Synthesis of Arylcalcium Halides — General Procedure, Scope and Limitations

Abstract

Synthesis of Arylcalcium Halides -General Procedure, Scope and Limitations -The iodides crystallize as tetrakis(THF) complexes. -(GAERTNER, M.; GOERLS, H.; WESTERHAUSEN*, M.; Synthesis 2007, 5, 725-730; Inst. Anorg. Anal. Chem., Friedrich-Schiller-Univ., D-07743 Jena, Germany; Eng.) -Mais

Synthesis of [2]ferrocenophanes containing trivalent diphosphine units

“…After stirring with Mg overnight, the reaction mixture exhibited a new 31 P{ 1 H} NMR signal at 20.6 ppm, suggesting that only one diastereomer was formed. Further reaction with Mg, however, resulted in the appearance of several signals around À26 ppmdthat is, in the range of signals of R 2 P À anions such as (Ph 2 P) 2 Mg (À41 ppm) [23], suggesting cleavage of the PdP bond. The species having the 31 P{ 1 H} NMR signal at 20.6 ppm could be isolated with a deactivated Al 2 O 3 column, and determined to be (P t Bu) 2 -bridged [2]ferrocenophane 10a by using 1 H and 13 C{ 1 H} NMR as well as X-ray analysis.…”

“…Based on the similarity of the chemical shift to that of 10a, the signal at 8.7 ppm is assigned to the desired (P n Bu) 2 -bridged [2]ferrocenophane 10b, and the signals around À40 ppm might be those of anionic phosphide species together with Mg 2þ cation. Phosphide magnesium has been reported to form aggregates [23], which could have been responsible for the observed multiplet. The signal at À70 ppm had a low intensity and could not be characterized.…”

Synthesis and stabilization—advances in organoalkaline earth metal chemistry

“…For calcium, this involves either (1) dissolving the bulk calcium metal in liquid ammonia followed by evaporation of the ammonia (depending on conditions, this may lead either to calcium amide or finely dispersed calcium powder), (2) reduction of CaI 2 by K metal, leaving a finely dispersed Ca powder, 121 or (3) co-condensation of metal vapors onto a cooled surface, leaving a metal powder. 24,122 The choice method for calcium seems to be dissolving Ca metal in ammonia; however, this method does not work well for other alkaline earth metals, as both Sr and Ba rapidly form M(NH 2 ) 2 in ammonia solutions. Metal powders are preferred due to their increased surface area and, therefore, increased rate of metal insertion into the carbon-halide bond.…”

Heterofunctionalization catalysis with organometallic complexes of calcium, strontium and barium

“…inorganic synthesis, a well-defined reaction chemistry encompassing the heavier elements of Group II has remained unreported. It is revealing that, although syntheses of 'heavy Grignards' (ArMX and RMX, X = halide) were documented contemporaneously with Grignard's original reports of his eponymous reagents (Grignard 1900;Beckmann 1905;Gilman & Schulze 1926;Gilman et al 1943), only in the last 3 years have arylcalcium halides been isolated and structurally characterized (Gartner et al 2007b;Westerhausen 2008). Furthermore, the solidstate structures of the analogous strontium and barium complexes are, as yet, unknown (Langer et al 2007).…”