Preparation and properties of sterically demanding and chiral distibine ligands

A series of new rigid distibines, 1,8-bis(R(2)Sb)naphthalene (R = Me: (); R = Ph: ()), and chiral distibines, 2,2'-bis(R(2)Sb)-1,1'-binaphthyl (R = Me: (); R = Ph: () obtained as racemic mixtures) and the discrete enantiomers of 4,5-bis((R(2)Sb)methyl)-2,2-dimethyl-1,3-D/L-dioxolane (R = Me: () (l), () (d); R = Ph: () (l), () (d)) have been obtained in high yields, using either electrophilic halostibine reagents with di-lithium reagents (()-()) or nucleophilic stibide reagents with dibromo-derivatives (()-()). The distorted octahedral complexes [Mo(CO)(4)(L)], L = ()-(), planar [PtCl(2)(L)], L = (), (), (), (), and neutral, five-coordinate [RhCl(cod)(L)], L = (), (), (), are reported and trends in the spectroscopic data are discussed in terms of the ligand donor properties. Crystal structures of () and [Mo(CO)(4)()] reveal significant structural changes occur upon coordination, and these are also reflected in the solution NMR spectroscopic parameters. Changes in the C-Sb-C angles and C-Sb bond distances upon coordination of () are discussed in term of increased s/p orbital mixing. Air oxidation of () forms a very unusual stibine oxide, the structure of which shows a distorted Sb(4)O(4) cubane core (bridging O atoms) with two orthogonal naphthalene units.