Novel heteroscorpionates featuring N and S donor atoms

Current coordination chemistry takes a great deal of interest in mixed N,S donors for modelling active sites of metalloenzymes. In this context, borate ligands containing pyrazolyl- (as histidine mimics) together with thioether substituents (as cysteine or methionine mimics) have proven to be particularly useful. One focus of our own research lies on the synthesis and coordination behavior of N,N,S donors. We have developed high-yield syntheses of derivatives of the bis(pyrazolyl)borate PhB(CH₂SCH₃)pz₂ and studied their ligand properties towards Fe(II), Fe(III), Cu(I), and Cu(II) ions. Moreover, we have prepared the heteroditopic poly(pyrazolyl)borate ligand 1 which has promising potential for the generation of heterodinuclear transition metal complexes. In all these ligand syntheses it is of prime importance to use donor-free methyl(thiomethyl)lithium to introduce the S donor substituent. The unique solid state structure of this organometallic reagent was determined using high resolution X-ray powder diffraction data.