Reactions of d0 Group 4 Amides with Dioxygen. Preparation of Unusual Oxo Aminoxy Complexes and Theoretical Studies of Their Formation

Synthesis of chiral binaphthol-based bishydroxylamines

Although bishydroxylamines have been widely used in chemistry, very little has been reported on corresponding chiral representatives. In this paper, we present the synthesis of two chiral binaphthyl-based bishydroxylamines with different substitution patterns at their NOH functions. The key step of the synthesis involves the reduction of the corresponding dinitrone compounds. The molecular structure in the solid state of one of the nitrone precursors is presented.

Dioxygen reacts with metal-carbon bonds in thorium dialkyls to produce bis(alkoxides)

Exposure of bis-amidinate and -guanidinate supported thorium dialkyl complexes to dioxygen results in facile oxygen atom insertion and formation of the corresponding thorium bis(alkoxide) species. Preliminary mechanistic studies suggest a radical propagation mechanism is operative. All new complexes were fully characterized by 1H and 13C NMR spectroscopy, IR, EA and X-ray crystallography.

Syntheses and characterization of hepta-coordinated Group 4 amidinate complexes

Hepta-coordinated Group 4 amidinate complexes have been synthesized and characterized by ¹⁵N chemical shifts through ¹H–¹⁵N gHMBC NMR.

Selective Incorporation of Primary Amines into a Trizirconium Imido System and Catalyic Cyclization of Aminoalkynes

The trinuclear zirconium imido complex [{LZr(NMe₂)}₃] (2, L = C₅Me₄CH₂CH₂N) was synthesized by amine elimination between Zr(NMe₂)₄ and endo-olefinic isomers of (tetramethylcyclopentadienyl)ethanamine (LH₃) (1). To study the fundamental reactivity of the trizirconium system, reactions of 2 with primary amines were examined. Selective incorporations of the primary amines were observed, depending on steric and electronic natures of the amine substrates. The amine-incorporated complexes [(LZrNHR)(LHZrNHR)(LHZr)(μ-NHR)(μ₃-NR)] (3, R = Pr, Et), [(LZrNHR)₂(LHZr)(μ-NR)] (4, R = Pr, i-Bu), [(LZr)₂(LZrNMe₂)(μ-NR)] (5, R = neo-Pen), and [(LZr)(LZrNHAr)(LH₂Zr)(μ-NAr)₂] (6, Ar = Ph, C₆H₄-4-Br, C₆H₄-4-OMe) were structurally characterized by NMR and XRD analysis and showed several coordination modes of the substrate nitrogen ligands: i.e., terminal amides, bridging amides, and bridging imides but not terminal imides. Thermolysis of a mixture of 3 and 4 led to C-H bond activation, giving rise to the zirconaaziridines [{LZr(η²-NCHR)}(LZr)(LHZr)(μ-NHCH₂R)] (12, R = Et, Me). Complex 2 proved to be a competent precatalyst in the hydroamination of the aminoalkynes (H₂NCH₂CR¹₂CH₂C≡CR²) (13, R¹ = H, R² = Bu, Ph, t-Bu; 14, R¹ = Me, R² = Et, Ph). Stoichiometric or semicatalytic reactions of 2 and the aminoalkynes were studied to explore the reactivity of in situ formed Zr₃ species.

Reactions of d(0) tungsten alkylidyne complexes with O2 or H2O. Formation of an oxo siloxy complex through unusual silyl migrations

(Me3SiCH2)3(Me3SiC≡)W←O=PMe3 (1), an adduct between (Me3SiCH2)3W≡CSiMe3 (2) and O=PMe3, reacts with O2 to give O=W(OSiMe3)(CH2SiMe3)3 (3) and CO2. Reaction of 2 with H2O yields 3 and the trimer [(μ-O)W(CH2SiMe3)2(=O)(THF)]3 (4). In the reaction of D2O with 2, 3-d(n) and methane isotopologues CH2D2, CHD3 and CD4 have been observed.

Novel dinuclear dimethylamido-3,5-dimethylpyrazolato and tetranuclear dimethylamido-3,5-dimethylpyrazolato-polyoxo zirconium(IV) complexes. Synthesis and structural characterisation

The dinuclear dimethylamido-tris(3,5-dimethylpyrazolato)-zirconium(IV) complex [Zr(3,5-Me2Pz)3(NMe2)]2 1 is prepared by treatment of [Zr(NMe2)4] with 3 equivalents of 3,5-dimethylpyrazole (3,5-Me2PzH) with elimination of dimethylamine. When [Zr(NMe2)4] reacted with 2 equivalents of 3,5-Me2PzH, the bis(dimethylamido)-bis(3,5-dimethylpyrazolato)zirconium(IV) compound [Zr(3,5-Me2Pz)2(NMe2)2]2 2 is obtained. Hydrolysis of [Zr(3,5-Me2Pz)3(NMe2)]2 in wet toluene affords the tetranuclear oxo compound [Zr4(eta2-3,5-Me2Pz)4(NMe2)2(mu3-O)2(mu2-3,5-Me2Pz)4(mu2-NMe2)2] . All synthesised compounds are characterised by NMR spectroscopic and analytical methods. Single crystal X-ray diffraction analysis has established the molecular structures of 1 and 4.

Design of precursors for the CVD of inorganic thin films

Applications of inorganic thin films in the electronics industry have spurred activity in the area of chemical vapor deposition (CVD). This article discusses the increasingly sophisticated design strategies for precursor complexes through a series of case studies on CVD of metal oxide and metal nitride films.