Sandwich double-decker Er(III) and Yb(III) complexes, containing naphthalocyanine moiety: synthesis and investigation of effect of a paramagnetic metal center
Novel heteroleptic Er (III) and Yb (III) naphthalocyaninato-phthalocyaninates containing octa-phenyl or octa-phenoxysubstituted naphthalocyanine deck were synthesised and identified by 1H NMR, EPR and high resolution MALDI-TOF/TOF mass spectrometry. Direct synthesis of novel homoleptic Yb (III) bis(octa-phenylnaphthalocyaninate) was carried out. Downfield lanthanide induced shifts of the aromatic protons in target compounds were observed comparing with corresponding diamagnetic Lu (III) complexes. In the Near-IR absorption spectra, an increase in ionic radius going from Lu(III) to Er(III) results in a bathochromic shift of the intervalence band up to 1473 nm. This work presents the first experimental ESR study of Yb(III) bisnaphthalocyaninate, where a set of magnetic parameters and properties (including spin, magnitude and sign of magnetic anisotropy parameter D, increased splitting in a crystal field, ferromagnetic f-π interaction etc.) was determined and interpreted by both ESR and SQUID techniques and supported by theoretical considerations.