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The reactions of nickelocene with the neutral square-planar metal dithiolene complexes [M(S2C2(R¹)(R²))2] gave the η⁵-cyclopentadienyl nickel(III) dithiolene complexes [CpNi(S2C2(R¹)(R²))] (R¹, R² = Ph (2); R¹ = Ph, R² = H (3); R¹, R² = Me (4)) in 58−62% yields. The monoanions of the square-planar dithiolene complexes [M(S2C2(R¹)(R²))2]^- reacted with nickelocenium to form [CpNi(S2C2(R¹)(R²))] (R¹, R² = COOMe (5) or CN (6)) in 67% or 68% yield, respectively, when the R¹ and R² substituents are electron-withdrawing groups. The CpNi dithiolene complexes 3 and 5 were also obtained by the thermal reactions or photoreactions of nickelocene with 1,3-dithiol-2-one or 1,3-dithiol-2-thione derivatives, [E&dbd;C(S2C2(R¹)(R²))] (E = O, S; R¹ = Ph, R² = H; R¹, R² = COOMe). The most efficient synthetic method for the CpNi dithiolene complex was the reaction of the hexacoordinated platinum dithiolene complex [Pt(S2C2Ph2)2(dppe)] (dppe = bis(diphenylphosphino)ethane) with nickelocene (96% yield for complex 2). The structure of complex 6 was determined by X-ray crystal structure analysis. The electronic and ESR properties of the CpNi dithiolene complexes 2−6 were investigated.

The crystal structures of LaGaO3, LaGa0.9Mg0.1O2.95, and La0.9Sr0.1Ga0.9Mg0.1O2.9 have been investigated by high-temperature neutron powder diffraction in order to clarify a mechanism for high oxide ion conduction properties in LaGaO3-based compounds. Parent phase LaGaO3 crystallized in the orthorhombic (Pbnm) up to 150 °C and the rhombohedral (R&thremacr;c) at between 160 and 800 °C. LaGa0.9Mg0.1O2.95 crystallized in the orthorhombic (Ibmm) up to 340 °C and the rhombohedral (R&thremacr;c) at between 350 and 800 °C. On the other hand, La0.9Sr0.1Ga0.9Mg0.1O2.9 crystallized in the monoclinic (I2/a) up to 400 °C and the rhombohedral (R&thremacr;c) at between 410 and 800 °C. The correlations between the crystal structures and conduction properties of LaGaO3-based materials were discussed on the basis of the analytical results.

Some 16-electron pentacoordinated iridium dithiolene complexes were synthesized by the reactions of [Cp*Ir(Cl)(μ-Cl)]2 (Cp* = C5Me5) with 1,3-dithiol-2-one derivatives. The iridium dithiolene complex [Cp*Ir{S2C2(COOMe)2}] (1) reacted with ethyl diazoacetate or (trimethylsilyl)diazomethane to give the 1:1 alkylidene adducts of iridium dithiolene complexes [Cp*Ir{S2C2(COOMe)2}(CHR)] (R = COOEt (3a), SiMe3 (3b)), respectively. The structures of complexes 3a,b were determined by X-ray crystal structure analyses:  the COOEt unit of complex 3a is located at the exo position with respect to the iridadithiolene ring, and the SiMe3 group of complex 3b is located at the corresponding endo position with respect to the same ring. In solution, the endo (3b-1) and exo (3b-2) isomers of complex 3b were observed. In an electrochemical investigation, the oxidized species of the exo isomer (3b-2⁺) was isomerized to the stable endo isomer (3b-1⁺). The reaction of complex 1 with diazomethane gave the novel 2:2 methylene adduct of a binuclear iridium dithiolene complex [Cp*Ir{S2C2(COOMe)2}(CH2)][Cp*Ir{SC2(COOMe)2S}(CH2)] (4). This complex 4 has a five-membered iridadithiolene ring and a six-membered iridacycle. The dimeric complex 4 was also formed from the desilylation of the monomeric complex 3b with TBAF. The complex (5a) that includes a six-membered iridacycle [Cp*Ir{SC2(COOMe)2S}(CHCOOEt)(P(OMe)3)] was obtained by the reaction of the alkylidene-bridged complex 3a with trimethyl phosphite. The reactions of complex 3b with HCl gave [Cp*Ir(Cl){S(SCH2SiMe3)C2(COOMe)2}] (6b) due to Ir−C bond cleavage.

Various types of cobaltadithiolene complexes having the sulfilimine structure CpCo[S(NTs)SC2(COOMe)2](PR3) were newly synthesized. The lifetimes of the sulfilimine complexes are influenced by the basicities and by the cone angles of PR3 ligands used. Some of the sulfilimine complexes rapidly eliminate PR3 ligands by a one-electron reduction (PR3 = PPh3, P(OPh)3, P(p-C6H4Me)3, P(p-C6H4Cl)3, PCy3, P(p-C6H4OMe)3) to give the precursor of the sulfilimine complex, the imido-bridged cobaltadithiolene adduct [CpCo{S2C2(COOMe)2}(NTs)]. On the other hand, the complexes of PBu3 and P(OMe)3 were stable during a one-electron reduction. The elimination of the imido group (NTs) by a second reduction was confirmed in all of the sulfilimine complexes. The investigation of the reactivity of the sulfilimine complexes showed that some of the sulfilimine complexes were the intermediates in the imido migration to the Cp ring (PR3 = PPh3, P(OPh)3, P(p-C6H4Me)3, P(p-C6H4Cl)3). The basicities (or nucleophilicities) of PR3 were important parameters for the imido migration. Sulfilimine complexes containing strongly nucleophilic PR3 ligands (PR3 = P(p-C6H4OMe)3, PBu3, P(OMe)3) did not undergo migration of the imido group. In the formation of the disubstituted Cp complex [{C5H3(NTs)(PR3)}Co{S2C2(COOMe)2}], the basicity (or nucleophilicity) of PR3 ligands is also an important parameter (PR3 = PPh3, P(p-C6H4Me)3).

The crystal structures of lanthanum gallate perovskite compounds, LaGaO3, LaGa0.8Mg0.2O2.9, and La0.8Sr0.2Ga0.8Mg0.2O2.8 which is well-known as a superior oxide ion conductor, have been analyzed by neutron powder diffraction to clarify the effect of the substitutions on the perovskite structures. The crystal structure of Mg²⁺-substituted LaGaO3, LaGa0.8Mg0.2O2.9, belongs to the same orthorhombic space group, Pbnm, as that of LaGaO3, and the oxygen vacancies were found to be created at the planar O2 atom sites of GaO6 octahedron. On the other hand, the crystal structure of doubly Sr²⁺- and Mg²⁺-substituted LaGaO3, La0.8Sr0.2Ga0.8Mg0.2O2.8, belongs to the cubic space group Pm&thremacr;m and the oxygen vacancies were found to be in disorder. The distortion in the perovskite structures and the oxide ion conduction mechanism are discussed on the basis of the analytical results, together with the results of X-ray diffraction and total conductivity up to 800 °C.

The mechanism of phosphine- and phosphite-induced migration of the imido group from sulfur to a Cp ring in a tosylimido-bridged cobaltadithiolene complex was investigated, and a probable intermediate was isolated and characterized. The presence of a large excess of PPh3 causes the formation of the imido- and phosphine-substituted Cp complex.