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Access to Monomeric Lead(II) Hydrides with Remarkable Thermostability and Their Use in Catalytic Hydroboration of
Shuo Wang1, Kang-Yu Liu1, Han-Jung Li2
1Department of Applied Chemistry, National Yang Ming Chiao Tung University, 1001 Daxue Rd, East District, Hsinchu City 30010, Taiwan.
Abstract:
We report on the remarkable stability of unprecedented, monomeric lead(II) hydrides M[LPb(II)H] (M[1-H]), where L = 2,6-bis(3,5-diphenylpyrrolyl)pyridine and M = (18-crown-6)potassium or ([2.2.2]-cryptand)potassium. The half-life of [K18c6][1-H] of ∼2 days in tetrahydrofuran at 25 °C is significantly longer than those reported for dimeric lead(II) hydrides supported by bulky terphenyl ligands (few hours at low temperatures), which are the only examples known for lead(II) hydride compounds. The presence of a Pb-H bond in [1-H] was unambiguously identified by multinuclear NMR spectroscopy. Remarkably, a 1H resonance of the hydride ligand was found at δ = 41.43 ppm (1JPbH = 1312 Hz). For reactivity study, [1-H] serves as an excellent hydroboration catalyst with high turnover numbers and turnover frequencies for several carbonyl compounds.
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