Solid‐state and Computational Study of “Venus fly‐trap” Geometric Parameters for 1,5‐Cyclooctadiene in Pd^II and Pt^II β‐Enaminonato Complexes

Abstract

The cod ligand (cis,cis‐1,5‐cyclooctadiene) can be superficially considered to mimic similarities in spatial behavior of a leaf of the Venus fly‐trap (Dionaea muscipula). Thus, the synthesis of an unsymmetrical bidentate trans ligand (N,O‐donor atoms) based on the β‐enaminonate backbone is introduced to evaluate the electronic and steric influence on the structural behavior of the cod ligand when coordinated to a square planar transition metal. A range of platinum(II) / palladium(II) complexes of the type [M(cod)(N,O‐Bid)]A (M = PtII, PdII; β‐enaminonato ligand (N,O‐Bid) = NH‐acac, NMe‐acac, NPh‐acac; A = BF4–, PF6–) is reported. The complexes were fully characterized, including by detailed X‐ray structural investigations. Theoretical calculations on the [M(cod)(N,O‐Bid)]+ complexes for the complete nickel triad are also described and the structural behavior of the cod ligand critically evaluated. The influence of the variation of the β‐enaminonato ligands on the coordination arrangement of the cod was investigated and found that no significant changes to the M–C and C=C bond lengths were observed. The Venus fly‐trap jaw angle (ψ), however, varies by ca. 8° and the twist angle (τ) by ca. 10°, whereas the cod bite angle (χ), as well as the β‐enaminonato ligand bite angle (N–M–O; θ) both remain virtually constant. Calculated spectroscopic tendencies within the Ni‐triad are also included.

Nucleophile-assisted carbon dioxide fixation for a cleaner environment

“…Special focus will be given to the influence the ligands have on the coordinated COD which "mimics" the Venus fly-trap plant, illustrated in Fig. 1(b-d), and the related kinetic studies by a neutral ligand to replicate CO2 [4]. Interestingly, the results from the kinetics showed that the forward reaction rate (k1) for the amidine-containing rhodium complex was k1 = 2.16 x 10 3 M -1 s -1 with a half-life of 321 ms and ten-times faster for the rhodium complex containing the guanidine ligand.…”