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A coordination polymer of the general formula [Co(OOCCMe 3 ) 2 ] n (2) was prepared by mild thermolysis of the coordination polymer of variable composi tion [(HOOCCMe 3 ) x Co(OH) n (OOCCMe 3 ) 2-n ] m , the dinuclear cobalt com plex Co 2 (µ H 2 O)(OOCCMe 3 ) 4 (HOOCCMe 3 ) 4 , the tetranuclear cobalt cluster Co 4 (µ 3 OH) 2 (OOCCMe 3 ) 6 (HOEt) 6 , and the hexanuclear cluster [Co 6 (µ 4 O) 2 (µ n OOCCMe 3 ) 10 (C 4 H 8 O) 3 (H 2 O)]•1.5(C 4 H 8 O) (7) in organic solvents. In the crystal, the poly mer has a chain structure. Unlike thermolysis of cobalt pivalates, thermolysis of the dinuclear complex Ni 2 (µ H 2 O)(OOCCMe 3 ) 4 (HOOCCMe 3 ) 4 gave rise to the hexanuclear complex Ni 6 (µ 2 OOCCMe 3 ) 6 (µ 3 OOCCMe 3 ) 6 (3). The magnetic properties of compound 2 are sub stantially different from those of 3. Compound 2 undergoes the magnetic phase transition into the ordered state at T c = 3.4 K (H = 1 Oe), whereas compound 3 exhibits antiferromagnetic properties. Solid state decomposition of polymeric cobalt carboxylate 2 (below 350 °C) af forded the octanuclear cluster Co 8 (µ 4 O) 2 (µ 2 OOCCMe 3 ) 6 (µ 3 OOCCMe 3 ) 6 (9) as the major product, which sublimes without decomposition. Decomposition of 3 gave nickel oxide as the final product. Pivalates 2 and 3 reacted with 2,3 lutidine in acetonitrile at 80 °C to form the isostructural dinuclear complexes (2,3 Me 2 C 5 H 3 N) 2 M 2 (µ OOCCMe 3 ) 4 (M = Co or Ni). The structures of compounds 3 and 7 were established by X ray diffraction. The structure of polymer 2 was determined by powder X ray diffraction analysis.The development of efficient methods for the synthe sis of convenient starting "spin materials" is of importance for the chemical design of molecular magnets with de sired properties and the preparation of precursors for the production of various inorganic materials by thermo chemical methods. Polynuclear (or even polymeric) metal complexes of constant composition with particular struc tures, which are highly reactive toward various organic donors and are readily decomposed at moderate tempera tures (60-450 °C), hold promise as spin materials. It is desirable that the starting complexes be able to generate "magnetic molecules" (for example, in reactions with or ganic donors) or form materials (for example, oxides by mild thermolysis) with desired physical properties. Among such compounds are pivalate coordination poly mers of simple composition [M(OOCCMe 3 ) 2 ] n (M is a 3d element). Compounds with M = Fe (S = 2), 1,2 Co (S = 3/2), 3,4 or Ni (S = 1) 5,6 have already found use in the synthesis of carboxylate complexes. How ever, only the structure of [Fe(OOCCMe 3 ) 2 ] n (1) was established by X ray diffraction. 7 Most of analogous Co II and Ni II compounds, which were prepared from salts of these metals by the exchange reactions with KOOCCMe 3 in water or by melting aqua acetates (M = Co) with pivalic acid, 3,5 have variable composition [(HOOCCMe 3 ) x M(OH) n (OOCCMe 3 ) 2-n ] m (M = Co or Ni). The structures of these compounds are unknown, * Dedicated to...

New dinuclear lanthanide pivalate complexes [Tb2(piv)6(Hpiv)6], [Tb2(piv)6(bpy)2], [Tb2(piv)6(phen)2], [Tb2(piv)6(bath)2]·1.5EtOH, and [Eu2(piv)6(bath)2]·2EtOH, as well as the coordination polymer {Tb(piv)3}n, in which piv = (CH3)3CCO2–, bpy = 2,2′‐bipyridine, phen = 1,10‐phenanthroline, bath = 4,7‐diphenyl‐1,10‐phenanthroline, and EtOH = ethanol, were synthesized and characterized by X‐ray diffraction. For the terbium complexes, the magnetic properties and the solid‐state thermolysis were investigated. The phase composition of the solid decomposition products was determined by X‐ray powder diffraction. The photophysical properties of these complexes were analyzed by luminescence, excitation, and phosphorescence spectroscopy, and by lifetime measurements. A comparison of the photophysical data for bpy, phen, and bath complexes shows that the supramolecular organization affects the efficiency of the sensitization of Ln3+ luminescence. All the results obtained provide good prospects for the use of dinuclear lanthanide pivalate complexes as efficient light‐conversion molecular devices (LCMD).

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Extraction of polymer (1). formed in the reaction of CoCI~ with KOOCBu t, with boiling hexane gives crystals of hexamer Co6(~.3-OH)2(OOCBu~)I0(HOOCBut)4 (2). According to data of X-ray study, four Co H atoms in the hexanuclear molecule 2 have an octahedral ligand environment and two Co H atoms have a tetrahedral one. Dissolution of polymer 1 in EtOH results in its splitting into Co4(~t3-OH)~(OOCBut)~(HOEt)6 tetramers (3). In molecule 3, two asymmetric dimeric (q2-OOCBur fragments are bound by two tridentate bridging OH groups.Key words: cobalt trimethylacetates, polynuclear complexes, carboxylate ligands, synthesis. X-i-ay araalysis.Polynuclear transition-metal complexes with carboxylate bridging ligands often have unusual structures and possess unique chemical and physical (first of all, magnetic) properties. Lz In particular, trimethylacetate derivatives, which are highly volatile and readily soluble in organic solvents, can be of interest as initial compounds for preparing thin films (e.g., oxide films) and immobilized catalysts. Particular attention is paid to these compounds because of structural analogies between some of their metal fragments and those of the active sites of natural enzymes. 3-13Recently, we have shown that the action of various amines on the nonanuclear hydroxocarboxylate Nig(HOOCBu~)4(Ft4-O)3(I-t3-OH)3(. tt-OOCBut) 12, which is readily obtained in 70--90% yields in the reaction of NiCt2-6H20 with potassium pivalate, results in various nickel(10 trimethytacetates whose structure and magnetic properties can be deliberately modified. 14 in this context, the availability of the starting oligomeric cobalt complex and relatively easy "control" over reactions also were prerequisites to extending the approaches found to transformations of cobalt trimethylacetates. In this work, we report the results of our studies on the synthesis of the first hexa-and tetranuclear cobalt(n) trimethylacetates.

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