ISSN:
1573-9171
Keywords:
carbocationic complexes
;
stabilization of carbocations
;
polarography
;
cyclic voltammetry
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The electrochemical reduction of the carbocationic complexes [Cp2M2(CO)4-μ-η2:η3(HCCCR1R2)]+BF4 −, where M/R1, R2 = Mo/H, H (1+), Mo/H, Me (2 +), Mo/Me, Me (3+), Mo/H, Pri (4+), has been studied by polarography and cyclic voltammetry on a Hg-electrode in THF solution. It has been suggested that carbocationic center-directed reversible two-electron reduction of1 +−4 + takes place according to an ECE-mechanism and results in the carbanionic complexes [Cp2M2(CO)4-μ-η2:η3-(HCCCR1R2)] (1 −−4 −) as final productsvia carbon-centered radicals as intermediates. Anions1 −-4 − are capable of irreversible two-electron reduction at more negative potentials or protonation resulting in their transformation into the corresponding acetylene complexes [Cp2M2(CO)4(HCCCHR1R2)], which are also capable of irreversible two-electron reduction. Anions1 −−4 − and their protonated forms are reduced with cleavage of the Mo-Mo bond. The reduction pathways of complexes1 +,2 +, and4 + with C-H bonds at the carbon atom of the carbocationic center are different on a Pt-electrode. It is suggested that this difference is due to the abstraction of a H-atom from the intermediate radical species by platinum.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01169709
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