Classified as a transition metal alkyl complex, hexamethyltungsten is an air-sensitive, red, crystalline solid at room temperature; however, it is extremely volatile and sublimes at −30 °C.

[5] The octahedral assignment remained for nearly 20 years until 1989 when Girolami and Morse showed that [Zr(CH3)6]2− was trigonal prismatic as indicated by X-ray crystallography.

[6] They interpreted the non-octahedral structure as the result of a second-order Jahn-Teller effect, and predicted that other d0 ML6 species such as [Nb(CH3)6]−, [Ta(CH3)6]−, and W(CH3)6 would also prove to be trigonal prismatic.

[7] In 1996, Seppelt et al. reported that W(CH3)6 had a strongly distorted trigonal prismatic coordination geometry based on single-crystal X-ray diffraction, which they later confirmed in 1998.

[4][8] As shown in the top figure at right, the ideal or D3h trigonal prism in which all six carbon atoms are equivalent is distorted to the C3v structure observed by Seppelt et al. by opening up one set of three methyl groups (upper triangle) to wider C-W-C angles (94-97°) with slightly shorter C-W bond lengths, while closing the other set of three methyls (lower triangle) to 75-78° with longer bond lengths.

Prior to 1989, there was no reason to suspect that ML6 compounds were anything but octahedral, yet new evidence and improved characterization methods suggested that perhaps there were exceptions to the rule, as evidenced by the case of W(CH3)6.

A patent application was submitted in 1991 suggesting the use of W(CH3)6 in the manufacture of semiconductor devices for chemical vapor deposition of tungsten thin films;[14] however, to date it has not been used for this purpose.