Reaction of formaldehyde with mer-(ethylenediamine)(glycylglycinato)nitrocobalt(III). Crystal structure of mer-(ethylenediamine)[N-((5,6-dihydro-5,5-bis(hydroxymethyl)-1,3-oxazin-4-yl)- carbonyl)glycinato]nitrocobalt(III) trihydrate

Abstract

Three new compounds result from the reaction of mer-[Co(NH2CH2CONCH2CO2)NO 2(en)] with formaldehyde in alkaline aqueous solution: mer-(ethylenediamine)[N-((5,6-dihydro-5,5-bis(hydroxymethyl)-1,3-oxazin-4-yl) carbonyl)glycinato]nitrocobalt(III) trihydrate (mer-[Co{(CH2OH)2CCH2OCH 2N=CCONCH2CO2}NO 2(en)]·3H2O), mer-(ethylenediamine)[N-(((methylimino)methyl)carbonyl)glycinato] nitrocobalt(III) (mer-[Co(CH3N=CHCONCH2CO2)NO2(en)]), and mer-(ethylenediamine)(N-methylideneglycylglycinato)nitrocobalt(III) (mer-[Co(CH2=NCH2CONCH2CO2)NO 2(en)]). They were separated by adsorption chromatography on a cationic exchanger, in the hydrogen form, and characterized by elemental analysis, electronic spectroscopy, and 1H and 13C NMR spectroscopy. The structure of mer-[Co{(CH2OH)2CCH2OCH 2N=CCONCH2CO2)-NO 2(en)]·3H2O was determined by X-ray crystallography. It crystallizes in the monoclinic space group P21/n in a unit cell of dimensions a = 8.843(1) Å, b = 26.809 (2) Å, c = 8.910 (1) Å, β = 115.91 (2)°, V = 1899.9 Å3, and ρcalcd = 1.62 g cm-3, with Z = 4. Refinement converged to R = 0.031 for 3260 independent observed (I/σ(I) > 3) reflections. The 1,3-oxazine derivative is tridentate, coordinated through carboxylato oxygen, peptide nitrogen, and imino nitrogen atoms. The equatorially disposed ligand forms with cobalt three fused rings, two five-membered chelates, and one six-membered heterocyclic ring. © 1990 American Chemical Society