Towards Carbohydrate Derivatives of the ReI(CO)3 Fragment

• Published in: Chemistry : a European journal 2006-06, Vol.12 (17), p.4675-4683
• Main Authors: Hinrichs, Matthias, Hofbauer, Florian R., Klüfers, Peter
• Format: Article
• Language: English
• Subjects: Benzopyrenes - chemistry; bioinorganic chemistry; carbohydrates; Carbohydrates - chemistry; carbonyl ligands; Cyclohexanes - chemistry; Cyclopentanes - chemistry; Molecular Structure; Organometallic Compounds - chemistry; polyols; rhenium; Rhenium - chemistry; Sugar Alcohols - chemistry
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200501567

With the [Re(CO)3Br3]2− ion as a precursor for the ReI(CO)3 fragment, the diols (1R,2R)‐cyclohexane‐1,2‐diol [(1R,2R)‐Chxd], anhydroerythritol (AnEryt), and (1S,2S)‐cyclopentane‐1,2‐diol [(1S,2S)‐Cptd] form dinuclear monoanions in the salts (NBu4)[(Re2(CO)6{μ‐(1R,2R)‐ChxdH−1}3] (1), [K([18]crown‐6)][Re2(CO)6(μ‐OMe)2(μ‐AnErytH−1)] (2) and (NBu4)[Re2(CO)6{μ‐(1S,2S)‐CptdH−1}3] (3). The monoanionic diolato ligands in these triply bridged dirhenates(I) are monodentate. Bridging triolato ligation in the trirhenates(I) is supported by the anions of glycerol (Glyc) and methyl β‐D‐ribopyranoside (Me‐β‐D‐Ribp), the latter binding in its 1C4 conformation, in (DBUH)2[Re3(CO)9(μ3‐O)(μ3‐GlycH−3)]⋅0.5 MeCN (4 a), (NEt4)[Re3(CO)9(μ3‐OMe)(μ3‐GlycH−3)] (4 b) and (DBUH)[Re3(CO)9(μ3‐OMe)(μ3‐1C4‐Me‐β‐D‐Ribp2,3,4H−3)] (5). The chiral sugar alcohols L‐threitol (L‐Thre) and D‐arabitol (D‐Arab) act as tetra‐ and pentadentate ligands, respectively, in (NEt4)[Re2(CO)6(L‐ThreH−3)]⋅MeCN (6) and (NEt4)2(DBUH)2[Re6(CO)18(D‐ArabH−5)2] (7). Complexes 6 and 7 are free of supporting oxo or methoxo ligands and use solely the O‐atom pattern of the polyol for the connection of the ReI(CO)3 moieties. Tetradenticity hits the mark; bi‐ and tridentate chelation fails: The tetradentate O atom pattern of an L‐threitolato ligand is necessary to lend enough hydrolytic stability to a carbohydrate‐based ReI(CO)3 complex for it to form in an aqueous solution of the components. The figure shows the structure of this binuclear [Re2(CO)6(L‐ThreH−4)]2− rhenate(I), which paves the way towards aqueous carbohydrate chemistry of this therapeutically important metal fragment.