Friedel-crafts acetylation of a (NiC 3N 2)-quasi-aromatic ring in a nickel(II) complex, Nioyl

Abstract

Electrophilic substitution of an acetyl group onto the quasi-aromatic ring of Nioyl, (2,2,3,9,10,10-hexamethyl-5,7- dioxa-6-hydra-1,4,8,11-tetraazacyclotetradeca-3,8,11,13-tetraene)nickel(II) was accomplished at 70 °C utilizing acetyl bromide and aluminum chloride dissolved in tetrachloroethylene. 1H and 13C NMR were used to establish the basic structure which results from substitution of the hydrogen by an acetyl group on the central carbon of the metal containing aromatic ring. The single crystal X-ray structure is presented which confirms the position of substitution and that the basic Nioyl structure is maintained. Ni 1O 3N 4Cl 15H 24, M r = 367.1, orthorhombic, Pbca, a = 17.684(9), b = 10.244(4), c = 18.542(8) Å, V = 3359.0 Å 3, Z = 8, D x = 1.456(2) g cm −3, (Mo Kα) = 0.71073 Å, μ = 11.8 cm −1, F(000) = 1560, T = 297 K, R = 0.031, R w = 0.038, for 1246 observed reflections (of 4306 unique data). The IR absorption band ascribed to the carbonyl stretching frequency (1584 cm −1) is much lower than expected for a free uncoordinated acetyl group. The bond distances and angles in the molecule are compared with the parent Nioyl in an attempt to understand the nature of the bonding of the acetyl group to the metal containing ring.