Structural characterization of cyclopentadienyl(duroquinone)cobalt dihydrate

Abstract

The structure of cyclopentadienyl(duroquinone)cobalt dihydrate, (C 5H 5)Co-[(CH 3) 4C 6O 2]·2H 2O, has been determined by three-dimensional X-ray analysis. The crystal structure consists of discrete cyclopentadienyl(duroquinone)cobalt molecules linked together by a complex network of hydrogen bonds between water molecules and duroquinone oxygen atoms. Each (C 5H 5)Co[(CH 3) 4C 6O 2] molecule consists of a cobalt atom sandwiched between a cyclopentadienyl ring and a duroquinone ring. A detailed comparison of the molecular parameters of this complex with those of closely related complexes is given. Crystallographic evidence that the metalduroquinone interaction in cyclopentadienyl(duroquinone)cobalt dihydrate is considerably stronger than that in the electronically-equivalent 1,5-cyclooctadiene(duroquinone)nickel complex is given not only by the metalC(olefin) distances being 0.12 Å (av) shorter in the duroquinonecobalt complex [ viz., 2.104(8) Å vs. 2.222(7) Å] but also by the much greater C 2 v -type distortion of the duroquinone ring from the planar D 2 h configuration in free duroquinone. The compound crystallizes with two formula species in a triclinic unit cell of symmetry P 1 and reduced cell dimensions á = 8.60 Å, b = 9.00 Å, c = 10.15 Å, α = 87° 34′, β = 84° 10′, γ = 73° 44′. Least-squares refinement yielded final unweighted and weighted discrepancy factors of R 1 = 10.8% and R 2 = 12.0%, respectively, for 2481 independent diffraction maxima collected photographically.