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

A coordination polymer of the general formula [Co(OOCCMe₃)₂]_n (2) was prepared by mild thermolysis of the coordination polymer of variable composition [(HOOCCMe₃)_xCo(OH)_n(OOCCMe₃)_2−n ]_m, the dinuclear cobalt complex Co₂(μ-H₂O)(OOCCMe₃)₄(HOOCCMe₃)₄, the tetranuclear cobalt cluster Co₄(μ₃-OH)₂(OOCCMe₃)₆(HOEt)₆, and the hexanuclear cluster [Co₆(μ₄-O)₂(μ_n-OOCCMe₃)₁₀(C₄H₈O)₃(H₂O)]·1.5(C₄H₈O) (7) in organic solvents. In the crystal, the polymer has a chain structure. Unlike thermolysis of cobalt pivalates, thermolysis of the dinuclear complex Ni₂(μ-H₂O)(OOCCMe₃)₄(HOOCCMe₃)₄ gave rise to the hexanuclear complex Ni₆(μ₂-OOCCMe₃)₆(μ₃-OOCCMe₃)₆ (3). The magnetic properties of compound 2 are substantially 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) afforded the octanuclear cluster Co₈(μ₄-O)₂(μ₂-OOCCMe₃)₆(μ₃-OOCCMe₃)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-Me₂C₅H₃N)₂M₂(μ-OOCCMe₃)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. Dedicated to Academician O. M. Nefedov on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1841–1850, November, 2006.     

Synthesis and structures of nickel(II) trimethylacetate dimers with coordinated diamines

Thermal decomposition of the tetranuclear nickel(II) complex Ni₄lη²-o-(NH₂)(NHPh)C₆H₄|₂(MeCN)₂(μ-OOCCMe₃)₄(η²-OOCCMe₃)₂ (I) under an inert atmosphere (o-xylene, 140 °C) was investigated. Under these conditions, the asymmetric binuclear complex Ni|η²-o-(NH₂)(NHPh)C₆H₄‖(η¹-o-(NH₂))(NHPh)C₆H₄|(η²,η-O,O-OOCCMe₃)(η²-OOCCMe₃) (2) was formed at the first stage. Complex2 was converted into the symmetric dimer Ni|η¹-o-(NH₂)(NHPh)C₆H₄|(μ-OOCCMe₃)₄ (3) upon recrystallization from benzene. The structures of complexes2 and3 were established by X-ray diffraction analysis. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1915–1918, November, 2000.     

Trimethylacetate nickel complexes

The present review is devoted to the chemistry of trimethylacetate Ni^II complexes with various nitrogen-containing ligands. Pathways of formation of complexes containing the Ni₂(μ-OH₂)(μ-OOCCMe₃)₂ and Ni₂(μ-OOCCMe₃)₄ fragments are discussed. Pathways of degradation of the nine-nuclear complex Ni₉(HOOCCMe₃)₄(μ₄-OH)₃(μ₃-OH)₃)₃(μ₄-OOCCMe₃)₁₂ under the action of primary amines (aniline or propargylamine) as well as the process of dehydration ofN-phenyl-o-phenylenediamine up to the bischelate mononuclear complex [1,2-(NH)(NPh)C₆H₄]₂Ni are demonstrated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 409–419, March, 1999.     

Formation of cobalt(iii) cations with semiquinonediimine ligands

The reactions of polynuclear cobalt(ii) trimethylacetates [Co(OH) _n (OOCCMe₃)_2–n ] _x , Co₆(₃-OH)₂(OOCCMe₃)₁₀(HOOCCMe₃)₄, or Co₄(₃-OH)₂(OOCCMe₃)₆(HOEt)₆ with an excess of N-phenyl-o-phenylenediamine (1) in toluene followed by treatment with atmospheric oxygen afforded the diamagnetic complex [Co{²-(NPh)(NH)C₆H₄}₂{¹-(NH₂)C₆H₄(NPhH)}]⁺(Me₃CCOO...H...OOCCMe₃)^– (3), whose cation contains the Co^III atom. The reaction of Co₄(₃-OH)₂(OOCCMe₃)₆(HOEt)₆ with a deficient amount of diamine 1 in acetonitrile under an argon atmosphere gave rise to the antiferromagnetic ionic complex [Co{²-(NPh)(NH)C₆H₄}₂MeCN]⁺[Co₂(₂,²-OOCCMe₃)(₂-OOCCMe₃)₂(²-OOCCMe₃)₂]^–·2MeCN (4), whose cation is an isoelectronic analog of the cation in complex 3. The structures of the new compounds were established by X-ray diffraction analysis.     

