cis ‐ and trans ‐Dimolybdenum(II) Complexes with Asymmetrically 2,7‐Disubstituted Naphthyridines as Bridging Ligands

Treatment of [Mo(CO) 6 ] with Hmamnp (2‐acetamido‐7‐methyl‐1,8‐naphthyridine) in diglyme at 100°C affords the mononuclear complex [Mo(CO) 4 (Hmamnp)] 1 , an intermediate product on the reaction pathway to tetrasubstituted species of the type [Mo 2 L 4 ]. A disubstituted intermediate product cis ‐[Mo 2 (mphamnp) 2 (OAc) 2 ] 2 (Hmphamnp) (2‐acetamido‐5‐methyl‐7‐phenyl‐1,8‐naphthyridine) may be isolated from the reaction of [Mo 2 (OAc) 4 ] with mphamnp – in THF. The relative stabilisation of such products is a result of the steric demands of the coplanar 2‐acetamido substituents. 2 and the tetrasubstituted complexes trans ‐[Mo 2 (mbznnp) 4 ] 3 (Hmbznnp = 2‐benzylamino‐7‐methyl‐1,8‐naphthyridine), cis ‐[Mo 2 (mphonp) 4 ] 4 , and trans ‐[Mo 2 (mphonp) 4 ] 5 (Hmphonp = 5‐methyl‐7‐phenyl‐1,8‐naphthyridin‐2‐one) all exhibit the electronically prefered μ‐N 1 ,X 2 bridging mode. Steric effects are responsible for the isolation of the unusual cis isomer 4 .