Toward absolute asymmetric synthesis of coordination polymers with bidentate sulfide ligands

摘要

In search for sulfide-containing coordination polymers that crystallize as conglomerates, five new copper(I) complexes with prochiral sulfide ligands have been prepared and characterized by single crystal X-ray structure determination. Three unsymmetrical sulfides have been used: phenyl propargyl sulfide (Sprop), allyl methyl sulfide (Sally), and 2,5-dithiahexane (SS). In [CuCl(Sprop)] _n (1), layers are formed via π-coordination of propargyl groups to copper(I). In [Cu_2Br_2(Sprop)_4] (2), discrete dimers form with non-coordinating propargyl groups. In [CuCl(Sally)]_n (3), layers are formed via π-coordination of allyl groups to copper(I), but disordered Sally ligands are also found. The mesitylcopper complex [Cu _4(Mes)_4(Sally)_2] (4) is chiral but discrete. In [Cu_4(Mes)_4(SS)]_n (5), racemic chains are formed by the SS ligand. Three out of five complexes prepared thus form coordination polymers, and all of the five complexes (1-5) exhibit terminal sulfide ligands that could be oxidized selectively when incorporated in an enantiopure polymer. Unfortunately none of 1-5 crystallized as a conglomerate, but whether this reflects an inherent tendency in this system is too early to say.