Dinuclear rhodium(II) pivalate complexes with N-donor ligands

Eight dinuclear rhodium(II) complexes containing various, (primarily, polyfunctional) N-donor ligands in the trans position with respect to the Rh-Rh bond were synthesized and characterized by X-ray diffraction. In the Chinese-lantern dinuclear rhodium(II) pivalates, Rh^II ₂ (μ-OOCCMe₃)₄(L)₂ (L is 2,3-diaminopyridine (2), 7,8-benzoquinoline (4), 2,2′:6′,2″-terpyridine (5), N-phenyl-o-phenylenediamine (7)), and Rh^II ₂ (μ-OOCCMe₃)₄L¹L² (3, L¹ is 2-phenylpyridine, L² = MeCN), the steric effects of the axial ligands are most strongly reflected in the Rh-N(L) and Rh-Rh bond lengths. The introduction of chelating ligands containing a conformationally rigid chelate ring leads to the cleavage of two carboxylate bridges to form the dinuclear double-bridged structure Rh^II ₂ (μ- OOCCMe₃)₂(OCCMe₃)₂(η²-L³)₂, where L³ is 8-amino-2,4-dimethylquinoline (6). The reaction of complex 7 containing coordinated N-phenyl-o-phenylenediamine with pyrrole-2,5-dialdehyde afforded the new Rh^II ₂(μ-OOCCMe₃)₄(L⁴)₂ complex (8) containing 5-(1-phenyl-1-H-benzimidazol-2-yl)-1H-pyrrole-2-carbaldehyde (L⁴) in the axial positions of the dirhodium tetracarboxylate fragment. The coordinated diamine differs in reactivity from the free diamine. The reaction of the former with the above dialdehyde affords the [1+1]-condensation product, viz., 5-{(E)-[(2-anilinophenyl)imino]methyl}-1-H-pyrrole-2-carbaldehyde, whereas the reaction of unsubstituted o-phenylenediamine gives 5-{(E)-[(2-aminophenyl)imino]methyl}-1-H-pyrrole-2-carbaldehyde (L⁵) . The reaction of the latter with Rh^II ₂(μ-OOCCMe₃)₄(H₂O)₂ affords the dinuclear complex Rh^II ₂(μ-OOCCMe₃)₂(OOCCMe₃)₂(η²-L⁵)₂ (9), which is an analog of complex 6 containing only two bridging carboxylate groups.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 581–591, March, 2005.     

Formation and Transformations of Polynuclear Hydroxo- and Oxotrimethylacetate Complexes of Ni(II) and Co(II)

