Synthesis and chemistry of 1,1-bis(3-indenyl)ethane; crystal structure of [{Ru(CO)2}2{η5:η5-CH3CH(C9H6)2}]

Abstract

The compound 1,1-bis(3-indenyl)ethane has been synthesised. Its reaction with [Ru₃(CO)₁₂] yielded [{Ru(CO)₂}₂{η⁵:η⁵-CH₃CH(C₉H₆)₂}] as a mixture of diastereoisomers which have different faces of each five-membered ring of the indenyl units complexed to a Ru(CO)₂ fragment. The crystal structure of 1 shows that the major diastereoisomers present are bound to inequivalent faces of the ligand [trigonal, space group P3₁21 (D₃⁴, no. 152), Z= 3, a= 10.226(6), c= 16.896(8)Å and γ= 120°; R 0.0384 for 1666 unique reflections]. The reaction of 1,1 -bis(3-indenyl)ethane with [Mo(CO)₃(NCMe)₃] or [Cr(CO)₃(NH₃)₃] gave [M{η⁶-CH₃CH(C₉H₇)₂}(CO)₃](M = Mo or Cr respectively) as a mixture of diastereoisomers. In all cases ¹H and ¹³C NMR spectroscopy proved to be useful tools for detecting the diastereoisomers.