Global InformationTetramesityl compounds information
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Homoleptic tetra-mesityl complexes of transition metals in the +4 oxidation state, (IV), denoted as M(mes)4, constitute a category of organometallic substances that remain relatively unexplored.[1] Characterized by tetrahedral coordination geometry, these compounds exhibit distinctive electrochemical, magnetic, and optical properties.[2] Their unique attributes surpass those of their isostructural counterparts in group 14, commonly employed as fundamental components in advanced molecular materials like covalent- and metal–organic frameworks, polymers, self-assembled monolayers, and single-molecule electronic devices.[3] Recent advancements, showcase the potential of modular, isostructural M(aryl) units in providing novel avenues for adjusting the electrochemical energy storage capacity, electrocatalytic functionality, and electrical conductivity/conductance of such materials, opening up various applications.[3]
The synthesis and reaction chemistry of several homoleptic transition metal tetramesityl complexes has been reported, and conclusive identification has been provided through X-ray structural studies. Among the various M(aryl)4 materials, Os(IV) and Ru(IV) are particularly noteworthy, especially when they feature ortho-methylated sigma-aryl ligands. This is because these compounds exhibit remarkable robustness, as their stability can be attributed to a d4 low-spin electronic configuration, with the ligand methyl groups effectively inhibiting decomposition pathways such as reductive elimination and ortho-hydrogen abstraction.[4] These compounds can be purified through air chromatography and their aryl ligands can be subjected to chemical functionalization using various methods such as bromination, Suzuki coupling, and Friedel-Crafts acylation. Os(aryl)4 compounds have rich redox chemistry, which allows for the early isolation of a stable paramagnetic Os(V) complex.[5]
- ^ Koschmieder, Stefan U.; Wilkinson, Geoffrey (1991-01-01). "Homoleptic and related aryls of transition metals". Polyhedron. 10 (2): 135–173. doi:10.1016/S0277-5387(00)81585-5. ISSN 0277-5387.
- ^ Bayliss, S. L.; Laorenza, D. W.; Mintun, P. J.; Kovos, B. D.; Freedman, D. E.; Awschalom, D. D. (2020-12-11). "Optically addressable molecular spins for quantum information processing". Science. 370 (6522): 1309–1312. arXiv:2004.07998. Bibcode:2020Sci...370.1309B. doi:10.1126/science.abb9352. ISSN 0036-8075. PMID 33184235.
- ^ a b Parr, Joseph M.; Olivar, Clarissa; Saal, Thomas; Haiges, Ralf; Inkpen, Michael S. (2022-07-12). "Pushing steric limits in osmium(IV) tetraaryl complexes". Dalton Transactions. 51 (27): 10558–10570. doi:10.1039/D2DT01706G. ISSN 1477-9234. PMID 35770688.
- ^ Stavropoulos, Pericles; Savage, Paul D.; Tooze, Robert P.; Wilkinson, Geoffrey; Hussain, Bilquis; Motevalli, Majid; Hursthouse, Michael B. (1987-01-01). "The synthesis and X-ray crystal structures of homoleptic tetrahedral aryls of osmium(IV) and of cyclohexyls of ruthenium(IV), osmium(IV), and chromium(IV)". Journal of the Chemical Society, Dalton Transactions (3): 557–562. doi:10.1039/DT9870000557. ISSN 1364-5447.
- ^ Arnold, John; Wilkinson, Geoffrey; Hussain, Bilquis; Hursthouse, Michael B. (1988-01-01). "Redox chemistry of the homoleptic aryl Os(2-MeC6H4)4: synthesis and characterization of the first osmium(V) organometallic [Os(2-MeC6H4)4][CF3SO3]". Journal of the Chemical Society, Chemical Communications (20): 1349–1350. doi:10.1039/C39880001349. ISSN 0022-4936.