Deposition of osmium thin films using pyrazolate complexes as CVD source reagents

The reaction of Os-3(CO)(12) with 1.2 eq. of pyrazole (3,5-(CF3)(2)-pz) H at 190 degreesC affords triosmium complex Os-3(CO)(10)(3,5-(CF3)(2)-pz)(mu-H) (1) as the isolable product. Upon further treatment with excess pyrazole (3,5-(CF3)(2)-pz)H under more forcing conditions, complex 1 converts to a diosmium pyrazolate complex [Os(CO)(3)(3,5-(CF3)(2)-pz)](2) (2) in high yield. These osmium complexes are characterized by spectroscopic methods and single crystal X-ray diffraction study, showing the expected triangular and linear Os-Os backbone and with one and two bridging pyrazolate ligands for complexes 1 and 2, respectively. The thermal properties are studied by TG analysis and the deposition experiments are carried out using a cold-wall CVD apparatus. The as-deposited thin films are characterized using XPS, XRD and SEM and electrical resistivity measurement. It seems that the Os metal thin films are best deposited at an optimal temperature of 450-500 degreesC and using complex 2 as the source reagent.