Syntheses and crystal structures of two isomeric pyrazoles with ferrocenyl groups

Ferrocenoylacetone I reacts with terephthaloyl hydrazide in the presence of a catalytic amount of p-toluenesulfonic acid to afford complex 1 whereas acylation of 3(5)-ferrocenyl-5(3)-methylpyrazole II with terephthaloyl chloride leads to an isomer of complex 1, viz. complex 2. Two new complexes have been characterized by elemental analyses and IR,¹H NMR, UV spectra and structurally characterized by single-crystal X-ray crystallography. Complex 1 (C₃₆H₃₀Fe₂N₄O₂) crystallizes in the monoclinic space group P2₁/c, with lattice constants: a = 11.593(2) ?, b = 12.9962(17) ?, c = 10.0030(17) ?, β = 113.227(4)°, V = 1462.1(4) ?³, Z = 4, D _c = 1.505 g·cm⁻³, F(000) = 684, R ₁ = 0.0307, wR ₂ = 0.0739. Complex 2 (C₃₆H₃₀Fe₂N₄O₂) crystallizes in the monoclinic space group P2₁/n, with lattice constants: a = 12.2388(18) ?, b = 7.3200(15) ?, c = 17.288(4) ?, β = 90.89(3)°, V = 1466.9(5) ?³, Z = 2, D _c = 1.500 g·cm⁻³, F(000) = 684, R ₁ = 0.0410, wR ₂ = 0.1247. Supplementary material Full crystallographic data (CCDC No. 602174 for complex 1 and CCDC No. 602175 for complex 2) have been deposited at the Cambridge Crystallographic Database Centre and are available on request from the Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (Fax: +44-1223-336-033; Email:deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).