BINUCLEAR AND TRINUCLEAR CATIONIC COMPLEXES INVOLVING BONDS BETWEEN MERCURY AND 5-COORDINATE PLATINUM(II) - MOLECULAR-STRUCTURE OF ROLINE)-(Z-MEO(2)CCH=CHCO(2)ME)(H2O))HG-2](BF4)(2)

Three cationic five-coordinate platinum(II) complexes bearing alkylmer cury fragments as ''ligands'' have been isolated. The complexes of gen eral formula [Pt(HgR)H2O)dmphen)(ZR' O2CCH=CHCO(2)R')] (BF4) (dmphen=2 ,9-dimethyl-1,10-phenanthroline; R, R(t)=Me; R=Me, R(t) =(t)Bu; R=(t)B u, R(t)=Me) are stabilized by the factors operating in related neutral species. Two of the new complexes slowly demercuriatez in solution, a ffording the mononuclear complexes [Pt(Me)H2O)(dmphen(ZR' O2CCH=CHCO(2 )R(t))](BF4) (R(t)=Me or (t)Bu). When R=(t)Bu, a slow redistribution r eaction is observed, yielding the trinuclear cluster (dmphen)(Z-MeO(2) CCH=CHCO(2)Me)H2O)}Hg-2](BF4)(2). The structure of this complex has be en determined by X-ray analysis.