Synthesis of HC[(CBu^t)(NAr)]₂Al (Ar = 2,6-Prⁱ₂C₆H₃) and Its Reaction with Isocyanides, a Bulky Azide, and H₂O

Abstract

The reaction of H2C[(CBu t )2(NAr)2] (Ar = 2,6-Pr i 2C6H3) with AlEt3 in refluxing toluene gave HC[(CBu t )2(NAr)2]AlEt2 (1) in high yield. Treatment of 1 with 2 equiv of iodine in toluene yielded HC[(CBu t )2(NAr)2]AlI2 (2). Reduction of 2 with potassium resulted in the formation of the tert-butyl-substituted β-diketiminato aluminum(I) compound HC[(CBu t )2(NAr)2]Al (3). Reactions of 3 with isocyanides, H2O, and a bulky terphenyl azide were investigated. 3 reacted with 2 equiv of CNAr to give two C−C coupling products: in dilute solution, the C−C coupling of two CNAr molecules was followed by the C−H activation of one of the CHMe2 groups on the Ar ring of CNAr, while in concentrated solution or in the presence of an excess of the isocyanide, the coupling was accompanied by cleavage of one of the C−N bonds of the ligand backbone. Reaction of 3 with the bulky azide 2,6-Ar2C6H3N3 yielded the C−H activation product 6. Hydrolysis of 3 in toluene afforded a hydroxyaluminum hydride. Compounds 1 and 3−5 were characterized by X-ray single-crystal analysis.

Synthesis, Structure, and Reactivity of a Monomeric Iminoalane

“…However, no reports have described the CN bond cleavage of β‐diketiminato complexes induced by NHCs. The mechanism might be similar to that reported by us for the reaction of 1 with the isocyanide, CNAr 8. Notably, NHC‐stabilized group‐13 species having multiple bonding are only confined to those containing a BB bond 15…”

“…Since the isolation of the first β‐diketiminato monovalent aluminum compound [Al{HC[(CMe) 2 (NAr) 2 ]}] ( 1′ ) by Roesky and co‐workers, its reactivity has been extensively investigated 6. 7 Very recently, we reported the synthesis of Al I monomer 1 (Scheme ), which contains larger groups, that is, tert ‐butyl groups, on the β position of the ligand backbone, and its CN bond cleavage reaction with an isocyanide 8. The results prompted us to examine reactions of 1 with other Lewis bases, especially those that are isoelectronic with isocyanides, such as NHCs, for the understanding of the reaction mechanism.…”

On the non-innocence of “Nacnacs”: ligand-based reactivity in β-diketiminate supported coordination compounds

“…5). 59,60 This clearly demonstrates the role played by ancillary ligands coordination in destabilizing the Al(I) species and triggering BDI degradation. 55 This phenomenon appears to be promoted by the coordination of sigma donors, which destabilize the low-valent metal species.…”

“…The most striking feature of this structure, shown on Fig. 59,296 Similarly, our group isolated a metallacyclobutane amido species from the reaction of (MAD)Nb(vNar)(N t Bu)(OEt 2 ) with t BuN 3 , the formation of which is explained by a two-step process involving (a) nitrene transfer and reformation of an dissymmetric BDI ligand leading the Nb(III) imido (BDI (Dipp,tBu),Me )Nb (NDipp) intermediate species (see section 4) and (b) imidomediated C-H bond activation of the t Bu group from the asymmetric BDI ligand (Scheme 84bottom). 292 Note that upon substitution by arylchloride groups, intramolecular ortho chlorine coordination appears to be necessary to stabilize the cationic molybdenum imido alkylidene species (Scheme 82).…”

Serendipitous Observation of AlI Insertion into a C−O Bond in L2PhB (L=Oxazol‐2‐ylidene)

“…In 2004, Roesky et al. reported that NacNacAl: 1 (NacNac=HC(CMeNAr) 2 − and Ar=2,6‐ i Pr 2 C 6 H 3 ), readily activates the P−P bond of white phosphorus P 4 and the S−S bond in elemental sulfur S 8 ,. Recently, Schulz et al.…”