1,1,2,2-Tetramethyl-1,2-bis(phenylthiomethyl)disilane, a Flexible Ligand for the Construction of Macrocyclic, Mesocyclic, and Bridged Dithioether Complexes. Synthesis of the Bis-silylated Olefins Z-(PhSCH2)Me2SiC(H)C(Ar)SiMe2(CH2SPh) by Catalytic Activation of the Si−Si Bond