Reactions of Amidinate-Supported Silylene with Organoboron Dihalides

Abstract

The silicon atom in LSiCl or LSiMes (L = PhC­(NtBu)2, Mes = 2,4,6-Me3C6H2) inserts into the B–X bond of RBX2 (R = Ph, Mes, N­(SiMe3)2; X = Cl, Br), which is followed by the migration of the amidinate ligand and the halide atom. By this way, LB­(R)­SiCl3 (R = Ph, 2; Mes, 3; N­(SiMe3)2, 4) and LB­(R)­SiX2Mes (R = Ph, X = Cl, 5; R = Mes, X = Cl, 6; R = Mes, X = Br, 7) were obtained. Furthermore, a silylene–borane adduct LClSi → BPhCl2 (1) was obtained as an intermediate in the formation of compound 2. Compounds 2–7 are rare examples of borylhalosilanes.

Excellent yield of a variety of silicon-boron radicals and their reactivity

“…The 11 B NMR spectrum of 4 shows one resonance at δ -11.40 ppm which agrees with boron silicon adducts (Figure S5). 23 The formation of…”

Reactivity of (TMS)2N(η1-Cp*)Si═Si(η1-Cp*)N(TMS)2 toward the Halides of Groups 13–15

“…17−19 However, the reported reactions mainly utilized either RBX 2 or R 3 B type of precursors. [15][16][17]20,21,42 There are very few reports where BX 3 or R 2 BX (X = F, Cl, Br) boron substrates are reacted with the Si(II) compounds, [17][18][19][20][21]35,38 and only one report on disilene reaction with haloboranes (B-chlorocatecholborane and B-chloropinacolborane) reported by Tokitoh and co-workers. 38 Recently, few reports appeared on the oxidative addition of the Lewis acidic boron halides to the Si(II) center of NHSi and amidinato bis-silylene, resulting in the ring expansion via the insertion of boron atom into the Si(II)−N bond.…”

“…38 Recently, few reports appeared on the oxidative addition of the Lewis acidic boron halides to the Si(II) center of NHSi and amidinato bis-silylene, resulting in the ring expansion via the insertion of boron atom into the Si(II)−N bond. 20,21,44 Therefore, we planned to explore the reactivity of 1 toward some other boron halides. Treatment of 1 with 2 equiv of BCl 3 in toluene at room temperature led to the formation of 2 as a major product (Scheme 1) with some unidentified products in a small amount.…”

“…After the first report of a silylene-borane adduct, followed by the Si-insertion into the B–C bond by Metzler and Denk, a stock of compounds with the Si–B bonds have been isolated by utilizing different boron sources. ,,− It is noteworthy to mention that the access to silylboranes via the reaction of silylene with borane precursors is very much desired, which otherwise involves a tedious synthetic approach. − However, the reported reactions mainly utilized either RBX 2 or R 3 B type of precursors. − ,,, There are very few reports where BX 3 or R 2 BX (X = F, Cl, Br) boron substrates are reacted with the Si­(II) compounds, − ,, and only one report on disilene reaction with haloboranes (B-chlorocatecholborane and B-chloropinacolborane) reported by Tokitoh and co-workers . Recently, few reports appeared on the oxidative addition of the Lewis acidic boron halides to the Si­(II) center of NHSi and amidinato bis-silylene, resulting in the ring expansion via the insertion of boron atom into the Si­(II)–N bond. ,, Therefore, we planned to explore the reactivity of 1 toward some other boron halides. Treatment of 1 with 2 equiv of BCl 3 in toluene at room temperature led to the formation of 2 as a major product (Scheme ) with some unidentified products in a small amount.…”

“…; X = H, halide, N, etc.) due to their high nucleophilicity. − The resultant products are mainly derived from the oxidative addition, auto-ionization, and sometimes insertion into the Si–N bonds, followed by rearrangements. , Among the reported Si­(II) compounds, there is an interesting class of disilenes, which can exist in equilibrium with their singlet silylene fragments (Chart ). − Disilenes are generally synthesized through dimerization of their corresponding silylenes, and in most cases, they do not revert to their respective silylenes because of their thermal stability.…”