The modification of ArSCH2(3,5-Me2Pz) (Ar = phenyl or 2-pyridyl, Pz = pyrazol-1-yl) by organotin group and related reactions

Reaction of 1-arylthiomethyl-3,5-dimethylpyrazole [ArSCH2(3,5-Me2Pz), Ar = phenyl or 2-pyridyl, Pz = pyrazol-1-yl] with Mo(CO)6 produces complexes ArSCH2(3,5-Me2Pz)Mo(CO)4, while similar reaction with W(CO)6 yields analogous complexes ArSCH2(3,5-Me2Pz)W(CO)4 and concomitant desulfurized complex (3,5-Me2PzH)W(CO)5 in the reaction of PhSCH2(3,5-Me2Pz). Succedent treatment of complexes PhSCH2(3,5-Me2Pz)M(CO)4 with SnCl4 gives heterobimetallic complexes PhSCH2(3,5-Me2Pz)M(CO)3(Cl)(SnCl3) (M = Mo or W) in good yields. ArSCH2(3,5-Me2Pz) act as S,N chelating bidentate ligands through the sulfur and the pyrazolyl nitrogen atoms in the aforementioned complexes. The modification of ArSCH2(3,5-Me2Pz) by organotin group at the methylene group has been successfully carried out, which yields functionalized ligands Ph3SnCH(SAr)(3,5-Me2Pz). Markedly different reactions are observed, upon treatment of Ph3SnCH(SPh)(3,5-Me2Pz) and Ph3SnCH(SPy)(3,5-Me2Pz) (Py = 2-pyridyl) with W(CO)5THF. The former yields complex Ph3SnCH(SPh)(3,5-Me2Pz)W(CO)4, as well as PhSCH2(3,5-Me2Pz)W(CO)4 with a partial loss of the organotin moiety, while no reaction takes place in the latter. In addition, reaction of Ph3SnCH(SPy)(3,5-Me2Pz) with Mo(CO)6 results in the oxidative addition reaction of the Sn–Csp3 bond to the molybdenum(0) atom to yield novel heterometallacyclic complex CH(SPy)(3,5-Me2Pz)Mo(CO)3SnPh3, in which [(2-pyridyl)thiomethyl](3,5-dimethylpyrazol-1-yl)methide acts as a tridentate κ3-[N,C,N] chelating ligand through the carbon atom, the pyrazolyl and the pyridyl nitrogen atoms, as the sulfur atom does not coordinate to the molybdenum atom anymore. Interestingly, treatment of this heterometallacyclic complex with P(OR)3 (R = Ph or Et) gives rise to the isomerization of the C–S bond to the C–N bond, generating the thione–S coordinated complex CH(NC4H4C = S)(3,5-Me2Pz)Mo(CO)2(P(OR)3)SnPh3, in which the ligand binds in a novel tridentate, monoanionic κ3-[N,C,S] chelating mode to the molybdenum atom.