The β-diketiminato magnesium hydride, [(BDI)MgH]]2, reacts with alkenes and catalyses their hydrosilylation with PhSiH3.
The β-diketiminato aluminum dihydrides, [HC{(Me)CNAr}2AlH2] [4: Ar = 2,6-di-isopropylphenyl (Dipp), 5: 2,4,6-trimethylphenyl (Mes)] react directly with N-aryl-substituted N-heterocyclic carbenes (NHCs) by C–N bond activation to afford aluminum amido-alkyl derivatives of the form [HC{(Me)CNAr}2AlCH2(N(Ar′)CH)2]. The more sterically congested alane (4), bearing N-Dipp substitution, does not react with either 1,3-bis(2,6-di-isopropylphenyl)imidazol-2-ylidene (IPr) or 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes), even under forcing conditions. In contrast, in situ generation of 1,3-bis(phenyl)imidazol-2-ylidene through deprotonation of the corresponding imidazolium tetrafluoroborate by KN(SiMe3)2 in the presence of compound 4 provides facile ring opening of the NHC at room temperature to yield [HC{(Me)CNDipp}2AlCH2(N(Ph)CH)2]. Although compound 5 also does not react with IPr, relaxation of the steric demands of the supporting β-diketiminate ligand to N-mesityl substitution enables analogous ring opening of IMes, with the formation of [HC{(Me)CNMes}2AlCH2(N(Mes)CH)2] (7), when the reaction is heated to 80 °C. DFT calculations performed on model systems suggest that in comparison to the parent alane (AlH3) the enhanced propensity of these systems to induce NHC ring cleavage is a consequence of the relative stability of the initially formed five- and four-coordinate adducts as well as the augmented hydridic character of the Al–H bonds within the β-diketiminate-supported molecules.
Reactions of dimeric β-diketiminato (BDI) magnesium and calcium hydrides with [(BDI)Mg] + [Al{OC(CF 3 ) 3 } 4 ] − provide ionic multimetallic hydride derivatives, which have been characterized by single-crystal X-ray diffraction analysis. The exclusively magnesium centered species comprises a cation in which two [(BDI)Mg] + units are connected by a single μ 2 -bridging hydride. In contrast, the greater lability of the calcium-containing system is underscored by the isolation of a cyclic heterotrimetallic species in which a CaH 2 moiety is coordinated by a molecule of benzene and an aryl substituent of a [{(BDI)Mg} 2 H] + cation. The homometallic dimagnesium species displays a greater facility toward reaction with diphenylacetylene than neutral [(BDI)MgH] 2 , although the resultant crystallographically characterized vinyldimagnesium cation equilibrates into a complex mixture of neutral and ionic species in solution. An initial assessment of both systems for the hydrosilylation of 1-hexene and diphenylacetylene evidences an inferior catalytic performance of [(BDI)MgH] 2 in isolation.
A new protocol that enables the immobilization of DNA probes on aminated micro-titer plates activated with aldehyde-dextran via an amino group artificially introduced in the 3' end of the oligonucleotide probe is reported in this work. The method is based on the use of hetero-functional-dextran as a long and multifunctional spacer arm covalently attached to an aminated surface capable of immobilizing DNA oligonucleotides. The immobilization occurred only via the amino introduced in the 3' end of the probe, with no implication of the DNA bases in the immobilization, ensuring that the full length of the probe is available for hybridization. These plates having immobilized oligonucleotide probes are able to hybridize complementary DNA target molecules. The tailor-made hetero-functional aldehyde-aspartic-dextran together with the chemical blocking of the remaining primary amino groups on the support using acetic anhydride avoid the nonspecific adsorption of DNA on the surface of the plates. Using these activated plates, (studying the effect of the probe concentration, temperature, and time of the plate activation on the achieved signal), thus, the covalent immobilization of the aminated DNA probe was optimized, and the sensitivity obtained was similar to that achieved using commercial biotin-streptavidin systems. The new DNA plates are stable under very drastic experimental conditions (90% formamide, at 100 degrees C for 30 min or in 100 mM NaOH).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.