Ein cyclisches Silylon (“Siladicarben”) mit einem elektronenreichen Silicium(0)‐Atom

Abstract

König der Donoren: Das chelatisierende Bis(carben) 1 ermöglichte die Synthese des neuen Silyliumyliden‐Salzes 2, das durch Natrium‐Naphthalinid zum ersten cyclischen Siladicarben 3 entchloriert werden konnte. 3 enthält ein einzelnes Si0‐Atom mit einer bemerkenswert hohen Basizität. Der geringe C‐Si‐C‐Winkel von 89.1° und der mittlere C‐Si‐Abstand von 1.869 Å sind konsistent mit Ergebnissen von Rechnungen, die bestätigen, dass 3 am besten als Silylon beschrieben wird.

Recent Advances in the Field of Main‐Group Mono‐ and Diatomic “Allotropes” Stabilised by Neutral Ligands

“…GeCl 2 -dioxane was used as the Ge source for 14 Ge b (Scheme 4), while 18 was used as the Si II source for 14 Si b prior to reduction with sodium napthalene. [43] The key difference in 14 Si b from 20 is that the Si centre is much more electron rich as indicated by 29 Si NMR signals (d = À80 ppm, c.f. 67 ppm in 20), which was rationalised by the Here we see a case in which the choice of carbene could allow for tuning of reactivity-the use of CAAC generates a more stable compound, while use of NHC potentially results in a more reactive one.…”

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

“…[5c,d] Using ad onor-stabilized disilylene,B aceiredo et al described another type of carbon dioxide activation which gives rise to the bis(m-oxo)carbonato silicon complex D. [5b] Starting from the N-heterocyclic carbene (NHC) supported disilicon complex (NHC)Si = Si(NHC), [6] Robinson and coworkers recently synthesized the NHC-supported siliconcarbon mixed oxide E,featuring also abridged carbonate,by reacting with CO 2 . In fact, with the silylone (bis-NHC)Si 1 (bis-NHC = H 2 C[{NC(H)=C(H)N(Dipp)}CD] 2 , Dipp = 2,6-iPr 2 C 6 H 3 ), az ero-valent silicon complex, in hand, [9] we succeeded in the synthesis and isolation of the unprecedented silicon dicarbonate complex F (Scheme 1). However,pressure-induced reaction (at 18-26 GPa) between CO 2 and amicroporous SiO 2 was reported, giving ametastable silicon carbonate phase.…”

“…[5e] Compound 2 crystallizes in the monoclinic space group P2 1 /c with two independent molecules and four THF molecules in the asymmetric unit ( Figure 1). [9] TheS i ÀOi nteractions in 2,r anging from 1.750(2) to 1.810 (2) ,a re comparable to the values found in A (Scheme 1, 1.779(2) and 1.785 (3) ), [5c,d] which feature also as ix-coordinate silicon center, but they are much longer than those observed in B (1.717(1) ) [5b] and C (1.666 (4) ) [5e] with five-coordinate and four-coordinate silicon centers,respectively. Thet wo planar carbonato ligands are twisted and almost perpendicular to each other (about 89.58 8 between the two planes).…”

“…[10] TheI R-spectrum of 2 exhibits an intense stretching vibration mode at n = 1746 cm À1 for the C=Og roups which is shifted to 1718 cm À1 after 18 O-labelling.The C = Ostretching mode (1746 cm À1 )o f2,h owever,i sv ery close to that for the bridged silicon carbonate species C(1751 cm À1 ). [9] TheS i ÀCd istances of 2,r anging from 1.955(3) to 1.975 (3) ,a re significantly longer than those in 1 (1.864(1) and 1.874(1) ), but close to the corresponding distances found in the bis-NHC supported chlorosilyliumylidene cation (1.960(4) and 1.963 (4) ). Thes tructure of 2 reveals as ix-coordinate silicon center coordinated by ab is-NHC and two carbonato chelating ligands,r esulting in ad istorted octahedral coordination arrangement.…”

Fusing N‐Heterocyclic Carbenes with Carborane Anions

“…[1] This is largely due to the fact that NHCs, such as the imidazolylidenes 1, have found extraordinary utility as ligands for catalysts [1b,f, 2] and the stabilization of reactive species, [3] as well as catalysts in their own right [4] (Figure 1). [1] This is largely due to the fact that NHCs, such as the imidazolylidenes 1, have found extraordinary utility as ligands for catalysts [1b,f, 2] and the stabilization of reactive species, [3] as well as catalysts in their own right [4] (Figure 1).…”