Chiral diazadiene and beta-ketoimine ligands from the reaction of N,N '-bis-aryl-oxalimidoylchlorides with (S)-prolinol and their reactivity towards iron carbonyls

N.N'-Bis-aryl-oxalimidoylchlorides react with (S)-prolinol to give chiral N ,N'-bis-aryl-tetrahydropyrrolo-[2,1-c][1,4]oxazine-3,4- diylidenediamines. These compounds exhibit a 1,3-diazadiene subunit which may be reacted eithe r with Fe(CO)(5) under photochemical or with Fe-2(CO)(6) under thermal reac tion conditions to yield dinuclear complexes of the general formula (ligand )Fe-2(CO)(6). In these complexes an unsymmetrical binding mode of the Fe-2( CO)(6) moiety is realized. One of the iron atoms is coordinating both imine nitrogen atoms, whereas the second iron atom is connected to one of the C- N double bonds in a side-on fashion. If the aromatic substituent of the oxa limidoylchloride is p-OCH3-C6H4 the reaction with Fe(CO)(5) or Fe-2(CO)(9) produces a mixture of diastereomers. In all other cases the (S)-configurati on of the starting material is retained. If the aromatic substituent is p-B r-C6H4 the corresponding tetrahydropyrrolo-[2, 1-c][1,4]oxazine derivative undergoes a quantitative rearrangement reaction to produce the isomeric 2-( 4-bromphenyl)-3-(4-bromphenylimino)-tetrahydropyrrolo[1,2-a]pyrazine-4-one. The reaction of this ligand with Fe(CO), or Fe,(CO), ends up in the format ion of a complex of the general formula [(ligand),Fe][(mu(2)-H)Fe-3(CO)(11) ](2) consisting of an octahedrally coordinated Fe2+ and two triangular [(mu (2)-H)Fe-3(CO)(11)] anions. (C) 1999 Elsevier Science S.A. All rights reser ved.