Reactions of Fe-2(CO)(9) with azine, derivatives: Discovery of new coordination modes and reactivity of new bimetallic compounds

Abstract

Reaction of N,N'-bis-(3-phenyl-allylidene)-hydrazine (1) with Fe-2(CO)(9) was studied. When the reaction was carried out in refluxing THF, the three mononuclear compounds Fe(CO)(3)-[PhCH =CHCH=NN=CHR-trans] (3), Fe(CO)(3)-[PhCH=CHCH=NN=CHR-cis] (4), and Fe(CO)(3)[PhCH=CHCH=N=CHR] (5; R = -CH=CHPh) were obtained. In refluxing toluene, the novel dinuclear compound Fe(CO)(3)[PhCH=CHCH=NN=CHCH=CHPh]Fe(CO)(3) (2) was obtained. Further treatment of 3-5 with Fe2(CO)9 in refluxing toluene eventually led to 2. A detailed study of the reaction of 3-5 with/without Fe2(CO)9 allowed us to establish an overall reaction sequence from 1 to 2. Reaction of the alkyl analogue MeCH=CHCH=NN= CHCH=CHMe (10) with Fe-2(CO)(9) yielded the two dinuclear compounds Fe(CO)(3)[MeCH= CHCH=NN=CHCH=CHMeFe(CO)(3) (11 and 11') or the two mononuclear compounds. Fe(CO)(3)[MeCH=CHCH=NN=CHR'-trans] (12) and Fe(CO)(3)[MeCH=CHCH=NN=CHR'] (13; R' = -CH=CHMe) and the dinuclear compound anti-Fe(CO)(3)[MeCH=CHCH=NN=CHCH=CHMe]Fe(CO)3 (14), respectively, depending upon the reaction conditions. Treatment of 2 with MeLi yielded the dimeric compound [PhCH=CHCH=NN=CHCH= CHPh](2)Fe-4(CO)(12) (16), containing four iron atoms, and treatment with MeLi followed by MeI afforded the dimethyl adduct Fe(CO)(3)[PhCH=CHCHMeN=NCHMeCH=CHPh]Fe(CO)(3) (17). The molecular structures of 3-5, 8, 11, 11', 14, and 16 were cofirmed by X-ray diffraction studies.