Synthesis, Nujol matrix and solution photochemistry of M(CO)2[η5,η3-C5H4-C(CH3)2-C5H6] (where M = Cr or Mo):: molecular structures of Cr(CO)2[η5,η3-C5H4-C(CH3)2-C5H6], Mo(CO)2[η5,η3-C5H4-C(CH3)2-C5H6], and Mo(CO)[P(C6H5)3][η5,η3-C5H4-C(CH3)2-C5H6]

Reaction of chromium or molybdenum carbonyl with 2,2-bis(cyclopentadienyl)propane yields mixtures of products including M-2(CO)(6)[eta(5),eta(5)-C5H4-C(CH3)(2)-C5H4]. M-2(CO)(6)[eta(5)-C5H4-C(CH3)(2)-C5H4](2), and the title compounds, M(CO)(2)[eta(5),eta(3)-C5H4C-(CH3)(2)-C5H6], in which an eta(3)-pentenyl group is tethered to the eta(5)-cyclopentadienyl (Cp) group by a 2,2-propyl linkage. Although several isomers are possible for the cyclopentenyl groups, chromium and molybdenum appear to form only single, but unique isomers. Photolysis of M(CO)(2)[eta(5),eta(3)-C5H4-C(CH3)(2)-C5H6], M = Cr or Mo, in Nujol glass at ca, 77 K has been found to be wavelength-dependent with low energy photolyses resulting in eta(3)-->eta(1) transformations while higher energy photolyses result in loss of carbon monoxide. Solution photolysis of the molybdenum derivative with triphenylphosphine yields as a first product Mo(CO)(2)[P(C6H5)(3)][eta(5),eta(1)-C5H4-C(CH3)(2)- which undergoes decomposition upon work-up to yield both starting material, and Mo(CO)[P(C6H5)(3)][eta(5).eta(3)-C5H4-C(CH3)(2) -C5H6]. The molecular structures of three compounds have been determined: Mo(CO)(2)[eta(5), eta(3)-C5H4-C(CH3)(2)-C5H6]: monoclinic, P2(t)/c a = 8.2767(4), b = 19.875(1) c = 7.960(1) Angstrom, beta = 96,720(6)degrees V = 1300.4(1) Angstrom(3), Z = 4, R(F)= 2.82; Cr(CO)(2)[eta(5),eta(3)-C5H4-C(CH3)(2)-C5H6]: monoclinic. p2(1)/c. a = 9.960(1) b = 9.1015(6), c = 13.997(1) Angstrom, beta = 92.460(9)degrees, V= 1267.7(2) Angstrom(3), Z = 4, R(F)= 4.67; Mo(CO)[P(C6H5)(3)][eta(5), eta(3)-C5H4-C(CH3)(2)-C5H6]: monoclinic, P2(1)/c, a = 7.939(1), b = 22.381(3), c = 15.050(2) Angstrom, beta = 103.55(1)degrees, V = 2599.8(5) Angstrom(3), Z = 4, R(F) = 4.01. (C) 1999 Published by Elsevier Science S.A. All rights reserved.