Role of basic sites of substituted ferrocenes in interaction with the trinuclear 3,5-bis(trifluoromethyl)pyrazolates: thermodynamics and structure of complexes

Formation of complexes of the macrocycles (ML)(3), where L = 3,5-(CF3)(2)Pz = 3,5-bis(trifluoromethyl) pyrazolate, M = Cu and Ag, and the acylferrocenes FcC(O)CH2R (Fc = (C5H5)Fe(C5H4); R = H (1), Ph (2)) was studied by means of variable temperature IR, UV-vis, NMR spectroscopy. The sole site of coordination in solution is the oxygen atom of the CO group. The complex composition (1 : 1) and thermodynamic parameters in hexane solution were determined, the formation constants and the enthalpies decreasing from 1 to 2 and from Ag to the Cu macrocycle. The same coordination site featuring triple coordination of oxygen to all metal atoms of a macrocycle was found in the solid state by single crystal X-ray diffraction. There are no shortened contacts of the metal in the macrocycles with p-electron system of the ferrocene's cyclopentadienyl ligands in all complexes. The complexes of (ML)(3) with 1 have 1 : 2 composition and bipyramidal structure whereas 2 forms the 1 : 1 complex with (AgL)(3). The latter is packed in the infinite stacks involving additional contacts with Ph groups.