Structural, Electronic, and Computational Studies of Heteroleptic Cu(I) Complexes of 6,6′-Dimesityl-2,2′-bipyridine with Ferrocene-Appended Ethynyl-2,2′-bipyridine Ligands

Abstract

Optical characterization and computational modeling of three ferrocene-appended ethynyl-2,2'-bipyridine ligands and the associated heteroleptic copper(I) complexes of 6,6'-dimesityl-2,2'-bipyridine are reported. These dyes have been studied using electrochemical analysis, electronic absorption, and Raman and resonance Raman spectroscopies, coupled with density functional theoretical approaches. For the complexes, optical spectra are dominated by a low energy copper(I) centered metal to ligand charge transfer (MLCT) transition; this is modulated by the presence of pendant ferrocene units and the extent of conjugation of the ferrocenyl bipyridine backbone. Electronic tuning due to ferrocene is shown to result in a redshift of the MCLT transition of up to ∼0.2 eV, while an elongation of conjugation appears to result in an increased MLCT intensity of around 50%.

Enhancement of Second-Order Nonlinear Optical Properties of Centrosymmetric Ferrocenyl Borasiloxane by a Broken-Symmetry Approach

“…In the electronic absorption spectrum, we observed higher energy at 252 and 263 nm, which begins with ligand-centered π–π* electronic transition [intramolecular charge transfer (ICT)] and other bands with lower energy in visible regions at 431 and 444 nm created by a Fe­(II) d–d transition (assigned to 1 E 1g ← 1 A 1g ). − Furthermore, the molar extinction coefficient (ε) was calculated using Lambert–Beer’s law (Supporting Information), which at 252 nm is 13.0 × 10 4 M –1 cm –1 and 431 nm is 0.7 × 10 4 M –1 cm –1 for FcBSi ( 1 ), which is higher than that for the corresponding Py adduct 2 (5.0 × 10 4 M –1 cm –1 at the peak of 262 nm and 0.2 × 10 4 M –1 cm –1 at 444 nm), , as shown in Table S6. Because of the induced dipole of the FcBSiPy ( 2 ), it makes the molecule less soluble as compared with FcBSi ( 1 ) . The calculated coefficients (ε) of both 1 and 2 were less than those of the ferrocenyl boranes in the literature − because of the smaller ring size and formation of the four-coordinated Py adduct in 2 .…”

Application of terpyridyl ligands to tune the optical and electrochemical properties of a conducting polymer

“…Cu + favors a tetrahedral arrangement and Cu 2+ favors a trigonal bipyramidal arrangement. 43,44 The binding pockets of TPy 2 and TPPyTPy are more trigonal bipyramidal like, hence are best suited to a Cu 2+ cation. When considering Zn 2+ and Fe 2+ cations, Cu + would be preferred (À45 and À122 kJ mol À1 respectively).…”

Ferrocene Rotary Switches Featuring 2‐Pyridyl‐1,2,3‐triazole “Click” Chelates

“…The structure was solved in the primitive space group P and the asymmetric unit contained the expected [(dimesbpy) 2 Cu 2 ( 2 )] 2+ cation and two hexafluorophosphate counteranions. The Cu(I) ions were coordinated in a distorted tetrahedral fashion (τ 4 =0.69 for Cu1 and 0.74 for Cu2), [33] and the mesityl substituents of the dimesbpy units displayed π‐π interactions with the pytri chelates, as has been observed in similar related structures [21c,32a,34] …”