- Electron transfer versus nucleophilic pathways in the ion-pair annihilation of organoborate anions by carbonylmanganese(I) cations
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Substituted carbonylmanganese cations [Mn(CO)5L]+, where L = py, PPh3 and PPh2Me, readily react with various organoborate anions (tetramethylborate, methyltriphenylborate and tetraphenylborate) in THF solution to afford a mixture of dimanganese carbonyls, hydridomanganese carbonyls and alkylmanganese carbonyls. The formation of the dimanganese carbonyl dimers as well as the hydridomanganese carbonyls suggests the involvement of 19-electron carbonylmanganese radicals that stem from an initial electron transfer. On the other hand, the acetonitrile-substituted analogue [Mn(CO)5(CH3CN)]+ reacts with the same borate anions to afford the alkylated RMn(CO)5, where R = CH3 and C6H5, as the sole carbonylmanganese product. As such, this alkylative annihilation is best formulated as a direct attack on the carbonyl carbon by the borate nucleophile. The two different pathways can be understood in terms of the balance between the electrophilicity of the carbonyl ligand and the electron affinity of the carbonylmanganese cation.
- Zhu, Dunming,Kochi, Jay K.
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p. 295 - 303
(2007/10/03)
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- Charge-transfer salts of carbonylmetalates as outer-sphere ion pairs in photochemical and thermal electron transfer
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Highly colored, crystalline salts result from the combination of the carbonylmetalates Co(CO)4-, Mn(CO)5- and HFe(CO)4- with perphenyl-phosphonium and sulfonium cations.The unique colors are associated with the interionic
- Wei, C.-H.,Bockman, T. M.,Kochi, J. K.
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- Synthesis and reactivity of metallacyclic manganese α-(silyloxy)alkyl complexes (CO)4MnC(R)(OSi(CH3)3)P(C6H 5)2. A new thermodynamic driving force for CO insertion
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Reaction of (CO)5MnR (2) with (C6H5)2PSi(CH3)3 (3) gives metallacyclic α-(silyloxy)alkyl complexes (CO)4MnC(R)(OSi(CH3)3)P(C6H 5)2 (4) in 42-75% yields (R = CH3 (a), CH2Si(CH3)3 (b), C6H5 (c), 2-naphthyl (d)). These reactions are of interest in that the metallacyclic carbon is derived from an insertion of CO into the manganese-carbon bond of 2 - a step for which subsequent silicon-oxygen bond formation provides an additional thermodynamic driving force. Reaction of (CO)5MnCOC6H5 with 3 also gives 4c (63%). Phosphines (C6H5)3P and 3 react with 2a at nearly the same rate, both separately and in competition experiments. Passage of 4b through wet silica gel gives acyl complex cis-(CO)4Mn(COCH2Si(CH3)3)P(C 6H5)2H (6b, 84%), presumably via metallacyclic α-hydroxyalkyl complex (CO)4MnC(CH2Si(CH3)3)(OH)P(C 6H5)2 (7b). Reaction of 2b with (C6H5)2PH also gives 6b (91%). Reaction of (CO)5MnH and 3 in hexanes gives cis-(CO)4Mn(H)P(C6H5)2Si(CH 3)3 (8, 72%). Both 8 and 4a are inert to 300-360 psi of CO. The thermodynamics of these transformations are analyzed.
- Vaughn, George D.,Krein, K. Alex,Gladysz
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p. 936 - 942
(2008/10/08)
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- PHOTO-INDUCED DEGRADATION REACTIONS OF SOME ALKYL- AND ARYL-CARBONYL DERIVATIVES OF MANGANESE, MOLYBDENUM AND TUNGSTEN
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Photo-induced degradation of CH3Mn(CO)5 in pentane solution results in the formation of Mn2(CO)10, methane and carbon monoxide.Both CH3D and CH4 are formed when CH3Mn(CO)5 is photolyzed in C6D6.Photolysis of C6H5CH2Mn(CO)5 in pentane solution produces Mn2(CO)10, toluene and bibenzyl.Analogous photodegradation of C6H5Mn(CO)5 in pentane solution yields Mn2(CO)10, benzene and carbon monoxide, but not biphenyl.The thermally unstable complex C2H5Mn(CO)5 was studied by photolyzing it in solution at -40 degC.GC analysis indicates that both ethylene and ethane are formed, and that the mole ratio of these products is dependent on the initial concentration of C2H5Mn(CO)5.These results are consistent with a β-hydrogen elimination mechanism for this reaction.Photolysis of CpMo(CO)3CH2C6H5 in pentane solution produces 2 and toluene, whereas photolysis of CpW(CO)3CH2C6H5 affords 2, CpW(CO)2(η3-benzyl), toluene, and a small amount (2percent) of bibenzyl.When CpM(CO)2(η3-benzyl) (M=Mo, W) complexes are subjected to photolysis under similar conditions, the only identifiable product is toluene.CpW(CO)3C6H5 degrades photochemically in pentane solution to form 2 and benzene, together with a small amount (6percent) of biphenyl.
- Gismondi, Thomas E.,Rausch, Marvin D.
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