Boryl Anion Attacks Transition‐Metal Chlorides To Form Boryl Complexes: Syntheses, Spectroscopic, and Structural Studies on Group 11 Borylmetal Complexes

Abstract

Transition-metal boryl complexes [1] have been proposed as intermediates in many catalytic transformations of boroncontaining substrates.[2] Since some isolated boryl complexes show unique catalytic acitivity, [2, 3] syntheses of boryl complexes would provide the possibility for new catalytic reactions. However, methods for the synthesis of boryl complexes are still limited. In fact, the following three types of reactions are the major methodologies to introduce a boryl ligand:[1] 1) salt elimination through the reaction of anionic metal carbonyl complexes with haloboranes; [4] 2) oxidative addition of a boron-heteroatom bond to low-valent transition metals;[5] and 3) s-bond metathesis reactions between alkyl metal complexes and hydroboranes in the presence of light [6] or oxygen-substituted metal complexes and diborane. [7,8]

Synthesis and structure of two new (guanidinate)boron dichlorides and their attempted conversion to boron(i) derivatives

“…The latter undergoes reactions with group 11 metal chlorides to afford the corresponding boryl complexes 5 and the former reacts with MgBr 2 ·OEt 2 to form boryl-magnesium derivatives. 6 In terms of neutral carbene-analogous systems, the guanidinate ligand [Cy 2 NC{NR} 2 ] − has proved to be effective for the support of Ga (5) 7 and In (6) 7 in the +1 oxidation state (C, Scheme 1).…”

A Computational Study on the Kinetic Stability of Cyclic Boryl Anions~!2007-12-13~!2008-05-13~!2008-06-11~!

“…Considering the exothermicities the saturated boryl anion (3a) and NHC (3a-C) have lower exothermicities than that of the unsaturated ones. In fact, the bulky-group substituted 3a, has been synthesized successfully and shows little influence on its donor ability with group 11 metals [6]. Moreover, TS of 3a has a longer Ntransferred H but shorter B-transferred H bond than that of 1a (see Fig.…”

“…In another approach, boryllithium may act as a nucleophile and attack on Group 11 metal chloride complexes. On this basis, Segawa and coworkers reported the examples of borylsilver and borylgold complexes [6].…”

“…The effects of substituents (R and R') and types of atoms in the ring (X 1 , X 2 , X 3 and X 4 in Scheme 1) are investigated. Currently available cyclic boryl anions possess a five-membered ring [4,6], which is isoelectronic with the five-membered N-heterocyclic carbine (NHC) [12]. Five-membered N-heterocyclic carbines (NHCs) are widely used in catalysis [12][13][14].…”

Recent Developments of Boryl Anions: Boron Analogues of Carbanion

“…is slightly bent as was observed for the B-Cu-C angle of 47 (168.07 (16) ), 92 whereas that of 56 was almost linear (179.41 (15) ). 96 This difference may come from the less-bulky bridging bromide ligand on the central copper atom in 53 compared to carbene ligand in 47. Lithium boryldibromozincate 54 100,101 is the first example containing a 2c-2e B-Zn bond, and the B-Zn bond length (2.075(5) Å ) is slightly shorter 102 than the sum of covalent radii (2.13 Å ) 44 of boron and zinc atoms, and than the shortest B-Zn bond length (2.15(2) Å ) among the previously reported multicenter-multielectron BZn bond.…”