Annealing [FeL2][BF4]2⋅2 H2O (L=2,6‐bis‐[5‐methyl‐1H‐pyrazol‐3‐yl]pyridine) affords an anhydrous material, which undergoes a spin transition at T1/2=205 K with a 65 K thermal hysteresis loop. This occurs through a sequence of phase changes, which were monitored by powder diffraction in an earlier study. [CuL2][BF4]2⋅2 H2O and [ZnL2][BF4]2⋅2 H2O are not perfectly isostructural but, unlike the iron compound, they undergo single‐crystal‐to‐single‐crystal dehydration upon annealing. All the annealed compounds initially adopt the same tetragonal phase but undergo a phase change near room temperature upon re‐cooling. The low‐temperature phase of [CuL2][BF4]2 involves ordering of its Jahn–Teller distortion, to a monoclinic lattice with three unique cation sites. The zinc compound adopts a different, triclinic low‐temperature phase with significant twisting of its coordination sphere, which unexpectedly becomes more pronounced as the crystal is cooled. Synchrotron powder diffraction data confirm that the structural changes in the anhydrous zinc complex are reproduced in the high‐spin iron compound, before the onset of spin‐crossover. This will contribute to the wide hysteresis in the spin transition of the iron complex. EPR spectra of copper‐doped [Fe0.97Cu0.03L2][BF4]2 imply its low‐spin phase contains two distinct cation environments in a 2:1 ratio.

Q-band electron paramagnetic resonance (EPR) data conclusively demonstrate that the iron and cobalt centers in the solid solution [Fe(bpp)][Co(terpy)][BF] (bpp = 2,6-dipyrazol-1-ylpyridine) undergo allosteric spin-state switching during light-induced excited-spin-state trapping (LIESST) at 20 K and thermal relaxation around 80 K. EPR of [Cu(terpy)] and [Cu(bpp)], doped into the same host lattice, also indicates expansion of the copper coordination sphere during LIESST excitation.

Enantiomerically-enriched trichloromethyl-containing alcohols, obtained by asymmetric reduction, can be transformed regioselectively into 1-substituted piperazinones by modified Jocic reactions with little or no loss of stereochemical integrity. This methodology can be easily used to synthesise important pharmaceutical compounds such as the fluorobenzyl intermediate of a known PGGTase-I inhibitor.

including the URL of the record and the reason for the withdrawal request.Chart 1 Jahn-Teller isomers of the complexes in this work. 6,9 Short and long Cu−N bonds are indicated by full and dotted lines, respectively. The red ligand in each molecule represents the 'L' co-ligand (Chart 2). Chart 2The ligands and complexes employed in this work. is usually ferromagnetic in character, but is 10x smaller when the radical occupies an axial 19,20 rather than an equatorial site 16,[20][21][22] in a tetragonal Cu(II) complex.

One-electron oxidation of the compound shown shows no evidence for intervalence charge transfer in the macrocylic ligand radical product. In contrast, related [{Pt(L)}3(μ3-ctc˙)]+ (H6ctc = cyclotricatechylene), exhibits class II mixed valency.