Bioorganometallic Chemistry. 7. A Novel, Linear, Two-Coordinate Rh(I) Anionic Amide Complex Formed by the Reaction of the Nucleobase, 1-Methylthymine, with the [(CpRh)2(.mu.-OH)3]+ Cation at pH 10: Molecular Recognition and Electrostatic Interaction within an Organometallic Hydrophobic Cavity

Recently authors were able to characterize several ({eta}{sup 5}-pentamethylcyclopentadienyl) rhodium(Cp{sup *}Rh) -cyclic trimer structures with 9-methyladenine 9-ethylhypoxanthine, adenosine, adenosine 3`-, methyl-5`-, and 5`-monophosphates and, in this process, discovered the first examples of molecular recognition by several bioorganometallic Cp{sup *}Rh-cycle trimer nucleobase, nucleoside, and nucleotide hosts with aromatic amino acid guests in H{sub 2}O at pH 7.0. They now extend their bioorganometallic/molecular recognition studies to the nucleobase 1-methylthymine (1-MTH) and describe the synthesis and structural characterization of the first example of a novel, linear, two-coordinate Rh(I) anionic amide complex [Rh({eta}{sup 1},N{sup 3}-1-MT){sub 2}]{sup -} (1), from the reaction of 1-MTH with in situ generated [(Cp{sup *}Rh){sub 2}({mu}-OH){sub 3}]{sup +} (2) performed at pH 10. This unusual coordination around the Rh(I) complex is presumed to be stabilized by three factors: an organometallic hydrophobic cavity, generated from 1.5 molecules of 2; an electrostatic interaction of anionic 1 with cation 2; and a possible shielding of the Rh(I) center to nucleophilic attack by the 4 sets of oxygen lone pair electrons. 19 refs., 3 figs.