QTAIM View of Metal–Metal Bonding in Di- and Trinuclear Disulfido Carbonyl Clusters

Abstract

The experimental and theoretical charge densities in the sulfido-bridged cluster compounds Fe2(μ-S2)(CO)6 (1), Fe3(μ3-S)2(CO)9 (2), Mn2(μ-S2)(μ-CO)(CO)6 (3), and Fe2(μ-S2)(CO)5(PPh3) (4) have been studied using the quantum theory of atoms in molecules (QTAIM) methodology. High-resolution X-ray diffraction data have been measured for compounds 2–4 at 100 K. The topological analyses show that only in compounds 1 and 4 is there any evidence for metal–metal bonding in terms of the presence of a bond path. For compound 1, the topology of the Fe2S2 cage is highly dependent on the Fe–Fe separation, and the deformation along this vector is an extremely soft mode. The experimentally observed topology for compound 4 is the open “butterfly” topology. The orbital decomposition of the delocalization indices associated with the metal–metal interactions, δ(ΩM–ΩM), implies significant direct Fe–Fe bonding in compounds 1 and 4 and for two of the Fe–Fe vectors in 2 but only a very minor Mn–Mn interaction in compound 3. The crystal structure of 2 shows a small amount (∼1%) of orientational disorder. As a result, a small degradation of the derived topological parameters is detectable, in comparison with the ordered structures of 3 and 4, and this leads us to discourage any quantitative QTAIM studies on disordered systems.

NATURE OF Mδ+···δ+C-Oδ-INTERACTIONS IN METAL CARBONYLS. AN ELECTRONIC STUDY BASED ON THE TOPOLOGY OF THE ELECTRON CHARGE DENSITY DISTRIBUTION AND ITS LAPLACIAN FUNCTION

“…Recientemente, esta teoría también ha sido utilizada para caracterizar interacciones metal-metal y metal-ligando con densidades electrónicas obtenidas experimentalmente y por métodos de la teoría del funcional de la densidad. 21,22 Por otra parte, recientemente hemos mostrado por medio de la QTAIM que muchas interacciones como los enlace de hidrógeno, 23,24 enlaces de litio, 25 enlaces de berilio, 25 enlaces de boro 25 y enlaces de halógeno, [26][27][28][29] débiles y no tan débiles, pueden ser caracterizadas en base a la topología de la densidad electrónica y su función derivada el Laplaciano de la densidad electrónica. En estos trabajos hemos discutido acerca de la covalencia de las interacciones y en varios sistemas hemos observado que la transferencia de carga y la interacción electrostática entre el núcleo del ácido de Lewis y el par electrónico de la base juegan un rol importante no solo en la estabilización del complejo sino también en la determinación de la geometría molecular de los mismos.…”

“…[8][9][10][11][12][13]21,22,33 Por otra parte, es conocido el hecho que en la molécula de CO el átomo de carbono tiene carga positiva (+1,17) y el átomo de oxígeno tiene carga negativa (-1,17). 34 Esto nos lleva a preguntarnos ¿Cómo es posible que cationes metálicos interactúen atractivamente con átomos de C en los carbonilos metálicos?…”

Synthesis, characterization, and some electrocatalytic properties of heteromultinuclear FeI/RuII Clusters

“…The alternating Fe and S atoms occupy the base and the Ru atom defines the top in the distorted square pyramid. The two iron‐ruthenium bonds are almost the same (Fe(1)‐Ru(1) 2.6422(8) Å and Fe(2)‐Ru(1) 2.6545(8) Å) but are longer than the iron–iron bonds in Fe 3 S 2 (CO) 9 (2.60497(15) and 2.60047(15) Å) . Also, the Ru‐S average distances (2.2707 Å) are longer than the corresponding distances in Fe 3 S 2 (CO) 9 (2.2542 Å).…”

Experimental and Theoretical AIM and NCI Index Study of Substituted Arene Tricarbonyl Complexes of Chromium(0)

“…To check, how correctly the NCI index describes the Cr‐arene interactions we decided to use source function (SF) and delocalization index (DI) . The reference points ( rp ) for the SF were selected at the middle of the Cr‐C arene distances.…”

“…At the present time source function (SF), [12, 13, 14 and ref. therein] delocalization index (DI) and electron localizability indicator (ELI‐D) are the most often applied in the capacity of continuous bonding indicators. In turn, it was recently proposed to use a noncovalent interaction (NCI) index, based on the reduced electron density gradient (RDG), to characterize and visualize different types of weak interactions .…”