Formation and structural characterization of novel polynuclear palladium selenolato complexes [Pd3Se(SePh)3(PPh3)3]Cl and [Pd6Cl2Se4(SePh)2(PPh3)6]

In addition to well-known dinuclear phenylselenolato palladium complexes, the reaction of [PdCl2(PPh3)2] and NaSePh affords small amounts of novel trinuclear and hexanuclear complexes [Pd3Se(SePh)3(PPh3)3]Cl (1) and [Pd6Cl2Se4(SePh)2(PPh3)6] (2). Complex 1 is triclinic, P1̄, a=13.6310(2), b=16.2596(2), c=16.9899(3) Å, α=83.1738(5), β=78.9882(5), γ=78.7635(5)°. Complex 2 is monoclinic, C2/c, a=25.7165(9), b=17.6426(8), c=27.9151(14) Å, β=110.513(2)°. There are no structural forerunners for 1, but the hexanuclear complex 2 is isostructural with [Pd6Cl2Te4(TeR)2(PPh3)6] (R=Ph, C4H3S) that have been observed as one of the products in the oxidative addition of R2Te2 to [Pd(PPh3)4]. Mononuclear palladium complexes may play a significant role as building blocks in the formation of the polynuclear complexes.