Novel thermolytic products and their structures derived from thermolysis of isomerized products of spiro[4.4]nona-1,3-diene(dicarbonyl)[ethoxy(aryl)carbene]iron phosphine adducts [(η3-C9H12)Fe{C(OC2H5)Ar}(CO)2PPh3]

Heating a benzene solution of the isomerized product of spiro[4.4]nona-1,3-diene(dicarbonyl)[ethoxy(aryl)carbene]iron phosphine adduct [(η3-C9H12)Fe{C(OC2H5)(C6H4CH3-o)}(CO)2PPh3] (1) in a sealed quartz tube at 85–90 °C for 72 h gave the ring-opened η4 olefin-coordinated dicarbonyliron phosphine complex [Fe{η4-C5H7CHCHCH2CHC(OC2H5)C6H4CH3-o}(CO)2PPh3] (3) and cyclobutane derivative [C24H22O7] (4). The thermal decomposition of analogous isomerized product [(η3-C9H12)Fe{C(OC2H5)(C6H4CH3-p)}-(CO)2PPh3] (2) afforded the corresponding η4 olefin-coordinated dicarbonyliron phosphine complex [Fe{η4-C5H7CHCHCH2CHC(OC2H5)C6H4CH3-p}(CO)2PPh3] (6) and compound 4. The structures of products 3 and 4 have been established by X-ray diffraction studies.