Synthesis, Structure, and Reactivity of Molybdenum- and Tungsten-Indane Complexes with Tris(pyrazolyl)borate Ligand.

The reaction of molybdenum complexes with a tris(pyrazolyl)borate ligand (Et4N[TpMo(CO)3] and Et4N[Tp*Mo(CO)3] (Tp = hydridotris(pyrazolyl)borate, Tp* = hydridotris(3,5-dimethylpyrazolyl)borate)) and InBr3 at a 1:1 molar ratio afforded molybdenum-indane complexes (Et4N[TpMo(CO)3(InBr3)] 1 and Et4N[Tp*Mo(CO)3(InBr3)] 2). In addition, tungsten-indane complexes, Et4N[TpW(CO)3(InBr3)] 3 and Et4N[Tp*W(CO)3(InBr3)] 4, were obtained by the reaction of corresponding tungsten complexes. Complex 4 reacted with H2O to form the hydrido complex Tp*W(CO)3H, in which the W-In bond was cleaved. On the other hand, 4 reacted with three equiv. of AgNO3 to form Et4N[Tp*W(CO)3{In(ONO2)}] 5, in which three substituents on the In were exchanged while retaining the W-In dative bond. Complexes 1-5 were fully characterized using NMR measurements and elemental analyses, and the structures of 1-5 and Et4N[Tp*W(CO)3] were determined via X-ray crystallography. These are the first examples of mononuclear molybdenum- and tungsten-indane complexes with Mo-In and W-In dative bonds.

Synthesis and Characterization of Phosphinecarboxamide and Phosphinecarbothioamide, and Their Complexation with Palladium(II) Complex.

Reactions of isocyanates/isothiocyanates with primary and secondary phosphines without solvent at room temperature afforded phosphinecarboxamide/phosphinecarbothioamide, respectively, in excellent yields. Furthermore, palladium complex Pd(COD)Cl2 was allowed to react with Ph2PC(O)NHPh (1a) to afford [Pd{Ph2PC(O)NHPh-κP}2Cl2] (3). On the other hand, the reaction of Pd(COD)Cl2 with 1 eq. of Ph2PC(S)NHPh (2a) afforded [PdCl2{Ph2PC(S)NHPh-κP,S}] (4). In the case of a 1:2 molar ratio, [PdCl{Ph2PC(S)NHPh-κP,S}{Ph2PC(S)NHPh-κP}]Cl (5) was formed. The newly obtained compounds were fully characterized using multielement NMR measurements and elemental analyses. In addition, the molecular structures of Ph2PC(O)NH(CH2)2Cl (1j), Ph2PC(S)NHPh(4-Cl) (2c), and 3-5 were determined using single-crystal X-ray diffraction.

Iridium-Catalyzed Aerobic Coupling of Salicylaldehydes with Alkynes: A Remarkable Switch of Oxacyclic Product.

The iridium(III)/copper(II)-catalyzed dehydrogenative coupling of salicylaldehydes with internal alkynes proceeds efficiently under atmospheric oxygen through aldehyde C-H bond cleavage and decarbonylation. A variety of benzofuran derivatives can be synthesized by the environmentally benign procedure. DFT calculations suggest that this unique transformation involves the facile deinsertion of CO in the key metallacycle intermediate, which is in marked contrast to the corresponding rhodium(III) catalysis that leads to CO-retentive chromone derivatives.

Selective Double Addition Reaction of an E‒H Bond (E = Si, B) to a C≡N Triple Bond of Organonitriles.

The catalytic double hydrometalation such as hydrosilylation and hydroborylation of organonitriles has attracted considerable attention because the obtained products are widely used in organic synthesis and it is thought to be one of the effective methods for reduction of organonitriles. However, the examples of these reactions are quite limited to date. This paper summarizes the development of selective double hydrosilylation, double hydroborylation, and dihydroborylsilylation of organonitriles, including their reaction mechanisms and the role of the metal species in the catalytic cycle.

Selective Double Hydroboration and Dihydroborylsilylation of Organonitriles by an Iron-indium Cooperative Catalytic System.

