The synthesis and reactivity of a silyliumylidene cation stabilized by an amidinate ligand and 4-dimethylaminopyridine (DMAP) are described. The reaction of the amidinate silicon(I) dimer [LSi:]2 (1; L = PhC(NtBu)2) with one equivalent of N-trimethylsilyl-4-dimethylaminopyridinium triflate [4-NMe2C5H4NSiMe3]OTf and two equivalents of DMAP in THF afforded [LSi(DMAP)]OTf (2). The ambiphilic character of 2 is demonstrated from its reactivity. Treatment of 2 with 1 in THF afforded the disilylenylsilylium triflate [L'2(L)Si]OTf (3; L' = LSi:) with the displacement of DMAP. The reaction of 2 with [K{HB(iBu)3}] and elemental sulfur in THF afforded the silylsilylene [LSiSi(H){(NtBu)2C(H)Ph}] (4) and the base-stabilized silanethionium triflate [LSi(S)DMAP]OTf (5), respectively. Compounds 2, 3, and 5 have been characterized by X-ray crystallography.

The synthesis and characterization of a singlet delocalized 2,4-diimino-1,3-disilacyclobutanediyl, [LSi(μ-CNAr)(2)SiL] (2, L: PhC(NtBu)(2), Ar: 2,6-iPr(2) C(6) H(3)), and a silylenylsilaimine, [LSi(=NAr)-SiL] (3), are described. The reaction of three equivalents of the disilylene [LSi-SiL] (1) with two equivalents of ArN=C=NAr in toluene at room temperature for 12 h afforded [LSi(μ-CNAr)(2)SiL] (2) and [LSi(=NAr)-SiL] (3) in a ratio of 1:2. Compounds 2 and 3 have been characterized by NMR spectroscopy and X-ray crystallography. Compound 2 was also investigated by theoretical studies. The results show that compound 2 possesses singlet biradicaloid character with an extensive electronic delocalization throughout the Si(2)C(2) four-membered ring and exocyclic C=N bonds. Compound 3 is the first example of a silylenylsilaimine, which contains a low-valent silicon center and a silaimine substituent. A mechanism for the formation of 2 and 3 is also proposed.

The synthesis and characterization of new amidinate-stabilized germatrisilacyclobutadiene ylides [L(3)Si(3)GeL'] (L=PhC(NtBu)(2); L'=ËL; Ë=Ge (3), Si (7)) are described. Compound 3 was prepared by the reaction of [LSi-SiL] (1) with one equivalent of [LGe-GeL] (2) in THF. Compound 7 was synthesized by the reaction of 2 with excess 1 in THF. The bisamidinate germylene [L(2)Ge:] (4) is a by-product in both reactions. Moreover, compound 7 was prepared by the reaction of 3 with one equivalent of 1 in THF. Compounds 3 and 7 have been characterized by NMR spectroscopy, X-ray crystallography, and theoretical studies. The results show that compounds 3 and 7 are not antiaromatic. The puckered Si(3) Ge four-membered rings in 3 and 7 have a ylide structure, which is stabilized by amidinate ligands and the electron delocalization within the Si(3) Ge four-membered ring.

The aromatic low‐valent lead analogue of an indenyl anion (see scheme; 1) undergoes oxidation with SnCl2 to form the base‐stabilized lead(I) dimer 2. Reduction of 2 with lithium regenerates 1. These compounds were characterized by NMR spectroscopy and X‐ray crystallography.

The reaction of [CH2(PPh2S)2] (1) with 2 equiv of MeLi in Et2O followed by addition of 0.5 equiv of SiCl4 afforded the base-stabilized 2-silaallene [(PPh2S)2CSiC(PPh2S)2] (2). It has been characterized by X-ray crystallography, NMR spectroscopy, and theoretical studies. The results show that compound 2 comprises a C¯–Si2+–C¯ ylidic skeleton with a negative charge at the Cmethanediide atoms and two positive charges at the Si atom. The reaction of 2 with excess PriNCNPri in refluxing toluene gave the thiophosphinoyl-stabilized silene [(PPh2S)2C–Si+(NPri)2CC(PPh2S)2] (3).

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In the present study, a new series of ionic liquids (ILs) derived from low-cost amides and lactams (cyclic amides), such as N,N-dimethylformamide (DMF), were synthesized and characterized. Unlike other nucleophiles like amines, the alkylation reaction of the amides with alkyl triflates to form cationic species takes place at the carbonyl oxygen atom, instead of the nitrogen atom. For these O-alkylated amidium ILs, the basic physicochemical properties, such as melting point, glass transition temperature, plastic crystal phase transition, thermal stability, density, surface tension, viscosity, ionic conductivity and electrochemical window, were investigated and studied. Generally, these ILs are distinguished by low viscosity and high conductivity, in particular the DMF-derived ILs with viscosity as low as 21.6 cP and conductivity up to 15.45 mS cm–1 at 25 °C. This result should be attributed to the cationic DMF structures: planar geometry, low symmetry, C2-proton and ether moiety, resulting in much lower viscosity and higher conductivity than the best-known imidazolium ILs. Meanwhile, these amidium ILs also possess wide electrochemical windows (∼4.5 V) comparable to imidazolium ILs, implying their potential in electrochemical applications. Furthermore, several of the amidium ILs can form plastic crystal with a maximum enthalpy gain of −35.7 J g–1 at the temperature range of −10–90 °C.