The tungsten hydride complex (eta(5)-C5H5)W(CO)(3)H (1-W) functions as a hydrogen atom donor in the [(eta(5)- C5Me5)Ru(NCMe)(3)]PF6-mediated Bergman cycloaromatization reaction of (Z)-dodeca-4,8-diyn-6-ene. The strong M-H bond in 1-W does not react with the enediyne substrate but does react with the diradical arising from cyclization, thereby demonstrating the advantages of strong metal-hydrogen bonds in the hydrogen atom transfer reactions of metal hydrides with substrates involving alkenes and alkynes.