Liquid cobalt(I) hydride complexes as precursors for chemical vapor deposition

Volatile cobalt (I) hydride complexes HCo[(ROP)-O-1(OR2)(2)](4) were synthesized, where R-1 = Me, Et, i-Pr, n-Pr, n-Bu, i-Bu, Ph, and benzyl, and R-2 = Me and Et. The cobalt complexes were obtained as liquids as RI was lengthened from ethyl to longer chains. The thermal stability of the complex was lowered with bulky R-1, thus, HCo[n-PrOP(OMe)(2)](4) and HCo[n-BuOP-(OMe)(2)](4) were distillable but HCo[i-BuOP(OMe)(2)](4) was not. Pure cobalt films of smooth and dense surface morphology were deposited on Si at temperatures as low as 270 degreesC using the cobalt hydrides as precursors under reduced pressure without employing H-2.