RESUMO
The synthesis, structures, and reactivity of the first unsaturated AlSi2 three-membered ring systems were described. Reactions of dilithiodisilene [(NHB)LiSiâSiLi(NHB)] (1, NHB = diazaborolyl) with aluminum halides AlCl3, Ar(SiMe3)NAlCl2 (Ar = 2,6-iPr2C6H3), Cp*AlBr2 (Cp* = C5Me5), and TipAlBr2·Et2O (Tip = 2,4,6-iPr3C6H2) led to the formation of AlSi2 three-membered ring species, solvated (NHBSi)2AlCl(OEt2) (2) and solvent-free (NHBSi)2AlN(SiMe3) Ar (3), (NHBSi)2AlCp* (4), and (NHBSi)2AlTip (5), in good yields. X-ray diffraction studies and DFT calculations disclosed delocalized AlSi2 2π electron systems. Methanolysis of 4a resulted in cleavage of the Al-Si σ and Si-Si π bonds, giving trihydrodisilane (NHB)H(MeO)SiSiH2 (NHB) (6). Reaction of 4b with 4 equiv of N2O and H2CâCH2 resulted in the insertion of four oxygen atoms and four H2CâCH2 π bonds into all of the Al-Si and Si-Si bonds, yielding the O- and CH2CH2-bridged polycyclic species 7 and 8, demonstrating the synergistic reactivity of the Al-Si and Si-Si bonds in the AlSi2 ring system.
RESUMO
An arene-tethered silylene ligand, L (L = PhC(tBuN)2SiCH2C(tBu)NAr, Ar = 2,6-iPr2C6H3), allowed the synthesis of three-coordinate Fe(ii) silylamido and piano-stool Fe(0) dinitrogen complexes LFe[N(SiMe3)2]2 (3) and LFe-N2 (4), which not only exhibit interesting bonding but also enabled the catalytic silylation of N2 to yield N(SiMe3)3 under 1 atm of N2 at room temperature with high TONs.
RESUMO
Reaction of the aluminum hydroxide LAl(OH)[C(Ph)CH(Ph)] (1, L = HC[(CMe)(NAr)](2), Ar = 2,6-iPr(2)C(6)H(3)) with Y(CH(2)SiMe(3))(3)(THF)(2) yielded the oxo-bridged heterobimetallic yttrium dialkyl complex LAl[C(Ph)CH(Ph)](µ-O)Y(CH(2)SiMe(3))(2)(THF)(2) (2). Alkane elimination reaction of 2 with 2-(imino)pyrrole [NN]H ([NN]H = 2-(ArNâCH)-5-tBuC(4)H(2)NH) afforded the yttrium monoalkyl complex LAl[C(Ph)CH(Ph)] (µ-O)Y(CH(2)SiMe(3))[NN](THF)(2) (5). Alternatively, 5 can be prepared in high yield by reaction of 1 with [NN]Y(CH(2)SiMe(3))(2)(THF)(2) (3). The analogous samarium alkyl complex LAl[C(Ph)CH(Ph)](µ-O)Sm(CH(2)SiMe(3))[NN](THF)(2) (6) was prepared similarly. Reactions of 5 and 6 with 1 equiv of iPrOH yielded the corresponding alkoxyl complexes 7 and 8, respectively. The molecular structures of 3, 6, and 8 have been determined by X-ray single-crystal analysis. Complexes 2, 3, 5, 7, and 8 have been investigated as lactide polymerization initiators. The heterobimetallic alkoxyl 8 is highly active to yield high molecular weight (M(n) = 6.91 × 10(4)) polylactides with over 91% conversion at the lactide-to-initiator molar ratio of 2000.
RESUMO
The synthesis and characterization of the two homoleptic mononuclear nickel complexes (2,6-Dipp2C6H3NH)2Ni ( 1) and [2-C(H)NDippC6H4NH] 2Ni (2) (Dipp = 2,6-Pr(i)2C6H3) are described. 1 is formally two-coordinate and adopts a strictly linear geometry, while 2 features a slightly distorted square-planar geometry. Electrochemistry of 1 and 2 shows that they can be reduced to the corresponding nickel(I) species and oxidized to the corresponding nickel(III) species reversibly or quasi-reversibly. A solid-state magnetic measurement (mu(eff )= 2.79 mu(B)) for paramagnetic 1 indicates the presence of two unpaired electrons on the nickel center.
RESUMO
The reaction of LAl[eta2-(C2(SiMe3)2)] (1; L = HC[(CMe)(NDipp)]2, Dipp = 2,6-iPr2C6H3) with dioxygen leads to the elimination of bis(trimethylsilyl)acetylene and the formation of the corresponding aluminum monohydroxide via the oxidation of one of the CHMe2 groups on the Dipp ring.
RESUMO
A short Ga-N bond with double-bond character is displayed by the first monomeric imide of gallium, which was obtained by the reaction of [{HC(MeCDippN)2 }M:] (Dipp=2,6-iPr2 C6 H3 , M=Ga; see picture) with N3 -2,6-Trip2 C6 H3 (Trip=2,4,6-iPr3 C6 H2 ). The analogous aluminum (M=Al) compound is also readily available.