An electron-rich molybdenum-molybdenum quintuple bond spanned by one lithium atom.

Take five: A unique quintuply bonded dimolybdenum complex [Mo(2)(µ-Li){µ-HC(N-2,6-Et(2)C(6)H(3))(2)}(3)] (see picture) was synthesized and characterized. The Mo-Mo interaction includes an unexpected bridging Li(+) ion. Calculations indicate the bridging Li(+) ion does not perturb the Mo-Mo bond length (2.0612(4) Å), but results in a relatively small effective Mo-Mo bond order of 3.67.