Mo(PMe3)(6) cleaves the Si-H bonds of SiH4, PhSiH3, and Ph2SiH2 to afford a variety of novel silyl, hypervalent silyl, silane, and disilane complexes, as respectively illustrated by Mo(PMe3)(4)(SiH3)(2)H-2, Mo(PMe3)(4)(kappa(2)-H-2-H2SiPh2H)H, Mo(PMe3)(3)(sigma-HSiHPh2)H-4, and Mo(PMe3)(3)(kappa(2)-H-2-H2Si2Ph4)H-2. Mo(PMe3)(4)(kappa(2)-H-2-H2SiPh2H)H and Mo(PMe3)(3)(kappa(2)-H-2-H-2\Si2Ph4)H-2 are respectively the first examples of complexes that feature a hypervalent kappa(2)-H-2-H2SiPh2H silyl ligand and a chelating disilane ligand, and both compounds convert to the diphenylsilane adduct, Mo(PMe3)(3)(sigma-HSiHPh2)H-4, in the presence of Hy. Mo(PMe3)(4)(SiH3)(2)H-2 undergoes isotope exchange with SiD4, and NMR spectroscopic analysis of the SiHxD4-x isotopologues released indicates that the reaction does not occur via initial reductive elimination of SiH4, but rather by a metathesis pathway.