SURFACE-MEDIATED ORGANOMETALLIC SYNTHESIS - HIGH-YIELD SYNTHESES OF THE ANION [H3OS4(CO)12]- FROM [OS(CO)3CL2]2 OR OSCL3 ON THE SILICA SURFACE IN THE PRESENCE OF K2CO3

K[H3Os4(CO)12] has been prepared in high yields by reductive carbonyla tion under rather mild conditions (1 atm and 150-degrees-C) of alpha-[ Os(CO)3Cl2]2 or OsCl3 supported on SiO2 in the presence of K2CO3 (mola r ratio K2CO3.Os = 10-15:1); in the latter case a two-step process is required. These surface-mediated syntheses of the anionic cluster are more convenient than the traditional ones in solution (higher yields a nd selectivity) and do not require clusters such as [H4Os4(CO)12] or [ Os3(CO)12] as starting materials.