The fluxional behaviour of some nitrosyl bis(cyclopentadienyl) molybdenum sulphur complexes

Abstract

The ¹H n.m.r. spectra of [Mo(C₅H₅)₂(NO)(S₂CNMe₂)], (I), and of [Ph₄P][Mo(C₅H₅)₂(NO){S₂C₂-(CN)₂}], (II), have been studied over the temperature range –80 to +130°: the limiting low-temperature spectra are consistent with the structure [Mo(h⁵-C₅H₅)(h¹-C₅H₅)(NO)–(S–S)](S–S = sulphur ligand); at intermediate temperatures, the monohapto-ring is fluxional, and at high temperatures the rings in (I) undergo site exchange, and the methyl groups become equivalent.