83350-37-2Relevant academic research and scientific papers
(Tertiary phosphinomacrocycle)cobalt(II) halide coordination chemistry. Identification and interconversion of four types of complexes
Kyba, Evan P.,Alexander, David C.,Hohn, Arthur
, p. 1619 - 1623 (2008/10/08)
The cobalt(II) halide coordination chemistry of six macrocyclic (11-, 13-, and 14-membered) ligands (MC) containing the l,2-bis(phenylphosphino)benzene moiety and, with one exception, at least one other potential ligating site (oxygen or nitrogen) has been studied. Four different types of complexes have been isolated, depending on the reaction conditions and the MC. If the stoiehiometry 1:0.5 (MC:CoHal2) is used, type I complexes are formed kinetically, which are trans octahedral (MC)2CoHal2 species with elongated Co-Hal bonds (shown by single-crystal X-ray crystallography for the bromide), as would be expected for a 19-electron system. The thermodynamic product (type II) with the 1:0.5 stoiehiometry is either [(MC)2Co]2Hal or [(MC)2CoHal]Hal, with the evidence favoring the former, since the 31P NMR and electronic spectra are independent of the halogen. The type I and II materials are formed if the additional ligating site in the MC is ineffectual, e.g., aryl N, aryl 0, or ether 0, which forms seven-membered chelates. If 1:1 stoichiometries are utilized, type HI species are produced that are [(MC)2Co] [CoHal4], which feature UV absorptions identical with those for type II species but which differ in the visible region. When the MC is 11-membered and contains either NMe (11-P2NMe) or 0 (11-P2O), type IV complexes are formed, with the stoiehiometry (MC)CoHal2 and electronic spectra similar to those for known (tridentate ligand)CoHal2 complexes. The type IV species may be transformed into type I complexes at rates which depend on MC (11-P2O > 11-P2NMe), halogen (Cl > Br ? I), and solvent (CH2C12 > THF).
