Four compounds of 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid ) H 2 CA) with organic and metal complex partners, [Hmel][CA] 0.5 ‚H 2 O (1), [Htptz][HCA]‚H 2 O (2), [Fe(terpy) 2 ][CA]‚6H 2 O (3), and [TTF][CA] 0.5 [ red H 4 CA] 0.5 ( 4) (mel ) melamine, tptz ) 2,4,6-tris(2-pyridyl)-1,3,5-triazine, terpy ) 2,2′,6′,2′′-terpyridine, TTF ) tetrathiafulvalene) are synthesized and characterized by single-crystal X-ray diffraction. For the obtained compounds, chloranilic acid shows various oxidation states and hydrogen bonding modes with multistage deprotonation processes. For compounds 1 and 3, chloranilic acid shows its complete deprotonated form (CA 2-). For compound 2, the monodeprotonated form of chloranilic acid (HCA -) is observed. Interestingly, compound 4 shows a reduced form of protonated chloranilic acid (1,4-dichloro-2,3,5,6-tetrahydroxybenzene: red H 4 CA).

Novel intercalation compounds constructed from the common two-dimensional hydrogen-bond-supported layers and functional guests [(H(0.5)phz)(2)[Fe(CA)(2)(H(2)O)(2)].2H(2)O](n)(1), ([Fe(Cp)(2)][Fe(CA)(2)(H(2)O)(2)])(n)(2), ([Fe(Cp*)(2)][Fe(CA)(2)(H(2)O)(2)])(n)(3), and [(TTF)(2)[Fe(CA)(2)(H(2)O)(2)]](n)(4) (H(2)CA = chloranilic acid, phz = phenazine, [Fe(Cp)(2)] = ferrocene, [Fe(Cp*)(2)] = decamethylferrocene, TTF = tetrathiafulvalene) are described. The guest cations are introduced between the ([Fe(CA)(2)(H(2)O)(2)](m-))(l) layers by electrostatic (1-4) and pi-pi stacking (3, 4) interactions. [Fe(Cp*)(2)](+) cations in 3 are stacked on each other making tilted columns which are included in the channel created by the chlorine atoms of CA(2-) dianions. TTF cations in 4 are stacked face to face with two types of S...S distances (type A; 3.579(3) A, and type B; 3.618(3) A) making a columnar structure. The TTF cations in the stacked column have a head-to-tail arrangement with respect to the iron-chloranilate layer. Mössbauer spectroscopy suggests that [Fe(CA)(2)(H(2)O)(2)](m-) anion in 3 is consistent with high-spin (S = 5/2) iron(III) ions and [Fe(Cp*)(2)](+) in the low-spin (S = 1/2) iron(III) ions. In 4, Mössbauer spectroscopy shows high-spin iron(II) ions (IS = 1.10 mm.s(-1) and QS = 1.66 mm.s(-1) at 297 K) and high-spin iron(III) ions (IS = 0.42 mm.s(-1) and QS = 1.27 mm.s(-1) at 297 K), suggesting that the anionic layer of iron-chloranilate has a valence-trapped mixed-valence state. At the temperature range of 77-300 K, the compounds 1, 2, and 3 are EPR silent, whereas the EPR spectrum of 4 shows two types of signals with g = 2.008 indicating the radical form of TTF.