title: Binuclear β-diketiminate complexes of copper(i).
abstract: The reaction of a series of dinucleating bis(β-diketiminate) pro-ligands with mesitylcopper in the presence and absence of mono and diphosphines has allowed the isolation of a new series of dicopper(i) complexes. Inclusion of trans-1,2-cyclohexyl (1), 2,6-pyridyl (2), and 2,2'-oxydiaryl (3) spacers between the β-diketiminate units has been studied. The isolation of three new copper(i) phosphine complexes [1·Cu2(PPh3)2], [2·Cu2(PPh3)2] and [3·Cu2(PPh3)2] is reported. While these compounds display large CuCu separations of 5.4-7.9 Å in the solid state, solution data are consistent with a large degree of conformational freedom. Modification of the monophosphine to a diphosphine, DPPE, allowed the isolation of the novel 11-membered bimetallic macrocycle [2·Cu2(DPPE)] containing both a binucleating nitrogen based ligand and a chelating diphosphine. While acetonitrile adducts of this series could also be generated in situ, under forcing conditions reaction of the 2,6-pyridyl bridged ligand with mesityl copper led to the formation [2·Cu2]2. This latter complex is a dimer of dicopper(i) units in which the bis(β-diketiminate) ligand now binds four copper(i) centers through not only the expected κ2-N,N'-chelation but also κ1- and η2-binding of the central pyridine through orthogonal Cu-N and Cu-arene interactions. Reversible coordination of alkenes, pyridine and quinoline to the copper cluster was identified allowing the isolation and structural characterisation of a further series of dinuclear complexes [2·Cu2(pyridine)2], [2·Cu2(cyclopentene)2] and [2·Cu2(norbornene)2]. Solution studies allow quantification of the reversible binding event through a van't Hoff analysis. Both solution and the solid state data suggest a weak anagostic interaction exists in the latter two alkene complexes of copper(i). The new complexes have been characterized by X-ray diffraction, multinuclear NMR spectroscopy and CHN analysis.
authors.affiliation: Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK. m.crimmin@imperial.ac.uk.
authors.forename: Andreas
authors.initials: A
authors.lastname: Phanopoulos
authors.affiliation: Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK. m.crimmin@imperial.ac.uk.
authors.forename: Alice H M
authors.initials: AH
authors.lastname: Leung
authors.affiliation: Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK. m.crimmin@imperial.ac.uk.
authors.forename: Shuhui
authors.initials: S
authors.lastname: Yow
authors.affiliation: Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK. m.crimmin@imperial.ac.uk.
authors.forename: David
authors.initials: D
authors.lastname: Palomas
authors.affiliation: Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK. m.crimmin@imperial.ac.uk.
authors.forename: Andrew J P
authors.initials: AJ
authors.lastname: White
authors.affiliation: Department of Chemical Engineering, Imperial College London, South Kensington, London, SW7 2AZ, UK.
authors.forename: Klaus
authors.initials: K
authors.lastname: Hellgardt
authors.affiliation: PTI/DX Emerging Technologies, Shell Global Solutions International B.V., P.O. Box 38000, 1030 BN Amsterdam, The Netherlands.
authors.forename: Andrew
authors.initials: A
authors.lastname: Horton
authors.affiliation: Department of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, UK. m.crimmin@imperial.ac.uk.
authors.forename: Mark R
authors.identifier: http://orcid.org/0000-0002-9339-9182
authors.initials: MR
authors.lastname: Crimmin