Two neutral pyrazolato diimine rhenium(I) carbonyl complexes with formula [Re(CO)(3)(N-N)(btpz)] where N-N = 2,2'-bipyridine (1) and 1,10-phenanathroline (2), and btpz = 3,5-bis(trifluoromethyl) pyrazolate, were synthesized and characterized by elemental analysis, routine spectroscopic methods, and single-crystal X-ray diffraction study. Ground and excited state properties of these complexes were investigated by steady-state and time-resolved spectroscopies. Complexes 1 and 2 show photoluminescent emission in both solution and solid-state at room temperature, arising from metal to ligand charge-transfer (MLCT) transition with strong overlapping of intraligand pi --> pi transitions. The long-lived excited state lifetimes of complexes 1 and 2, which are on the order of microseconds, indicate the presence of phosphorescent emission. As these complexes hold the potential to serve as phosphors for organic light-emitting diodes (OLEDs), their electroluminescent performances were evaluated by employing them as dopants of various electron transport layer (ETL) or hole transport layer (HTL) hosts. For complex 1, a green electrophosphorescence emission centered at lambda(max) = 530 nm was observed at low turn-on voltage ( approximately 6 V) with luminous power efficiency of 0.72 lm/W, external quantum efficiency of 0.82%, and luminance of 2300 cd/m(2) at a current density of 100 mA/cm(2).

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The reaction of Os 3 (CO) 12 with 1.2 eq. of pyrazole (3,5-(CF 3 ) 2 -pz)H at 190 uC affords triosmium complex Os 3 (CO) 10 (3,5-(CF 3 ) 2 -pz)(m-H) (1) as the isolable product. Upon further treatment with excess pyrazole (3,5-(CF 3 ) 2 -pz)H under more forcing conditions, complex 1 converts to a diosmium pyrazolate complex [Os(CO) 3 (3,5-(CF 3 ) 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 uC and using complex 2 as the source reagent.

The reaction of Ru 3 (CO) 12 with three equivalent of 3,5-bis(trifluoromethyl) pyrazole [(3, ) 2 -pz)H] at 180 C produces the double pyrazolate-bridged ruthenium complex [Ru(CO) 3 (3,5-(CF 3 ) 2 -pz)] 2 , (1), in high yield. This ruthenium complex has been characterized by spectroscopic methods, revealing a molecular structure similar to that of the diosmium analogue [Os(CO) 3 (3,5-(CF 3 ) 2 -pz)] 2 . Thermogravimetric analysis (TGA) of complex 1 showed an enhanced volatility compared to the parent carbonyl compound Ru 3 (CO) 12 and the closely related, unsaturated 3,5-di-tert-butyl pyrazole complex (2) [Ru 2 (CO) 5 (3,5-t-Bu 2 -pz) 2 ]. Using complex 1 as the CVD source reagent, ruthenium metal with a preferred (002) orientation can be deposited at 400 C using H 2 as the carrier gas. If, however, O 2 is used as the carrier gas, RuO 2 thin films with a (101) orientation are obtained. The as-deposited metal thin films were characterized by various surface techniques, as well as by electrical resistivity measurements.

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