Copper complexes of mono- and ditopic [(methylthio)methyl]borates: Missing links and linked systems en route to copper enzyme models

TMEDA-free (TMEDA: tetramethylethylenediamine) LiCH(2)- SMe is a suitable reagent for the selective introduction of (methylthio)methyl groups into PhBBr(2) and its p-silylated derivative Me(3)Si-C(6)H(4)-BBr(2)- ne resulting compounds, R*-C(6)H(4)-B(Br)(CH(2)SMe) (R* = H: 2; R* = SiMe(3): 7) and PhB(CH(2)SMe)(2) (3), form cyclic dimers through B-S adduct bonds in solution and in the solid state. Compounds 2 and 3 have successfully been used for preparing the (NS) scorpionate [PhBpz(2)(CH(2)SMe)](-) ([5](-)) (pz: pyrazol-1-yl) and the (NS(2)) scorpionate [PhBpz(CH(2)SMe)(2)](-), respectively Compound 7 proved to be an excellent building block for the heteroditopic poly (pyrazol-1-yl)borate P-[PZ(3)BC(6)H(4)-Bpz(2)(CH(2)SMe)](2-) ([10](2-)) that mimics the two ligation sites of the copper enzymes peptidylglycine a-hydroxylating monooxygenase and dopamine P-monooxygenase. Treatment of the monotopic tripod [5](-) with CuCl and CuBr(2) results in the formation of complexes K[CU(5)(2)] and [CU(5)(2)]. An X-ray crystallography study of K[CU(5)2] revealed a tetrahedral (N(2)S(2)) coordination environment for the Cu(I), ion, whereas the Cu(II) ion of [CU(5)(2)] possesses a square-pyramidal (NS) ligand sphere (S-atom in the axial position). The remarkable redox properties of K[Cu(5)(2)] and [Cu(5)(2)] have been assessed by cyclic voltarnmetry and quantum chemical calculations. The reaction of K[CU(5)(2)] with dry air leads to the Cu(II) species [Cu(5)(2)] and to a tetranuclear Cu(II) complex featuring [PhB(O)pz(2)](2-) ligands. Addition of CuCl to K(2)[10] gives the complex K,[CU(10)(2)] containing two ligand molecules per Cut center. The Cu(I) ion binds to both heteroscorpionate moieties and thereby establishes a coordination environment similar to that of the Cu(I) ion in K[CU(5)(2)].