A pseudotetrahedral cobalt(II) complex with a positive axial zero-field splitting parameter of D = 12.7 cm(-1), as determined by high-field EPR spectroscopy, is shown to exhibit slow magnetic relaxation under an applied dc field.

A combination of four-electron donors, such as alkynes, with strongly donating and strong-field scorpionate ligands is appropriate to create pseudotetrahedral rhodium(I) environments, as found in [Rh(PhBP3 )(HCCPh)], which promotes HC bond activation and CC coupling reactions under very smooth conditions.

The preparation and characterization of two mononuclear cobalt(III) tropocoronand complexes, [Co(TC-5,5)](BF4) and [Co(TC-6,6)](BPh4), are reported. The cobalt(III) centers exist in rare pseudotetrahedral conformations, with twist angles of 65° and 74° for the [Co(TC-5,5](+) and [Co(TC-6,6)](+) species, respectively. Structural and electrochemical characteristics are compared with those of newl...

l-Penicillamine (Pen) has been investigated as a ligand for metalloprotein design by examining the binding of Co(II) to the sequence NH(2)-KL(Pen)EGG.(Pen)IG(Pen)GA(Pen).GGW-CONH(2). For comparison, we have studied Co(II) binding to the analogous sequence with Cys ligands, the ferredoxin maquette ligand IGA that was originally designed to bind a [4Fe-4S] cluster. The Co(II) affinity and UV-vis ...

This Communication describes a pseudotetrahedral d7 complex, [PhBP3]Co(OSiPh3), that exhibits thermally induced spin-crossover both in solution and in the solid state. Magnetic crossover behavior is achieved by confluence of the X-type ligand and the tripodal auxiliary employed. Four-coordinate platforms of the present geometry type may offer a new approach to magnetic spin-crossover behavior d...