title: Design of new heteroscorpionate ligands and their coordinative ability toward Group 4 transition metals; an efficient synthetic route to obtain enantiopure ligands.
abstract: The reaction of different types of bis(pyrazol-1-yl)methane derivatives with Bu(n)Li and alkyl or aryl-containing-isocyanates or isothiocyanates, some of these as chiral reagents, gives rise to the preparation of new heteroscorpionate ligands in the form of the lithium derivatives [Li(NNE)]2 (1-10), although a similar process with trimethylsilyl isocyanate or isothiocyanate gave the complexes [Li(NCX)(bdmpzs)(THF)](X = O, 11; X = S, 12)[bdmpzs = bis(3,5-dimethylpyrazol-1-yl)trimethylsilylmethane]. Compounds 1-8 reacted with [TiCl4(THF)2] or [MCl4](M = Zr, Hf) to give a series of cationic complexes [MCl3{kappa3-NNE(H)}]Cl (13-36) where the heteroscorpionate ligand contains either an acetamide or thioacetamide group resulting from the protonation of the corresponding acetamidate or thioacetamidate. However, under appropriate experimental conditions neutral Ti complexes were isolated-namely [TiClx(NMe2)3-x(S-mbbpam)](37-39)[S-mbbpam =(S)-(-)-N-alpha-methylbenzyl-2,2-bis(3,5-dimethylpyrazol-1-yl)acetamidate]. Finally, two alkoxide-containing titanium complexes [TiClx(OR)3-x(S-mbbpamH)]Cl (40-41) were also prepared. The structures of these complexes have been determined by spectroscopic methods and, in addition, the X-ray crystal structures of 1, 12, and 19 were also established.
authors.affiliation: Departamento de Química Inorgánica, Orgánica y Bioquímica, Universidad de Castilla-La Mancha, Campus Universitario, 13071, Ciudad Real, Spain. Antonio.otero@uclm.es
authors.forename: Antonio
authors.initials: A
authors.lastname: Otero
authors.forename: Juan
authors.initials: J
authors.lastname: Fernández-Baeza
authors.forename: Antonio
authors.initials: A
authors.lastname: Antiñolo
authors.forename: Juan
authors.initials: J
authors.lastname: Tejeda
authors.forename: Agustín
authors.initials: A
authors.lastname: Lara-Sánchez
authors.forename: Luis
authors.initials: L
authors.lastname: Sánchez-Barba
authors.forename: Margarita
authors.initials: M
authors.lastname: Sánchez-Molina
authors.forename: Sonia
authors.initials: S
authors.lastname: Franco
authors.forename: Isabel
authors.initials: I
authors.lastname: López-Solera
authors.forename: Ana M
authors.initials: AM
authors.lastname: Rodríguez