Bertram A. Frenz

DI(η5-cyclopentadienyl)pentacarbonyldivanadium. A prototypal example of semibridging carbonyl groups

Abstract The crystal and molecular structures of the compound have been determined; they provide an explanation of the unusual infrared spectrum, which is inconsistent with a symmetrical, singly-bridged structure. Instead it is found that there are three terminal CO groups of a completely conventional type and two which are intermediate between and strictly bridging. The (η 5 -C 5 H 5 )V moieties are structurally normal. The V—V distance, 2.462(2) A, is indicative of some multiple bond character. From the sturcture and infrared spectrum of the pentacarbonyl together with the infrared spectrum of the substitution product, (η 5 -C 5 H 5 ) 2 V 2 (CO) 4 PPh 3 , the position of the PPh 3 is predicted. The principal crystallographic data are: space group, P 2 /n ; a = 8.246(2), b = 15.769(5), c = 11.729(2) A; β = 91.66(2)°; Z = 4. Using 1134 independent reflections with intensive greater than times their esds the structure was refined to residuals of R 1 = 0.044 and R 2 = 0.070.