Mononuclear Neutral Boron Hydrides Affordable as [N,N’] Chelates of Iminophosphonamides

Abstract

Reaction of the iminophosphonamine ligand, LH with BHCl2⋅SMe2 afforded the adduct LH⋅BHCl2 (1) at room temperature (LH=[(2,6‐iPr2C6H3N)P(Ph2)(NtBu)]H). However, when the lithium iminophosphonamide, LLi⋅2OEt2 was reacted with BHCl2⋅SMe2, PhBCl2 and BH2Cl⋅SMe2 the corresponding mononuclear heteroleptic boron complexes, LBHCl (2), LB(Ph)Cl (3) and LBH2 (4) were obtained. A phenylborane complex, LB(Ph)H (5) was prepared in good yields by the substitution of Cl− in 3 with H− using AlH3⋅NMe2Et. Complexes 2, 4 and 5 represent first examples of boron hydrides incorporated in four‐membered chelates. All the complexes (except 3) reported in this work provide different number of reactive hydride groups at central boron atom and could be useful synthon in stepwise functionalization of the B−H bonds. Complexes 1–5 were characterized using multinuclear NMR, IR and HRMS techniques. Solid state structures of complexes 1–5 have also been elucidated using single crystal X‐ray diffraction technique.