Search

The reactivity of aluminium compounds is dominated by their electron deficiency and consequent electrophilicity; these compounds are archetypal Lewis acids (electron-pair acceptors). The main industrial roles of aluminium, and classical methods of synthesizing aluminium-element bonds (for example, hydroalumination and metathesis), draw on the electron deficiency of species of the type AlR.sub.3 and AlCl.sub.3.sup.1,2. Whereas aluminates, [AlR.sub.4].sup.-, are well known, the idea of reversing polarity and using an aluminium reagent as the nucleophilic partner in bond-forming substitution reactions is unprecedented, owing to the fact that low-valent aluminium anions analogous to nitrogen-, carbon- and boron-centred reagents of the types [NX.sub.2].sup.-, [CX.sub.3].sup.- and [BX.sub.2].sup.- are unknown.sup.3-5. Aluminium compounds in the +1 oxidation state are known, but are thermodynamically unstable with respect to disproportionation. Compounds of this type are typically oligomeric.sup.6-8, although monomeric systems that possess a metal-centred lone pair, such as Al(Nacnac).sup.Dipp (where (Nacnac).sup.Dipp = (NDippCR).sub.2CH and R = .sup.tBu, Me; Dipp = 2,6-.sup.iPr.sub.2C.sub.6H.sub.3), have also been reported.sup.9,10. Coordination of these species, and also of ([eta].sup.5-C.sub.5Me.sub.5)Al, to a range of Lewis acids has been observed.sup.11-13, but their primary mode of reactivity involves facile oxidative addition to generate Al(iii) species.sup.6-8,14-16. Here we report the synthesis, structure and reaction chemistry of an anionic aluminium(i) nucleophile, the dimethylxanthene-stabilized potassium aluminyl [K{Al(NON)}].sub.2 (NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene). This species displays unprecedented reactivity in the formation of aluminium-element covalent bonds and in the C-H oxidative addition of benzene, suggesting that it could find further use in both metal-carbon and metal-metal bond-forming reactions.An aluminium compound is synthesized in which the aluminium is formally anionic; reactions with various substrates suggest that this compound acts as the nucleophilic partner in both metal-carbon and metal-metal bond-forming reactions., Author(s): Jamie Hicks [sup.1] , Petra Vasko [sup.1] [sup.2] , Jose M. Goicoechea [sup.1] , Simon Aldridge [sup.1] Author Affiliations:(1) Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, [...]

The synthesis and structures of four Bi-Ni heteroatomic clusters closo-[[[Bi.sub.3][Ni.sub.4][(CO).sub.6]].sup.3-], closo-[[[Bi.sub.3][Ni.sub.4][(CO).sub.6]].sup.2-], the open cluster [[[Bi.sub.3][Ni.sub.4][(CO).sub.9]].sup.3-], and the intermetalloid closo-[[[Ni.sub.x]@{[Bi.sub.6][Ni.sub.6][(CO).sub.8]}].sup.4-] are presented. The clusters are characterized in compounds with potassium cations sequestered by 2,2,2-crypt or 18-crown-6 ether.

Reaction of nine-atom deltahedral clusters of germanium with Ni(COD)2 and Ni(PPH3)2)(CO)2 in ethylenediamine yielded the Ni-centered heteoatomic 10-atom clusters (Ni @ (Ge9-Ni-CO))(super 2-) and (Ni @ (Ge9Ni-en))(super 2-), as well as the empty 10-atom heteroatomic cluster (Ge9Ni-CO)(super 3-). All species were structurally characterized in crystalline compounds with (K-(2,2,2-crypt))(super +) countercations.

A study synthesizes the deltahedral nine-atom clusters of silicon, Si(sub 9)(super 2-) by mild oxidation of a liquid ammonia solution of K12Si17 with Ph3GeCl in the presence of 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) or 2,2,2,-crypt(4,7,13,16,21,24-hexaoxa-1, 10-diazabicyclo[8.8.8] hexacosane). The structural similarities and differences between Si(sub 9)(super 3-) and Si(sub 9)(super 2-) are discussed.

In Fig. 1 of this Letter, the hydrogen (H) atoms attached to each of the two nitrogen (N) atoms in the chemical structure of (NON)H.sub.2 were inadvertently missing. The original figure has been corrected online., Author(s): Jamie Hicks [sup.1] , Petra Vasko [sup.1] [sup.2] , Jose M. Goicoechea [sup.1] , Simon Aldridge [sup.1] Author Affiliations:(1) Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, [...]

Spontaneous ejection of chloride from a three-coordinate boron Lewis acid is affected by using electron rich metal substituents and has led to the formation of a sterically unprotected terminal (dimethylamino)borylene complex that has a short metal-boron band and resistance to attack by nucleophilic and protic reagents.

The reaction of an ethylenediamine (en) solution of the Zintl phase precursor [K.sub.4][Ge.sub.9] with Fe[Ar.sub.2] (Ar = 2,6-[Mes.sub.2][C.sub.6][H.sub.3]) in the presence of 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) has produced the endohedral Zintl ion [[Fe@[Ge.sub.10]].sup.3-]. The Zintl ion has displayed a pentagonal prismatic 10-atom germanium cage with an interstitial iron atom in the central cavity.

A study reports about a largest single-cage deltahedron, [(Pd-Pd)@Ge(sub 18)](sub 4-), which was structurally characterized in [K(2,2,2-crypt)](sub 4)[Pd(sub 2)@Pb(sub 18].2tol. This complex structure is synthesized by reaction of an ethylenediamine solution of K(sub 4)Ge(sub 9) with excess of Pd[PPh(sub 3)](sub 4).

Liquid ammonia is used as a solvent in extracting the first nine- and five- atom naked clusters of silicon in solution, and the structural characterization of Si9 (super 3-) and Si5 (super 2-) in compounds crystallized from such solutions, is described. Potential technology built on such deposition could be of great importance for the development of various novel microdevices of silicon.