37701-79-4Relevant academic research and scientific papers
Syntheses of transition metal methoxysiloxides
Richers, Casseday P.,Bertke, Jeffery A.,Rauchfuss, Thomas B.
, p. 8756 - 8762 (2017)
The paper describes three methods for the preparation of methoxysiloxide complexes, a rare class of complexes of relevance to room temperature vulcanization (RTV) of polysiloxanes. The salt metathesis reaction involves the use of the recently described re
Mechanistic Interrogation of Alkyne Hydroarylations Catalyzed by Highly Reduced, Single-Component Cobalt Complexes
Suslick, Benjamin A.,Tilley, T. Don
supporting information, p. 11203 - 11218 (2020/07/08)
Highly reactive catalysts for ortho-hydroarylations of alkynes have previously been reported to result from activation of CoBr2 by Grignard reagents, but the operative mechanism and identity of the active cobalt species have been undefined. A mechanistic analysis of a related system, involving hydroarylations of a (N-aryl)aryl ethanimine with diphenylacetylene, was performed using isolable reduced Co complexes. Studies of the stoichiometric reaction of Co(I) or Co(II) precursors with CyMgCl implicated catalyst initiation via a β-H elimination/deprotonation pathway. The resulting single-component Co(-I) complex is proposed as the direct pre-catalyst. Michaelis-Menten enzyme kinetic studies provide mechanistic details regarding the catalytic dependence on substrate. The (N-aryl)aryl ethanimine substrate exhibited saturation-like behavior, whereas alkyne demonstrated a complex dependency; rate inhibition and promotion depend on the relative concentration of alkyne to imine. Activation of the aryl C-H bond occurred only in the presence of coordinated alkyne, which suggests operation of a concerted metalation-deprotonation (CMD) mechanism. Small primary isotope effects are consistent with a rate-determining C-H cleavage. Off-cycle olefin isomerization catalyzed by the same Co(-I) active species appears to be responsible for the observed Z-selectivity.
Cobalt(-i) triphos dinitrogen complexes: Activation and silyl-functionalisation of N2
Apps, Samantha L.,Miller, Philip W.,Long, Nicholas J.
supporting information, p. 6579 - 6582 (2019/06/13)
The cobalt dinitrogen complexes [{(EP3Ph)Co(μ-N2)}2Mg(THF)4], with triphos ligand scaffolds (EP3Ph, E = N or CMe), were prepared via two electron reductions of the Co(i) precurso
η4-Coordination of dienes and heterodienes to the tripodcobalt(I) template [CH3C(CH2PPh2)3CO]+: Synthesis, structure, and dynamics
Rupp, Rolf,Frick, Axel,Huttner, Gottfried,Rutsch, Peter,Winterhalter, Ute,Barth, Annette,Kircher, Peter,Zsolnai, Laszlo
, p. 523 - 536 (2007/10/03)
CH3C(CH2PPh2)3CoCl (1) is easily accessible from CH3C(CH2PPh2)3CoCl2 by reduction with activated zinc powder. Upon dehalogenation with TlPF6, 1 reacts with dienes to give [tripodCo(I)-(η4- diene)]+ (2). The heterodienes acrolein and methyl vinyl ketone produce the analogous η4-heterodiene compounds 3. When crotonaldehyde is used as the potential η4-diene ligand, decarbonylation is observed leading to [tripodCo(I)-(CO)2]+ (4). Reaction of [tripodCo(aq)](BF4)2 with allyl mercaptan produces [tripodCO(I)-(η4-thioacrolein)]+ (3a) through dehydrogenation of the ligand precursor. 1,2-Diketones such as benzil and phenanthrenequinone do not coordinate in a η4 fashion but rather generate η2-coordinate enediolato ligands by an electron-transfer process, resulting in compounds of the type {tripodCo(III)-[η2-RC(O)=C(O)R]}+ (5). All the compounds have been characterized by standard analytical and spectroscopic techniques, including X-ray analysis in some cases. Compounds 4 and 5 show trigonal-bipyramidal coordination in the solid state, whereas the coordination polyhedra in compounds 2 and 3 are better described as square- pyramidal. While a minimum of two phosphorus resonances might be expected for each of these coordination geometries, only one time-averaged signal is normally observed, only with the η4-coordinated heterodienes acrolein, methyl vinyl ketone, and thioacrolein present in 3 is there a resolution of the signals of the three chemically distinct phosphorus nuclei at low temperatures. By 31P-NMR line-shape analysis, the activation barriers for the rotational reorientation of the heterodienes are found to be around ΔH(≠)=47 kJmol-1 for all three compounds 3.
Complexes of Cobalt(II) Chloride with the Tripodal Trisphosphane triphos: Solution Dynamics, Spin-Crossover, Reactivity, and Redox Activity
Heinze, Katja,Huttner, Gottfried,Zsolnai, Laszlo,Schober, Peter
, p. 5457 - 5469 (2008/10/09)
Depending on the reaction conditions, different products are obtained from the reaction of CoCl2 with CH3C(CH2-PPh2)3 (triphos), including the low-spin complexes (triphos)Co(μ-Cl)2Co(triphos)]2+ (12+) and [(triphos)CoCl2] (3), their solid-state structures being determined by X-ray methods. In solution, additionally, a four-coordinate high-spin complex [(η2-triphos)CoCl2] (2) is present, its concentration relative to that of 3 depending on the solvent and the temperature. The reactivity of these species toward Lewis acids is investigated leading to the novel heterodinuclear complexes [(triphos)Co(μ-Cl)2MCl2] (M = Fe (5), Co (6)). Reactions with Lewis bases L yield complexes of the rare type [(triphos)CoCl(L)]+ (L = CO (7+), PMe3 (8+), NH3 (9+), CH3CN (10+)). One-electron reduction of 3 leads to the previously prepared pseudotetrahedral [(triphos)CoICl] complex 11, and one-electron oxidation to the novel trigonal-bipyramidal low-spin complex [(triphos)CoIIICl2]+ (12+).
Preparation and Structure of Allyl(tripod)cobalt(I) and the Comparison with the Analogous Cobalt(I) Complex
Sernau, Volker,Huttner, Gottfried,Scherer, Johannes,Zsolnai, Laszlo,Seitz, Thomas
, p. 193 - 196 (2007/10/02)
The synthesis of the 18-electron diamagnetic allyl(tripod)cobalt(I) complex Co(η3-C3H5)> (1) is presented.Its structure is established by the usual analytical techniques as well as by X-ray analysis, and it is proved to be significantly different from that of the cationic 17-electron species 1(+). - Key Words: Tripod ligands/ Cobalt complexes/ Allyl complexes
