Heavy metal boryl chemistry: complexes of cadmium, mercury and lead

Abstract

Synthetic routes to the first boryl complexes of cadmium and mercury are reported via transmetallation from boryllithium; the syntheses of related group 14 systems highlight the additional factors associated with extension to more redox-active post-transition elements.

1,3,2‐Diazaborolyl Anions – From Laboratory Curiosities to Versatile Reagents in Synthesis

“…The oxidative addition of the N–H bonds of ammonia has remained a great challenge in synthesis, which is due to the paucity of transition metal systems that are capable to facilitate such a transformation, and in view of the importance of NH‐activation for various industrial processes. Only a decade ago, G. Bertrand et al succeeded in the activation of NH 3 by cyclic (alkyl)(amino) carbenes (CAACs) . Here, the addition of an excess of gaseous NH 3 to the benzene solution of 61 led to the rapid separation of orange red crystalline 66 in ca.…”

“…of 2 in benzene. Pb–B distances of 2.363(4) and 2.372(4) Å and an angle B–Pb–B of 118.3(1)° were measured by X‐ray techniques (Scheme ).…”

Cobalt Boryl Complexes: Enabling and Exploiting Migratory Insertion in Base‐Metal‐Mediated Borylation

“…Complexes incorporating avery strong trans s-donor displayunparalleled inertness,reflected in retention of the M À Bb ond even in the presence of extremely strong acid. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] However, exploitation of such reagents in the synthesis of transition-metal complexes with d n configurations (n ¼ 6 0, 10) is hampered by their tendency to effect reduction chemistry rather than salt metathesis. Suchc hemistry provides ap athwayf or the generation of coordinative unsaturation, thereby enabling ligand substitution and/or substrate assimilation.…”

“…[1][2][3] When combined with the direct metal-catalyzed borylation of unactivated CÀHb onds, [4] such methods facilitate hitherto inaccessible CÀHt oC ÀEt ransformations.A number of these processes involve metal-mediated transfer of the boryl ( À BR 2 )fragment (typically using Rh, Ir, Pd, or Pt), and so the fundamental patterns of reactivity of complexes of the type L n MBR 2 are of key importance. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] However, exploitation of such reagents in the synthesis of transition-metal complexes with d n configurations (n ¼ 6 0, 10) is hampered by their tendency to effect reduction chemistry rather than salt metathesis. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] However, exploitation of such reagents in the synthesis of transition-metal complexes with d n configurations (n ¼ 6 0, 10) is hampered by their tendency to effect reduction chemistry rather than salt metathesis.…”

“…[5][6][7][8] Recently, nucleophilic boryllithium reagents [9][10][11][12] have opened up routes to classes of MÀBb ond which cannot be accessed by established procedures employing boron electrophiles or oxidative addition chemistry. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] However, exploitation of such reagents in the synthesis of transition-metal complexes with d n configurations (n ¼ 6 0, 10) is hampered by their tendency to effect reduction chemistry rather than salt metathesis. [28] Very recently,h owever, we reported an approach which mitigates such redox problems:( THF) 2 Li-{B(NDippCH) 2 }( 1;D ipp = 2,6-diisopropylphenyl) reacts with organometallic esters [L n M{C(O)OR}],t og ive novel bora-acyl complexes [L n M{C(O)B(NDippCH) 2 }],which rearrange under thermal or photolytic conditions to give [L n M-{B(NDippCH) 2 }] and CO.T his approach not only shows that classical CO extrusion from metal acyl species can be extended to the boryl ligand class, [29] but also provides access to ar are example of ac obalt boryl complex, namely [(Ph 3 P)Co(CO) 3 {B(NDippCH) 2 }] (5).…”