Donor‐Stabilized Aluminum(II) Bromide

Abstract

Cryochemically prepared AlBr and AlBr3 react in anisole to form donor‐stabilized AlBr2, which precipitates in the form of yellow needles with the composition Al2Br4 · 2 anisole. In the solid state the compound is stable at room temperature with regard to disproportionation into Al and Al‴ species. The Al‐Al distance in the adduct (252.7pm) is roughly as short as that in the radical anion [Al2R4].− (RCH(SiMe3)2), which contains an ALAL a bond (253 pm) strengthened by π bond contributions.

K[Al4(PPh2)7PPh]: An AlII Phosphanide / Phosphinidene Intermediate on the Path to AlP Formation

“…(1) and 2.527(1) Å, respectively. [6,15] The four non-bonding Al···Al separations in 1 are in the range 3.385(1) to 3.581(1) Å.…”

A Stable Neutral Radical in the Coordination Sphere of Aluminum

“…[2] In general, these species are highly unstable,and it is of utmost importance to choose aproper ligand to stabilize the metal centers.Since the first isolation and structural characterization of N-heterocy-clic carbenes (NHCs) by Arduengo et al, [3] NHCs have been used as neutral ligands to stabilize radicals and radical ions of main-group elements in low-oxidation states. [9] Al II complexes are typically unstable and readily dimerize or oligomerize with concomitant formation of compounds with Al À Al bonds.T herefore,m onomeric species have only been generated and characterized at low temperatures.Already in 1988, Uhl reported on the tetrasubstituted dialuminum compound [(Me 3 Si) 2 CH] 4 Al 2 , [10] and afterwards,d onor-stabilized dialuminum species of the composition LX 2 AlÀAlX 2 L, including Al 2 X 4 ·2 L(X= Cl, Br,L= NMe 2 (SiMe 3 ); X= I, L = PEt 3 ) [11] and Al 2 Br 4 ·2 MeOPh, [12] were successively isolated. In contrast, stable radical complexes with neutral aluminum centers have not been isolated whereas stable M II (boryl) 2 (M = Ga, In, Tl) radicals have recently been reported by the groups of Aldridge and Jones.…”

Ein stabiles neutrales Radikal in der Koordinationssphäre des Aluminiums

“…Einige Beispiele fürA luminium-Radikalanionen, wie [K(DME) 3 ] + [{(Me 3 Si) 2 CH} 4 Al 2 ]C À , [5] [Na(THF) 4 ] n [Al(dpt) 3 ]( n = 1, 2, 3; Hdpt = 1,3-diphenyltriazen), [6] [K(2.2.2-Cryptand)] + [(tBu 2 MeSi) 3 Al]C À [7] und [Li 2 ] + [(Trip) 4 Al 2 ] À [8] (Trip = 2,4,6-iPr 3 C 6 H 2 )w urden schon beschrieben. Bereits 1988 berichtete Uhl über die tetrasubstituierte Dialuminiumverbindung [{(Me 3 Si) 2 CH} 4 Al 2 ], [10] daraufhin konnten donorstabilisierte Dialuminiumverbindungen der Zusammensetzung LX 2 Al-AlX 2 Lm it Al 2 X 4 ·2 L( X= Cl, Br,L= NMe 2 (SiMe 3 ); X= I, L = PEt 3 ) [11] und Al 2 Br 4 ·2 MeOPh [12] erfolgreich isoliert werden. Al II -Komplexe sind normalerweise instabil und dimerisieren oder oligomerisieren leicht zu Verbindungen mit Al-Al-Bindungen.…”