Reaction mechanisms of metal–metal bonded carbonyls. Part II. The insertion reaction of stannous halides with hexacarbonylbis-(tri-n-butylphosphine)dicobalt

The kinetics of the thermal insertion reaction of SnCl2 with the metal–metal bonded complex [P(OC6H5)3Co(CO)3]2 have been studied by following the change in the visible spectrum in THF over the temperature range 35.0 to 55.0 °C. The activation enthalpy and entropy for the reaction are 24.7 ± 0.4 kcal/mol and 2.4 ± 1.3 cal mol−l deg−1 respectively. The data are consistent with a two-stage mechanism identical to that proposed for the corresponding reaction with [P(n-C4H9)3Co(CO)3]2 and from a comparison of the two reactions it is concluded that the cobalt–cobalt bond is slightly weakened when tributylphosphine is replaced by the better π-electron acceptor triphenylphosphite. The insertion products [LCo(CO)3]2SnCl2 are shown to undergo further reaction with [LCo(CO)3]2 to form [LCo(CO)3]3SnCl (L = CO, P(n-C4H9)3, P(OC6H5)3).

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Kinetics of the Insertion Reaction of Tin(II) Chloride with Hexacarbonylbis(triphenylphosphite)dicobalt

Barrett¹

1974

“…Cleavage of the M-M bond to form two radicals appears to be the consequence either of these excitations, or of the higher energy process involving the transition of an electron from a o orbital of the M-M bond to a o* orbital associated with this bond. In our studies of the thermal insertion of tin(I1) halides into the M-M bonds of a number of complexes (S), we have noted that some of these reactions are greatly accelerated when performed in the presence of laboratory light (9,10). A preliminary study of the photoinsertion of SnCl, into the M-M bond of [P(n-C,H,),-Co(CO),], has previously been reported (lo), but we now present the results of a quantitative study of this reaction and discuss two mechanisms which are consistent with the variation in the observed quantum yields with changes in the reactant concentrations, and the intensity and wavelength of the radiation.…”

Section: Introductionmentioning

confidence: 99%

The photoinsertion of tin(II) chloride into the metal–metal bond of hexacarbonylbis(tri-n-butylphosphine)dicobalt

Barrett¹,

Fox²,

March³

1977

. Can. J. Chem. 55, 2279Chem. 55, (1977. The photochemical insertion reaction of SnCI, into the metal-metal bond of [P(n-C4Hg),-C O ( C O )~]~ has been studied in THF at 23.0°C at the irradiating wavelengths 365 nm, 436 nm, and 546 nm. At 365 nm, the quantum yield for the reaction increases with increasing concentration of SnCI, and approaches a limiting value of 1.0. At 436 nm, however, the quantum yield increases above 1.0 and at 546 nm, quantum yields as high as 6 were measured. The uv-visible absorption spectrum of [P(n-C,H,),Co(CO),], shows an intense band at 372 nm and a broad shoulder at about 440 nm. A simple mechanism is proposed to operate on irradiation at 365 nm due to absorption by the intense band, but a more complicated chain mechanism is suggested to operate at 546 nm as a result of absorption by the lower energy shoulder band. It appears that both mechanisms operate on irradiation at 436 nm due to the overlap of the two absorption bands at this wavelength. Introduction the basis of the homolytic fission of the M-M There has been a recent surge of interest in the bond (I), or in solvents of high donicity, on the mechanisms of the photochemical reactions of heterolytic fission of this bond (2). Studies have transition metal carbonyl complexes containing shown that the lowest excited states of the M-M metal-metal (M-M) bonds (1-7). The photo-bonded species produced on absorption of radiachemistry of these complexes can be explained on tion result from an electronic transition which weakens the M-M bond, either by an electron

“…Previous studies (4,5) have reported the kinetics of the insertion of tin(I1) halides into the metal-metal bonds of hexacarbonylbis(tri-nbutyl-phosphine)dicobalt and cyclopentadienyliron dicarbonyl dimer. From these investigations information regarding the strength of metalmetal bonds has been obtained as well as details of the mechanisms of insertion reactions.…”

Section: Introductionmentioning

confidence: 99%

The Kinetics of the Thermal Insertion Reaction of Tin(II) Halides with Cyclopentadienylnickel Carbonyl Dimer

Barrett¹,

Clancy²

1971

Self Cite