Half-Sandwich Iron(II) and Ruthenium(II) Complexes with the Dicarbollylamino Ligand System

Abstract

The syntheses of half-sandwich iron(II) complexes [(η 5:η 1 -C 2 B 9 H 10 -CH 2 NMe 2 )FeL 2 ] (L = CO ( 4a ), CNBu t ( 4b ), PMe 3 ( 4c ), 1,5-cycloctadiene (cod) ( 4d )) are reported, and the structure of 4a has been established by an X-ray diffraction study. The complex 4a adopts a characteristic three-legged “piano stool” structure with the iron atom η 5 -coordinated on one side by a nido o -carboranyl group and the other by the dimethylamino group and two CO ligands. Thus, treatment of the lithium salt of DcabH N [ nido -7-NMe 2 CH 2 -7,8-C 2 B 9 H 11 ] 1 - ( 2 ) with FeCl 2 (THF) n in THF affords solutions of the labile species [(η 5:η 1 -C 2 B 9 H 10 -CH 2 NMe 2 )Fe(THF) 2 ] ( 3 ), which readily reacts with CO, CNBu t, PMe 3, and cod, yielding the species 4a − d . In particular, the η 4 -bonding mode of the cycloctadienyl group to the metal of complex 4d is displaced in the reaction with CNBu t and PMe 3, yielding 4b and 4c, respectively. [Ru(CO) 3 Cl 2 ] 2 reacts with the lithium salt of 2 in THF to give [(η 5:η 1 -C 2 B 9 H 10 -CH 2 NMe 2 )Ru(CO) 2 ] ( 5 ), having a molecular structure closely related to that of 4a, as confirmed by an X-ray diffraction study. Further decarbonylation reaction of 5 with Me 3 NO was carried out in acetonitrile solution to give the corresponding monosubstituted complex [(η 5:η 1 -C 2 B 9 H 10 -CH 2 NMe 2 )Ru(CO)(NCMe)] ( 6 ).