TUNING OF THE ELECTRONIC AND OPTICAL-PROPERTIES OF MANGANESE(I) SESQUIFULVALENE COMPLEXES

Template syntheses of sesquifulvalenes (2,4,6-cycloheptatrien-1-yliden e)cyclopentadiene (1) and beptatrien-1-ylidene)etheneylidene]cyclopent adiene (2) lead to air-stable complexes [(1)Mn(CO)(2)L]BF4 (4) and [(2 )Mn(CO)(2)L]BF4 (8) (a, L = CO; b, L = P(OMe)(3); c, L = PPh(3)). The different sigma-donor/pi-acceptor abilities of the Ligands L allow a t uning of the electronic and optical properties of complexes 4 and 8, w hich are particularly studied by UV/vis spectroscopy. The first molecu lar hyperpolarizabilities beta of complexes 4 and 8 have been determin ed in dichloromethane and acetonitrile solutions by hyper Raleigh scat tering. The X-ray crystal structures of 4b, 8b, and of the alkenylcycl opentadienyl complex [4,5 eta-(2,4,6-cyclohepeatrien-1-gamma l)-eta(5) -cyclopentadienyl]dicarbonylmanganese(I) (5) are reported.