1H NMR spectral analysis in series of heteroleptic triple-decker lanthanide phthalocyaninato complexes: Contact and dipolar contributions of lanthanide-induced shifts

Model-free separation of lanthanide-induced shifts to contact and dipolar contributions was performed for the series of heteroleptic REE(III) trisphthalocyaninates, namely [(15C5)(4)Pc]M(Pc)M(Pc), where Pc2- - phthalocyaninato-dianion, [(15C5)(4)Pc](2-) - 2,3,9,10,16,17,24,25-tetrakis(15-crown-5)phthalocyaninato-dianion, M = Nd, Sm, Eu, Tb, Dy, Er, Tm and Y as a diamagnetic reference. Application of one nucleus technique evidenced of abrupt changes of contact F-k and dipolar A(2)(0) < r(2)> . G(k) terms between Tb and Dy. Not withstanding structural non-equivalence of lanthanide ions, they have virtually equal values of crystal-field parameters, which justified application of several crystal-field techniques for the further analysis of LIS data. Both two (Delta delta(k)/(S-Z)(Ln); Delta delta(l)/(S-Z)(Ln)) and three nuclei (Delta delta(k)/(S-Z)(Ln); Delta delta(l)/(S-Z)(Ln); Delta delta(m)/(S-Z)(Ln)) crystal-field independent graphical analysis evidenced of isostructurality of the complete series, therefore variation of solely A(2)(0)(r(2)) between Tb and Dy was responsible for changes of dipolar terms. To study the behavior of contact terms, another three nuclei technique was firstly applied to lanthanide phthalocyaninates. Plotting Delta delta(k)/Delta delta(m) versus Delta delta(l)/Delta delta(m) demonstrated that in studied complexes F-k actually vary between Eu and Tb, therefore evidencing of non-simultaneous variations of contact and dipolar terms. Altogether, it let us refine the values of these terms, which would be subsequently applied for structural analysis of triple-decker crown phthalocyaninates and their supramolecular assemblies in solution. (C) 2009 Elsevier Ltd. All rights reserved.