title: Uranium Metalla-Allenes with Carbene Imido R2 C=U(IV) =NR' Units (R=Ph2 PNSiMe3 ; R'=CPh3 ): Alkali-Metal-Mediated Push-Pull Effects with an Amido Auxiliary.
abstract: We report uranium(IV)-carbene-imido-amide metalla-allene complexes [U(BIPM(TMS) )(NCPh3 )(NHCPh3 )(M)] (BIPM(TMS) =C(PPh2 NSiMe3 )2 ; M=Li or K) that can be described as R2 C=U=NR' push-pull metalla-allene units, as organometallic counterparts of the well-known push-pull organic allenes. The solid-state structures reveal that the R2 C=U=NR' units adopt highly unusual cis-arrangements, which are also reproduced by gas-phase theoretical studies conducted without the alkali metals to remove their potential structure-directing roles. Computational studies confirm the double-bond nature of the U=NR' and U=CR2 interactions, the latter increasingly attenuated by potassium then lithium when compared to the hypothetical alkali-metal-free anion. Combined experimental and theoretical data show that the push-pull effect induced by the alkali metal cations and amide auxiliary gives a fundamental and tunable structural influence over the C=U(IV) =N units.
authors.affiliation: School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
authors.forename: Erli
authors.initials: E
authors.lastname: Lu
authors.affiliation: School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
authors.forename: Floriana
authors.initials: F
authors.lastname: Tuna
authors.affiliation: School of Chemistry, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK).
authors.forename: William
authors.initials: W
authors.lastname: Lewis
authors.affiliation: School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK. nikolas.kaltsoyannis@manchester.ac.uk.
authors.forename: Nikolas
authors.initials: N
authors.lastname: Kaltsoyannis
authors.affiliation: School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK. steve.liddle@manchester.ac.uk.
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Liddle
keywords: amido; carbene; imido; metalla-allene; push-pull effect; uranium