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Topologic Equivalents of Coronands, Cryptands and Their Inclusion Complexes: Synthesis, Structure and Properties of {2}‐Metallacryptands and {2}‐Metallacryptates
Author(s) -
Saalfrank Rolf W.,
Dresel Andreas,
Seitz Verena,
Trummer Stefan,
Hampel Frank,
Teichert Markus,
Stalke Dietmar,
Stadler Christian,
Daub Jörg,
Schünemann Volker,
Trautwein Alfred X.
Publication year - 1997
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19970031222
Subject(s) - chemistry , deprotonation , hexafluorophosphate , crystallography , cyclic voltammetry , crystal structure , triethylamine , hydride , potassium , hyperfine structure , mössbauer spectroscopy , stereochemistry , inorganic chemistry , electrochemistry , organic chemistry , hydrogen , catalysis , ion , ionic liquid , physics , electrode , quantum mechanics
The synthesis and structural characterisation of two dinuclear iron(III) complexes are reported. The compounds of general structure [Fe 2 L 1 3 ] [ 8 ; L 1 = dianion of 2,2′‐dicyano‐2,2′‐isophthaloyldi(isopropyldicarboxylate)] and [K ⊂ Fe 2 L 2 3 ] + (PF 6 ) ‐ [ 10 ; L 2 = dianion of 1,1′‐(2,6‐pyridylene)bis‐1,3‐(4‐dimethyl)‐pentanedione] are formed by the deprotonation of ligands 7 and 9 with triethylamine and potassium hydride respectively, followed by addition of iron(III) chloride and work up with water or aqueous potassium hexafluorophosphate. X‐ray crystallographic studies reveal that 8 is a racemic mixture composed of triple helicates with (Δ,Δ)‐ fac and (Δ,Δ)‐ fac configuration at the two iron bridgeheads. In contrast to racemic 8 , the two iron centres in the meso ‐ 10 [(Δ,Δ)‐ fac ] have opposite configuration. Investigations of the redox‐active iron centres in {2}‐metallacryptand 8 and {2}‐metallacryptate 10 by cyclic voltammetry show slightly different behaviour. The peaks for the two consecutive reductions of the two iron centres of 8 can hardly be resolved, whereas 10 shows two well‐separated peaks. Mössbauer measurements were performed on 8 and 10 between 4.2 and 300 K, with and without a field applied perpendicular or parallel to the γ‐beam. All zero‐field and 20 mT spectra exhibit a broad and unresolved absorption pattern. Application of 5.3 T at 4.2 K results in well‐resolved magnetic hyperfine patterns which are practically the same for 8 and 10.