| Popis: |
The coordinatively unsaturated species [PhP(Me 2 pz) 2 M(CO) 3 ] (Me 2 pz = 3,5-dimethylpyrazolyl; M = Mo, I; M = W, II) react reversibly with CO, and irreversibly with H 2 , C 2 H 4 , P(OMe) 3 and PF 3 , but not with N 2 and Ph 3 P. The tricarbonyl/tetracarbonyl interconversion (I, II) + CO ⇄ [PhP(Me 2 pz) 2 - M(CO) 4 ] (III, M = Mo; IV; M = W) involves a novel structural interchange between the pseudo C 3v , phosphorus-free, six-membered [P(NN) 2 M] boat metallocyclic form of I and II, and the pseudo C 2v , phosphorus-coordinated, four-membered [ PNNM ] metallocyclic structures of III and IV. The reaction of 1 with PF 3 gives [PhP(Me 2 pz) 2 Mo(PF 3 ) 2 ] (V), in which the pyrazolylphosphine ligand again defines a four-membered [ PNNM o] chelate structure. A trans -dicarbonyl, cis-( bis -trifluorophosphine) arrangement is indicated. |
