Pentakis(methoxycarbonyl)cyclopentadiene chemistry. Part 3. Synthesis and crystal structure of the trivalent metal complex [Cr{C5(CO2Me)5}3]·ca.3.75H2O

Abstract

The crystal structure of [Cr{C₅(CO₂Me)₅}₃]·ca.3.75H₂O, synthesised by the reaction of chromium(II) acetate with the parent acid in methanol, was determined by single-crystal X-ray diffraction methods and refined to a residual of 0.066 for 632 ‘ observed ’ reflections at 295 K. Crystals are rhombohedral, space group R, with a = 16.545(20)Å, α= 60.49(7)°, and Z = 3. The molecule lies with the chromium atom situated in a three-fold symmetry axis, chelated by the carbonyl oxygen atoms of adjacent carboxyl groups, to give a tris-chelate complex : mean Cr–O 1.93 Å.