A New Binucleating Ligand Based on Anthracene and Its Cofacial Dirhodium(I) and Diiridium(I) Complexes.
A new bis(beta-keto enamine) ligand (2a, ABIH(2)) containing a 1,8-anthracenediyl bridging group has been synthesized by a four-step procedure that relies on the Pd-catalyzed cross-coupling between (3,5-dimethylisoxazol-4-yl)trialkyltin and 1,8-dibromoanthraquinone or -anthracene. The molecular structures of the 1,8-bis(3,5-dimethylisoxazol-4-yl)anthraquinone (8) and -anthracene (10) intermediates were determined by X-ray analysis. Crystal data for 8: orthorhombic, space group Pbca; a = 14.351 (2), b = 11.932 (1), c = 23.278 (2) Å; V = 3986 (1) Å(3); Z = 8; R = 0.057 for 2615 reflections. Crystal data for 10: orthorhombic, space group P2(1)2(1)2(1); a = 7.104 (1), b = 12.805 (1), c = 22.280 (2) Å; V = 2026.7 (6) Å(3); Z = 4; R = 0.066 for 3423 reflections. The rigid ABIH(2) ligand, whose chelating moieties are constrained to be cofacial, allows the preparation of a new family of cofacial bimetallic complexes (ABI)[ML(2)](2) with controllable environments around the metal centers. Two novel cofacial binuclear complexes 4 and 5, with ML(2) = dicarbonylrhodium(I) and (eta(4)-1,5-cyclooctadiene)iridium(I), have been synthesized by reaction of ABIH(2) with [(&mgr;-Cl)Rh(CO)(2)](2) and [(&mgr;-Cl)Ir(COD)](2), respectively. NMR data indicate the formation of meso and racemic atropisomers for 2a, 4, and 5.
Benites
María del Rosario
MR
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803.
Fronczek
Frank R.
FR
Hammer
Robert P.
RP
Maverick
Andrew W.
AW