title: 2-Azetidinones as Precursors of Pincer Ligands: Preparation, Structure, and Spectroscopic Properties of CC'N-Osmium Complexes.
abstract: A metal-promoted degradation of 2-azetidinones to afford CC'N-pincer ligands is reported. The hexahydride complex OsH6(P(i)Pr3)2 (1) reacts with (±)-cis-1-(4-methoxyphenyl)-3-phenoxy-4-(pyridin-2-yl)azetidin-2-one (I), (±)-cis-1-(4-methoxyphenyl)-3-phenoxy-4-(isoquinolin-2-yl)azetidin-2-one (II), and (±)-cis-1-(4-methoxyphenyl)-3-phenoxy-4-(quinolin-2-yl)azetidin-2-one (III) to give the respective OsH2(P(i)Pr3)2(CC'N) (2-4) complexes, which add HBF4·OEt2 to yield [OsH2(P(i)Pr3)2(CC″N)]BF4 (5-7). These salts are the result of the addition of the proton of the acid to the dianionic CC'N-pincer ligand. The hydride ligands of these compounds undergo quantum mechanical exchange coupling, which has been experimentally quantified according to a two-dimensional harmonic oscillator model, where Jex is determined by the separation between the hydrides, their hard sphere radius, and a ν parameter describing the H-M-H vibrational wag mode allowing the movement along the H-H vector. The comparison of the results reveals that the phenomenon is particularly intense for 5-7. Furthermore, in these compounds, the separation between the hydrides is ∼0.1 Å shorter than in the respective neutral species 2-4, whereas the hydride hard sphere radius increases by ∼10%, and the ν value decreases by ∼20%.
authors.affiliation: Departamento de Química Orgánica, Facultad de Ciencias Químicas, Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad Complutense , 28040 Madrid, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Casarrubios
authors.affiliation: Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad de Zaragoza-CSIC , 50009 Zaragoza, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Esteruelas
authors.affiliation: Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad de Zaragoza-CSIC , 50009 Zaragoza, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Larramona
authors.affiliation: Departamento de Química Orgánica, Facultad de Ciencias Químicas, Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad Complutense , 28040 Madrid, Spain.
authors.forename: Jaime G
authors.initials: JG
authors.lastname: Muntaner
authors.affiliation: Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad de Zaragoza-CSIC , 50009 Zaragoza, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Oñate
authors.affiliation: Departamento de Química Orgánica, Facultad de Ciencias Químicas, Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad Complutense , 28040 Madrid, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Sierra