Synthesis, structure and properties of molybdenum(0) bialkyne complexes

The reaction of Mo(NN)(CO)₄ (NN = bipyridine, phenathroline) with CH₃OOCCCCOOCH₃ (DMAC) gives Mo(NN)(CO)₄(DMAC)₂. An X-ray diffraction study of the product (NN = bipyridine) indicates that the two CO groups are cis to each other, while the two DMAC ligands are in trans arrangement, and are mutually perpendicular with each DMAC eclipsing and N---Mo---CO vector. In solution, the DMAC ligands appear to rotate about the Mo---DMAC bond as shown by the fluxional behavior in the NMR spectra of the products.