Syntheses of Variations of Stereogenic-at-Metal Imido Alkylidene Complexes of Molybdenum

Abstract

In this paper we describe the syntheses of several new stereogenic-at-metal imido alkylidene complexes of molybdenum, Mo(NR)(CHR′)(X)(Y), many of which had to be prepared through selective nucleophilic displacement reactions in imido alkylidene complexes. The reported compounds include Mo(NAd)(CHCMe[subscript 2]Ph)(MesPyr)[subscript 2] (1a; MesPyr = 2-mesitylpyrrolide, Ad = 1-adamantyl), Mo(NAd)(CHCMe[subscript 2]Ph)(2-CNPyr)[subscript 2] (1b; 2-CNPyr = 2-cyanopyrrolide), Mo(NAd)(CHCMe[subscript 2]Ph)(MesPyr)(OTPP) (2a; OTPP = 2,3,5,6-tetraphenylphenoxide), Mo(NAd)(CHCMe[subscript 2]Ph)(MesPyr)(OBr[subscript 2]Bitet) (2b; OBr[subscript 2]Bitet = (R)-3,3′-dibromo-2′-(tert-butyldimethylsilyloxy)-5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl-2-olate), Mo(NAd)(CHCMe[subscript 2]Ph)(OHIPT)(2-Mespyr) (2c; HIPT = 2,6-(2,4,6-iPr[subscript 3]C[subscript 6]H[subscript 2])[subscript 2]C[subscript 6]H[subscript 3]), Mo(NAd)(CHCMe[subscript 2]Ph)(OTf)(OHIPT) (3), Mo(NAd)(CHCMe[subscript 2]Ph)(OTf)(OHIPT)(PMe[subscript 3]) (3(PMe[subscript 3])), Mo(NAd)(CHCMe[subscript 2]Ph)(2-CNPyr)(OHIPT) (4), Mo(NAd)(CHCMe[subscript 2]Ph)(OHIPT)(OCMe[subscript 3]) (5), Mo(NR)(CHCMe[subscript 2]Ph)(OR[subscript F6])(OHMT) (OR[subscript F6] = OCMe(CF[subscript 3])[subscript 2]; HMT = 2,6-Mes[subscript 2]C[subscript 6]H[subscript 3]; R = 2,6-iPr[subscript 2]C[subscript 6]H[subscript 3] (Ar, 6a), 2,6-Me[subscript 2]C[subscript 6]H[subscript 3] (Ar′, 6b), 2-iPrC[subscript 6]H[subscript 4] (Ar[sueprscript iPr], 6c), Ad (6d)), Mo(NR)(CHCMe[subscript 2]Ph)(OR[subscript F6])[N(H)HMT] (7a (R = Ar′) and 7b (R = Ar[superscript iPr])), and Mo(NAd)(CHCMe[subscript 2]Ph)(OR[subscript F6])(HMT) (8). X-ray structural studies were carried out on 1b, 2a–c, 3(PMe[subscript 3]), 4, 5, 6d, 7b, and 8. Compound 1b is an octamer in which two η[superscript 1]-pyrrolides are trans to one another at each metal center and cyano groups bind from neighboring Mo centers trans to the alkylidene and imido ligands.