A series of new manganese(II) pivalate-phosphonate complexes with various nuclearities (Mn 4 , Mn 10 , and Mn 20 ) under aerobic conditions was synthesized by self-assembly of simple reagents. The constitution of polynuclear architectures is affected by the reaction temperature. The structures of the complexes were determined by single crystal X-ray analysis. Magnetic behavior of the compounds points to dominant antiferromagnetic exchange interactions. Antiferromagnetic coupling with J Mn-Mn = À0.097(1) cm À1 , g Mn = 1.993(1) for an equilateral tetrahedron model simulates the magnetic behavior of the tetranuclear complex Mn 4 with a cube-like core.

One-dimensional coordination polymer [Co(Piv)2(4-ptz)(C2H5OH)2]n (compound 1, Piv(-) = pivalate, 4-ptz = 2,4,6-tris(4-pyridyl)-1,3,5-triazine) was synthesized by interaction of Co(II) pivalate with 4-ptz. Desolvation of 1 led to formation of [Co(Piv)2(4-ptz)]n (compound 2), which adsorbed N2 and H2 at 78 K as a typical microporous sorbent. In contrast, absorption of methanol and ethanol by 2 at 295 K led to structural transformation probably connected with coordination of these alcohols to Co(II). Formation of 2 from 1 was accompanied by change of color of sample from orange to brown and more than 2-fold decrease of molar magnetic susceptibility (χM) in the temperature range from 2 to 300 K. Resolvation of 2 by ethanol or water resulted in restoration of spectral characteristics and χM values almost to the level of that of 1. χMT versus T curves for 1 and samples, obtained by resolvation of 2 by H2O or C2H5OH, were fitted using a model for Co(II) complex with zero-field splitting of this ion.

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