Synthesis and Fluxionality of a Tungsten-Triosmium Cluster Compound $CpWOs_3(CO)_{11}({\mu}_3-CTol)$

The reaction of $Os_3(CO)_{10}(NCMe)_2$ with a tungsten alkylidyne $Cp(CO)_2W{\equiv}CTol(Cp={\eta}^5-C_5H_5,\;Tol=p-C_6H_4Me)$ produces the compound, $CpWOs_3(CO)_{11}({\mu}_3-CTol)$(1). The structure of compound 1 can be viewed as one in which the metalla-alkyne, $Cp(CO)_2W{\equiv}CTol$, is ${\mu}_3-{\eta}^2-{\bot}$ (perpendicular) bound to an $Os_3(CO)_9$ fragment. Variable-temperature $^{13}C$ NMR spectra of 1 show no evidence for the analogous rotation of the metalla-alkyne molecule as shown alkyne rotation in $Os_3(CO)_9(C_2Tol_2)$ compound. This lack of the metalla-alkyne fluxionality supports the apparent saturated nature of compound 1.