2,3,4,7-Tetrahydro-1<i>H</i>-inden-2-ol: synthesis, molecular structure and coordination chemistry

2,3,4,7-Tetrahydro-1<i>H</i>-inden-2-ol (<b>1</b>) has been synthesised by Birch reduction of indan-2-ol. A single-crystal X-ray structure analysis of <b>1</b> shows the compound to exist as hydrogen-bonded polymers along the c-axis due to the presence of a series of hydrogen-bonds between hydroxo functions. The ferrocene ester derivatives, ferrocene carboxylic acid 2,3,4,7-tetrahydro-1<i>H</i>-inden-2-yl ester (<b>2</b>) and ferrocene carboxylic acid indan-2-yl ester (<b>3</b>) have been prepared by peptidic coupling of ferrocene carboxylic acid with <b>1</b> and with indan-2-ol, respectively. The single-crystal X-ray structure analyses of <b>2</b> and <b>3</b> reveal in both cases the cyclopentadienyl rings to adopt an eclipsed conformation with the indenyl substituent being rotated out of the Cp ester plane by almost 90°, allowing no efficient interaction between the π-system of the Cp ring and the indene moiety. The dienyl derivative 2 reacts with RuCl₃ • <i>n</i>H₂O in refluxing ethanol to afford [Ru(arene)Cl₂]₂ (<b>4</b>) (arene=ferrocene carboxylic acid indan-2-yl ester) as a mixture of isomers.