New polynuclear cobalt trimethylacetate complexes: synthesis and structure

Golubnichaya, M. A.; Сидоров, А. А.; Фомина, И. Г.; Ponina, M. O.; Deomidov, S. M.; Нефедов, С. Е.; Ermenko, I. L.; Моисеев, И. И.

doi:10.1007/bf02494824

Cited by 37 publications

(14 citation statements)

References 11 publications

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“…This behavior strongly differs from the magnetic prop erties of the known symmetrical cubane [Co 4 (µ 3 OMe) 4 (µ 2 OOCBu t ) 2 (η 2 OOCBu t ) 2 (MeOH) 4 ]•4MeOH (8), 11 which we synthesized according to the new method by recrystallization of the tetranuclear complex [Co 4 (µ 3 OH) 2 (µ 2 OOCBu t ) 4 (η 2 OOCBu t ) 2 (EtOH) 4 ]•2EtOH with the planar metal core from methanol. 28 According to the results of magnetic measurements, the effective magnetic moment of complex 8 monotoni cally decreases throughout the 300-2 K temperature range from 9.82 to 4.20 µ B due to spin orbital and spin spin antiferromagnetic exchange interactions (Fig. 3, c).…”

Section: Resultsmentioning

confidence: 91%

Pivalates with the MII 4O4 cubane core (M = Co, Ni): synthesis, structure, magnetic properties, and solid-state thermolysis

et al. 2009

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Methods were developed for the controlled thermal synthesis of high spin cubane like pivalates {M II 4 (µ 3 OR) 4 } (M = Co or Ni; R = H or Me) starting from mono and polynuclear complexes. The solid state thermal decomposition of the known pivalate clusters [M II 4 (µ 3 OMe) 4 (µ 2 OOCBu t ) 2 (η 2 OOCBu t ) 2 (MeOH) 4 ] and the new clusters [M II 4 (µ 3 OH) 4 (η 1 OOCBu t ) 3 (µ (NH 2 ) 2 C 6 H 2 Me 2 ) 3 (η 1 (NH 2 ) 2 C 6 H 2 Me 2 ) 3 ] + (OOCBu t ) -(M = Co or Ni) was studied by differential scanning calorimetry and thermogravimetry. The thermolysis of cubane like Co II and Ni II pivalates is a destructive process. The phase composition of the decomposition products is determined by the nature of coordinated ligands and the structural features of the metal core.Key words: cobalt, nickel, cubane like cobalt and nickel pivalate complexes, 4,5 dimethyl 1,2 phenylenediamine, solid state thermolysis, X ray diffraction study, magnetic properties.Among polynuclear transition metal carboxylates, compounds containing 3d metals, including high spin cobalt(II) and nickel(II) derivatives, are well known to have cubane like structures with the {M 4 O 4 } core. 1-14,** The magnetic behavior of symmetrical cubane like Co II and Ni II containing pivalates is very unusual and depends on the electronic state of the metal center or the charac teristic features of the bridging ligands that partially replace carboxylate groups. 5,11,12 It would be expected that the use of these two factors will facilitate the assembly of new types of magnetoactive cubanes, the results of these chemical transformations of the metal core or the ligand periphery being difficult to predict. These investigations are, apparently, helpful for the development of techniques for the molecular assembly of new molecular magnets as potential components of molecular electronics devices, because certain cubanes containing Co II or Ni II atoms were found to exhibit ferromagnetic properties. 15-19 It should be noted that, in this case, the chemical assembly of the target systems having particular magnetic charac teristics is a key step in the design of such molecular magnetic materials. The control over the composition and fragments of the molecular structures of complexes is an important tool for the directed chemical influence on the magnetic behavior of compounds.In the present study, we examined the possibility of synthesizing new unsymmetrical cubane like Co II and Ni II pivalate complexes and investigated their magnetic prop erties. In addition, we considered ''mild thermolysis'' of known and the newly synthesized cubane like molecules, which can be used as molecular precursors for the prepara tion of oxide materials with different compositions. 8,20-24

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Section: Resultsmentioning

confidence: 91%

Pivalates with the MII 4O4 cubane core (M = Co, Ni): synthesis, structure, magnetic properties, and solid-state thermolysis

et al. 2009

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“…The aim of the present study was to search for condi tions of the formation of stable polymers of constant com position [M(OOCCMe 3 ) 2 ] n containing high spin atoms M = Co II (2) or Ni II (3), which are analogs of polymeric iron pivalate 1, from various polynuclear compounds, in vestigate their structures, the magnetic properties, and solid state thermolysis, and simulate their chemical be havior toward α substituted pyridines, which initiate the formation of tetracarboxylate dimers. 8-10…”

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High-spin carboxylate polymers [M(OOCCMe3)2]n of group VIII 3d metals

et al. 2006

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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...

