title: Complexes of an anionic gallium(I) N-heterocyclic carbene analogue with group 14 element(II) fragments: synthetic, structural and theoretical studies.
abstract: The reactions of the anionic gallium(I) N-heterocyclic carbene (NHC) analogue, [K(tmeda)][:Ga{[N(Ar)C(H)]2}], Ar = C6H3Pri2-2,6, with the heavier group 14 alkene analogues, R2E=ER2, E = Ge or Sn, R = -CH(SiMe3)2, have been carried out. In 2:1 stoichiometries, these lead to the ionic [K(tmeda)][R2EGa{[N(Ar)C(H)]2}] complexes which exhibit long E-Ga bonds. The nature of these bonds has been probed by DFT calculations, and the complexes have been compared to neutral NHC adducts of group 14 dialkyls. The 4:1 reaction of [K(tmeda)][:Ga{[N(Ar)C(H)]2}] with R2Sn=SnR2 leads to the digallyl stannate complex, [K(tmeda)][RSn[Ga{[N(Ar)C(H)]2}]2], presumably via elimination of KR. In contrast, the reaction of the gallium heterocycle with PbR2 affords the digallane4, [Ga{[N(Ar)C(H)]2}]2, via an oxidative coupling reaction. For sake of comparison, the reactions of [K(tmeda)][:Ga{[N(Ar)C(H)]2}] with Ar'2E=EAr'2, E = Ge, Sn or Pb, Ar' = C6H2Pri3-2,4,6, were carried out and led to either no reaction (E = Ge), the formation of [K(tmeda)][Ar'2SnGa{[N(Ar)C(H)]2}] (E = Sn), or the gallium(III) heterocycle, [Ar'Ga{[N(Ar)C(H)]2}] (E = Pb). Salt elimination reactions between [K(tmeda)][:Ga{[N(Ar)C(H)]2}] and the guanidinato group 14 complexes [(Giso)ECl], E = Ge or Sn, Giso = [Pri2NC{N(Ar)}2]-, gave the neutral [(Giso)EGa{[N(Ar)C(H)]2}] complexes. All complexes have been characterized by NMR spectroscopy and X-ray crystallographic studies.
authors.affiliation: Center for Fundamental and Applied Main Group Chemistry, School of Chemistry, Main Building, Cardiff University, Cardiff, CF10 3AT, U.K.
authors.forename: Shaun P
authors.initials: SP
authors.lastname: Green
authors.forename: Cameron
authors.initials: C
authors.lastname: Jones
authors.forename: Kai-Alexander
authors.initials: KA
authors.lastname: Lippert
authors.forename: David P
authors.initials: DP
authors.lastname: Mills
authors.forename: Andreas
authors.initials: A
authors.lastname: Stasch
mesh_terms: D000838:Anions / Q000737:chemistry; D018360:Crystallography, X-Ray; D005708:Gallium / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry; D019216:Metals, Heavy / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D000838:Anions; D006571:Heterocyclic Compounds; D006838:Hydrocarbons; D019216:Metals, Heavy; D009942:Organometallic Compounds; C030011:carbene; D005708:Gallium; D008697:Methane