The initiation of ring-opening metathesis polymerisation of norbornadiene by seven-coordinate molybdenum(II) compounds. X-ray crystal structure of [Mo(μ-Cl)(SnCl3)(CO)3(η-NBD)]

The new heterobimetallic complex Mo(μ-Cl)(SnCl₃)(CO)₃(η⁴-NBD)] (1) has been prepared by reaction of (CO)₄Mo(μ-Cl)₃Mo(SnCl₃)(CO)₃] with norbornadiene (NBD) at room temperature. The structure of complex 1 was established by X-ray crystallography. The IR, ¹H- and ¹³C-NMR spectra of 1 are also described and can be correlated with the crystallographically observed geometry. In the presence of an excess of NBD compound 1 initiates the ring-opening metathesis polymerisation (ROMP). The initiation mechanism of ROMP by seven-coordinate molybdenum(II) compounds have been discussed. The microstructure of polynorbornadiene formed was determined by ¹H- and ¹³C-NMR spectroscopy.