RHODIUM HYDRIDES-TRIFLUOROPHOSPHINES

Rhodium hydride tetrakis(trifluorophosphine) [RhH(PF3)4]

Table. Comparison of vapor pressure [RhH(PF3)2]2 vs other Rh (MO)CVD precursors

   Rhodium hydrido tetrakis(trifluorophosphine) complex [RhH(PF3)4] is liquid under ordinary conditions, relatively stable (under ~1-2 atm overpressure of H2 and PF3). Is fairy toxic so must be maintained in the seal container.

[RhH(PF3)4] is synthesized using anhydrous RhCl3 or (K,Na)2RhCl6 as starting material under high pressure of  PF3 and H2 in the presence of Cu:

   RhCl3 + PF3 + H2      (Cu) ->   RhH(PF3)4

K2RhCl6 + PF3 + H2   (Cu)  ->  RhH(PF3)4 + 2 KCl

[RhH(PF3)4] was found to have high vapour pressure (~2000Pa (15 Torr) at 20°C and ~101000 Pa (~760) Torr at 100°C) – three to five orders of magnitude higher than other inorganic and organometallic rhodium complexes used as rhodium (MO)CVD precursors (See Table).[i]

  [RhH(PF3)4] was applied as precursor for the CVD growth of thin rhodium coatings on molybdenum substrates.  However, [RhH(PF3)4] complex is stable only under 1-2 atm overpressure of PH3 and H2, what makes more difficult its application for the CVD growth of rhodium coatings.

[i]  B. Bryskin, A. Kostylev, J. Pokrovsky, J. Organomet. Chem., 2012, Vol.64, Iss.6, pp 682-687 , « Chemical Vapor Deposition of Iridium and Rhodium Coatings from Hydridotetrakis(trifluorophosphine) Complexes », http://link.springer.com/article/10.1007/s11837-012-0336-y#page-1 

[RhH(PF3)4] for Rh coatings by MOCVD

    Rhodium hydridotetrakis(trifluorophosphine) complex [RhH(PF3)4] was used for the deposition of rhodium coatings by CVD. [RhH(PF3)4] is inorganic volatile C- and O-free compound, which undergoes a decomposition reaction in the CVD reactor at growth temperatures as low as 450°C, forming highly pure rhodium metallic films on Mo substrates. The growth pressure (basepressure) was 0.1 Pa, growth time 20-30 minutes. The properties of obtained Rh coatings on the deposition process process was investigated.[i]

[i]  B. Bryskin, A. Kostylev, J. Pokrovsky, J. Organomet. Chem., 2012, Vol.64, Iss.6, pp 682-687 , « Chemical Vapor Deposition of Iridium and Rhodium Coatings from Hydridotetrakis(trifluorophosphine) Complexes »,http://link.springer.com/article/10.1007/s11837-012-0336-y

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