Diamond electrodes doped with this element may be used in organic electro-synthesis due to their large electrochemical window. Hydroxylation reactions often use a disiamyl-substituted compound of this element. A bulky compound of this element and a phosphine form the classic frustrated Lewis pair. A base attacks this element before transmetallating an aryl group onto palladium in the (*) Suzuki coupling. This element adds across a double bond, (-5[1])followed by oxidation with a peroxide, in an anti-Markovnikov (10[2])addition of water across a double bond. (-5[1])This element’s trihydride dimerizes into a compound with two three-center, two-electron bonds, (10[1])since this element typically only forms three covalent (10[1])bonds in violation of the octet rule. For 10 points, name this trivalent (10[1])element whose atomic number is 5. (10[1])■END■ (10[2]0[1])