In pursuit of the molybdenum(III) tris(thiolate) fragment: Unusual structure of a dimolybdenum mu-nitrido complex

The new molybdenum nitrido-thiolate complex N drop Mo(SAd)(3) (Ad = 1-adama ntyl) was prepared by a ligand exchange route involving reaction of Ti(SAd) ((OPr)-Pr-i)(3) with Chisholm's nitrido-butoxide complex N drop Mo((OBu)-Bu -t)(3). In an effort to abstract the nitrido nitrogen from N drop Mo(SAd)(3 ), the compound was treated with Mo(N[Bu-t]Ph)(3), a three-coordinate molyb denum(III) complex. This resulted in formation of the unusual and thermally unstable (mu-nitrido)dimolybdenum complex (AdS)(3)Mo(mu-N)Mo(N[Bu-t]Ph)(3) , which was isolated and characterized. An X-ray study revealed (AdS)(3)Mo( mu-N)Mo(N[tBu]Ph)3 to possess an unsymmetrical Mo-(mu-N)-Mo linkage, the Mo -thiolate fragment exhibiting a substantially longer bond to the bridging n itrogen atom. The structure of (AdS)(3)Mo-(mu-N)Mo(N[Bu-t]Ph)(3) is notewor thy, displaying trigonal monopyramidal coordination at the (mu-N)-Mo-thiola te Mo center. Since N drop Mo(N[Bu-t]Ph)(3) is a good leaving group, (AdS)( 3)Mo(mu-N)Mo(N[Bu-t]Ph)(3) should be a source of the reactive Mo(SAd)(3) fr agment. In all the studied reactions of the (mu-nitrido)dimolybdenum comple x one of the observed products was N drop Mo([Bu-t]Ph)(3). Two products con taining the Mo(SAd)(3) fragment were observed: (AdS)(3)Mo drop Mo(SAd)(3) a nd [(ON)Mo(mu-SAd)(SAd)(2)](2). Upon treatment with pyridine, the tris(thio -1-adamantyl)(nitrosyl)molybdenum dimer forms the pyridine adduct (AdS)(3)M o(NO)(py), which is a monomer.