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Synthesis, structural characterisation and reactivity of molybdenum half-sandwich complexes containing keto- and amido-phosphines


Reference:

Andrews, C. D., Burrows, A. D., Jeffery, J. C., Lynam, J. M. and Mahon, M. F., 2003. Synthesis, structural characterisation and reactivity of molybdenum half-sandwich complexes containing keto- and amido-phosphines. Journal of Organometallic Chemistry, 665 (1-2), pp. 15-22.

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Abstract

The keto-functionalised N-pyrrolyl phosphine ligand PPh2NC4H3{C(O)CH3-2}. L-1 reacts with [MoCl(CO)(3)(eta(5)-C5R5)] (R = H, Me) to give [MOCl(CO)(2)(L-1-kappa(1)P)(eta(5)-C5R5)] (R = H 1a; Me 1b). The phosphine ligands PPh2CH2C(O)Ph (L-2) and Pph(2)CH(2)C(O)NPh2 (L-3) react with [MoCl(CO)(3)(eta(5)-C5R5)] in an analogous manner to give the compounds [MoCl(CO)(2)(L-kappa(1)P)(eta(5)-C5R5)] (L = L-2, R=H 2a, Me 2b; L=L-3, R = H 3a, Me 3b). Compounds 1-3 react with AgBF4 to give [MO(CO)2(L-kappa(2) P,O)(eta(5) -C5R5)]BF4 (L = L-1, R = H 4a, Me 4b; L = L-2, R = H 5a, Me 5b; L = L-3, R = H 6a, Me 6b) following displacement of chloride. The X-ray crystal structure of 4a revealed a lengthening of both Mo-P and C=O bonds on co-ordination of the keto group. The lability of the co-ordinated keto or amido group has been assessed by addition of a range of phosphines to compounds 4-6. Compound 4a reacts with PMe3, PMe2Ph and PMePh2 to give [Mo(CO)(2)(L-1-kappa(1)P)(L)(eta(5)-C5H5)]BF4 (L = PMe3 7a; PMe2Ph 7b; PMePh2 7c) but does not react with PPh3, 5a reacts with PMe2Ph, PMePh2 and PPh3 to give [MO(CO)(2)(L-2-kappa(1)P)(L)(eta(5)- C5H5)]BF4 (L = PMe2Ph 8b; PMePh2 8c; PPh3 8d), and 6a reacts with PMe3, PMe2Ph, PMePh2 and PPh3 to give [Mo(CO)(2)(L-3- kappa(1)P)(L)(eta(5) -C5H5)]BF4 (L = PMe3 10a; PMe2Ph 10b; PMePh2 10c; PPh3 10d). No reaction was observed for the pentamethylcyclopentadienyl compounds 4b-6b with PMe3, PMe2Ph, PMePh2 or PPh3. These results are consistent with the displacement of the co-ordinated oxygen atom being influenced by the steric properties of the P,O-ligand, with PPh3 displacing the keto group from L 2 but not from the bulkier Lt. In the reaction of [Mo(CO)(2)(L-2-kappa(2)P,O)(eta(5) -C5H5)]BF4 (5a) with PMe3 the phosphine does not displace the keto group, instead it acts as a base, with the only observed molybdenum-containing product being the enolate compound [Mo(CO)(2){PPh2CH=C(O)Ph-kappa(2)P,O}(eta(5) -C5H5)]9, Compound 9 can also be formed from the reaction of 2a with BuLi or NEt3, and a single crystal X-ray analysis has confirmed the enolate structure. (C) 2002 Elsevier Science B.V. All rights reserved.

Details

Item Type Articles
CreatorsAndrews, C. D., Burrows, A. D., Jeffery, J. C., Lynam, J. M. and Mahon, M. F.
DepartmentsFaculty of Science > Chemistry
RefereedYes
StatusPublished
ID Code5083
Additional InformationID number: ISI:000180689100004

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