The [11]ane-P2CNHC macrocycle in cation [1]+ has been generated in a template-controlled reaction at iron(II). The macrocycle was synthesized in high overall yield by a base-induced elimination of 2 equiv. of HF from the facially coordinated complex with an NH,NH-stabilized NHC ligand and a diphosphane bearing fluoro-substituted phenyl substituents.
Complex [Fe(η5-C5H5)(η6-PhMe)]PF6 reacts with 1,2-bis[bis(2-fluorophenyl)phosphanyl]benzene (2) in acetonitrile under irradiation for 6 h to give complex [Fe(η5-C5H5)(2)(CH3CN)]PF6 ([3]PF6). Reaction of [3]PF6 with 1 equiv. of 2-azidoethyl isocyanide (4) yields complex [Fe(η5-C5H5)(2)(4)]X ([5]X) (X = Br, PF6). Staudinger reaction with PPh3 at the azido function followed by hydrolysis of the iminophosphorane with HBr yields compound [6]X (X = Br–, PF6 –) with an NH,NH-stabilized NHC ligand. The facially coordinated NH,NH-stabilized NHC and the fluorinated diphosphane ligands were linked by N,N′-deprotonation of the NHC and nucleophilic attack of the nitrogen atoms at two C–F bonds, which gave – after anion exchange with NH4PF6 – complex [1]PF6 bearing the macrocyclic [11]ane-P2CNHC ligand.