Rare Earth Metal Boryl Complexes: Synthesis, Structure, and Insertion of a Carbodiimide and Carbon Monoxide

Abstract

Among the first of their kind: Scandium boryl complex 1 and its Gd analogue were prepared by reaction of a boryl lithium compound with [Ln(CH2SiMe3)2(THF)x][BPh4] (Ln=Sc, Gd). Reaction of 1 with N,N′‐diisopropylcarbodiimide gave bis(amidinate) complex 2, which affords 3 by double CO insertion into the ScB bond, nucleophilic addition of an amidinate, and migration of the SiMe3 to the resulting ketene moiety (see scheme).

Roles of Horseradish Peroxidase in Response to Terbium Stress

“…Due to special physical and chemical properties, REEs have been widely used in agriculture, industry, military affairs, medicine, and environmental protection [1][2][3][4][5][6]. The wide and increasing applications have led to REE pollution in the environment [7][8][9][10][11][12][13][14][15], including soil, atmosphere, and water.…”

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.…”

“…[28] Carbon monoxide insertion/de-insertion into metal-alkyl bonds is known to be reversible,and is akey mechanistic step in catalytic processes such as hydroformylation. [22] Thegreater intrinsic strength of MÀB(over MÀ C) bonds is presumably af actor in these contrasting observations, [30] but the implication of other MÀBi nsertion processes in noble-metal-catalyzed hydro/diboration reactions, [4,8,[31][32][33][34][35][36][37][38][39][40][41][42][43][44] for example,encouraged us to target complexes capable of CO insertion. Bora-acyl species,b yc ontrast, irreversibly evolve CO to generate metal boryl complexes,a nd the reverse reaction, that is,n et insertion of carbon monoxide into aM À Bb ond, has no precedent.…”

“…[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). [22] Thegreater intrinsic strength of MÀB(over MÀ C) bonds is presumably af actor in these contrasting observations, [30] but the implication of other MÀBi nsertion processes in noble-metal-catalyzed hydro/diboration reactions, [4,8,[31][32][33][34][35][36][37][38][39][40][41][42][43][44] for example,encouraged us to target complexes capable of CO insertion. Formal CO insertion via metal-to-carbonyl migration of an alkyl group is therefore aw idely precedented pathway for generating coordinative unsaturation at am etal center.…”