Aromaticity in Silole Dianions:  Structural, Energetic, and Magnetic Aspects

Abstract

Structural, energetic, and magnetic criteria confirm that the silole dianion (CH)4Si2- (7) and its alkali-metal ion pairs, e.g. (CH)4SiLi- (7a), (CH)4SiLi2 (7b), (CH)4SiNa2 (13), and (CH)4SiK2 (14), are highly aromatic. Inverse sandwich structures and strongly delocalized silole rings are prefered by 7b, 13, and 14. The degree of aromaticity in [η5-(CH)4Si]Li- (7a) exceeds that of the isoelectronic third-period heterocycles (CH)4PLi (5a) and (CH)4SLi+ (6a) and even approaches that of (CH)5Li (3a).

Synthesis and Properties of [NiCp*(2,5‐tBu2PC4H2)], a 20‐Valence‐Electron Phosphanickelocene

“…These results are in accord with the high aromaticity associated with the phospholide anion [45][46][47][48] and underline its similarities with cyclopentadienides. [49] The inherent stability of the 19ve phosphanickelocenium sandwich configuration is not entirely clear at this stage because of the absence of useful phosphoruscontaining reference structures.…”

Novel Superalkali Superhalogen Compounds (Li3)+(SH)−(SH=LiF2, BeF3, and BF4) with Aromaticity: New Electrides and Alkalides

“…[19][20][21][22] Natural bond orbital (NBO) [23,24] and atoms in molecules (AIM) [25] analysis at the MP2 level were performed to provide an insight into the bonding nature of these Li 3 ÀSH species. The nucleus-independent chemical shifts (NICS) [26][27][28][29] were obtained by the GIAO-MP2/aug-cc-pVDZ//MP2/aug-cc-pVDZ method, and the molecularorbital plots were made by the GaussView program.…”

“…NICS, proposed by Schleyer and coworkers, [27][28][29] is an efficient and simple method to probe the aromaticity of a molecule, and is based on the negative of the magnetic shielding computed, for example, at or above the geometrical centers of rings or clusters. Systems with negative NICS values are aromatic.…”

Silylene and Germylene Intermediates in the Reactions of Silole and Germole Dianions with N,N′‐Di‐tert‐butylethylenediimine

“…The silole [1] and germole [2] (metallole) dianions I (Figure 1) are interesting compounds both from theoretical and practical points of view due to their aromaticity [3,4] and unique reactivity. Metallole dianions act as strong reducing agents [5] and nucleophiles.…”