Stable bidentate silylene adducts of alkaline‐earth amides

Abstract

The coordination chemistry of silylenes is known for a vast number of elements of all blocks of the periodic table. However, only a handful of examples of silylene complexes have been reported for heavy alkaline‐earth elements, which is mainly attributed to the “hard‐soft” mismatch between the “hard” metal center and the “soft” silicon donor. Herein, we report the synthesis and characterization of a series of alkaline‐earth silylene complexes comprising a bidentate pyridyl‐amido‐silylene ligand. The isolated Ca, Sr and Ba complexes show considerably increased stability in comparison to other known alkaline‐earth silylene complexes. The molecular structures of all three complexes are essentially similar. Interestingly, depending on the central metal, the 1H NMR chemical shifts of the ortho‐H atom show unexpected large differences. DFT computations were conducted to elucidate this trend in the NMR resonances.

Phospholyl and Arsolyl Triple-Decker Sandwich Complexes of Europium(II) and Strontium(II)

“…Attempts to desolvate the products to obtain the solvent-free triple-decker complexes by heating the complexes under vacuum (120 °C and 10 −3 mbar) were unsuccessful. Due to the similarities in ionic radii and general coordination behavior of strontium and divalent europium, 18,19 we also attempted to synthesize the analogous Sr complexes. This successfully resulted in compounds [{(η 5 -Dtp)-Sr II (thf)} 2 {μ-η 8 :η 8 -C 8 H 8 }] (3) and [{(η 5 -Dtas)Sr II (thf)} 2 {μη 8 :η 8 -C 8 H 8 }] (4) as colorless single crystals after slow evaporation of the solvent (Scheme 1).…”

Amidinatotetrylenes Donor Functionalized on Both N Atoms: Structures and Coordination Chemistry

“…In this regard, the metal complexes that are equipped with polydentate ATs have been generally prepared from metal-free ATs (generically E(R 1 NC(R 2 )NR 1 )X; E = heavier tetrel atom, X = anionic group; see Figure ) functionalized with at least one additional donor group (D). Figure shows the currently known types of metal-free potentially polydentate ATs, − which formally result from (a) attaching a donor fragment to the E atom (X position; type I ), − (b) connecting with a linker, which can also have additional donor or prone to undergo metalation groups, two ATs through their E atoms (X position; type II ), − through the amidinate central C atoms (R 2 position; type III ) − or through one of the two amidinate N atoms (R 1 position; type IV ), and (c) attaching a donor fragment to one of the N atoms (R 1 position; type V ). , By far, types I and II , whose syntheses normally imply an easy Cl replacement with an appropriate lithiated group on well-known chlorido-ATs, are the most explored donor-functionalized ATs, having led to a great variety of metal complexes fitted with κ 2 E , D -, − κ 2 E , E -, , κ 3 E , D , E -, κ 3 E , C , E - ligands, many of them with catalytic applications . On the other hand, the functionalization pathways that lead to types III , IV , and V , which imply modifications on the amidinate skeleton befor...…”