Synthesis of a Ruthenium(II) Complex Containing an [11]ane-P2CNHC (NHC = Imidazolidin-2-ylidene) Macrocycle

Reaction of [RuCl(Cp)(PPh3)(2)] with bis[di(2-fluorophenyl)phosphino]benzene, 3, yields complex [RuCl(Cp)(3)], [4]. The chloro ligand in [4] can be exchanged for the 2-azidoethyl isocyanide ligand 2, giving complex [Ru(Cp)(2)(3)]Cl, [5]Cl, which reacts with NH4BF4 to give [5]BF4. The azido group of the coordinated isocyanide ligand in [5]Cl or [5]BF4 can be reduced with Zn/NH4Cl/H2O to give the complex with the 2-aminoethyl isocyanide ligand. This ligand is not stable but cyclizes by an intramolecular nucleophilic attack of the amino group at the isocyanide carbon atom to give an NH, NH-stabilized NHC ligand in complexes [6]X (X = Cl, [6]Cl; X 0.5 ZnCl4, [6](2)(ZnCl4); X = BF4, [6]BF4). Deprotonation of the NH,NH-stabilized NHC ligands in cations of type [6](+) leads to an intramolecular nucleophilic attack of the amido nitrogen atoms at the fluorinated phenyl groups of the diphosphine ligand under formation of the complex with the facially coordinated macro cyclic [11]anc-P2CNHC ligand [1]X (X = Cl, [1]Cl; X = 0.5 ZnCl4, [1](2)(ZnCl4); X = BF4, [1]BF4). Formation of the macrocycle is facilitated by the steric pressure excerted by the cyclopentadienyl ligand. The molecular structures of [4], [5]BF4, [6]BF4 center dot CH2Cl2, and [1]Cl center dot CH2Cl2 center dot 0.5H(2)O have been determined by X-ray diffraction.