Applications of manganocene in the synthesis of Mn(II) amide and imide cages

摘要

The reactions of manganocene, Cp_2Mn (Cp = C_5H_5), with 2-aminopyrimidines give similar, octameric amido/imido cage complexes of general formulae [{CpMnNHR} {MnNR}]_4 [R = 4,6-Me_2pm (1a), 4-MeO-6-Mepm (1b), 4,6-(MeO)_2-pm (1c); pm = pyrimidinyl]. The structures of these complexes can be visualised as being composed of central Mn_4N_4 imido cubane units that are coordinated at their peripheries by four [CpMnNHpm] monomers. In contrast, less acidic 2-aminopyridine (2-NH_2py) and 8-aminoquinoline (8-NH_2quin) are only single deprotonated under similar conditions, giving the unusual hexanuclear amido complex [Cp_2Mn_3(NHpy)_4]_2 (2) and the dimer [CpMn-(μ-8-HNquin)]_2 (3). N,N'-Dibenzylethylenediamine [(BnNHCH_2)_2] only forms the simple adduct [(η~1-Cp)(η~5-Cp)-Mn{BnNHCH_2)_2}] (4) (Bn = CH_2Ph) with Cp_2Mn, in which no deprotonation of the organic acid has occurred. The X-ray structures of the new complexes 1b-c, 3 and 4 are reported (1a and 2 having been communicated previously).