Synthesis and Redox Behavior of Chalconido Clusters of Nickel, Palladium, and Platinum

合成了9个[M_3E_2(diphos)_3]^<2+> （M=Ni, Pd, Pt， E=S, Se, Te, diphos=1,2-bis（diphenylphosphino）乙烷（dppe））团簇和6个[M_3Se_2(diphos)_3]^<2+> （M=Ni, Pd, Pt, diphos=1,3-bis（diphenylphosphino）丙烷（dppp）或1,4-bis（diphenylphosphino）丁烷（dppb））团簇，并测定了[Pt_3E_2(dppe)_3][BPh_4]_2 （E=Se, Te）的x射线结构。该结构由三个共享两个mu_3-E配体的方形平面PtE_2P_2配位面组成。[M_3E_2(dppe)_3]^<2+> （M=Ni， E=S, Se, Te）的循环伏安图（CV） （20 C或-18 C）给出了两个可逆的单电子偶。[M_3E_2(dppe)_3]^<2+>单电子过程的CV （20 C或-18 C）除（M=Pt， E=S）外，[M_3E_2(dppe)_3]^<2+> （M=Pd, Pt， E=S, Se, Te）的CV值（20 C OR -18 C）为双电子转移的可逆偶对。在这些团簇中，易于还原的顺序为Te>Se>S [M_3E_2(dppe)_3]^<2+> (M=Ni, Pd, Pt)。含有5元螯合环的[M_3Se_2(dppe)_3]^<2+> (M=Ni, Pd, Pt)的CV为可逆偶，含有6元螯合环的[M_3Se_2(dppp)_3]^<2+> (M=Ni)的CV为可逆偶，而[M_3Se_2(dppp)_3]^<2+> (M=Pd, Pt)的CV为不可逆偶。[M_3Se_2(dppp)_3]^<2+> (M=Ni, Pd, Pt)（7元螯合环）的CV都是不可逆的。具有7元螯合环的[M_3Se_2(dppb)_3]^<2+> (M=Ni, Pd, Pt)的还原电位最高，因此最容易还原。

Nine [M_3E_2(diphos)_3]^<2+> (M=Ni, Pd, Pt, E=S, Se, Te, diphos=1,2-bis(diphenylphosphino) ethane (dppe)) and six [M_3Se_2(diphos)_3]^<2+> (M=Ni, Pd, Pt, diphos=1,3-bis(diphenylphosphino)propane (dppp) or 1,4-bis(diphenylphosphino)butane (dppb)) clusters have been synthesized and X-ray structures of [Pt_3E_2(dppe)_3][BPh_4]_2 (E=Se, Te) were determined. The structures comprise three square-planar PtE_2P_2 coordination planes sharing two mu_3-E ligands. Cyclic voltammograms (CV) (20ﾟC or -18ﾟC) of [M_3E_2(dppe)_3]^<2+> (M=Ni, E=S, Se, Te) give two reversible couples which are one-electron process. CV's (20ﾟC or -18ﾟC) of [M_3E_2(dppe)_3]^<2+>one-electron process. CV's (20ﾟC OR -18ﾟC) of [M_3E_2(dppe)_3]^<2+> (M=Pd, Pt, E=S, Se, Te) except for (M=Pt, E=S) show one reversible couple which involves two-electron transfer. The ease of reduction follows the order Te>Se>S in these clusters [M_3E_2(dppe)_3]^<2+> (M=Ni, Pd, Pt).The CV's of [M_3Se_2(dppe)_3]^<2+> (M=Ni, Pd, Pt) containing 5-membered chelate rings give reversible couples and that of [M_3Se_2(dppp)_3]^<2+> (M=Ni) (6-membered chelate ring) gives reversible couples, but those of [M_3Se_2(dppp)_3]^<2+> (M=Pd, Pt) are irreversible. The CV's of [M_3Se_2(dppp)_3]^<2+> (M=Ni, Pd, Pt) (7-membered chelate ring) are all irreversible. Reduction potentials of [M_3Se_2(dppb)_3]^<2+> (M=Ni, Pd, Pt) having 7-membered chelate rings are the highest and accordingly these are the easiest to reduce.