CYCLOADDITION REACTIONS OF THE MANGANESE VINYLIDENE CP'(CO)(2)MN=C=C(H)R, CARBYNE [CP'(CO)(2)MN-CCH(2)R](-) (R=H,ME) COMPLEXES WITH 1,4-DIPHENYL-1-AZABUTADIENE(), AND ANIONIC CARBENE [CP'(CO)(2)MN=C(OET)CHR]()

The reactivity of vinylidene Cp'(CO)(2)Mn=C=CH(R) (3a-b), cationic car byne [Cp'(CO)(2)Mn=CCH(2)R](+) ([2a-b]+), and anionic carbene [Cp'(CO) (2)Mn=C(OEt)CHR](-) ([1a-b](-)) complexes towards 1,4-diphenyl-1-azabu tadiene (4) was examined. Complexes 3a-b react with 4 to give selectiv ely the 2-azetidinylidene complexes Cp'(CO)(2)Mn=CN(Ph))CH(CH=CH(Ph))C H(R) (5a-b) through net [2 + 2] cycloaddition reactions. The same comp lexes 5a-b were obtained upon treatment of [2a-b](+) first with 4 foll owed by addition of triethylamine. By contrast, complexes [1a-b](-) re act with 4 to afford primarily the 2-tetrahydropyridinylidene complexe s Cp'(CO)(2)Mn=CN(Ph)C(H)=C(H)CH(Ph)CH(R) (8a-b), and the 2-dihydropyr idinylidene complex Cp'(CO)(2)Mn=CN(Ph)C(H)=C(H)C(Ph)=CH (9a), resulti ng from net [2 + 4] cycloaddition reactions. The solid state structure of 9a was determined by X-ray crystallography.