Deposition of metal-containing films

Provided are methods for depositing a metal-containing film by in situ generation of an iodine-bond containing metal species with an iodine-containing reagent and a metal-containing precursor followed by reduction at a process temperature below 400 DEG C. In particular, the film can be a molybdenum-containing film. The methods may also include simultaneous introduction of the reagent and the precursor or an optional pretreatment with a passivation gas. Also provided are methods for depositing molybdenum-containing films on semiconductor using low valent molybdenum-containing precursors. The low valent molybdenum precursors of one or two molybdenum atoms may have at least one ligand which is an isocyanohaloalkyl, an allyl, an aryl, a tertiary organophosphino or an alkoxide group.