Bocian Wojciech, Jaźwiński Jarosław, Sadlej Agnieszka
Institute of Organic Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warszawa, Poland.
Magn Reson Chem. 2008 Feb;46(2):156-65. doi: 10.1002/mrc.2149.
Adduct formations of rhodium(II) tetraacetate and tetratrifluoroacetate with some 1H-imidazoles, oxazoles, thiazoles, 1H-pyrazoles and isoxazole have been investigated by the use of 1H, 13C, 15N NMR and electronic absorption spectroscopy (VIS) in the visible range. Azoles tend to form axial adducts containing rhodium(II) tetraacylates bonded via nitrogen atom. Bulky substituents close to the nitrogen atom prevent the Rh--N bond formation, and in several cases switch over the binding site to the oxygen or sulphur atoms. The (15)N adduct formation shift Deltadelta(15N) (Deltadelta = delta(adduct) - delta(ligand)) varied from ca - 40 to - 70 ppm for the nitrogen atom involved in complexation, and of a few parts per million only, from ca - 6 to 3 ppm, for the non-bonded nitrogen atom within the same molecule. The Deltadelta(1H) values do not exceed one ppm; Deltadelta(13C) ranges from - 1 to 6 ppm. Various complexation modes have been proved by electronic absorption spectroscopy in the visible region (VIS). For comparison purposes, some adducts of pyridine, thiophene and furan derivatives have been measured as well. The experimental findings were compared with calculated chemical shifts, obtained by means of DFT B3LYP method, using 6-311 + G(2d,p), 6-31(d)/LanL2DZ and 6-311G(d,p) basis set.
通过使用1H、13C、15N核磁共振以及可见光范围内的电子吸收光谱（VIS），对四乙酸铑（II）和四三氟乙酸铑（II）与一些1H-咪唑、恶唑、噻唑、1H-吡唑和异恶唑的加合物形成情况进行了研究。唑类倾向于形成通过氮原子键合的含四酰基铑（II）的轴向加合物。靠近氮原子的庞大取代基会阻止Rh-N键的形成，在某些情况下，结合位点会切换到氧或硫原子上。对于参与络合的氮原子，（15）N加合物形成位移Δδ（15N）（Δδ = δ（加合物）-δ（配体））在约-40至-70 ppm之间变化，而对于同一分子内未键合的氮原子，仅为百万分之几，约为-6至3 ppm。Δδ（1H）值不超过1 ppm；Δδ（13C）范围为-1至6 ppm。通过可见光区域（VIS）的电子吸收光谱证明了各种络合模式。为了进行比较，还测量了吡啶、噻吩和呋喃衍生物的一些加合物。将实验结果与通过DFT B3LYP方法，使用6-311 + G（2d，p）、6-31（d）/LanL2DZ和6-311G（d，p）基组获得的计算化学位移进行了比较。
