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![Synthesis of complexes [M(κ²‐Si,N‐Ln)3] (Ln=L2, L3, L4 and L5).](publication/380822285/figure/fig4/AS:11431281284456690@1729266688308/Synthesis-of-complexes-Mk-Si-N-Ln3-LnL2-L3-L4-and-L5.png)
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![Synthesis of the complex [Re(κ²‐N,Si‐L1)(CO)4] (1).](publication/380822285/figure/fig2/AS:11431281284522772@1729266687970/Synthesis-of-the-complex-Rek-N-Si-L1CO4-1_Q320.jpg)
![Synthesis of complexes [M(Cl)(κ²‐N,Si‐L2)2] (M=Rh, 2; Ir, 3) and...](publication/380822285/figure/fig3/AS:11431281284440460@1729266688128/Synthesis-of-complexes-MClk-N-Si-L22-MRh-2-Ir-3-and_Q320.jpg)
![Synthesis of complexes [M(κ²‐Si,N‐Ln)3] (Ln=L2, L3, L4 and L5).](publication/380822285/figure/fig4/AS:11431281284456690@1729266688308/Synthesis-of-complexes-Mk-Si-N-Ln3-LnL2-L3-L4-and-L5_Q320.jpg)
![Synthesis of the complex [Co(κ²‐N,Si‐L6)3] (13).](publication/380822285/figure/fig5/AS:11431281284502946@1729266688690/Synthesis-of-the-complex-Cok-N-Si-L63-13_Q320.jpg)
The chemistry of transition‐metal (TM) complexes with monoanionic bidentate (κ²‐L,Si) silyl ligands has considerably grown in recent years. This work summarizes the advances in the chemistry of TM‐(κ²‐L,Si) complexes (L=N‐heterocycle, phosphine, N‐heterocyclic carbene, thioether, ester, silylether or tetrylene). The most common synthetic method has...
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A modular synthesis of bis(phosphine) monoxide (BPMO) ligands has been realized using the Michaelis–Arbuzov reaction of dialkylphosphinite esters. The modular synthetic method allows the chemoselective synthesis of BPMO ligands in which the substituents on the two phosphorus centers are different. This methodology also provides a route to N‐heteroc...
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Seven‐coordinate ruthenium complexes 1a and 1b, featuring silyl–2,2´‐bipyridine SiNN‐pincer ligands with i‐Pr and t‐Bu groups on Si, respectively, were synthesized. Their capped octahedral structures were revealed by single‐crystal X‐ray diffraction study. The stoichiometric reactions of 1a and 1b with styrene in THF afforded η²‐silylalkene chelate complexes. In contrast, performing the same reaction using 1a in C6D6 resulted in the liberation of deuterated styrene (PhDC═CD2), alongside the formation of a deuterated η²‐silylalkene complex. Complex 1a exhibited efficient catalytic activity for the triple deuteration of vinyl hydrogens in mono‐substituted olefins with C6D6 to afford RDC═CD2 (R = Ph, C6H4‐4‐OMe, t‐Bu) with high deuterium incorporation (92%–99%D).
The semihydrogenation of simple allenes remains an issue because of the difficulty in control of selectivity without coordination assistance of directing groups, wherein over‐hydrogenated alkanes and E/Z‐mixed stereo‐ and regio‐isomers can be potentially formed. We report here an electron‐rich cyclic (alkyl)(amino)carbene (CAAC)‐phosphine‐ligated chromium(III) complex serving as precatalyst in promoting the selective semihydrogenation of undirected allenes by forming active silylchromium species. The semihydrogenation allows the selective addition of H2 to the less substituted and electron‐rich alkyl‐substituted C=C bonds of allenes with enabling the suppression of competitive over‐hydrogenation, proving general to form trisubstituted E‐alkenes in high chemo‐, regio‐ and stereoselectivity. By this CAAC‐phosphine‐Cr‐catalyzed selective semihydrogenation, unsaturated nitro, nitrile, alkenyl and hydrogenation‐sensitive bromide, chloride and fluoride were compatible with various substitution environments. The in‐situ forming silylchromium as active catalyst by reaction of low‐valent chromium complex with chlorosilane was established by studying the catalytic and stoichiometric reactivity of this species in the semihydrogenation. Deuterium labeling experiments, HRMS, XPS, EPR and magnetic susceptibility analysis of the related intermediates and theoretical studies support a pathway involving sila‐metalation of allene and b‐silyl elimination processes with silyl as non‐innocent ligand, leading to the E‐alkene products.
