The reaction of the β-diketiminatochlorogermylene L(Cl)Ge {1, L = HC[C(Me)N-2,6-iPr2C6H3]2} with Ru3(CO)12 in molar ratios of 3:1 or 6:1 led to the Ge2Ru complex [L(Cl)Ge]2Ru(CO)3 (3). A speculative GeRu intermediate, L(Cl)GeRu(CO)4, was detected when the reaction was monitored by 1H NMR spectroscopy at elevated temperatures. The formation of this intermediate was supported by similar monitoring of the reaction of L(PhC≡C)Ge (2) with Ru3(CO)12 by 1H NMR spectroscopy and the isolation of a mixture of L(PhC≡C)GeRu(CO)4 (4) and [L(R)Ge]2Ru(CO)3 (5) from this reaction in a molar ratio of 3:1 as well as the clean formation of 5 from such a reaction in a 6:1 molar ratio. Complex 3 reacted with LiHBEt3 through an unusual Cl/Et metathesis to give L(Et)GeRu(CO)4 (6). However, the reaction of 3 with LiN(SiMe3)2 resulted in the base-assisted dehydrochlorination involving one methyl group of each L ligand backbone and the chlorine atom at the Ge center to yield [L′Ge]2Ru(CO)3 {7, L′ = HC[C(Me)N-2,6-iPr2C6H3][C(CH2)N-2,6-iPr2C6H3]}. The further reaction of 7 with a stoichiometric amount of H2O afforded L(HO)GeRu(CO)4 (8) through a 1,4-dipolar addition across the L′Ge functionality. In addition, the reaction of 3 with I2 occurred through an oxidative addition at the Ru center to generate L(Cl)GeRuI2(CO)3 (10).

The reactions of MXCl(PPh3)3 (M = Ru, Os; X = Cl, H) with (C6H3-2,6-Trip2)GeCl (Trip = 2,4,6-iPr3C6H2) have been investigated. Teatment of MXCl(PPh3)3 with (C6H3-2,6-Trip2)GeCl led to the formation of dichlorogermyl chloro or hydrido ruthenium/osmium complexes (PPh3)XMGeCl2(C6H3-2-{η6-Trip}-6-Trip) (M = Ru, X = Cl, 1; M = Os, X = Cl, 2; M = Ru, X = H, 3; M = Os, X = H, 4) through insertion of the germylene into the M–Cl bond followed by η6-coordination of one of the Trip groups of the terphenyl to the Ru/Os center with concomitant dissociation of PPh3 ligands. Noteworthily, the reaction on OsHCl(PPh3)3 also led to the formation of an unexpected minor product Os(H)(PPh2C6H4)GeCl(C6H3-2-{η6-Trip}-6-Trip) (5) containing a diphenylphosphinophenyl-germyl ligand, which is presumably formed by orthometalation of the PPh3 ligand through dehydrochorination in the germylidene intermediate followed by migration of the metalated phenyl group to germanium. Reaction of 1 with PMe3 or treatment of 1 with DMSO in the presence of CuCl as the phosphine scavenger produced the PMe3- or DMSO-substituted derivatives (L)ClRuGeCl2(C6H3-2-{η6-Trip}-6-Trip) (L = PMe3, 6; L = DMSO, 7). The reaction of 1 with LiHBEt3 afforded hydrido ruthenium complex 3, while treatment of 3 with PhCH2MgCl led to benzylation at Ge to give hydrido ruthenium–dibenzylgermyl complex (PPh3)(H)RuGe(CH2Ph)2(C6H3-2-{η6-Trip}-6-Trip) (8).

An efficient Rh(III)-catalyzed direct ortho-C–H olefination of acetanilides with vinyl acetate was developed. This protocol provides a straightforward pathway to a series of (E)-2-acetamidostyryl acetates, giving access to indole derivatives following a simple hydrolysis/cyclization process.

A copper-catalyzed aminobenzannulation of (o-alkynyl)arylketones with amines has been developed. This method features the use of a cheap copper catalyst, the facile annulation involving various amines, and the good functional group tolerance.

An unusual Rh/Cu-catalyzed synthesis of pyrido[2,1-a]indoles starting from 1-(pyridin-2-yl)-1H-indoles and γ-substituted propargyl alcohols was presented. The multi-step cascade transformations formally involve the cleavage of two C–H, three C–C, and one C–N bonds with concomitant construction of two C–H, four C–C, and one C–N bonds with excellent chemoselectivity in one-pot reaction.

A silver nitrate-mediated, efficient phosphorylation of benzothiazoles and thiazoles with diarylphosphine oxides was developed. This process provides a convenient route for the synthesis of a variety of 2-diarylphosphoryl benzothiazoles and thiazoles which are promising precursors of a series of hemilabile P,N-ligands with small bite angles.

