Donor-Stabilized Silyl Cations 4:  N-Isopropylidene Hydrazides, Novel Bidentate Ligands for Penta- and Hexacoordinate Silicon Chelates¹

Abstract

Novel chelating agents derived from N-isopropylidene hydrazides, N-isopropylideneimino-O-(trimethylsilyl)acylimidates ( 1), have been utilized to prepare hexacoordinate dihalosilicon complexes (2) unique in their trans geometry and in their facile ionization to pentacoordinate siliconium halide salts (3).

A Novel Synthesis of AlCl[(NPh)2P(O)H] and SiCl2[(NPh)2P(O)H]: Two New Phosph(V)azane Derivatives

“…The 29 Si NMR spectrum of 3 contained only one sharp singlet at 10.52 ppm indicating the formation of a single product, with the silicon-29 resonance appearing at a low field that supported the coordination number of four around the silicon atom in 3. 16,17 There was no indication of the presence of a NH bond in 2 and 3 from either 1 H NMR or IR spectra. On the other hand, IR spectra exhibited characteristic bands of Si Cl, Si N, and Al N strechings at 476, 955, and 600 cm −1 , respectively.…”

Heterocations in Superacid Systems

“…The observed 29 Si NMR resonances are at d 29 Si 29.1 and À69.7, and for the cationic Si atom at d 29 Si 303. [669][670][671][672][673][674] Due to the interaction called internal solvation, 675 the silicon atom becomes pentacoordinated and largely loses its ionic character, that is, such ions differ in principle from the trivalent silicenium ions. A temperaturedependent NMR study shows that there is a rapid exchange of Me groups through 1,3methyl migration between the peripheral Si atoms with an activation energy of 13.1 -0.4 kcal mol À1 .…”

Synthesis, characterisation and insulin-mimetic activity of oxovanadium(IV) complexes with amidrazone derivatives

“…In 171 of them the metal ion is chelated by oligodentate ligands having (N 2 , CO) set and additional donor groups. Sixteen structures are formed by ligands chelating exclusively through the (N 2 , CO) couple [42][43][44][45][46][47][48][49][50][51][52][53], in some cases with metal ions with a chemical behaviour similar to VO 2+ , like MoO 3+ [42]. It is worth noting [50].…”