Low valent transition metal complexes have been utilized as reagents and catalysts for mediating bond formation reactions. Various reagents have been developed for reducing higher oxidation metal precursors such as metal halides; however, the interaction of the resulting salts with the desired low-valent or zero-valent metal species disturbed their intrinsic reactivity and catalytic performance. We focused our attention to develop a new methodology for generating low-valent metal species in salt-free manner and we found that 1,4-bis(trimethylsilyl)-cyclohexa-2,5-diene (Si-CHD) and 1,4-bis(trimethylsilyl)-1,4-dihydropyradine (Si-DHP) and their derivatives have a potential to reduce a wide variety of transition metals as well as some p-block and f-block elements in a salt-free manner. In this contribution, we report that Si-CHD and its derivative reduced MCl5 (M = Nb and Ta), WCl6, and W(=NC6H3-2,6-iPr2)Cl4 in the presence of -diimine ligand as N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-2,3-dimethyl-1,3-butadieneproduced the corresponding -diimine complexes, M(a-diimine)Cl3 (M = Nb and Ta), W(a-diimine)Cl4, and W(=NC6H3-2,6-iPr2)(a-diimine)Cl3.1,2 Furthermore, we disclose that Si-DHP and its derivatives reduced Ni(acac)2 to give an amorphous Ni(0) nanoparticle (Ni aNPs), which served as an effective catalyst for reductive C—C bond-forming reactions.3
References:
1) Hiromasa Tanahashi, Hideaki Ikeda, Hayato Tsurugi, Kazushi Mashima, Inorg. Chem. 55, 1446-1452 (2016). 2) Teruhiko Saito, Haruka Nishiyama, Kento Kawakita, Michael Nechayev, Benjamin Kriegel, Hayato Tsurugi, John Arnold, Kazushi Mashima, Inorg. Chem., 54, 6004-6009 (2015). 3) Taiga Yurino, Yohei Ueda, Yoshiki Shimizu, Shinji Tanaka, Haruka Nishiyama, Hayato Tsurugi, Kazuhiko Sato, and Kazushi Mashima, Angew. Chem. Int. Ed., 54, 14437-14441 (2015).