The first examples of half-sandwich boratabenzene ruthenium complexes have been prepared and well-characterized. Treatment of RuCl2(PPh3)3 with the anionic boratabenzene ligands C5H5BORNa (R = Et, Me) produced the B-alkoxy complexes (η6-C5H5BOR)RuCl((PPh3)2 (R = Et, 1a; Me, 1b), while the reaction of RuCl2(PPh3)3 with the neutral borabenzene–PPh3 adduct C5H5BPPh3 led to the formation of the dinuclear complex (μ2-η6,η6-C5H5BOBC5H5)[RuCl(PPh3)2]2 (2), with an oxo-bis(boratabenzene) bridging ligand connected by the B–O–B linkage. The B-hydroxy complex (η6-C5H5BOH)RuCl(PPh3)2 (3) was obtained from the nucleophilic substitution of complexes 1a, 1b, or 2 with water at the boron atoms, and the complexes 1a, 1b, 2, and 3 could interconvert through the nucleophilic substitution reactions. While the reaction of 1a with phenylacetylene did not successfully afford the vinylidene complex as expected, reactions of 1a with terminal ω-alkynols HC≡C(CH2)nCH(R)OH (R = H, n = 1, 2; R = Me, n = 1) proceeded smoothly to provide the neutral oxacyclocarbene complexes (η6-C5H5BOEt)RuCl(═CCH2CH2CH2O)(PPh3) (4), (η6-C5H5BOEt)RuCl(═CCH2CH2CH2CH2O)(PPh3) (5), and (η6-C5H5BOEt)RuCl(═CCH2CH2CH(Me)O)(PPh3) (6) via intramolecular nucleophilic attack of the hydroxyl group to the corresponding vinylidene intermediates.

The Rh(III)-catalyzed C–H activation initiated cyclization of benzoic acids with electron-rich geminal-substituted vinyl acetates was described. The reaction was employed to prepare a range of 3-aryl and 3-alkyl substituted isocoumarins selectively.

An efficient and practical method for the construction of 2-aryl- and 2-alkyl-substituted benzothiazoles via a copper-catalyzed redox condensation process between benzothiazoles and aldehydes or benzylic alcohols has been developed. The reaction proceeded under mild reaction conditions using environmentally benign tert-butyl hydroperoxide (TBHP) as the oxidant. A reaction mechanism involving the ring-opening of benzothiazoles initiated by the attack of acyl radical on the thiazole ring and intramolecular condensation is proposed based on the isolation of an anilide disulfide intermediate.

A half-sandwich 1,2-azaborolyl (Ab) ruthenium complex, (Ab–CCPh)RuCl(PPh3)2 (1), has been synthesized by treating RuCl2(PPh3)3 with lithium 1,2-azaborolide L-1, or by treating either RuCl2(PPh3)3 or RuHCl(PPh3)3 directly with 1,2-azaborole LH-1. It is evaluated as a suitable precatalyst in [2 + 2] cycloadditions of norbornene derivatives with DMAD and in atom transfer radical additions of halogenated compounds with olefins.

The η2-alkene coordinated α,β-unsaturated ketone complex Os(CHC(PPh3)C(O)-η2-CHCH2)Cl2(PPh3)2 (3) is very stable even at elevated temperature due to the strong steric hindrance effect of PPh3 ligands. However, compound 3 in a chloroform solution can be almost quantitatively converted into the corresponding osmafuran [OsCl(CO)(PPh3)2(CHC(PPh3)C(CH3)O)]Cl (6) via hydrolysis of the η2-coordinated olefin under photochemical conditions. Osmafuran 6 has been characterized by single crystal X-ray diffraction analysis, NMR spectroscopy and elemental analysis data. The UV-induced reaction provides a new highly efficient method for preparation of osmafurans by hydrolysis of η2-α,β-unsaturated ketone complexes.The η2-alkene coordinated α,β-unsaturated ketone complex 1 which is very stable even at elevated temperature can be converted to the corresponding osmafuran 2 almost quantitatively by ultraviolet irradiation. This new highly efficient method for the preparation of osmafurans via photochemically assisted hydrolysis of η2-α,β-unsaturated ketone complexes, presents an addition to previous synthetic approaches.

Treatment of osmabenzene [Os(CHC(PPh3)CHC(PPh3)CH)Cl2(PPh3)2]OH (3) with various diisocyanides in the presence of NH4PF6 afforded a series of diisocyanide-bridged bisosmabenzenes [(μ-CN−R−NC){Os(CHC(PPh3)CHC(PPh3)CH)Cl2(PPh3)}2][PF6]2 (R = 4,4′-C6H4-C6H4 (5a), 4,4′-C6H4CH2C6H4 (5b), 4,4′-C6H4OC6H4 (5c), 1,4-C6H4 (5d)) in good yields through ligand substitution reactions. Similarly, reaction of osmafuran [Os(CHC(PPh3)C(OEt)O)Cl2(PPh3)2] (6) with 1,4-phenylenediisocyanide produced the diisocynide-bridged bisosmafuran [μ-(1,4-phenylenediisocyanide){Os(CHC(PPh3)C(OEt)O)Cl(PPh3)2}2]Cl2 (7). Bisosmabenzenes containing a chloro and a phosphonium substituent on each metallacycle [(μ-CN−R−NC){Os(CHC(PPh3)CHCClCH)Cl(PPh3)2}2]Cl2 (R = 4,4′-C6H4-C6H4 (9a), 4,4′-C6H4CH2C6H4 (9b), 4,4′-C6H4OC6H4 (9c), 1,4-C6H4 (9d)) could be obtained in modest yields from the reactions of the osmacycle [Os(CH═C(PPh3)CH(OH)-η2-C≡CH)Cl2(PPh3)2] (8) with corresponding diisocyanides in the presence of NH4PF6 and NaCl via nucleophilic addition reactions. All of these complexes have been fully characterized by 1H, 31P{1H}, and 13C{1H} NMR spectrometry, IR spectrometry, and elemental analyses. Moreover, the structure of 9d has been established by X-ray crystallography. The electrochemical properties of stable bisosmabenzenes 9a−d have been investigated, which revealed that the two metal centers in 9c and 9d can interact with each other through a diisocyanide bridge.

