Borane to Boryl Hydride to Borylene Dihydride: Explicit Demonstration of Boron-to-Metal α-Hydride Migration in Aminoborane Activation

Abstract

The sequence of fundamental steps implicit in the conversion of a dihydroborane to a metal borylene complex have been elucidated for an [Ir(PMe(3))(3)] system. B-H oxidative addition has been applied for the first time to an aminodihydroborane, H(2)BNR(2), leading to the generation of a rare example of a primary boryl complex, L(n)(H)M{B(H)NR(2)}; subsequent conversion to a borylene dihydride proceeds via a novel B-to-M α-hydride migration. The latter step is unprecedented for group 13 ligand systems, and is remarkable in offering α- substituent migration from a Lewis acidic center as a route to a two-coordinate ligand system.

Fluoroarene Complexes with Small Bite Angle Bisphosphines: Routes to Amine–Borane and Aminoborylene Complexes

“…This bears parallels with the double B–H activation of transient H 2 B=NMe 2 observed here, although aminoboranes bind end‐on rather than the side‐on mode adopted by alkenes , . Aminoborane to aminoborylene transformations by double B–H activation of H 2 B=NR 2 (R = Cy, i Pr) have been observed with mononuclear iridium and ruthenium complexes,, and related transformations on boranes are also known , . However, to the best of our knowledge the complete amine–borane to aminoborylene transformation is unprecedented, and represents a new method for the preparation of bridging borylenes.…”

The Synthesis, Characterization and Dehydrogenation of Sigma‐Complexes of BN‐Cyclohexanes

“…2.6 Å or longer) [34, 35] and shorter M–B distances (less than 2.1 Å) respectively. [36, 37] The cyclic amine–borane adopts a chair conformation, Figure 1B, meaning there is no plane of symmetry in the molecule in the solid–state.…”

Dehydrogenative Boron Homocoupling of an Amine‐Borane

“…Well-defined homocoupling of boranes, as mediated by transition metals, is essentially limited to B À B bond formation in polyhedral boranes, for example pentaborane(9) (A), [7,8] guanidine bases (B), [9] and most recently the homocoupling of HBCat and related derivatives to give the corresponding diboranes (C) [10][11][12] (Scheme 1). [15,16] In particular, H 3 B·NMe 3 undergoes B-H activation at {Rh(PR 3 ) n } + fragments to give bimetallic hydrido-boryl products (n = 1, R 3 = Cy 3 ), [17] or in the presence of the alkene tert-butylethene (TBE, n = 2, R 3 = iBu 2 tBu) catalytic hydroboration occurs to afford Me 3 N·BH 2 CH 2 CH 2 tBu, I. [13,14] The homocoupling of boranes requires the B-H activation of two boranes at a metal center; we, and others, have recently reported on B-H activation at group 9 metal centers in both amine-and amino-boranes.…”