Bipyridine Adducts of Molybdenum Imido Alkylidene and Imido Alkylidyne Complexes.
Seven bipyridine adducts of molybdenum imido alkylidene bispyrrolide complexes of the type Mo(NR)(CHCMe(2)R')(Pyr)(2)(bipy) (1a-1g; R = 2,6-i-Pr(2)C(6)H(3) (Ar), adamantyl (Ad), 2,6-Me(2)C(6)H(3) (Ar'), 2-i-PrC(6)H(4) (Ar(iPr)), 2-ClC(6)H(4) (Ar(Cl)), 2-t-BuC(6)H(4) (Ar(t) (Bu)), and 2-MesitylC(6)H(4) (Ar(M)), respectively; R' = Me, Ph) have been prepared using three different methods. Up to three isomers of the adducts are observed that are proposed to be the trans and two possible cis pyrrolide isomers of syn alkylidenes. Sonication of a mixture containing 1a-1g, HMTOH (2,6-dimesitylphenol), and ZnCl(2)(dioxane) led to the formation of MAP species of the type Mo(NR)(CHCMe(2)R')(Pyr)(OHMT) (3a-3g). DCMNBD (2,3-dicarbomethoxynorbornadiene) is polymerized employing 3a-3g as initiators to yield >98% cis,syndiotactic poly(DCMNBD). Attempts to prepare bipy adducts of bisdimethylpyrrolide complexes led to formation of imido alkylidyne complexes of the type Mo(NR)(CCMe(2)R')(Me(2)Pyr)(bipy) (Me(2)Pyr = 2,5-dimethylpyrrolide; 4a - 4g) through a ligand-induced migration of an alkylidene α proton to a dimethylpyrrolide ligand. X-ray structures of Mo(NAr)(CHCMe(2)Ph)(Pyr)(2)(bipy) (1a), Mo(NAr(iPr))(CHCMe(2)Ph)(Pyr)(OHMT) (3d), Mo(NAr)(CCMe(2)Ph)(Me(2)Pyr)(bipy) (4a), and Mo(NAr(T))(CCMe(3))(Me(2)Pyr)(bipy) (Ar(T) = 2-(2,4,6-i-Pr(3)C(6)H(2))C(6)H(4); 4g) showed structures with the normal bond lengths and angles.
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139.
Alejandro G
AG
Lichtscheidl
Victor W L
VW
Ng
Peter
P
Müller
Michael K
MK
Takase
Richard R
RR
Schrock
Steven J
SJ
Malcolmson
Simon J
SJ
Meek
Bo
B
Li
Elizabeth T
ET
Kiesewetter
Amir H
AH
Hoveyda