PI-OLEFIN IRIDIUM COMPLEXES .17. SYNTHESI S OF NOVEL RHODACYCLOPENTADIENYL AND IRIDACYCLOPENTADIENYL COMPLEXES VIA BUTADIENE MAGNESIUM COMPOUNDS

The dinuclear dihydrido iridacyclopentadienyl complex ta5[1-(eta4-cod) -1,1-H-2-IrCH=CHCH=CH](eta4-cod)Ir (1) (cod = cycloocta-1,5-diene) as well as trinuclear (eta4-diene)-1-(mu-H)-MCH=CRCR=CH][(eta4-diene)M]2 compounds (2: M = IR, diene = cod, R = H; 3: M = Rh, diene = norbornad iene, R = H; 4: M = Rh, diene = norbornadiene, R = CH3) were obtained by reaction of [(diene)MCl]2 with the corresponding butenediylmagnesiu m reagents in tetrahydrofuran. The trinuclear tripeldecker-like specie s can be cleaved by trimethylphosphane to form dinuclear [1-(eta4-dien e)-1-(PMe3)-MCH=CRCR=CH](eta4-diene)M compounds (5: M = Ir, diene = co d, R = H; 6: M = Rb, diene = norbornadiene, R = H; 7: M = Rh, diene = norbornadiene, R = CH3). The possible structures of the novel complexe s are derived from NMR data and in the case of 2 and 7 confirmed by X- ray diffraction analysis.