Phase-dependent polymerization isomerism in the coordination complexes of a flexible bis(β-diketonato) ligand.

First prepared in the late 70s, the pro-ligand 1,3-bis(3,5-dioxo-1-hexyl)benzene (Hbdhb) contains two acetoacetyl terminations linked to a central 1,3-phenylene unit through dimethylene bridges. Since each termination can be either in diketonic or keto-enolic form, in organic solution it exists as a mixture of three spectroscopically resolvable tautomers. In the presence of pyridine, Co and the bdhb anion form a crystalline dimeric compound with formula [Co(bdhb)(py)] (2) and a Co⋯Co separation of more than 11 Å.

Guest selectivity of [Ni] supramolecular helicates.

Two new paramagnetic supramolecular helicates with the formula (X@[NiL]) (X = Cl, or Br; L = a bis-pyrazolylpyridine ligand) have been prepared and are described. Helicates of this metal are very rare with virtually no prior examples of them acting as hosts of anionic species. The persistence of the new assemblies in solution has been demonstrated unambiguously by mass spectrometry and paramagnetic H NMR.

Dual Structure of a Vanadyl-Based Molecular Qubit Containing a Bis(β-diketonato) Ligand.

We designed [VO(bdhb)] (') as a new electronic qubit containing an oxovanadium(IV) ion ( = 1/2) embraced by a single bis(β-diketonato) ligand [Hbdhb = 1,3-bis(3,5-dioxo-1-hexyl)benzene]. The synthesis afforded three different crystal phases, all of which unexpectedly contain dimers with formula [(VO)(bdhb)] (). A trigonal form () with a honeycomb structure and 46% of solvent-accessible voids quantitatively transforms over time into a monoclinic solvatomorph and minor amounts of a triclinic solventless phase ().

Quantum spin coherence and electron spin distribution channels in vanadyl-containing lantern complexes.

We herein investigate the heterobimetallic lantern complexes [PtVO(SOCR)] as charge neutral electronic qubits based on vanadyl complexes ( = 1/2) with nuclear spin-free donor atoms. The derivatives with R = Me (1) and Ph (2) give highly resolved X-band EPR spectra in frozen CHCl/toluene solution, which evidence the usual hyperfine coupling with the V nucleus ( = 7/2) and an additional superhyperfine interaction with the = 1/2 nucleus of the Pt isotope (natural abundance 34%). DFT calculations ascribe the spin density delocalization on the Pt ion to a combination of π and pathways, with the former representing the predominant channel.