Metallorganische Verbindungen XXII. Magnesium‐Aluminium‐Organische Komplexverbindungen

Abstract

93Die optischen Messungen In1 Zuge der Durcharbeitung der Chemie der organischen Verbindungen des Aluminiums interessierte uns die Frage, ob Magnesium-und Aluminiumalkyle miteinander komplexe Verbindungen eingehen konnen. Bekanntlich sind komplexe Alkalialuminium-tetraalkyle (und -aryle) wie NaAl(C2Hs)d oder LiAI(CH3j4 recht bestandige Stoffe, die zwar leicht durch Zusammenlagern von Alkali-und Aluminiumalkylen hergestellt werden konnen, in denen jedoch wesentliche Eigenschaften der Komponenten verschwunden oder stark modifiziert sind. Um das an einem charakteristischen Beispiel zu erlautern : Lithiumathyl und Aluminiumtriathyl addieren beide unter ahnlichen Bedingungen (80-1 lo", 100 at Druck) khylen zu hoheren Metallalkylen; die Komplexverbindung tut dies erst bei wesentlich hoheren Temperaturen. Die erhebliche Stabilisierung der Komponenten durch die Komplexbildung ist bei vielen analogen Stoffpaaren nachgewiesen. Es sei hier nur an die Arbeiten von G.WITTIG~) und insbesondere an das gegen Wasser bestandige Natriumbortetraphenyl (,,Kalignost") erinnert, ferner an das in kaltem Wasser einigermanen haltbare NaBH4. Natriumaluminiumtetraathyl zeigt in der Schmelze (bei 120") die recht betrachtliche 1) XXI. Mitteilung: Chem. Ber. 89, 434 (1956).

Deposition of Aluminum-Magnesium Alloys from Electrolytes Containing Organo-Aluminum Complexes

“…The electrolysis is carried out in toluene and preferably at 90±100 C. Since the required concentration of the magnesium in a freshly prepared electrolyte is only reached during the electrolysis, this has to be determined initially and the following procedures have been developed. l The coordination compound Mg[AlEt 4 ] 2 , a colorless, nonconducting liquid, [22,23] is added in toluene. The addition of 0.01 mol Mg[AlEt 4 ] 2 per 3.0 mol M[AlEt 4 ] to the electrolyte ªM1º, for example, generates a system that may be used directly for electroplating.…”

“…l A short pre-electrolysis is carried out during which the Mg-content of the deposited metal layer increases (as the result of the increasing Mg-concentration in the electrolyte solution) up to the point at which equal amounts of aluminum and magnesium are dissolved from the anode as deposited on the cathode. This point can be reached by adjusting either the anode partial current density or the Al-and Mg-content of the alloy anode, or l The coordination compound Mg[AlEt 4 ] 2 , a colorless, nonconducting liquid, [22,23] is added in toluene. The addition of 0.01 mol Mg[AlEt 4 ] 2 per 3.0 mol M[AlEt 4 ] to the electrolyte ªM1º, for example, generates a system that may be used directly for electroplating.…”

Chasing Multiple Bonding Interactions between Alkaline‐Earth Metals and Main‐Group Fragments

“…Only very recently the synthesis of the "simple" calcium alkyl [CaMe 2 ] n has been described. [50] Furthermore, tetraalkylaluminates[ Ae(AlR 4 ) 2 ] n (Ae = Mg, [51][52][53] Ca, [51] Ba) [54] as "metal alkyls in disguise" or even Ae-silyl complexes of the type [(thf) x Ae{Si(SiR 3 ) 3 } 2 ]( Ae = Ca, [55,56] Sr, [55,57] Ba) [55,58] display highly reactive precursors. Upon protonolysis,c ompounds [Ae(AlR 4 ) 2 ] n liberate RH and the Lewis acid AlR 3 ,w hich can stabilize [Ae=E] compounds through adduct formation.E ven thoughn ot yet applied it should be noted that activated metals (e.g.,Ca* prepared from Ca in NH 3 ) [59] and suitable proligands of Em ight be useful precursors for [Ae=E] species via direct synthesis.…”

“…The in situ generation of the Schrock-type carbene "[Cp 2 Ti=CH 2 ]" through addition of Lewis bases, for example, pyridine, toT ebbe's reagent is driven by the elimination of the Lewis acid-base adduct [(py)AlMe 2 Cl].A ny efforts to isolate transient" [Cp 2 Ti=CH 2 ]", which acts as ah ighly reactive and selective methylene transfer reagent in Wittig-type reactions, have not been successful [104]. Lewis-acid stabilizationm ight also emerge as av iable concept for Ae alkylidenes, in particular due to the factt hat related AlMe 3 -capped Ae alkyls are already well established (tetraalkylaluminates [Ae(AlR 4 ) 2 ] n , see Introduction) [51][52][53][54]. Using dialkylzinc ZnR 2 instead of AlR 3 as as tabilizing Lewis acid it was indeed pos-…”

Chemical Reactivities of [Me2AI (μ‐NiPr2)2MgMe]4 and [Me2AI(μ‐NiPr2)2MgCI]2: Crystal Structures of [Me2AI(μ‐Pz)2AIMe2], [Me2AI(μ‐P2)2Mg(μ‐Pz)2AIMe2], and [Me2Al(μ.‐NiPr2)(μ‐Me)Mg(μ‐NiPr2)(μ‐Me)AIMe2]

“…Compound A reacted with chloroform to produce a crystalline product characterized by elemental and spectral analyses to be [MezAI(j.l.-N(i-PrhhMgClh 4. Compound 4 reacted with t-BuLi to produce compound 5 and LiCl according to eq (1). Single crystals of compound 5 were not obtained.…”