Atomic layer deposition (ALD) type processes for producing metal containing thin films comprise feeding into a reaction space vapor phase pulses of metal containing cyclopentadienyl precursors as a metal source material, wherein the metal is zirconium. In preferred embodiments the metal containing cyclopentadienyl reactant comprises a metal atom that is not directly bonded to an oxygen or halide atom. In other embodiments the metal atom is bonded to a cyclopentadienyl compound and separately bonded to at least one ligand via a nitrogen atom. In still other embodiments the metal containing cyclopentadienyl compound comprises a nitrogen-bridged ligand.