The study on the reactivity of an osmium-coordinated alkyne alcohol complex OsCl2(CH═C(PPh3)CH(OH)-η2-C≡CH)(PPh3)2 (1) has been carried out. Treatment of 1 with acetic acid, ethylene diamine, 2,2′-bipyridine, trimethylphospine, or tributylphosphine led to the formation of several coordinated η2-α,β-unsaturated ketone osmacycles, including OsCl2(CH═C(PPh3)C(O)-η2-CH═CH2)(PPh3)2 (3), [OsCl(CH═C(PPh3)C(O)-η2-CH═CH2)(PPh3)(H2NCH2CH2NH2)]Cl (4), [OsCl(CH═C(PPh3)C(O)-η2-CH═CH2)(PPh3)(2,2′-bipy)]Cl (5), OsCl2(CH═C(PPh3)C(O)-η2-CH═CH2)(PMe3)2 (6), [OsCl(CH═C(PPh3)C(O)-η2-CH═CH2)(PMe3)3]Cl (8), and OsCl2(CH═C(PPh3)C(O)-η2-CH═CH2)(PBu3)2 (9). Similar chemistry was also observed starting from OsBr2(CH═C(PPh3)CH(OH)-η2-C≡CH)(PPh3)2 (10), which afforded OsBr2(CH═C(PPh3)C(O)-η2-CH═CH2)(PPh3)2 (11) on treatment with acetic acid. All these cyclic α,β-unsaturated ketone complexes are air-stable in the solid state, and most of them are also stable in solution except for OsCl2(CH═C(PPh3)C(O)-η2-CH═CH2)(PMe3)2 (6) and [OsCl(CH═C(PPh3)C(O)-η2-CH═CH2)(PMe3)3]Cl (8). Complex 8 can isomerize to the osmaphenol [OsCl(CHC(PPh3)C(OH)CHCH)(PMe3)3]Cl (12) as the major product in dry chloroform, but transforms into the osmafuran [Os(CO)(CHC(PPh3)C(CH3)O)(PMe3)3]Cl2 (13) in wet chloroform, while complex 6 is stable in dry solvent, but can convert to the osmafuran [OsCl(CO)(CHC(PPh3)C(CH3)O)(PMe3)2]Cl (14). The remarkable thermostability and chemical stability of the coordinated α,β-unsaturated ketone osmacycles have been studied preliminarily with 3 as a representative example. The coordinated α,β-unsaturated ketone metallacyclic framework of 3 is stable in different ligand environments. For example, treatment of 3 with carbon monoxide led only to ligand substitution to produce OsCl2(CH═C(PPh3)C(O)-η2-CH═CH2)(CO)(PPh3) (15).

The synthesis and characterization of an air-stable p-osmaphenol and some related complexes are presented.

A silver nitrate-mediated, efficient phosphorylation of benzothiazoles and thiazoles with diarylphosphine oxides was developed. This process provides a convenient route for the synthesis of a variety of 2-diarylphosphoryl benzothiazoles and thiazoles which are promising precursors of a series of hemilabile P,N-ligands with small bite angles.

An unusual Rh/Cu-catalyzed synthesis of pyrido[2,1-a]indoles starting from 1-(pyridin-2-yl)-1H-indoles and γ-substituted propargyl alcohols was presented. The multi-step cascade transformations formally involve the cleavage of two C–H, three C–C, and one C–N bonds with concomitant construction of two C–H, four C–C, and one C–N bonds with excellent chemoselectivity in one-pot reaction.

A half-sandwich 1,2-azaborolyl (Ab) ruthenium complex, (Ab–CCPh)RuCl(PPh3)2 (1), has been synthesized by treating RuCl2(PPh3)3 with lithium 1,2-azaborolide L-1, or by treating either RuCl2(PPh3)3 or RuHCl(PPh3)3 directly with 1,2-azaborole LH-1. It is evaluated as a suitable precatalyst in [2 + 2] cycloadditions of norbornene derivatives with DMAD and in atom transfer radical additions of halogenated compounds with olefins.