CHARACTERIZATION AND CRYSTAL-STRUCTURE OF NICKEL-COMPLEXES OF IMINE OXIMES CONTAINING TAUTOMERIZED ENOLATE LIGANDS

The nickel (II) complexes 3-hydroxy-3-penten-2-one oximato-N, O(3-meth ylimino-2-pentanone oximato-N,N')nickel(II), Ni(pen)(mei); 3-hydroxy-3 -penten-2-one oximato-N, O(3-ethylimino-2-pentanone oximato-N,N')nicke l(II), Ni(pen)(eti); 4-hydroxy-4-hexen-3-one oximato-N, O(4-methylimin o-3-hexanone oximato-N,N')nickel(II), Ni(hex)(mei); and 4-hydroxy-4-he xen-3-one oximato-N,O(4-ethylimino-3-hexanone oximato-N,N')nickel(II), Ni(hex)(eti) have been synthesized from the corresponding alkyldione monoximes and amines and characterized by NMR, IR, MS, and elemental a nalysis. The latter three complexes have not been previously reported, and the characterization shows their structure to be contrary to that reported for Ni(pen)(mei) in earlier literature. Their formation sugg ests two separate courses of the alkyldione monoxime: reaction with am ine;to form the imine and keto/enol tautomerization. The crystal struc ture of Ni(hex)(eti) has been determined: monoclinic, P2(1)/n, a = 8.2 350(1) Angstrom, b = 14.0895(2) Angstrom, c = 13.7965(1) Angstrom, bet a = 95.964(1)degrees, with four molecules per unit cell. The reactivit y of the complexes is explained based on the crystal structure and H-1 NMR data.