title: Metathesis reactions of a manganese borylene complex with polar heteroatom-carbon double bonds: a pathway to previously inaccessible carbene complexes.
abstract: A comprehensive study has been carried out to investigate the metathesis reactivity of the terminal alkylborylene complex [(η(5)-C5H5)(OC)2Mn═B(tBu)] (1). Its reactions with 3,3',5,5'-tetrakis(trifluoromethyl)benzophenone, 4,4'-dimethylbenzophenone, 2-adamantanone, 4,4'-bis(diethylamino)benzophenone, and 1,2-diphenylcyclopropen-3-one afforded the metathesis products [(η(5)-C5H5)(OC)2Mn═CR2] (R = C6H3-3,5-(CF3)23a, C6H4-4-Me 3b, C6H4-4-NEt23d; CR2 = adamantylidene 3c, cyclo-C3Ph23e). The cycloaddition intermediates were detected by NMR spectroscopy from reactions involving ketones with more electron-withdrawing substituents. The reaction of 1 with dicyclohexylcarbodiimide (DCC) only proceeds to form the cycloaddition product [(η(5)-C5H5)(OC)2Mn{κ(2)-C,B-C(═NCy)N(Cy)B(tBu)}] (4), which upon warming, rearranges to afford complex [(η(5)-C5H5)(OC)2Mn{CN(Cy)B(tBu)CN(Cy)}] (5). The reaction of 1 with triphenylphosphine sulfide SPPh3 also yields the metathesis product [(η(5)-C5H5)(OC)2Mn(PPh3)] via an intermediate which is likely to be a η(2)-thioboryl complex [(η(5)-C5H5)(OC)2Mn{(η(2)-SB(tBu)}] (6). Similar reactions have been studied using an iron borylene complex [(Me3P)(OC)3Fe═B(Dur)] (Dur = 2,3,5,6-tetramethylphenyl, 9). Extensive computational studies have been also carried out to gain mechanistic insights in these reactions, which provided reaction pathways that fit well with the experimental data.
authors.affiliation: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Bauer
authors.forename: Holger
authors.initials: H
authors.lastname: Braunschweig
authors.forename: Alexander
authors.initials: A
authors.lastname: Damme
authors.forename: Jose Oscar Carlos
authors.initials: JO
authors.lastname: Jimenez-Halla
authors.forename: Thomas
authors.initials: T
authors.lastname: Kramer
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Radacki
authors.forename: Rong
authors.initials: R
authors.lastname: Shang
authors.forename: Eva
authors.initials: E
authors.lastname: Siedler
authors.forename: Qing
authors.initials: Q
authors.lastname: Ye
mesh_terms: D001896:Boron Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003500:Cyclization; D007094:Imides / Q000737:chemistry; D007659:Ketones / Q000737:chemistry; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D009943:Organophosphorus Compounds / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry
chemical_list: D001896:Boron Compounds; D056831:Coordination Complexes; D007094:Imides; D007659:Ketones; D009943:Organophosphorus Compounds; D013440:Sulfides; C030011:carbene; C061896:triphenylphosphine; D002244:Carbon; D008697:Methane