Effect of the Nature of Haloacetic Acids on the Type of Morpholine Complexes Formed. Crystal Structure of the First Palladium Tetracarboxylate with Monocarboxylic Acid: Morpholinium Tetrakis(trifluoroacetato)palladate(II), (O(CH2CH2)(2)NH2)(2)[Pd(CF3COO)(4)]

摘要

The effect of the nature of halogen-substituted carboxylic acids RCOOH, where R is ClCH2, Cl2CH, Cl3C, or F3C, on the complexation of palladium halocarboxylates with morpholine C4H9NO was investigated. Reactions with ClCH2COOH and Cl2CHCOOH gave binuclear complexes [(C4H9NO)(2)Pd-2(mu-OOCR)(2)(OOCR)(2)] with palladium-coordinated morpholine, whereas reactions with Cl3CCOOH and F3CCOOH afforded the first tetra(halocarboxylate) palladium complexes with protonated morpholine as the cation, (C4H10NO)(2)[Pd(RCOO)(4)]. The acid-base balance of morpholine and halocarboxylic acid was the key factor determining the composition of the resulting complexes. For the formation of palladium tetra(halocarboxylates) with morpholine, the difference between the morpholine and acid pK(a) values should be not lower than 7.63. X-ray diffraction studies were carried out for the first tetra(halocarboxylate) palladium complex with a monocarboxylic acid (C4H10NO)(2)[Pd(OOCCF3)(4) center dot 2H(2)O] (I) and for trans-[(C4H9NO)(2)Pd(OOCCH2Cl)(2) center dot 2H(2)O] (II), trans-[(C4H9NO)(2)Pd(OOCCHCl2)(2)] (III), and trans-[(C4H9NO)(2)Pd(OOCCF3)(2) center dot 2H(2)O] (IV) (CIF files CCDC nos. 1008564, 1894300, 1008566, and 1894299, respectively).