PHOTOLYSIS OF (ETA(5)-C5H4C4H9)(2)MO-2(CO)(4)(MU-ETA(2 2)-RC-CR') IN FROZEN NUJOL MATRICES/

A series of compounds, (eta (5)-C5H4C4H9)(2)Mo-2(CO)(4)(mu-eta (2:2)-a cetylene), where acetylene = 3-hexyne, diphenylacetylene, phenylacetyl ene and 1-phenylpropyne, was prepared and characterized by IR,H-1- and C-13-NMR spectroscopies and MS. Photolysis of these compounds was car ried out in frozen Nujol at 77 K. IR spectra established the presence of two isomeric carbonyl-loss species, (eta 5-C5H4C4H9)(2)Mo-2(CO)(2)( mu -eta(1),eta(2)-CO)(mu-eta(2:2)-acetylene), A, and C5H4C4H9)(2)Mo-2( mu-CO)(3)(mu-eta(2:2)-acetylene), B. A is formed by photolysis into lo w energy electronic transitions associated with the tetrahedrane core of the parent molecule, while B is formed by either photolysis into el ectronic bands associated with A, or photolysis into the high energy c harge-transfer bands of the parent molecule. These photointermediates are likely to be involved in the formation of 'fly-over' compounds, re sulting from thermally or photochemically induced multiple substitutio n of acetylenes. (C) 1998 Elsevier Science S.A. All rights reserved.