Organonitriles (RC≡N) were selectively converted into the corresponding diborylamines (RCH2N(Bpin)2) in reactions with pinacolborane (pinBH) in the presence of a catalytic amount of the iron-indium complex [Fe(CH3CN)6][cis-Fe(CO)4(InCl3)2]. The catalytic reaction mechanism was tentatively proposed. In addition, this catalytic system was found to be applicable for the synthesis of borylsilylamine in high yield when organonitrile was treated with hydroborane and hydrosilane simultaneously.

Selective boryl silyl ether formation in the photoreaction of bisboryloxide/boroxine with hydrosilane catalyzed by a transition-metal carbonyl complex.

Selective B-O-Si bond formation was achieved in the reaction of bisboryloxide O(Bpin)2 (pin = (OCMe2)2)/boroxine (MeBO)3 system with tertiary silane R3SiH in the presence of stoichiometric water and a catalytic amount of [M](CO)5 ([M] = Mo(CO), W(CO), Fe) to give boryl silyl ethers. Moreover, this reaction can be applied to various hydrosilanes (disilyl compounds and secondary silanes) and hydrogermane. Some of the boryl silyl ethers thus formed were confirmed by X-ray analysis.

Selective dehydrogenative silylation-hydrogenation reaction of divinyldisiloxane with hydrosilane catalyzed by an iron complex.

A hydride and a silyl group of hydrosilane is introduced into 1,3-divinyldisiloxane in the presence of a catalytic amount of (η(5)-C(5)H(5))Fe(CO)(2)Me. Instead of the product expected from the well-known hydrosilylation reaction, the product obtained is that characteristic of dehydrogenative silylation at one vinyl group and hydrogenation at the other vinyl group of 1,3-divinyldisiloxane. Based on deuterium labeling experiments, a catalytic cycle for this new reaction has been proposed.

Regioselective double hydrophosphination of terminal arylacetylenes catalyzed by an iron complex.

The first catalytic double hydrophosphination of alkynes was achieved by reaction with diarylphosphines in the presence of an iron catalyst. The double hydrophosphination proceeded regioselectively and effectively for various secondary arylphosphines and terminal alkynes to give 1,2-bisphosphinoethane derivatives.

Convenient synthesis of phosphinecarboxamide and phosphinecarbothioamide by hydrophosphination of isocyanates and isothiocyanates.

Reactions of isocyanates with primary and secondary phosphines without solvent at room temperature afforded the corresponding phosphinecarboxamide (RN(H)COPR'2) in excellent yields. This reaction system is applicable for isothiocyanates. The compounds newly obtained were fully characterized using multielement NMR spectroscopy. In addition, the molecular structure of Cl(CH2)2N(H)COPPh2 was studied by single-crystal X-ray diffraction.

N-CN bond cleavage of cyanamides by a transition-metal complex.

N-CN bond cleavage of cyanamides (R(2)N-CN) has been attained at room temperature in the reaction of R(2)N-CN with Cp(CO)(2)Fe(SiEt(3)). The mechanistic investigation revealed that silyl migration from Fe to CN nitrogen of cyanamide gave an N-silylated eta(2)-amidino iron complex, which was isolated and characterized by X-ray analysis. Catalytic N-CN bond cleavage was also attained using a methyl molybdenum complex under thermal conditions.

Iron-catalyzed dehydrogenative coupling of tertiary silanes.

A variety of tertiary silanes, even those with functional substituents, undergo an unprecedented iron-catalyzed dehydrogenative coupling (see scheme) in a convenient approach to disilanes, including unsymmetrical disilanes and polymers with Si-Si bonds in the backbone. Consideration of the catalytic reaction pathway revealed the intermediacy of a hydrido(disilyl)iron(IV) complex.

Carbon-yl(η-cyclo-penta-dien-yl)(pyridine)(triethyl-stann-yl)iron(II).

In the title complex, [Fe(C(5)H(5)){Sn(C(2)H(5))(3)}(C(5)H(5)N)(CO)], the Fe atom is coordinated by carbonyl, pyridine, triethyl-stannyl and cyclo-penta-dienyl ligands in a typical three-legged piano-stool configuration. The Fe-Sn and Fe-N bond distances are 2.5455 (13) and 1.984 (6) Å, respectively.

