Abstract
Irradiation of tricarbonyl(η 5 -2,4-dimethyl-2,4-pentadien-1-yl)manganese ( 1 ) in tetrahydrofuran (THF) at 208 K affords the carmine solvent complex dicarbonyl(η 5 -2,4-dimethyl-2,4-pentadien-1-yl)(THF)manganese ( 2 ). Complex 2 thermally reacts with acetylene ( 3 ) to give tricarbonyl(η 3:2 -1,3-dimethyl-bicyclo[3.3.1]-3,6-nonadien-2-yl)manganese ( 4 ) and dicarbonyl(5-7,10-13-η-6,8-dimethyl-1,3,5,8,10,12-tridecahexaen-5-yl)manganese ( 5 ). The crystal structure of complex 4 was determined at room temperature [triclinic space group P1¯,$P\bar 1,$ a = 7.6891(9), b = 8.3860(8), c = 10.5252(13) Å, α = 93.000(9)°, β = 93.390(10)°, γ = 108.032(8)°, V = 642.43(13) Å 3 ]. The manganese atom is trigonal-bipyramidally coordinated by three carbonyl ligands, one ethenylic and one allylic fragment. Consequently, the bicyclic olefin ligand 1,3-dimethyl-bicyclo[3.3.1]-3,6-nonadiene coordinates the manganese atom in a η 3:2 mode. The constitution of complex 5 was deduced from IR data, elemental analysis, and 1 H NMR spectra. For the formation of complexes 4 and 5 , a reaction mechanism is proposed.