Synthesis, Characterization, and Crystal Structures of Scorpionate Complexes with the Hydrotris[3‐(2′‐thienyl)pyrazol‐1‐yl]borate Ligand

Six scorpionate complexes of group 10-12 metal elements (Cu-I, Cu-II, Zn-II, and Cd-II) containing the anionic hydrotris[3-(2'-thienyl)pyrazol-1-yl]borate (Tp(Tn)) ligand were prepared from the reaction of the thallium(I) salt of Tp(Tn) with the corresponding metal acceptors in chloroform solution. The air- and heat-stable complexes were characterized by analytical and spectroscopic methods (IR, conductivity, ESI-MS, H-1 NMR and C-13 NMR solution data) and structurally characterized by single-crystal X-ray studies. The Zn-II complexes [Zn(Tp(Tn))X] (X = Cl or Br) contain a tripodal tridentate Tp(Tn) ligand, in which the tetrahedral metal environment is completed by a halide; in [Cd(Tp(Tn))(2)], cadmium is found in an octahedral environment coordinated by two Tp(Tn) ligands. In [Cu(Tp(Tn))(PPh3)]center dot CHCl3 and [Cu(Tp(Tn))(OC(O)CH3)], Tp(Tn) is also coordinated in the tripodal fashion, in which the copper environment is completed by a triphenylphosphine ligand in the former complex and by a symmetrically coordinated bidentate acetate ligand occupying trans-coordinated sites in the latter complex. The reaction of [Zn(Tp(Tn))X] with an excess amount of [Tl(Tp(Tn))] in MeOH yielded [Zn(Tp(Tn))(2)] and TlX, whereas the reaction of [Zn(Tp(Tn))X] with Na(Tp) gave [Zn(Tp(Tn))(2)] and [Zn(Tp)(2)] in a 1:1 molar ratio but not [Zn(Tp(Tn))(Tp)]. By contrast, the reaction of [Tl(Tp(Tn))] with copper(II) sulfate monohydrate in chloroform gave a green powder, which was identified as the [(Hpz(3Tn))(4)CuSO4]((infinity|infinity)) coordination polymer containing OSO2O bridging sulfate groups and four coordinated pyrazole ligands on each metal center, the latter of which arises from the decomposition of the Tp(Tn) ligand through B-N bond breaking. Similarly, the interaction between [Tl(Tp(Tn))] and platinum(II) diiodide in chloroform/DMSO proceeded through Tp(Tn) decomposition to afford a monomeric trans-[(Hpz(3Tn))(2)PtI2]center dot 2(CH3)(2)SO complex, wherein two neutral pyrazole ligands are coordinated to the Pt-II center.