Conjugate base of a secondary phosphine selenide [P(Se)(O(i)Pr)2]- as the bridging unit for the construction of heterometallic Fe(II)-Hg(II)/Cd(II) complexes.

Reactions of perchlorate salts of Hg(II)/Cd(II) with [CpFe(CO)(2)P(Se)(O(i)Pr)(2)] (denoted as L) produced dicationic clusters [HgL(2)](ClO(4))(2), 1; [HgL(3)](ClO(4))(2), 2; and [CdL(3)(H(2)O)](ClO(4))(2), 11. However, the reactions of L with Hg(II)/Cd(II) halides yielded neutral complexes. For instance, HgI(2) produced [Hg(3)I(6)L(2)], 3, or [HgI(2)L(2)], 4, depending on the metal-to-ligand ratio used.