“…Such a circumstance is readily apparent in the corresponding IR spectrum, now displaying two CÀO stretching bands of strong and weak relative intensities (in order of decreasing frequency), as expected for a Mo 2 (CO) 2 oscillator with carbonyl ligands almost parallel to each other, and crystallographically verified for the related C,C,O-bonded alkenyl complex cis-[Mo 2 Cp 2 {l-g 1 ,j:g 2 -C(CO 2-Me)CH(CO 2 Me)}(l-PCy 2 )(CO) 2 ] [15]. In this sort of structure, the Cp ligands are placed close to the intermetallic axis, and the carbonyl ligands are almost perpendicular to that axis.…”