Transformations of high spin MnII and FeII polymeric pivalates in reactions with pivalic acid and o-phenylenediamines

Кискин, М. А.; Александров, Г. Г.; Доброхотова, Ж. В.; Новоторцев, В. М.; Shvedenkov, Yu. G.; Еременко, И. Л.

doi:10.1007/s11172-006-0337-5

Cited by 14 publications

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“…5) demonstrate that poly mer 2, like iron containing polymer 1 (T c = 3.8 K at H = 1 Oe), 16 undergoes the magnetic phase transition to the ordered state at T c = 3.4 K (H = 1 Oe) (see Fig. 5, b) and exhibits the properties of a soft magnet (without a hyster esis loop).…”

Section: Resultsmentioning

confidence: 92%

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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Section: Resultsmentioning

confidence: 92%

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

et al. 2006

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“…These structurally similar products are the known mono nuclear complex Co(η 2 (NH 2 ) 2 C 6 H 2 Me 2 )(η 1 (NH 2 ) 2 C 6 H 2 Me 2 ) 2 (OOCBu t ) 2 (5) 26 or the newly synthesized complex Ni(η 2 (NH 2 ) 2 C 6 H 2 Me 2 )(η 1 (NH 2 ) 2 C 6 H 2 Me 2 ) 2 (OOCBu t ) 2 (6), which is the crystallographically isostruc tural analog of the other known compound Fe(η 2 (NH 2 ) 2 C 6 H 2 Me 2 )(η 1 (NH 2 ) 2 C 6 H 2 Me 2 ) 2 (OOCBu t ) 2 . 27 The storage of dilute ethanolic solutions of complexes 5 and 6 results in crystallization of compounds 3 and 4, respectively. Undoubtedly, water that is present in ethanol (used as the solvent) plays a great role in the formation of the {M 4 (µ 3 OH) 4 } cubane like core; however, the influence of hydrocarbon substituents in ROH, apparently, cannot be excluded as well.…”

Section: Resultsmentioning

confidence: 99%

“…Blue crystal that precipitated after correspond to those of the molecular structure of Fe(η 2 (NH 2 ) 2 C 6 H 2 Me 2 )(η 1 (NH 2 ) 2 C 6 H 2 Me 2 ) 2 (OOCBu t ) 2 determined earlier by X ray diffraction. 27 B. Methanol (60 mL) was added to the complex Ni 6 (µ 2 OOCBu t ) 6 (µ 3 OOCBu t ) 6 (2) (0.3 g, 0.192 mmol) and 4,5 dimethyl 1,2 phenylenediamine (0.313 g, 2.3 mmol), and the reaction mixture was heated under argon at 60 °C until the starting reagents completely dissolved. The bright blue solution was filtered and concentrated at 0.1 Torr and 20 °C to 20 mL.…”

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“…correspond to those of the molecular structure of Fe(η 2 (NH 2 ) 2 C 6 H 2 Me 2 )(η 1 (NH 2 ) 2 C 6 H 2 Me 2 ) 2 (OOCBu t ) 2 established earlier by X ray diffraction. 27 Tetra(µ µ µ µ µ 3 methoxo)mono(η η η η η 1 trimethylacetato)mono (η η η η η 2 O,O´ trimethylacetato)bis(µ µ µ µ µ 2 O,O´ trimethylacetato)bis (η η η η η 2 4,5 dimethyl 1,2 phenylenediamino)mono(η η η η η 1 methanol) tetranickel pivalic acid and methanol solvate, [Ni 4 (µ µ µ µ µ 3 OMe) 4 (η η η η η 1 OOCBu t )(η η η η η 2 OOCBu t )(µ µ µ µ µ 2 OOCBu t ) 2 (η η η η η 2 (NH 2 ) 2 C 6 H 2 Me 2 ) 2 (MeOH)]•HOOCBu t 3 •MeOH (7•HOOCBu t •MeOH). A. Methanol (60 mL) was added to the complex Ni 6 (µ 2 OO CBu t ) 6 (µ 3 OOCBu t ) 6 (2) (0.…”

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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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“…The magnetic behavior of these molecular systems strongly depends on the geometry and electronic structure [2][3][4][5]. In a search for novel high spin metal containing systems we attempted to synthesize new manganese(II) carboxylates as precursors for ''spin material'' in molecular spintronic devices [6].…”

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