01279nas a2200157 4500008004100000022001400041245007600055210007000131260000800201300001400209490000700223520074700230100002100977700001700998856010601015 2024 eng d a0276-733300aIn silico discovery of a neutral 2π aromatic silicon aluminum compound0 aIn silico discovery of a neutral 2π aromatic silicon aluminum co cJUL a1583-15920 v433 a

The recently developed ab initio nanoreactor (AINR) approach to identifying reaction intermediates and pathways without the necessity of experimental input has been employed in the current work to locate new cyclic silicon-based structures that have the potential to display aromaticity. Using this approach, we have identified many cyclic silicon-based molecules that have been experimentally reported over the past three decades. More importantly, the current work showcases an interesting new molecule that has been discovered through this approach: a four-membered cyclic compound of silicon and aluminum that displays significant 2 pi aromaticity and is capable of the activation of important small molecules such as ammonia.

1 aSharma, Himanshu1 aVanka, Kumar uhttp://library.ncl.res.in/content/silico-discovery-neutral-2%CF%80-aromatic-silicon-aluminum-compound02630nas a2200205 4500008004100000022001400041245009200055210006900147260000800216490000700224520194000231100001702171700001902188700001702207700001802224700002102242700001702263700002402280856012002304 2024 eng d a2044-475300aIron-catalyzed (E)-selective hydrosilylation of alkynes: scope and mechanistic insights0 aIroncatalyzed Eselective hydrosilylation of alkynes scope and me cMAY0 v143 a

Iron-catalyzed hydrosilylation of internal alkynes has been rarely reported. Even in these rare cases, additives have been used for the success of the reaction, which often creates a problem for the functional group tolerance of the reaction. Herein, we report an additive-free iron-catalyzed (E)-selective hydrosilylation of internal alkynes in the presence of a phosphine ligand. A low-valent Fe(0) complex [Fe(CO)(3)(BDA)] {[Fe-1]} catalyzed the hydrosilylation of alkynes at 60 to 120 degrees C, exhibited a broad substrate (24 substrates) scope and tolerated different functional groups. The synthetic utility of the reaction was demonstrated by a gram scale experiment, preparing alkenes, and by chemo-selective hydrosilylation. The modus operandi of the reaction has been investigated by i) homogeneity test, ii) radical trapping experiments, iii) X-ray photoelectron spectroscopy, and iv) by preparing a Fe(II) complex as catalyst control. These mechanistic investigations revealed a two-electron pathway for the hydrosilylation of alkynes. In addition, kinetic investigations were undertaken to shed light on the rates of the reaction. Kinetic studies suggest the absence of an induction period, and the reaction is first order with respect to the concentration of iron catalyst [Fe-1] and zeroth order with respect to the substrate (alkyne). The Hammett plot suggests that strongly electron-withdrawing groups on the alkyne favour the hydrosilylation reaction. Meanwhile Eyring analysis suggests that the rate-determining step likely involves an associative pathway. Based on the findings of the mechanistic and kinetic investigation, a plausible Chalk-Harrod-type mechanism is likely to be operative. The proposed mechanism is substantiated by computational investigations, which suggested that the Chalk-Harrod mechanism is kinetically more favored by 15.8 kcal mol(-1) over the modified Chalk-Harrod mechanism.

1 aSen, Anirban1 aTewari, Tanuja1 aKumar, Rohit1 aVinod, C., P.1 aSharma, Himanshu1 aVanka, Kumar1 aChikkali, Samir, H. uhttp://library.ncl.res.in/content/iron-catalyzed-e-selective-hydrosilylation-alkynes-scope-and-mechanistic-insights01791nas a2200241 4500008004100000022001400041245009600055210006900151260000800220490000700228520099400235653001901229653002601248653001901274653001701293653001401310100001901324700002401343700002101367700001701388700002401405856012001429 2025 eng d a2193-580700aIron-catalyzed chemoselective reduction of enimines to N-Allylic amines via hydrosilylation0 aIroncatalyzed chemoselective reduction of enimines to NAllylic a cMAY0 v143 a

Chemoselective hydrosilylation of unsaturated imines is challenging as the two double bonds compete for the reaction. Here in, we report an iron-catalyzed chemoselective hydrosilylation of enimines leading to the generation of allyl amines in the presence of phosphine ligand. A low-valent Fe(0) complex [(BDA)Fe(CO)3] catalyzed the hydrosilylation of enimine at room temperature and exhibited broad substrate scope including a variety of enimine (cinnamylimine, allylimine) and ketimine. Mechanistic investigations revealed that the reaction proceeds through an oxidative addition of the silane compound, leading to the formation of an iron hydride intermediate. Subsequently, a two-electron pathway facilitates the hydrosilylation of the enimine substrate. This has been supported by preparing a well-defined Fe(II)-silane complex and using it as a catalyst control. Based on experimental and computational investigations, a plausible Chalk-Harrod-type mechanism is proposed.

10aCinnamyl amine10aImine hydrosilylation10airon catalysis10aIron hydride10aPhosphine1 aTewari, Tanuja1 aShaikh, Maulali, H.1 aSharma, Himanshu1 aVanka, Kumar1 aChikkali, Samir, H. uhttp://library.ncl.res.in/content/iron-catalyzed-chemoselective-reduction-enimines-n-allylic-amines-hydrosilylation