Synthesis and Reactivity of Functionalized Binary and Ternary Thiometallate Complexes [(RT)${}_4$S${}_6$], [(RSn)${}_3$S${}_4$]${}^{2-}$, [(RT)${}_2$(CuPPh${}_3$)${}_6$S${}_6$], and [(RSn)${}_6$(OMe)${}_6$Cu${}_2$S${}_6$]${}^{4-}$ (R=C${}_2$H${}_4$COOH, CMe${}_2$CH${}_2$COMe; T=Ge, Sn)