Oxygen scavenging by lithium zincates:: the synthesis, structural characterisation and derivatisation of [Ph(2-C5H4N)N]2ZnRLi•nthf (R = But, Bun; n = 1, 2)

The 1 : 2 reaction of ZnMe2 with N-2-pyridylaniline, Ph(2-C5H4N)NH 1, affords [Ph(2-C5H4N)N](2) Zn 10, the treatment of which with BuLi and thf affords the diastereomeric lithium zincate [Ph(2-C5H4N)N](2)ZnRLi.nthf (R = Bu-n, n = 2; 11a; R = Bu-t, n = 1, 11b). The sequential treatment of 10 (either in situ or after isolation) with organolithium substrates and molecular oxygen has afforded insights into the oxygen-scavenging capacity of mixed Group 1-Group 12 species. Hence, 10 reacts with (BuLi)-Li-n, O-2 and thf or dimethoxyethane (dme) to give {[Ph(2-C5H4N)N](2)(ZnOBuLi)-Li-n.nL}(2) (n = 1, L = thf, 12a; n = 0.5, L = dme, 12b), with the structural relationship between 11a and 12a strongly suggesting that for R = Bu n oxygenation proceeds by insertion into the Zn-C bond of an {[Ph(2-C5H4N)N](2)ZnR}(-) ion. The employment of (BuLi)-Li-t, O-2 and thf together with 10 affords only the previously reported complex [Ph(2-C5H4N)N](2)Zn[(mu(3)-O)Bu-t](2)(Li.thf)(2) 4, the formation of which may be rationalised in terms of the Bu-t van der Waals radius and cone angle.