A Quantum Chemical Study of the Haptotropic Rearrangements of Cr(CO)₃ on Naphthalene and Phenanthrene Systems

Abstract

First-principles gradient-corrected density functional theory electronic structure calculations of the haptotropic rearrangement of a Cr(CO)(3) unit on naphthalene and phenanthrene derivatives are reported. Coupled-cluster calibration studies of Cr(CO)(3) complexes with benzene and naphthalene derivatives confirm the accuracy of the applied Becke exchange and Perdew correlation functionals. Characteristic points on the energy hypersurface (reactants, products, intermediates, and transition states) were located for various substituents on the aromatic skeleton. It is argued that a -OH/-O(-) substituent may provide a means to steer the haptotropic shift depending on the pH value, i.e., to construct a molecular switch. In addition, the mechanism of the [3 + 2 + 1] benzannulation of chromium pentacarbonyl naphthylcarbene complexes with alkynes was investigated, and the preference of the angular benzannulation leading to phenanthrene complexes of Cr(CO)(3) over the linear benzannulation leading to corresponding anthracene complexes is explained.

Chromium Tricarbonyl and Chromium Benzene Complexes of Graphene, Their Properties, Stabilities, and Inter‐Ring Haptotropic Rearrangements – A DFT Investigation

“…For the isomers of 6, the benzene chro-271 mium group was found to adopt a staggered conformation whether it is located at the center or at the periphery of the graphenic model. This result is at variance with the eclipsed conformation found in (η 6 -naphthalene)Cr(η 6 -benzene) [54] and should be checked experimentally in the future. …”

“…[2][3][4][5][6][7][8][9][10] It is quite surprising that η 6 ,η 6 -IRHRs have been poorly studied experimentally and theoretically for transition-56 metal moieties that are different from metal carbonyl units, even quite common bis-arene derivatives such as the simplest chromium benzene complexes of naphthalene derivatives ( Figure 3). [11] A more complicated example is the η 6 ,η 6 -IRHR process 61 in chromium bis(η 6 -fluoranthene), which was experimentally observed and qualitatively studied by NMR spectroscopy at 100°C in C 6 D 6 (Figure 4). [12] www.eurjic.org FULL PAPER Recently, Haddon and co-workers have reported several experimentally investigated reactions of chromium carbonyl 66 and chromium benzene derivatives with different allotropic forms of carbon with a practically unlimited number of sixmembered aromatic rings, that is, graphites, nanotubes, and graphenes ( Figure 5).…”

“…On the other hand, it is quite strange and intriguing that η 6 ,η 6 -IRHRs in synthetically available and very stable complexes of PALs with transition metals other than chromium, for example, the group 8 elements (Fe, Ru, Os), which are important from a synthetic, pharmaceutical, and industrial 91 point of view, have practically not been investigated experimentally and have been examined only by density functional theory (DFT). [24] The influence of photochemical activation on the course of IRHRs has also been poorly studied, though many ther-96 mally induced reactions have photochemical analogues.…”

“…It is possible to explain this by the fact that the mechanism for most of these processes might be quite complicated and may involve not just the lowest triplet state. [25] Since the semi-empirical work of Albright et al, [26] 101 several quantum chemical investigations, mostly at the DFT level, of η n ,η n -IRHRs have been performed mainly for chromium tricarbonyl complexes of PALs [2,3,5,6,10] and to a considerably lesser extent for other transition metals. [7,8,18,[22][23][24]27,28] As such dynamic behavior could be 106 important for electronics, materials science, and catalysis, we have thoroughly investigated molecular models of chromium complexes of graphene to stimulate experimental investigations of transition-metal complexes of carbon allotropes such as fullerenes, graphites, nanotubes, or 111 graphenes.…”

The Stereospecific Ligand Exchange at a Pseudo‐Benzylic T‐4 Iridium Centre in Planar‐Chiral Cycloiridium (η6‐Arene)tricarbonylchromium Complexes

“…Geometry optimisations were carried out without symmetry constraint with the help of density functional theory by using the energy-gradient minimisation method with a BeckePerdew [52][53][54] GGA functional [55] associated with a triple-z polarised basis set for all atoms including Ir and Cr. To account for relativistic effects, we systematically applied scalar corrections within the zerothorder regular approximation (ZORA) [56] and used the ad hoc triple-z polarised basis sets provided with the Amsterdam density functional (ADF) [57] package.…”