The heteronuclear cluster chemistry of the group 1B metals. Part 7. Synthesis and gold-197 Mössbauer spectra of the mixed-metal cluster compounds [Au2Ru4(µ3-H)(µ-H){µ-Ph2E(CH2)nE′Ph2}(CO)12](n= 1 or 2, E = E′= As or E = As, E′= P; n= 2, E = E′= P). X-Ray crystal structure of [Au2Ru4(µ3-H)(µ-H)(µ-Ph2AsCH2PPh2)(CO)12]