni(PCH=NOH)Cl2]2, which show intramolecular hydrogen bonding to terminal chloride ligands. [ABSTRACT FROM AUTHOR]

The reduction of diferrous dithiolates with hydride reagents gives a new approach to an active site model for a vital intermediate. The terminal hydride reacts with Bronsted acids to give H2, in contrast to the nonreactivity of the isomeric mu-H compounds and the new synthetic approach is applicable to other diferrous dithiolates, including those bearing cyanide ligands.

The first example of H2 addition to hydrogenase model and the first dihydrogen complex of a hydrogenase active site model are presented. Experiments demonstrate that diruthenium dithiolates oxidatively add H2 and that the resulting dihydrido species can be protonated to form a dihydrogen complex.

The condensation of iron carbonyl sulfides, formaldehydes and amines to give the proposed azadithiolate cofactor of the Fe-only hydrogenases is detailed. Fe2(SCH)2(CO)6 efficiently condenses with formaldehyde in the presence of primary amines to give the corresponding azadithiolates on addition of diiron complex to a premixed THF solution of paraformaldehyde and the amine at 0 degree centigrade following warming at room temperature.

It has been established that quite basic analogues of the Fe-only hydrogenases can be effective catalysts for the reduction of protons to dihydrogen, starting with protonation at the Fe-Fe bond. The Fe-hydrogenases are believed to bind protons at a single Fe centre, but this catalyst protonates at the metal-metal bond.

Research describing the chemical characteristics of the reactions of dihydrogen activation by homolytic and heterolytic methods is presented. Particular attention is given to descriptions of homolytic activation and to the use of iridium sulfide.

Research investigating the chemical influence that cyanide has on the carbonylation process of iron is presented. Particular attention is given to reactions of carbonylation of iron salts and to determining the role of cyanide in stabilizing low-spin iron.

A structure for the binuclear center of the Fe-only hydrogenases was proposed. The series Fe2(SMe)2-(CO)6-n(CN)n(super n-) were the targets of initial preparative efforts. Solutions of Fe2(SMe)2(CO)6(super 9) in methanol or acetonitrile reacted in minutes with Et4NCN to give exclusively Fe2(SMe)2(CO)4(CN)2(super 2-). The results showed that the electron-rich species Fe2(S2C3H6)2(CN)2(CO)4(super 2-) bore a structural and stoichiometric resemblance to the Fe-only hydrogenases.

A study using spectroscopic and crystallographic analyses found that the ligands' metal and the C2S4 subunits are involved in the redox cycle of an M2C2S4 subunit. It was also observed that the redox properties of M2C2S4 core induce further development of reaction centers based on the M2C2S4 core. Electrochemical analysis show that the C2S4 complex can easily be affected by condensation processes that may trigger novel bonding modes for C2S4.

A study is conducted on the behavior of metal sulfide catalysts used in processing unsaturated organic compounds. Results show that adding excess bis(trimethylsilyl)acetylene, (TMS)2C2 to an MeCN solution of ReS4- caused a rapid reaction as indicated by the loss of the violet color of the thioanion. Golden crystals of (PPh4)(sub2) also precipitated in the case of the Ph4P+ salt of ReS4-.

Experiments were performed to investigate the synthesis, structure and reactivity of the iron sulfide triamine 1,4,7-triazacyclononane (TACN). An insoluble black species resulted from the sulfidation reaction between FeCl3(TACN) and Na2S.9H20. The utilization of TACN instead of Cp resulted to a metal sulfido complex that facilitated the analysis of the [(TACN)M]nSy series. The reactivity characteristics of molecular iron sulfido complexes may allow the formation of new iron sulfido clusters.

Solvatothermal synthesis techniques have successfully employed preformed C4Sx precursors in the creation of well-defined carbon sulfide polymers. The condensation of (PPh4)2C4Sx (x~5) with MeCN solvent at a temperature of 90 degrees centigrade created one of the polymers. Other research is discussed. Further research would confirm that solvatothermal techniques would be applicable to carbon sulfide polymer synthesis using a range of carbon sulfido precursors.