Crystalline Rhodium‐Tin Complexes with Radical Trianion and Tetraanion Phthalocyanine Ligands: Observation of Nimine(Pc)−Rh Coordination Bond

Abstract

AbstractCrystalline {Cryptand(Na+)}[(COD)RhICl⋅SnII(Pc3−)]−⋅2C6H4Cl2 (1) and {Cryptand(Cs+)}[(COD)RhI⋅SnII(Pc4−)]−⋅C6H5CH3 (2) complexes were obtained via the interaction of [SnII(Pc3−)]− and [SnII(Pc4−)]2−, respectively, with organometallic {(COD)RhCl}2 dimer (COD is 1,5‐cyclooctadiene). Dissociation of {(COD)RhCl}2 followed by the Rh−Sn binding is observed at the formation of 1. Elimination of the chlorine atom at the rhodium atom is observed in 2, and rhodium is additionally coordinated to the imine nitrogen atom of Pc4−. The complexes contain mono‐ Pc⋅3− and doubly reduced Pc4− species, respectively, that is supported by the data of XRD analysis as well as optical and magnetic properties of 1 and 2. There is an alternation of C‐Nimine bonds in the macrocycles, which gradually increases with increasing negative charge on the macrocycle. The difference between shorter and longer bonds increases from 0.051 Å in Pc3− to 0.075 Å in Pc4−. The formation of 1 is accompanied by an essential blue shift of the Q‐band of starting SnPc and the appearance of a new intense band at 1031 nm. The even stronger shift of the Q‐band is observed in the spectrum of 2, but the band in the near‐IR range becomes weaker. The value of effective magnetic moment of 1 is 1.76 μB at 300 K corresponding the contribution of the Pc3− radical trianions (S=1/2). Only weak magnetic coupling with the Weise temperature of −3 K is observed in 1 due to weak π–π interaction between the macrocycles in the chains. Paramagnetic Pc3− species additionally monitored by EPR spectroscopy show a strong temperature dependence of g‐factor and linewidth of the EPR signal. Complex 2 is diamagnetic and EPR silent.