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“…The start ing trimethylacetate [Cu 2 (piv) 4 (Hpiv) 2 ] and dimethylmalonate [(H 2 O) 8 K 8 Cu 4 (Me 2 mal) 8 ] n were synthesized according to the known procedures. 28, 32 The salts Li 2 cpdc and K 2 Me 2 mal were obtained by neutralization of the corresponding substituted mal onic acid with hydroxides LiOH (analytical grade, Khimmed) or KOH (analytical grade, Khimmed) in water.…”

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confidence: 99%

Effect of geometric parameters of substituted malonate anions on coordination environment of CuII atoms coordinated with 2,2′;6′,2″-terpyridine

et al. 2014

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Structural data for known and newly obtained copper(II) complexes with 2,2´;6´,2 terpyrid ine and substituted malonic (dimethylmalonic, 1,1 cyclopropane and 1,1 cyclobutanedicar boxylic) acid dianions R 2 mal 2-were used to show that the coordination environment of the metallocenter depends on the (O 2 C)C-C-C(CO 2 ) angle. A chelate coordination of the R 2 mal 2-dianion is realized for 1,1 cyclopropanedicarboxylate anion (~122.9), while the di methylmalonate and 1,1 cyclobutanedicarboxylate anions (107.4-110.8) are characterized by a monodentate coordination.It is known that the design of coordination compounds is frequently determined by the result of the selection of certain conditions (electronic or geometric) allowing to purposefully synthesize mono and polynuclear complex es of various architecture and composition. The means to control composition and structure of metal complexes in clude the use of ligands of different denticity, introduction in /removal from the metal atom coordination sphere of labile molecules blocking the coordination sites, "switch ing" of polydentate ligand functions (for example, from chelating to bridging). Carboxylate groups in transition metal complexes can exhibit monodentate, chelating, bridging, or chelate bridging types of coordination. The importance of studies of approaches to the assemblage of such complexes is determined by the necessity to synthe size new types of compounds, promising as the compo nents in various areas of application, such as, for example, development of photoactive systems, catalysis, nonlinear optics, or magnetism. 1-6Among polycarboxylic acids, malonic acid derivatives R 2 C(COOH) 2 (H 2 R 2 mal) attract special attention. The ability of their dianions to serve as both chelating and bridging ligands is important for the formation of stable structural blocks capable of forming more complicated architectures. For example, transition metal ions in the presence of a two fold excess of R 2 mal 2-can form mono nuclear fragments of the formula [M(R 2 mal) 2 L x ] 2-(M = V, Mn, Co, Ni, Cu, Zn; L is the neutral ligand, for example, H 2 O, x = 0-2), which depending on the cation nature form molecular or polymeric ionic compounds. 7-12 The blockage of some positions of the metallocenter coor dination surrounding with donor polydentate molecules can result in the change of the polymeric structure topolo gy, 13-17 leading to different types of coordination of carb oxylate anions or even to the formation of discrete mole cules. 18-22 Thus, in the work 23 it was demonstrated that the reaction of Cu(ClO 4 ) 2 , Na 2 mal, and 1,10 phenan throline (1,10 phen), depending on the reaction and crys tallization conditions, can lead to molecular complexes of different nuclearity or a coordination polymer based on the fragment {Cu(mal)(1,10 phen)}.Therefore, it can be suggested that a deliberate con finement of the metallocenter coordination sphere by means of strongly bound polydentate (for example, tri dentate) ligands would make it possible to find approaches to the di...

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New polynuclear cobalt trimethylacetate complexes: synthesis and structure

Cited by 37 publications

References 11 publications

Pivalates with the MII 4O4 cubane core (M = Co, Ni): synthesis, structure, magnetic properties, and solid-state thermolysis

Pivalates with the MII 4O4 cubane core (M = Co, Ni): synthesis, structure, magnetic properties, and solid-state thermolysis

High-spin carboxylate polymers [M(OOCCMe3)2]n of group VIII 3d metals

Effect of geometric parameters of substituted malonate anions on coordination environment of CuII atoms coordinated with 2,2′;6′,2″-terpyridine

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