The semihydrogenation of simple allenes remains an issue because of the difficulty in controlling of selectivity without coordination assistance from directing groups, wherein over‐hydrogenated alkanes and E/Z‐mixed stereo‐ and regio‐isomers can be potentially formed. We report here an electron‐rich cyclic (alkyl)(amino)carbene (CAAC)‐phosphine‐ligated chromium(III) complex serving as precatalyst in promoting the selective semihydrogenation of undirected allenes by forming active silylchromium species. The semihydrogenation allows the selective addition of H2 to the less substituted and electron‐rich alkyl‐substituted C═C bonds of allenes while enabling the suppression of competitive over‐hydrogenation, proving generally to form trisubstituted E‐alkenes in high chemo‐, regio‐, and stereoselectivity. By this CAAC‐phosphine‐Cr‐catalyzed selective semihydrogenation, unsaturated nitro, nitrile, alkenyl, and hydrogenation‐sensitive bromide, chloride, and fluoride were compatible with various substitution environments. The in situ forming silylchromium as active catalyst by reaction of low‐valent chromium complex with chlorosilane was established by studying the catalytic and stoichiometric reactivity of this species in the semihydrogenation. Deuterium labeling experiments, HRMS, XPS, EPR, and magnetic susceptibility analysis of the related intermediates and theoretical studies support a pathway involving sila‐metalation of allene and β‐silyl elimination processes with silyl as noninnocent ligand, leading to the E‐alkene products.
Hydrosilylation of terminal alkenes catalyzed by a scandium metalloligand supported Ni(0) complex are studied. The anti‐Markovnikov products are obtained in 62–89% yield, along with the alkanes and 1,1,2,2‐tetraphenyldisilane as minor products. The resting‐state complexes of hydrosilylation reactions are isolated and characterized by spectroscopic method and X‐ray diffraction studies, which represent rare‐example of Ni(0) silyl complexes supported by scandium ions via a Ni(0)→Sc(III) interaction. The catalytic cycle is proposed to be redox neutral with Ni(0) center, and is facilitated by metal‐ligand cooperation involving the Ni(0)Si bond.
The 18e saturated rhodium(III) species [Rh(H)(X)(κ²‐NSitBu2)(bipyMe2)] (NSitBu2={4‐methylpyridine‐2‐yloxy}ditertbutylsilyl; bipyMe2=4,4'‐dimethylbipyridine) (X=Cl, 1; OTf, 2) have been prepared and characterized by NMR spectroscopy and in the case of 2 it has been possible to determine its solid‐state structure by X‐ray diffraction. Complex 1 has proven to be an effective catalyst precursor for the reaction of styrene derivatives with hydrosilanes in CD2Cl2. However, under catalytic conditions complex 2 decomposes. The performance of the 1‐catalyzed reaction of styrene with hydrosilanes strongly depends on the nature of the silane, the best catalytic performance was achieved using HSiMe2Ph. Theoretical and ¹H NMR studies indicate that the hemilabile nature of the NSi ligand is key to understanding the catalytic activity of compound 1.
An active catalytic system for the cross-dehydrogenative coupling (CDC) of a wide range of secondary amines with silanes is reported. The iridium(III) derivatives [Ir(H)(X)(κ²-NSiDMQ)(L)] (NSiDMQ = {4,8-dimethylquinoline-2-yloxy}dimethylsilyl; L = coe, X = Cl, 2; L = coe, X = OTf, 3; L = PCy3, X = Cl, 4; L = PCy3, X = OTf, 5), which are stabilized by a weak yet noticeable Ir···H–C agostic interaction between the iridium and one of the C–H bonds of the 8-Me substituent of the NSiDMQ ligand, have been prepared and fully characterized. These species have proven to be effective catalysts for the CDC of secondary amines with hydrosilanes. The best catalytic performance (TOF1/2 = 79,300 h–1) was obtained using 5 (0.25 mol %), N-methylaniline, and HSiMe2Ph. The catalytic activity of the species [Ir(H)(OTf)(κ²-NSiQ)(PCy3)] (10, NSiQ = {quinoline-2-yloxy}dimethylsilyl) and [Ir(H)(OTf)(κ²-NSiMQ)(PCy3)] (11, NSiMQ = {4-methylquinoline-2-yloxy}dimethylsilyl), related to 5 but lacking the 8-Me substituent, is markedly lower than that found for 5. This fact highlights the crucial role of the 8-Me substituent of the NSiDMQ ligand in enhancing the catalytic performance of these iridium complexes.
