Synthesis and Complexation Behavior of Indenyl and Cyclopentadienyl Ligands Functionalized with a Naphthyridine Unit

Lithium indenide (Li-Ind) or cyclopentadienide (Li-Cp)
derivatives
react as nucleophiles with 8-(methylsulfinyl)-1,5-naphthyridine (Naph),
leading to donor-functionalized ligands IndNaph or CpNaph, respectively. The new ligands comprise two N-donor atoms,
which, for geometric reasons, cannot bind to the same metal atom.
In complexes, where the metal atom is bound by the Cp or Ind moiety,
the N5-donor atom is located in a distal position. The coordination
behavior to Rh or Zr metal centers has been investigated. The Cp-based
ligands show the expected chelating coordination mode with η5-Cp and N coordination, whereas the indenyl units act as dihapto,
trihapto, or pentahapto ligands. The dinuclear Rh­(I) complex 12 shows a rare coordination geometry with two η3 ligands bridging a Rh2(CO)3 fragment.