1H NMR spectral analysis of structural features in a series of paramagnetic homoleptic binuclear triple-decker phthalocyaninato lanthanide complexes

The search for efficient methods of comparative structural investigations of coordination compounds in solid state and solutions is a very relevant task. In this study, structural assignments in a series of Ln(2)[(15C5)4Pc]3 complexes (where [(15C5)4Pc]2-is 2,3,9,10,16,17,24,25-tetrakis(15-crown-5)phthalocyaninato-dianion, Ln = Nd3+, Tb3+, Dy3+, Ho3+, Er3+ and Tm3+) was performed using NMR relaxation and paramagnetic lanthanide induced shifts (LIS) data. Analysis of the paramagnetic chemical shifts and relaxation rates evidenced of isostructurality of the complete series of the investigated triple-decker complexes in the solutions. The performed systematic DFT calculations for a series of model complexes with methoxy-substituted ligands Ln(2)[(MeO)(8)Pc](3) demonstrate that the calculated geometrical factors are in agreement with characteristics extracted from experimental NMR data.

Automated summary

This study investigates the structural assignments of Ln(2)[(15C5)4Pc]3 complexes using NMR relaxation and paramagnetic lanthanide induced shifts (LIS) data. The analysis reveals isostructurality in the complete series of triple-decker complexes in solution. DFT calculations for model complexes with methoxy-substituted ligands show good agreement with experimental NMR data.