A coordination chemistry dichotomy for icosahedral carborane-based ligands

Abstract

Although the majority of ligands in modern chemistry take advantage of carbon-based substituent effects to tune the sterics and electronics of coordinating moieties, we describe here how icosahedral carboranes-boron-rich clusters-can influence metal-ligand interactions. Using a series of phosphine-thioether chelating ligands featuring meta- or ortho-carboranes grafted on the sulfur atom, we were able to tune the lability of the platinum-sulfur interaction of platinum(II)-thioether complexes. Experimental observations, supported by computational work, show that icosahedral carboranes can act either as strong electron-withdrawing ligands or electron-donating moieties (similar to aryl- or alkyl-based groups, respectively), depending on which atom of the carborane cage is attached to the thioether moiety. These and similar results with carborane-selenol derivatives suggest that, in contrast to carbon-based ligands, icosahedral carboranes exhibit a significant dichotomy in their coordination chemistry, and can be used as a versatile class of electronically tunable building blocks for various ligand platforms.

Monomeric phosphinoboranes

“…In hydroboration, similar activities were observed Ligands with carborane substituents are known for a variety of donor atoms [82,83]. The bonding properties of these carboranyl ligands are strongly dependent on the vertex to which the donor atom is bonded [84,85]. The borylphosphines 22a-e are the first examples of B-bound carboranyl phosphines and the (CO) stretching frequencies measured for their complexes 77a-e (Scheme 30) are lower than reported for any other phosphine ligand (Table 3) [47].…”

Defect-Tolerant Aligned Dipoles within Two-Dimensional Plastic Lattices

“…The chemical O9 was synthesized and characterized in accordance with previously published methods. 43 The Au{111}/mica substrates (Agilent Technology, Tempe, AZ) were hydrogen-flameannealed prior to SAM formation with 10 passes at a rate of 0.4 Hz. Both SAMs were prepared by immersion into 1 mM solutions in benzene, held at room temperature, for approximately 10 min.…”

“…The most common defects in these monolayers are substrate step edges and molecular domain boundaries in which there is a translational (phase) and/or rotational offset of the registry of the lattice of attachment to the substrate. 37,39,40,42,43 …”

Synthesis and characterization of carboranyl Schiff base compounds from 1-amino- o -carborane

“…Compound 4 is air-and moisture-stable and could be kept in the open air for a few months without noticeable change, because of the direct attachment of the electron-accepting o-carboranyl moiety [1,10]. This property significantly influences the reactivity of its amine group.…”