Covalent carbon–lithium bridged bonding in a typical alkynyl-lithium compound
Abstract
Low temperature carbon-13 n.m.r. spectroscopy of 1-lithio-3,3-dimethylbut-1-yne in tetrahydrofuran solution shows this compound to exist as a nonfluxional cubic tetramer with J[13C(1), 6Li] 6 Hz; above 190 °C this scalar coupling is averaged by fast inter-aggregate exchange of alkynyl groups and/or lithium atoms at a rate which is fast relative to the n.m.r. time scale.