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Coordination and Hydroboration of Ru(II)-Borate Complexes: Dihydridoborate vs. Bis(dihydridoborate)
Date Issued
28-03-2022
Author(s)
Pathak, Kriti
Gayen, Sourav
Saha, Suvam
Nandi, Chandan
Mishra, Shivankan
Indian Institute of Technology, Madras
Abstract
Treatment of [Cp*RuCl2]2, 1, [(COD)IrCl]2, 2 or [(p-cymene)RuCl2]2, 3 (Cp*=η5-C5Me5, COD= 1,5-cyclooctadiene and p-cymene=η6-iPrC6H4Me) with heterocyclic borate ligands [Na[(H3B)L], L1 and L2 (L1: L=amt, L2: L=mp; amt=2-amino-5-mercapto-1,3,4-thiadiazole, mp=2-mercaptopyridine) led to the formation of borate complexes having uncommon coordination. For example, complexes 1 and 2 on reaction with L1 and L2 afforded dihydridoborate species [LAM(μ-H)2BHL] 4–6 (4: LA=Cp*, M=Ru, L=amt; 5: LA=Cp*, M=Ru, L=mp; 6: LA=COD, M=Ir, L=mp). On the other hand, treatment of 3 with L2 yielded cis- and trans-bis(dihydridoborate) species, [Ru{(μ-H)2BH(mp)}2], cis-7 and trans-7. The isolation and structural characterization of fac- and mer-[Ru{(μ-H)2BH(mp)}{(μ-H)BH(mp)2}], 8 from the same reaction offered an insight into the behaviour of these dihydridoborate species in solution. Fascinatingly, despite having reduced natural charges on Ru centres both at cis-and trans-7, they underwent hydroboration reaction with alkynes that yielded both Markovnikov and anti-Markovnikov addition products, 10 a–d.
Volume
28