Jump to main content
Jump to site search

Issue 5, 2011
Previous Article Next Article

Organozinc hydroxylamides: on the bulk-dependent interplay of nuclearity, structure and dynamics

Author affiliations

Abstract

The reactions of zinc dialkyls, R2Zn (1a–d; R = Me (a), Et (b), iPr (c) and tBu (d)), with N,N-dialkylhydroxylamines, HO–NR′2 (2a–c; R′ = Me (a), Et (b) and iPr (c)), afford organozinc hydroxylamides under alkane extrusion. Species of different nuclearity are observed, depending on the hydroxylamine 2 employed. The smaller 2a and 2b give pentanuclear complexes of the general formula Zn(RZn)4O–NR′2)6 (R = Me, Et, iPr and tBu; R′ = Me and Et), whereas the derivatives of 2c are tetramers of the general formula (RZn)4(O–NR′2)4 (R = Me, Et and iPr; R′ = iPr) as governed by bulk issues about the N-donor. Due to the ability of the double-donor unit O–NR2 to change its bridging mode, two coordination isomers exist for both types of compounds. The pentanuclear species crystallise either in a heterofenestrane or an octahedroid motif. For these species, the central Zn atom exhibits either coordination number 4 or 6; in solution, a rapid change between coordination isomers is observed. Due to the absence of a central Zn atom in the tetranuclear species, these aggregate in heterocubane geometries or such derived thereof. They display the O–N units in either κ3O or κ2O1N mode. The tetranuclear species are also yielded with the less sterically encumbered precursors under thermodynamic conditions (i.e. reflux), as exemplified by the reaction of Me2Zn (1a) with HO–NEt2 (2b). They are non-dynamic in solution, showing that a central cation is mandatory for the fluxional behaviour observed for the pentanuclear derivatives. DFT studies on the O–NMe2 series reveal that the relative energies of the pentazinc isomers become more similar with increasing RZn group size; possible conversions of these to their tetrazinc counterparts were also scrutinised. Two κ3O-bridged degradation products of hydroxylamide complexes could be structurally characterised. They were formed either by partial product hydrolysis, or by in situ oxygenation of the starting zinc dialkyl.

Graphical abstract: Organozinc hydroxylamides: on the bulk-dependent interplay of nuclearity, structure and dynamics

Back to tab navigation

Supplementary files

Publication details

The article was received on 25 Aug 2010, accepted on 11 Nov 2010 and first published on 17 Dec 2010


Article type: Paper
DOI: 10.1039/C0DT01100B
Citation: Dalton Trans., 2011,40, 1144-1157

  •   Request permissions

    Organozinc hydroxylamides: on the bulk-dependent interplay of nuclearity, structure and dynamics

    M. Ullrich, R. J. F. Berger, S. Jana, T. Pape, R. Fröhlich and N. W. Mitzel, Dalton Trans., 2011, 40, 1144
    DOI: 10.1039/C0DT01100B

Search articles by author

Spotlight

Advertisements