A complex in which this element binds to both phosphorus atoms of bis·di·phenyl·phosphino·ferrocene is used to synthesize pinacol-based boronate esters. After this element coordinates to a double bond, a leaving group is expelled to make a tri·haptic pi-allyl complex in a popular method for asymmetric alkylation. Chlorides of copper (-5[1])and this element are used in the industrial oxidation of ethylene to acet·aldehyde. A reaction that uses (-5[1])this element to synthesize substituted (*) trans-alkenes from a halide and an (-5[1])alkene uses a migratory insertion and a beta-hydride elimination rather than the usual cycle of oxidative addition, (10[1])transmetallation, and reductive elimination. For 10 points, name this element used in cross-couplings developed by Negishi, Heck, and Suzuki, a white metal used with platinum in catalytic (10[1])converters. (10[1])■END■ (10[1])