Ruthenium-Promoted <i>Z</i>-Selective Head-to-Head Dimerization of Terminal Alkynes in Organic and Aqueous Media

[RuH(CH3CN)(NP3)]OTf effectively catalyzes the dimerization of both aliphatic and aromatic alkynes to give (Z)-enynes in high regio- and stereoselectivity. The catalytic system can tolerate a number of functional groups, which allows for its use in organic and aqueous medium.