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Oligomeric complexes of some heteroaromatic ligands and aromatic diamines with rhodium and molybdenum tetracarboxylates: 13 C and 15 N CPMAS NMR and density functional theory studies
Author(s) -
Leniak Arkadiusz,
Kamieński Bohdan,
Jaźwiński Jarosław
Publication year - 2015
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.4201
Subject(s) - chemistry , rhodium , molybdenum , bipyridine , chemical shift , diamine , density functional theory , nmr spectra database , nuclear magnetic resonance spectroscopy , proton nmr , ligand (biochemistry) , crystallography , inorganic chemistry , stereochemistry , computational chemistry , organic chemistry , spectral line , crystal structure , catalysis , physics , astronomy , biochemistry , receptor
Seven new oligomeric complexes of 4,4′‐bipyridine; 3,3′‐bipyridine; benzene‐1,4‐diamine; benzene‐1,3‐diamine; benzene‐1,2‐diamine; and benzidine with rhodium tetraacetate, as well as 4,4′‐bipyridine with molybdenum tetraacetate, have been obtained and investigated by elemental analysis and solid‐state nuclear magnetic resonance spectroscopy, 13 C and 15 N CPMAS NMR. The known complexes of pyrazine with rhodium tetrabenzoate, benzoquinone with rhodium tetrapivalate, 4,4′‐bipyridine with molybdenum tetrakistrifluoroacetate and the 1 : 1 complex of 2,2′‐bipyridine with rhodium tetraacetate exhibiting axial–equatorial ligation mode have been obtained as well for comparison purposes. Elemental analysis revealed 1 : 1 complex stoichiometry of all complexes. The 15 N CPMAS NMR spectra of all new complexes consist of one narrow signal, indicating regular uniform structures. Benzidine forms a heterogeneous material, probably containing linear oligomers and products of further reactions. The complexes were characterized by the parameter complexation shift Δδ ( Δδ = δ complex − δ ligand ). This parameter ranged from around −40 to −90 ppm in the case of heteroaromatic ligands, from around −12 to −22 ppm for diamines and from −16 to −31 ppm for the complexes of molybdenum tetracarboxylates with 4,4′‐bipyridine. The experimental results have been supported by a density functional theory computation of 15 N NMR chemical shifts and complexation shifts at the non‐relativistic Becke, three‐parameter, Perdew‐Wang 91/[6‐311++G(2d,p), Stuttgart] and GGA–PBE/QZ4P levels of theory and at the relativistic scalar and spin‐orbit zeroth order regular approximation/GGA–PBE/QZ4P level of theory. Nucleus‐independent chemical shifts have been calculated for the selected compounds. Copyright © 2015 John Wiley & Sons, Ltd.