Frustrated Lewis pair chemistry of hydride sponges. Issue 17 (23rd March 2022)

• Record Type: Journal Article
• Authors: Becker, Christian; Schwabedissen, Jan; Neumann, Beate; Stammler, Hans-Georg; Mitzel, Norbert W.
• Is Part Of: Dalton transactions. Volume 51:Issue 17(2022)
• Page Start: 6547
• Page End: 6564
• Publication Date: 2022-03-23
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d2dt00585a
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Hydride and proton sponges together form a Frustrated Lewis pair that cleaves NH3, H2 O, PH3, H2 S, H2 Se and HCN but not dihydrogen, although the formal dihydrogen adduct, obtained in a synthetic detour, is stable to air and moisture and up to 100 °C. Abstract : An improved synthesis for 1, 8-bis(dimethylboranyl)naphthalene (1, hydride sponge) was developed avoiding the use of tin(iv ) reagents. The related 1, 2-bis(dimethylboranyl)benzene (2 ) was prepared. 1 combined with 1, 8-bis(dimethylamino)naphthalene (3, proton sponge) is a Frustrated Lewis pair (FLP) that forms adducts [1 -EH n −1 ][3 -H] with the protic compounds EH n = H2 O, NH3, H2 S, PH3, H2 Se, HCN. Their structures show the chelation of the deprotonated substrates, except for CN − (binds to one B atom of 1 ). The mechanisms of formation of [1 -EH n −1 ][3 -H] were explored by NMR spectroscopy. Similar reactions took places for the FLP system 2 + 3, but the adducts [2 -EH n −1 ][3 -H] are less stable; only the PH3 adduct was isolated and AsH3 forms a chelated adduct [2 -NC(CD3 )AsH2 ][3 -H]. FLP 1 + 3 does not react with molecular hydrogen, but the formal adduct [1 -H][3 -H] was isolated via salt metathesis from K[1 -H] and [3 -H]Cl; it is stable towards water, atmospheric oxygen and up to 100 °C; its thermal decomposition proceeds without formation of H2 . The stabilities of both, the mixture 1 + 3 + H2 and the formal adduct [1 -H][3 -H], allow concluding that hydrogen activation of FLP 1 + 3 is kinetically prevented.