Synthesis of compounds with C–P–P and CP–P bond systems based on the phospha-Wittig reaction

A reactivity study of a β-diketiminate titanium( iii ) phosphanylphosphido complex [ Me NacNacTi(Cl){η 2 -P(SiMe 3 )–P t Bu 2 }] ( 1 ) towards ketones such as benzophenone, 9-fluorenone, acetophenone, cyclopentanone, cyclohexanone and cycloheptanone is reported. The reactions of 1 with aromatic ketones (without α-protons) directly lead to the Ti( iii ) complex [ Me NacNacTi(μ 2 -Cl)(OSiMe 3 )] ( 5 ) and Ti( iv ) complexes with the pinacol condensation product [ Me NacNacTi(OSiMe 3 )(η 2 -pinacolate)] ( 3 ), and phosphanylphosphaalkenes Ph 2 CP–P t Bu 2 ( 2 ) and (fluorenyl)CP–P t Bu 2 ( 6 ), respectively. The reaction with acetophenone leads to the titanium( iii ) complex with the aldol condensation product as ligand [ Me NacNacTi(Cl){OC{Me(Ph)}CH 2 (CO)Ph}] ( 8 ) and in parallel to phosphanylphosphaalkene (Ph)MeCP–P t Bu 2 ( 9 ) and 5 . The reactions of 1 with cyclic ketones (cyclopentanone and cyclohexanone) lead to Ti( iii ) complexes [{(ArNC(Me)CHC(Me)NAr)((CH 2 ) 4 CO)}Ti(Cl){P t Bu 2 –P(SiMe 3 )((CH 2 ) 4 CO)}] ( 10 ) and [{(ArNC(Me)CHC(Me)NAr)((CH 2 ) 5 CO)}Ti(Cl){P t Bu 2 –P(SiMe 3 )((CH 2 ) 5 CO)}] ( 11 ), which are formed via the successive insertion of two molecules of ketone to one molecule of 1 . The stability investigation of complexes 10 and 11 in a polar solvent (THF) revealed that under these conditions, the complexes decompose, resulting in titanium( iii ) complexes with aldol condensation products and the expected phosphanylphosphaalkenes (CH 2 ) 4 CP–P t Bu 2 ( 10a ) and (CH 2 ) 5 CP–P t Bu 2 ( 11a ). In the reaction of 1 with cycloheptanone, only the Ti( iii ) complex with the aldol condensation product [ Me NacNacTi(Cl){OC(CH 2 ) 6 }CH(CO)(CH 2 ) 5 ] ( 12 ) was isolated. The structures 3 , 5 , 8 , 10 , 11 , 11b and 12 were characterized by X-ray spectroscopy, while all the phosphanylphosphaalkenes were characterized by NMR spectroscopy.