Reactivity of the Donor‐Stabilized Silylenes [iPrNC(Ph)NiPr]₂Si and [iPrNC(NiPr₂)NiPr]₂Si: Activation of CO₂ and CS₂

Abstract

Activation of CO2 by the bis(amidinato)silylene 1 and the analogous bis(guanidinato)silylene 2 leads to the structurally analogous six-coordinate silicon(IV) complexes 4 (previous work) and 8, respectively, the first silicon compounds with a chelating carbonato ligand. Likewise, CS2 activation by silylene 1 affords the analogous six-coordinate silicon(IV) complex 10, the first silicon compound with a chelating trithiocarbonato ligand. CS2 activation by silylene 2, however, yields the five-coordinate silicon(IV) complex 13 with a carbon-bound CS2 (2-) ligand, which also represents an unprecedented coordination mode in silicon coordination chemistry. Treatment of the dinuclear silicon(IV) complexes 5 and 6 with CO2 also affords the six-coordinate carbonatosilicon(IV) complexes 4 and 8, respectively.

An Isolable Silicon Dicarbonate Complex from Carbon Dioxide Activation with a Silylone

“…The Si−C distances of 2 , ranging from 1.955(3) to 1.975(3) Å, are significantly longer than those in 1 (1.864(1) and 1.874(1) Å), but close to the corresponding distances found in the bis‐NHC supported chlorosilyliumylidene cation (1.960(4) and 1.963(4) Å) . The Si−O interactions in 2 , ranging from 1.750(2) to 1.810(2) Å, are comparable to the values found in A (Scheme , 1.779(2) and 1.785(3) Å),, which feature also a six‐coordinate silicon center, but they are much longer than those observed in B (1.717(1) Å) and C (1.666(4) Å) with five‐coordinate and four‐coordinate silicon centers, respectively.…”

“…the Supporting Information for details on the calculations). The 29 Si NMR chemical shifts of 2 reflect a far stronger shielding of the Si IV atom than in A ( δ =−164.4 to −171.7 ppm),, B ( δ =−100.7 and −101.6 ppm), and C ( δ =−91.5 ppm), consistent with the presence of octahedrally coordinated silicon and four oxygen donors in the coordination sphere …”

“…demonstrated the formation of the bridged carbonate A (Scheme ) and the spiro compound B from the reaction of decamethylsilicocene with CO 2 . Tacke and co‐workers recently showed the formation of bis(amidinato) silicon carbonate C by reaction of CO 2 with bis(amidinato)silylene ,. Using a donor‐stabilized disilylene, Baceiredo et al.…”

Carbon–Carbon Bond Forming Reactions Promoted by Aluminyl and Alumoxane Anions: Introducing the Ethenetetraolate Ligand

“…[9] We propose that the postulated sulfide is highly reactive and undergoes [2+2]-cycloaddition with a second equivalent of CS 2 to afford 1 ({c}: E = S) via Pathway 1 (Scheme 2). Such reductive disproportionation of CS 2 in situ is unusual in main group chemistry, [10] although the [2+2]cycloaddition of CS 2 to terminal Ge=S, [11] bridging M(m-S) 2 M (M = Sb, Bi), [12] and in situ generated Sn = S [13] bonds has produced a family of p-block trithiocarbonate compounds, equivalent to step {b} ! {c}.…”

“…Thermal displacement plot (30 % probability, C-atoms reduced for clarity, H-atoms omitted) of [K{Al(NON Dipp )(O 2 C)}] 2 ([4] 2 , ' = 1Àx, Ày, Àz). Selected bond lengths [] and angles [8]: C29-C29' 1.338(2), C29-O2 1.3842(15), C29-O3 1.3841(15), Al-O2 1.8217(9), Al-O3 1.8171(9); N1-Al-N2 108.81(5), O2-Al-O3 76.08(4), O2-C29-O3 108.18(10), O2-C29-C29' 126.26(15), O3-C29-C29' 125.54(15).…”