Enantiomerically Pure Complexes of Manganese, Iron, and Zirconium with Pinene-Fused Boratabenzene Ligands – Structures ofexo-FeCp*(C13H17BNMe2) andexo,exo-ZrCl2(C13H17BNMe2)2

Abstract

Complexes of pinene-fused boratabenzene ligands [(1R,9R)6,10,10-trimethyl-4-boratatricyclo[7.1.1.02,7]undeca-2,4,6trienes] C13H17BX (with a: X = NMe2; b: X = OMe; c: X = Me) are described. The lithium salt Li(C13H17BNMe2) [Li(1a)] reacts with [Cp*Fe(NCMe)3]PF6 and with Mn(CO)3Br(py)2 to give diastereomeric mixtures FeCp*(C13H17BNMe2) (4a) and Mn(CO)3(C13H17BNMe2) (7). The mixture 4a undergoes solvolysis in methanol to produce methoxy compounds 4b, which in turn react with LiMe in Et2O to give methyl derivatives 4c. The lithium salts Li(C13H17BX) [Li(1a–c)] react with ZrCl4 in toluene or Et2O to give exo,exo-ZrCl2(C13H17BX)2 complexes (8a–c). The dimethyl derivative exo,exo-ZrMe2(C13H17BNMe2)2 (9) can also be prepared from 8a/LiMe in Et2O. NOE difference spectra have been analyzed to determine the configurations of the diastereomers and to establish a chemical shift criterion for assessing the configuration of the metal–ligand coordination. An independent confirmation of the product stereochemistries has been obtained by single-crystal X-ray structure determinations of exo-4a and 8a.