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Coordination Behavior and Coligand‐Dependent cis / trans Isomerism of Calcium Bis(diphenylphosphanides)
Author(s) -
Langer Jens,
AlShboul Tareq M. A.,
Younis Fadi M.,
Görls Helmar,
Westerhausen Matthias
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201100241
Subject(s) - chemistry , metathesis , salt metathesis reaction , salt (chemistry) , medicinal chemistry , stereochemistry , calcium , lewis acids and bases , crystallization , crystallography , catalysis , organic chemistry , polymerization , polymer
The salt metathesis reaction of KPPh 2 with CaI 2 and SrI 2 in THF yields the corresponding complexes [(THF) 4 Ae(PPh 2 ) 2 ] [Ae = Ca ( 1 ), Sr]. Depending on the crystallization conditions, cis ‐ or trans ‐[(THF) 4 Ca(PPh 2 ) 2 ] can be isolated. In solution, a fast equilibrium converts these isomers into each other leading to a single set of resonances in the NMR spectra. The THF ligands can be replaced by stronger Lewis bases, such as N ‐methylimidazole (MeIm), which leads to the formation of [(MeIm) 4 Ae(PPh 2 ) 2 ] [Ae = Ca ( 2a ), Sr ( 2b )]. The use of tetradentate hexamethyltriethylenetetramine (hmteta) fixes a cis configuration yielding [(hmteta)Ca(PPh 2 ) 2 ] ( 3 ). All compounds are very air and moisture sensitive, therefore a few crystals of the partially oxidized product [(hmteta)Ca(PPh 2 )(OPPh 2 )] ( 4 ) were also obtained.