Bis(phosphine)-Pd(II) and -Pt(II) complexes containing chiral tetrazole-thiolato rings: Synthesis, structures, and reactivity toward some electrophiles

Bis(azido)bis(phosphine)-Pd(II) and -Pt(II) complexes, [M(N3)2L2] {L = PMe3, PEt3, PMe2Ph, dppe = 1,2-bis(diphenylphosphino)ethane}, underwent 1,3-dipolar cycloaddition with organic chiral isothiocyanates (R∗–NCS: R∗ = (S)-(+)-1-phenylethyl, (R)-(−)-1-phenylethyl, (±)-1-phenylethyl, (S)-(+)-1-indanyl) to give the corresponding tetrazole-thiolato Pd(II) and Pt(II) complexes, trans-[M{S[CN4(R∗)]}2L2] or [M{S[CN4(R∗)]}2(dppe)]. Spectroscopic (IR and NMR) and X-ray structural analyses of the products showed that the absolute configuration of the starting organic isothiocyanates is retained throughout the reaction. Further treatments of the isolated tetrazole-thiolato complexes with electrophiles such as HCl or benzoyl chloride produced heterocyclic compounds containing a tetrazole thione or a tetrazolyl sulfide group. In addition, organic tetrazole thiones, [S = {CN4H(R∗)}] containing a chiral moiety, were prepared from NaN3 and R∗–NCS in the presence of water.