Abstract
(η 3 -C 5 H 7 )Mo(P⌒P)(CO) 2 Br (P⌒P = dppe, dmpe) reacts with AgBF 4 in CH 2 Cl 2 to give the cations [(η 5 -C 5 H 7 )Mo(P⌒P)(CO) 2 ]BF 4 (P⌒P = dppe (1), dmpe (2)). In CH 3 CN, 1 and 2 each undergo rearrangement to produce the cations [(η3-c5h7)mo(p⌒P)(CO) 2 (CH 3 CN)]BF 4 (P⌒P = dppe (3), dmpe (4)). Compounds 3 and 4 can be alternatively prepared by the reaction between AgBF 4 and (η 3 -C 5 H 7 )Mo(P⌒P)(CO) 2 Br in CH 3 CN. In CHCl 3 and CH 3 COCH 3 , the η 3 cations 3 and 4 readily lose CH 3 CN to re-form 1 and 2 and reach equilibrium. The η 3 ⇆ η 5 equilibrium constants in CDCl 3 and CD 3 COCD 3 were determined from 31 P NMR spectra. The molecular structure of 1 has been determined from an X-ray diffraction study. Crystallographic data: space group P1̅, a = 10.739 (2) Å, b = 11.292 (3) Å, c = 14.428 (3) Å, α = 93.53°, β = 79.42 (2)°, γ= 116.60 (3)°, Z = 2, R F = 0.035, and R w = 0.028. © 1989, American Chemical Society. All rights reserved.