Tetrahedral cage complex with planar vertices: selective synthesis of Pt4L6 cage complexes involving hydrogen bonds driven by halide binding.

The reaction of Fe(η-C5H4NHC(O)PPh2)2 () with PtX2(PPh3)2 selectively formed cage-shaped complexes formulated as [(PtX)4()6]X4·CHCl3 (X = Cl, Br), in which the four square-planar Pt fragments were situated at each vertex and the six s were located in each side of a tetrahedral framework and hydrogen bonds existed between the NH groups in s and X(-) ions inside the cage.

Synthesis and characterization of [Fe(NCCH3)6][cis-Fe(InX3)2(CO)4] (X = Cl, Br, I) containing two terminal indium fragments.

Iron complexes, [Fe(NCCH3)6][cis-Fe(InX3)2(CO)4] (X = Cl: , Br: , I: ) containing two terminal indium fragments, were synthesized. Their structures were determined using X-ray analysis. The bonding mode of the Fe-In bonds in the anionic part was investigated using (57)Fe Mössbauer and IR spectroscopy. These complexes represent the first example of transition metal complexes containing two terminal indium fragments.

Synthesis of vinylphosphines and unsymmetric diphosphines: iron-catalyzed selective hydrophosphination reaction of alkynes and vinylphosphines with secondary phosphines.

Iron complex-catalyzed regioselective single hydrophosphination of terminal arylalkynes with secondary phosphines was achieved. Unsymmetric 1,2-bis(phosphino)ethanes with different phosphino groups were obtained by using our catalytic systems. The structures of the obtained vinylphosphine, unsymmetric 1,2-bis(phosphino)ethane, and iron catalyst precursors were confirmed by single crystal X-ray diffraction studies.

R/X exchange reactions in cis-[M(R)2{P(X)(NMeCH2)2}2] (M = Pd, Pt), via a phosphenium intermediate.

R/X exchange reactions in cis-[M(R)2{P(X)(NMeCH2)2}2] (M = Pd, Pt; R = aryl, alkyl; X = Cl, Br) were achieved for the first time to give cis-[M(X)2{P(R)(NMeCH2)2}2]. DFT calculations suggested that the exchange reaction proceeds via a phosphenium intermediate.

Palladium-catalyzed cyanoesterification of norbornenes with cyanoformates via the NC-Pd-COOR (R = Me and Et) intermediate.

[reaction: see text] Palladium-catalyzed cyanoesterification of norbornenes proceeds stereoselectively via NC-Pd-COOR (R = Me and Et) complexes as intermediates.

Catalytic C-C bond cleavage and C-Si bond formation in the reaction of RCN with Et3SiH promoted by an iron complex.

Catalytic C-C bond cleavage of acetonitrile and C-Si bond formation have been attained in the photoreaction of MeCN with Et3SiH in the presence of an iron complex, Cp(CO)2FeMe. This catalytic system can be applied for arylnitrile C-C bond cleavage.

Effective dehydrogenation of 2-pyridylmethanol derivatives catalyzed by an iron complex.

An unprecedented iron complex-catalyzed dehydrogenation of alcohols was achieved using CpFe(CO)2Cl with a base or CpFe(CO)(Py)(Ph) as a catalyst without sacrificing the hydrogen acceptors. This reaction effectively (up to TON 67,000) converted 2-pyridylmethanol derivatives to the corresponding ketones or aldehydes. The mechanistic study is also discussed.

Trans-selective hydrogermylation of alkynes promoted by methyliron and bis(germyl)hydridoiron complexes as a catalyst precursor.

Catalytic trans-selective hydrogermylation of terminal and internal alkynes was attained by a methyliron complex, CpFe(CO)(2)(Me), and a bis(germyl)hydridoiron(IV) complex as a catalyst precursor. The structures of (Z)-triphenyl-(2-phenylethenyl)germane and the bis(germyl)hydridoiron(IV) complexes CpFe(CO)(H)(GeR(3))(2) (R = Et, Ph) were confirmed by single crystal X-ray diffraction studies.