Perfect in‐Plane [5555] Metallo‐Annulene Frameworks and Nonmetallo‐Annulene Complexes: A Theoretical Prediction

ABSTRACT

Inspired by the newly discovered in‐plane [55555] metallo‐annulene frameworks in 3D [Os]C ₁₅ H ₁₀ ([Os] = OsL ¹ L ² and L represents PPh ₃ , CO, or PEt ₃ σ‐ligands in axial direction) and recently proposed perfect 2D in‐plane [55555] metallo‐annulene complexes D _{5 h} MC ₁₅ H ₁₀ (M = Pt, Pd, Ni), based on extensive first‐principles theory calculations, we predict herein a series of perfect in‐plane [5555] metallo‐annulene frameworks in 3D D _{4 h} [Fe]C ₁₂ H ₈ ( 1 , [Fe] = Fe(CO) ₂ ) and D _{4 h} [Co]C ₁₂ H ₈ ⁺ ( 2 , [Co] = Co(CO) ₂ ) and perfect 2D in‐plane [5555] nonmetallo‐annulene complexes including D _{4 h} PC ₁₂ H ₈ ^–  ( 3 ), D _{4 h} SC ₁₂ H ₈ ( 4 ), and D _{4 h} ClC ₁₂ H ₈ ⁺ ( 5 ). Detailed bonding pattern and ring current analyses indicate that planar tetracoordinate metal or nonmetal centers participate in the delocalized π‐bonding systems of the annulene complexes, rendering π‐aromaticity and extra stability to the systems. Such species with a planar [12]C ₁₂ H ₈ annulene ligand can be enlarged in 2D to form the C _{4 v} [Fe]C ₃₆ H ₁₆ ( 6 ), D _{4 h} [Co]C ₃₆ H ₁₆ ⁺ ( 7 ), D _{4 h} PC ₃₆ H ₁₆ ^– ( 8 ), D _{4 h} SC ₃₆ H ₁₆ ( 9 ), and C _s ClC ₃₆ H ₁₆ ⁺ ( 10 ) and expanded in 3D to generate the tubular nanobelt C _{2 v} (SC ₁₂ H ₄ ) ₁₂ ( 11 ) via partial dehydrogenations. The NMR, IR, and UV‐vis spectra of the most concerned species 1–5 are computationally simulated to facilitate their future experimental characterizations.