Synthesis, structures and reactions of new thermally stable silylenes

Higher carbene homologues: Naphtho[2,3-d]-1,3,2?2-diazagermole, -diazastannole, and attempted reduction of 2,2-dichloronaphtho[2,3-d]-1,3,2-diazasilole

“…1.1) or of the silicon(IV) heterocyclus 2 (Dd ca. 0.6) that was also observed in I [11,13,14] and II [12] and, to a smaller extent, for the t-butyl groups in di-t-butyl-1,3,2-k 2 -diazasilole [9]. This accounts for a ring current effect rather than for a local anisotropic influence because the different size and electronegativity of the group 14 heteroatoms with the respective changes of the E-N polarities are of minor importance.…”

“…On the other hand, the neopentyl groups did not hinder ring closure reactions with E IV Cl 4 and can easily be introduced [11,14]. Dilithiation of 1 in benzene and subsequent reaction (Equation 1) with one equivalent of silicon tetrachloride provided a good yield of 2,2-dichloro- Si-82 lie in the region of RSiO 3 and SiO 4 absorptions, respectively.…”

“…Thus, for silylenes with nucleophilic substituents, a considerable thermodynamic stabilization has been calculated increasing in the order halosilylenes Ͻ alkoxysilylenes Ϸ mercaptosilylenes K aminosilylenes [6] K diaminosilylenes Ͻ cyclic delocalized diaminosilylenes [7,8]. While germanium and tin are known to form isolable acyclic and cyclic dicoordinate diaminocarbene homologues [2][3][4], the less-favored silylenes are sufficiently stabilized only in the case of five-membered diaminosilylenes [9][10][11][12]. The formation of cyclodelocalized Hü ckel-p-systems causes an additional gain in energy that is small [8c,e,9] but may be decisive for compounds at the border of persistence.…”

Can N-heterocyclic germylenes behave as Lewis acids - is there another side to Meller germylenes?

“…Recently, Gehrhus et al investigated their Lewis acidity by reacting a benzo annelated Meller germylene with its carbene analogue [9] and found that the carbene indeed forms a C-Ge donor bond donating into the "empty" p-orbital of the germanium atom (see Scheme 1). This observation is not very surprising considering that the homologous stannylenes are well known to act as Lewis acids towards amines and aromatic ring systems [10,11]. The strength of the N-Ge bond in NHGe and ways to influence it have long been studied [12][13][14][15].…”

Theoretical Studies on the Alkylidene Silylenoid H2C = SiLiF and Its Insertion Reaction with R-H (R = F, OH, NH2)

“…1 The chemistry of silylenes has enjoyed a few decades of explosive growth, and stable silylenes have been reported. [2][3][4] Similar to carbenoid, silylenoid is the complex formed between the silylene and inorganic salt, which can be denoted as R 1 R 2 SiMX (M = alkali metal, X = halogen). Early in the 1960s, silylenoids were postulated as intermediates in some organosilicon reactions.…”