The synthesis and structural characterization of allenyl titanocene(IV) [TiClCp2 (CH=C=CH2 )] 3 and propargyl titanocene(IV) [TiClCp2 (CH2 -C≡C-(CH2 )4 CH3 )] 9 have been described for the first time. Advanced NMR methods including diffusion NMR methods (diffusion pulsed field gradient stimulated spin echo (PFG-STE) and DOSY) have been applied and established that these organometallics are monomers in THF solution with hydrodynamic radii (from the Stokes-Einstein equation) of 3.5 and 4.1 Å for 3 and 9, respectively. Full (1) H, (13) C, Δ(1) H, and Δ(13) C NMR data are given, and through the analysis of the Ramsey equation, the first electronic insights into these derivatives are provided. In solution, they are involved in their respective metallotropic allenyl-propargyl equilibria that, after quenching experiments with aromatic and aliphatic aldehydes, ketones, and protonating agents, always give the propargyl products P (when carbonyls are employed), or allenyl products A (when a proton source is added) as the major isomers. In all the cases assayed, the ratio of products suggests that the metallotropic equilibrium should be faster than the reactions of 3 and 9 with electrophiles. Indeed, DFT calculations predict lower Gibbs energy barriers for the metallotropic equilibrium, thus confirming dynamic kinetic resolution.
We have designed and synthesized eight isostructural 1D coordination polymers (CPs) with the general formula {[Ln(aapc)3(DMF)]}n [where Ln(iii) = Y (2), La (3), Nd (4), Eu (5), Gd (6), Tb (7), Dy (8), Er (9); and aapc = 3-((anthraquinone-1-yl)amino)propanoate]. These CPs consist of Ln-carboxylate infinite rods in which the bulky anthraquinone scaffolds arise from it in such a way that the resulting supramolecular packing exhibits isolated 1D chains. Solution structures have been corroborated through NMR methods including PGSE and EXSY NMR studies and, due to the presence of lanthanide ions, magnetic and luminescence properties have been studied. Alternating current magnetic measurements of compound 8 show slow relaxation of the magnetization, a characteristic of single molecule magnets (SMMs). The evaluation of solid-state photophysical properties reveals that the aapc scaffold sensitizes lanthanide(iii) based emission of compounds 4-9 both in the visible and near-infrared (NIR) regions at 10 K.
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