Alkali Metal Di‐ tert ‐butylphenylsilanides — t Bu 2 PhSiM (M = Li, Na, K) — Syntheses, Structures, and Reactivity

Section: Methodsmentioning

confidence: 99%

Pentasilatricyclo[2.1.0.0^2,5]pentane and Its Anion

Lee

Yokoyama

Takanashi

et al. 2009

“…In general, their preparation is limited to the cleavage of silicon-silicon bonds in phenyl-substituted disilanes, [32,34] the transmetallation of certain metallosilanes [35] and the direct lithiation of silyl halides. [36] The following chapter deals with the most important solid-state structures of silyllithium compounds and their main differences to the related alkyllithium compounds.…”

Section: Structure Principles Of Silyllithium Compoundsmentioning

confidence: 99%

Structure Formation Principles and Reactivity of Organolithium Compounds

Gessner

Däschlein

Strohmann

2009

241

111

The structure-reactivity relationship is an important feature of organolithium compounds. The knowledge of the structure of reactive species is crucial for the elucidation of reaction mechanisms and the understanding of observed selectivities. This concept article gives an overview over the structural principles of lithium organics and their Lewis base coordinated complexes in the solid state. The transition from the oligomeric parent structures to smaller adducts, such as dimers and monomers, as well as special degrees of aggregation is presented. Besides the commonly used alkyllithium compounds, a short overview over the structural principles of the higher homologous silyllithium compounds is given. Moreover, the structure-reactivity relationship is depicted by means of the reactivity of the Lewis bases towards intramolecular decomposition reactions with the organolithium compound. Selected examples confirm the importance of structure elucidation for the understanding of mechanistic pathways and selectivities.

“…In this discussion we consider all Na À C p interactions up to a value of 2.95 as bonds, which is a conservative limit for NaÀC p interactions. [17,38,39] Na1 is h 4 -coordinated by the N1'-C5'-C6'-N2' backbone of the diimine unit and h…”

mentioning

confidence: 99%

Sodium and Potassium Salts of Mono‐ and Dianionic α‐Iminopyridines

Nayek

Arleth

Trapp

et al. 2011

[a] a-Diimine (1,4-diaza-1,3-butadiene) ligands are well established in main-group, transition-metal, and lanthanide chemistry. [1][2][3][4][5][6][7] Beside their application as ligands for latetransition-metal complexes, which can function as active and selective catalysts for a-olefin polymerization, [8] a-diimine and related ligands are of special interest due to their ability to undergo redox chemistry.[9] They have frequently been described as "non-innocent" ligands. [10][11][12] For example, in lanthanide chemistry, it has been found that the formal oxidation state of Eu [13] and Yb [14] depends on the nature of the substituents on the a-diimine ligand and on the ligand on the metal center. Thus, in both cases, the a-diimine acts either as neutral ligand or as radical anion. Reduction of adiimines, using either alkali metals or electrochemical methods, leads in each case to the corresponding radical anions [15][16][17][18] and eventually to diamagnetic dianions, [17][18][19][20][21][22][23][24] albeit at much more negative potentials. In contrast to the well-established chemistry of a-diimines, the related a-iminopyridines are much less investigated. The three different redox states of a-iminopyridines are shown in Scheme 1. The neutral system L 0 has been extensively used as ligand for late transition metals. [4,[25][26][27][28][29] Only recently, the monoanion LC À and the doubly reduced dianion L 2À were investigated as ligands in more detail. Recent reports showed a series of bis(a-iminopyridine)-metal complexes featuring aluminum [30] and the first-row transition ions (Cr, Mn, Fe, Co, Ni, and Zn) [31,32] with the monoanionic, and thus paramagnetic p-radical form of the ligand in coordination complexes. The a-iminopyridine N-2,6-diisopropylphenylimino-2-pyridine (IPy) has also been introduced in lanthanide chemistry. [33,34] In this context, a potassium derivative of the monoanionic form of a-iminopyridine was prepared in situ, but not further characterized.[34] The doubly reduced dianion has only been observed in two magnesium complexes so far. [35] In contrast, the reaction of "GaI" with a-iminopyridine leads to reductive coupling of the coordinated ligand to give neutral diamido-digallium complexes. [36] Based on this information, we were interested in a comprehensive study of the properties of the alkali metal salts of the monoanionic p-radical and the doubly reduced dianion of a-iminopyridine in solution and in the solid state. We report here the synthesis, characterization and magnetic properties of sodium and potassium salts of the mono-and dianionic a-iminopyridines.N-2,6-Diisopropylphenylimino-2-pyridine (IPy) was prepared according to literature procedures.[37] As a first entry point, we examined the electrochemical properties of IPy using cyclic voltammetry at room temperature in THF. As can be seen from Figure 1, we detected a quasi-reversible one-electron reduction process centered at E 0 1=2 = À2.57 V (vs. the ferrocene/ferrocenium couple, Fc/Fc + ), with a peakto-peak separation of 15...