SYNTHESIS AND CHARACTERIZATION OF COBALT AND MOLYBDENUM COMPLEXES DERIVED FROM LINEAR CONJUGATED DIYNENES, TRIYNEDIENES AND TETRAYNETRIENES

Z-1,6-Bis(trimethylsilyl)hexa-1,5-diyn-3-ene (2a), E-hexa-1,5-diyn-3-ene (3b) and related compounds (3a, c and d) were synthesized by standard methods. The Grignard reagent (3e) derived from 1-phenylhexa-1,5-diyn-3-ene (3d) was coupled with E-1-chloro-4-phenyl-1-buten-3-yne to give E,E-1,10-diphenyldeca-1,5,9-triyne-3,7-diene (4) and with E-1,2-dichloroethene to give E,E,E-1,14-diphenyltetradeca-1,5,9,13-tetrayne-3,7,11-triene (5). Hexa-1,5-diyn-3-ene complexes coordinated to one (7a, 8) and two (6a-d) hexacarbonyldicobalt units were prepared from the appropriate ligands and octacarbonyldicobalt. Tris- (9) and tetrakis- (10) hexacarbonyldicobalt complexes of the triynediene (4) and tetraynetriene (5) ligands were prepared similarly. Mono (7b) and bis (6e) di-eta5-cyclopentadienyltetracarbonyldimolybdenum complexes of E-1,6-bis(trimethylsilyl)hexa-1,5-diyn-3-ene were prepared by treating free diynene (3a) with the appropriate amount of [(eta5-C5H5)Mo(CO)2]2. Spectroscopic characteristics (NMR, IR, UV) of the complexes are presented and discussed.