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\begin{wrapfigure}[10]{r}{5.5cm} \vspace{-1.2cm} \hspace{-0.1cm} \epsfig{file=test.eps} \end{wrapfigure} Microwave spectra for five unique $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}$C isotopomers of cyclopentadienyltungstentricarbonyl hydride were measured using a Flygare-Balle type microwave spectrometer system. The new rotational constants were combined with the previously obtained rotational constants for normal and deuterium analogues for various tungsten isotopes. A total of fifty-seven rotational constants were acquired and used in the least squares fit to obtain the gas phase structure of this d$4$ - metal mono hydride complex. The results from the structural fit yielded the W-H bond length: r(W-H)= 1.788(20) \AA, which agrees very well with the previously reported Kraitchman value of r(W-H)= 1.79(4) \AA. The present study also yielded the distance from tungsten to the centroid distance of the C$5$H$5$ ring: r(W-Cp)= 2.02(1) \AA, the ring radius of Cp: r(Cp)= 1.2016(4) \AA, the average bond length from tungsten to the carbonyl carbon, r(W-CO)= 1.981(14) \AA, and the average cyclopentadienyl C-C bond length of 1.421(4) \AA. \ Results obtained from the structural fit are in much closer agreement with the Kraitchman values than with the DFT results.