EXAFS Studies of Cobalt(II) Complexes with Amino Acids

X‐ray K‐absorption edges along with their extended X‐ray absorption fine structure (EXAFS) have been recorded for Co(II) complexes with amino acids using a laboratory XAFS spectrometer. The samples studied are biologically important because amino acids are very small bio molecules and are the principal building blocks of proteins and enzymes. The samples studied include cobalt glycinate, cobalt alanate, cobalt valinate and cobalt glutamate. Using the experimentally observed X‐ray absorption chemical shifts, effective nuclear charge (ENC) and percentage covalency have been estimated and a relative order of covalency amongst the studied complexes established which follows the sequence: alanate > glutamate > glycinate > valinate. Both X‐ray absorption near edge structure (XANES) and EXAFS have been utilized to obtain the average near neighbour distances in the samples. Further, the total phase shifts δ1 and phase parameters β1 i.e., back scattering phase shifts for these samples have been estimated. The valu...