Unexpected C=C bond formation via doubly dehydrogenative coupling of two saturated sp3 C-H bonds activated with a polymolybdate

In this communication, we demonstrate that polyoxomolybdates can activate sp(3) C-H bonds in aliphatic amines. Unexpectedly, a carbon-carbon double bond is formed from two aliphatic primary amines via the activation and dehydrogenative coupling of two sp(3) C-H bonds near the nitrogen atom bearing a hexamolybdate. Detailed experiments including H-1 NMR, C-13 NMR, IR, UV-vis, ESI-MS, and especially X-ray single-crystal diffraction substantially confirm the existence of carbon-carbon double bonds in a class of so-resulting organic-inorganic hybrid molecules, which are made up of two terminally substituted imidohexamolybdate cages bridged by a trans-tetrasubstituted, conjugated, rigid ethylene system. This discovery perhaps opens an interesting road to elaborate the CC double bond directly via the functionalization of saturated C-H bonds.