A template‐controlled reaction cascade starting from [Pt(PMe3)4](CF3SO3)2 and 2‐azidophenyl isocyanide yields the tetracarbene complex [1](CF3SO3)2. The four NH,NH‐stabilized carbene ligands in [1]2+ can be bridged at the metal template by reaction with N,N‐dimethylformamide (DMF) and diphosgene to give the coordinated cyclic tetracarbene ligand with crown ether topology in complex [2](Cl)2.

The reaction of 2-azidophenyl isocyanide (7) with [M(CO)(5)(thf)] (M=Cr, W) yields the isocyanide complexes [M(CO)(5)(7)] (M=Cr 8, M=W 9). Complexes 8 and 9 react with tertiary phosphines such as triphenylphosphane at the azido function of the isocyanide ligand to give the 2-triphenylphosphiniminophenyl isocyanide complexes 10 (M=Cr) and 11 (M=W). The polar triphenylphosphiniminophenyl function in complexes 10 and 11 can be hydrolyzed with H(2)O/HBr to afford triphenylphosphane oxide and the complexes containing the unstable 2-aminophenyl isocyanide ligand. This ligand spontaneously cyclizes by intramolecular nucleophilic attack of the primary amine at the isocyanide carbon atom to yield the 2,3-dihydro-1H-benzimidazol-2-ylidene complexes 12 (M=Cr) and 13 (M=W). Double deprotonation of the cyclic NH,NH-carbene ligands in 12 and 13 with KOtBu and reaction with two equivalents of allyl bromide yields the N,N'-dialkylated benzannulated N-heterocyclic carbene complexes 14 (M=Cr) and 15 (M=W). The molecular structures of complexes 9 and 11-15 were confirmed by X-ray diffraction studies.

Tungsten complex with a coordinated 2-azidoethyl isocyanide ligand reacts with PMe3 at the azido function to give a complex with a coordinated iminophosphorane which upon hydrolysis of the P=N bond yields a complex with an NH,NH-stabilized N-heterocyclic carbene ligand, 7; alkylation of the carbene ring nitrogen atoms gives a complex with an N,N'-dialkylated imidazolidin-2-ylidene ligand, 8 .

In einer templatkontrollierten Reaktionskaskade reagiert [Pt(PMe3)4](CF3SO3)2 mit 2‐Azidophenylisocyanid zum Tetracarben‐Komplex [1](CF3SO3)2. Die vier NH,NH‐stabilisierten Carben‐Liganden in [1]2+ können am Metalltemplat durch Reaktion mit DMF und Diphosgen zum cyclischen Tetracarben‐Liganden mit Kronenether‐Topologie in [2](Cl)2 verbrückt werden.

No abstract