Functionalized bis(pyrazol-1-yl)methanes by organotin halide on the methine carbon atom and their related reactions

The modification of bis(pyrazol-1-yl)methanes by organotin halide on the methine carbon atom has been successfully carried out, and their related reactions have also been studied. Bis(3,5-dimethylpyrazol-1-yl)(iododiphenylstannyl)methane Ph₂ISnCH(3,5-Me₂Pz)₂] can be obtained by the selective cleavage of the Sn-C_sp² bond in bis(3,5-dimethylpyrazol-1-yl)triphenylstannylmethane with I₂ in a 1:1 molar ratio, while {di(tert-butyl)chlorostannyl}bis(3,5-dimethylpyrazol-1-yl)methane (t-Bu)₂ClSnCH(3,5-Me₂Pz)₂] and {di(tert-butyl)chlorostannyl}bis(3,4,5-trimethylpyrazol-1-yl)methane (t-Bu)₂ClSnCH(3,4,5-Me₃Pz)₂] are easily prepared by the reaction of the bis(3,5-dimethylpyrazol-1-yl)methide or bis(3,4,5-trimethylpyrazol-1-yl)methide anion with di(tert-butyl)tin dichloride. The molecular structure of (t-Bu)₂ClSnCH(3,5-Me₂Pz)₂] determined by X-ray structure analysis indicates that bis(3,5-dimethylpyrazol-1-yl)methide acts as a bidentate monoanionic κ²-C,N] chelating ligand. Reaction of these bis(pyrazol-1-yl)methanes functionalized by organotin halide with W(CO)₅THF results in the oxidative addition of the relative electrophilic Sn-X (X = Cl or I) bond instead of the Sn-C_sp³ bond to the tungsten(0) atom, yielding new metal-metal bonded complexes R₂SnCHPz₂W(CO)₃X (R = Ph or t-Bu, Pz represents substituted pyrazol-1-yl). Furthermore, treatment of the oxidative addition product (t-Bu)₂SnCH(3,5-Me₂Pz)₂W(CO)₃Cl with n-BuLi results in known complex CH₂(3,5-Me₂Pz)₂W(CO)₄ with the loss of the organotin fragment. In addition, reaction of Ph₂ISnCH(3,5-Me₂Pz)₂ with 2-PySNa (Py = pyridyl) leads to the replacement of iodide by 2-PyS⁻ anion to give Ph₂(2-PyS)SnCH(3,5-Me₂Pz)₂, which subsequently reacts with W(CO)₅THF to result in the decomposition of this ligand, also yielding the known bis(3,5-dimethylpyrazol-1-yl)methane derivative of CH₂(3,5-Me₂Pz)₂W(CO)₄.