Bulking up CpBIG: A Penta-Terphenyl Cyclopentadienyl Ligand

The modification of cyclopentadienyl ligands with carefully selected substituents is a widely used strategy to tune their steric and electronic properties. We describe the synthesis of an extremely bulky penta-terphenyl cyclopentadienyl ligand (CpT5) by arylation of cyclopentadiene. Deprotonation reactions with various group 1 metals and bases afforded a complete series of alkali metal salts MCpT5 with M = Li to Cs. The compounds were isolated as solvate-free salts, which were characterized by multinuclear NMR spectroscopy, UV-vis spectroscopy and elemental analysis. Single-crystal X-ray diffraction studies on LiCpT5, NaCpT5 (crystallized as a solvate with one THF molecule per formula unit) and KCpT5 revealed the formation of metallocene-like sandwich structures in the solid state.

Pyrrolinium-substituted Persistent Zwitterionic Ferrocenate Derivative Enabling the Application of Ferrocene Anolyte

Here, we report the imidazolium-/pyrrolinium-substituted persistent zwitterionic ferrocenate derivatives, which were characterized by electron paramagnetic resonance (EPR) and ⁵⁷Fe Mössbauer spectroscopy. Additional theoretical studies on these zwitterionic ferrocenate derivatives clearly explain the origin of their thermal stability and the orbital interactions between iron and imidazolium-/pyrrolinium-substituted zwitterionic cyclopentadienyl ligand. Exploiting the facile Fe(II/I) redox chemistry, we successfully demonstrated that the ferrocene derivative can be applied as an example of derivatized ferrocene anolyte for redox-flow batteries. These zwitterionic ferrocenate derivatives will not only deepen our understanding of the intrinsic chemistry of ferrocenate but have the potential to open the way for the rational design of metallocenate derivatives for various applications.

Tuning the Spin-Crossover Properties of the [(Cp1-R)2Mn] Metallocenes

<p> In this work, we present a computational study using density functional theory (DFT) on how the single functionalization of the cyclopentadienyl ligand in<br> [(Cp^1-R)₂Mn] systems can be used to tune the spin-crossover properties in such systems. Using the OLYP functional, accurate values for the transition temperature (<i>T</i>_1/2) can be obtained, and our DFT methodology can be used to explore the effect that different substituents have on tuning such quantity. In particular, we show that the electronic structure of the [(Cp^1-R)₂Mn] can be tuned via the R group, allowing for a fine-tuning degree of the <i>T</i>_1/2 that expands between 0 and 400 K. Our results allow for a rational design of new manganocene based systems with tailored SCO properties.</p>

Tuning the Spin-Crossover Properties of the [(Cp1-R)2Mn] Metallocenes

<p> In this work, we present a computational study using density functional theory (DFT) on how the single functionalization of the cyclopentadienyl ligand in<br> [(Cp^1-R)₂Mn] systems can be used to tune the spin-crossover properties in such systems. Using the OLYP functional, accurate values for the transition temperature (<i>T</i>_1/2) can be obtained, and our DFT methodology can be used to explore the effect that different substituents have on tuning such quantity. In particular, we show that the electronic structure of the [(Cp^1-R)₂Mn] can be tuned via the R group, allowing for a fine-tuning degree of the <i>T</i>_1/2 that expands between 0 and 400 K. Our results allow for a rational design of new manganocene based systems with tailored SCO properties.</p>

Pentamethyl- and 1,2,4-tri(tert-butyl)cyclopentadienyl containing p-block complexes – differences and similarities

The sterically encumbered cyclopentadienyl ligand 1,2,4-(Me3C)3C5H2 (Cp′′′) effectively stabilizes the main group metals of Al, Ga, In, Ge and Sn with σ- or π-bonds.