[Cu${}_{24}$S${}_{12}$(PMeiPr${}_2$)${}_{12}$], [Cu${}_{28}$S${}_{14}$(PtBu${}_2$Me)${}_{12}$],[Cu${}_{50}$S${}_{25}$(PtBu${}_2$Me)${}_{16}$], [Cu${}_{70}$Se${}_{35}$(PtBu${}_2$Me)${}_{21}$], [Cu${}_{31}$Se${}_{15}$(SeSiMe${}_3$)(PtBu${}_2$Me)${}_{12}$] and [Cu${}_{48}$Se${}_{24}$(PMe${}_2$Ph)${}_{20}$]: New Sulfur- and Selenium-Bridged Copper Clusters