“Masked” Lewis-acidity of an aluminum α-phosphinoamide complex

Abstract

The reaction of PhP(DIPP)NH with AlMe cleanly gives an aluminum amide complex that crystallizes as a centrosymmetric dimer with a six-membered Al-N-P-Al-N-P ring. In aromatic solvents the dimer remains intact but the Al-P bond is readily broken upon addition of THF to form PhP(DIPP)NAlMe·THF. Efforts to use [PhP(DIPP)NAlMe] as a "masked" Lewis acidic activator for olefin polymerization catalysts were unsuccessful but the complex showed a Frustrated Lewis pair reactivity instead. The P/Al complex reacts with isocyanates to give the C[double bond, length as m-dash]O inserted product that crystallizes as a five-membered ring system Al-O-C(NR)-P-N. The reaction of [PhP(DIPP)NAlMe] with CO, however, gave an insertion in the N-Al bond and the dimeric product [PhP(DIPP)NCOAlMe] was isolated. The dimer [PhP(DIPP)NAlMe] is one of the few Al/P FLPs that can activate C[double bond, length as m-dash]C double bonds irreversibly. A reaction with allyl methyl sulfide and 1-hexene led to the clean formation of the structurally similar activated alkene products [(DIPP)N-PhP-CH(CHSMe)CH]AlMe and [(DIPP)N-PhP-CH(CH)CH]AlMe.

Synthesis and structural characterization of arsinoamides – early transition metal (Zr and Hf) and main group metal (Al, In, Sn, and Pb) complexes

“…The Al-N (1.819(3) Å) and Al-O (1.869(3) Å) bond lengths are in line with the reported values (e.g. Al-N: 1.792(2) Å and Al-O: 1.9246(10) Å) [29][30][31]. The three-coordinated nitrogen atom adopts an almost planar arrangement considering the sum of the bond angles around the nitrogen atom (357.4°).…”

Crystal structure of bis(μ2-triphenylacetato-κO:κO′)bis(diisobutylaluminium)

“…Three [AlR 2 (-O 2 CCX 3 )] 2 complexes with a substituted acetate anion possess R = Et and CX 3 = CPh 3 (RIJVEN; Roitershtein et al, 2013; this complex has a very similar structure compared with that described herein but a 'less flat' core), and R = tertbutyl, and CX 3 = CH 2 Ph, tert-butyl and CH 2 OC 2 H 4 OCH 3 (RITRAN, RITQOA and RITRER; Bethley et al, 1997). The other complexes are [Al(iBu) (Zijlstra et al, 2017) and ZIQLEQ (Chang et al, 1995)].…”

Solid‐State Nuclear Magnetic Resonance Techniques for the Structural Characterization of Geminal Alane‐Phosphane Frustrated Lewis Pairs and Secondary Adducts

“…Besides the widely studied borane‐phosphane FLPs, the alane‐phosphane homologs present a viable alternative in chemical reactivity and homogeneous FLP catalysis. [ 17 , 18 , 19 , 20 , 21 , 22 , 23 ] With few exceptions[ 20 , 21 , 22 , 23 ] the field of intramolecular Al/P systems has been focusing on geminal compounds,[ 19 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ] where the relative orientation of the orbitals limits the degree of possible overlap, rendering these generally more reactive in comparison to borane‐phosphane FLPs. To the best of our knowledge, solid‐state NMR techniques have never been used for the structural characterization of these systems.…”