Selective complexation of palladium and osmium with substituted pyrimidinethiols.

1-Amino-, 1-anilino- and 1-(2',4'-dinitroanilino)-4,4,6-trimethyl-1H,4H-2-pyrimidinethiols react with Pd(II) and Os(VIII), forming coloured complexes extractable into non-polar organic solvents. The optimum conditions for the complexation have been established. Beer's law is obeyed and by an extractive spectrophotometric procedure, microgram quantities of the two metals are determined in the presence of large amounts of diverse ions, including all the other metals of the iron and platinum groups.