Transformations of polymeric trimethylacetate complexes [M(OH) _n (OOCCMe₃)_{2 – n} ] _m (M = Ni (I) and Co (II)) and clusters Ni₉(₄-OH)₃(₃-OH)₃(-O,O-OOCCMe₃)(-O,O"-OOCCMe₃)₇(₃-O,O,O"-OOCCMe₃)₃(₄-O,O,O",O"-OOCCMe₃)(HOOCCMe₃)₄(III) and Co₆(₃-OH)₂(-OOCCMe₃)₁₀(HOOCCMe₃)₄(VIII), which are formed from Iand IIupon their recrystallization from nonpolar solvents, were studied. It was shown that the action of N-phenyl-o-phenylenediamine (L) on Ior IIIresults, depending on the solvent, in different tetranuclear clusters with the hydroxo bridges. For example, in benzene, the L₂Ni₄(₃-OH)₂(HOOCCMe₃)₄(-OOCCMe₃)₆complex (IX) is formed; its L molecules are coordinated in a monodentate way, whereas in acetonitrile, they chelate to give the {[o-C₆H₄(NH₂)(NHPh)]₂Ni₄(₃-OH)₂(MeCN)₂(OOCCMe₃)₂(-OOCCMe₃)₄} compound (X). Heating of Xin the presence of atmospheric oxygen yields IX, the mononuclear bissemiquinonediimine [o-C₆H₄(NH)(NPh)]₂Ni complex (XI), and water. It was noted that the use of aniline in these reactions affords, independent of the nature of the solvent, only one (NH₂C₆H₅)₂Ni₄(₃-OH)₂(HOOCCMe₃)₄(-OOCCMe₃)₆cluster (VI); in acetonitrile, this cluster is formed as the solvate VI· 2HOOCCMe₃(VIa). When treated with ethanol, Iand IIIgive the Ni₄(EtOH)₆(₃-OH)₂(₂-OOCCMe₃)₄(OOCCMe₃)₂cluster (V), which is structurally close to the known cobalt-containing analog IV. Thermolysis of IVin decalin at 170° causes its dimerization, giving the octanuclear Co₈(₄-O)₂( _n -OOCCMe₃)₁₂complex (VII) with the tetradentate oxo bridges.     

Magnetic properties of binuclear high-spin trimethylacetate nickel(II) complexes

The static magnetic susceptibility of mononuclear trimethylacetate nickel complex Ni(NH₂Ph)₄(OOCCMe₃)₂ (3) and binuclear complexes Ni₂(μ-OH₂)(μ-OOCCMe₃)₂(OOCCMe₃)₂(dipy)₂ (4) and Ni₂(μ-OOCCMe₃)₄py₂ (5) was measured in the temperature range of 2–300 K. The magnetic behavior of3 is typical of mononuclear complexes with the Ni¹¹ atom in the octahedral environment. Numerical calculations of the temperature dependence of magnetic susceptibility with inclusion of isotropic exchange interactions (J) and single-ion initial splitting parameters showed that the magnetic behavior of complexes4 and 5 can be interpreted in terms of ferromagnetic (for4) and antiferromagnetic (for5) interactions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 437–442, March, 2000.     

Role of metal center in reactions of polynuclear nickel(ii) and cobalt(ii) trimethylacetates with 8-amino-2,4-dimethylquinoline

The reactions of 8-amino-2,4-dimethylquinoline (L) (1) with polynuclear nickel(ii) and cobalt(ii) hydroxotrimethylacetato complexes under anaerobic conditions were studied. The nonanuclear cluster Ni₉(₄-OH)₃(₃-OH)₃(_n-OOCCMe₃)₁₂(HOOCCMe₃)₄ gave the mononuclear complex Ni(²-L)(²-OOCCMe₃)₂ (2). The tetranuclear complex Ni₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆ produced the mononuclear complex Ni(²-L)(²-OOCCMe₃)(OOCCMe₃)L (3). At room temperature, the cobalt-containing polynuclear trimethylacetates, viz., the polymer [Co(OH) _n (OOCCMe₃)_2–n ] _x and the tetranuclear complex Co₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆, were transformed into the trinuclear cobalt(ii) complex Co₃(₃-OH)(-OOCCMe₃)₄(²-L)₂(OOCCMe₃) (4). Meanwhile, at 80 °C these compounds generated the binuclear cobalt(iii) complex Co₂(₂²-(HN)C₉NMe₂)₂(-OOCCMe₃)(L)(OOCCMe₃)₃ (5). The structures of the resulting compounds were established by X-ray diffraction analysis. Compounds 2—4 exhibit the antiferromagnetic spin-spin exchange coupling, whereas compound 5 is diamagnetic.     

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

The thermolysis and reactions of the polymeric high spin Mn^II and Fe^II complexes [Mn(μ-OOCBu^t)₂(HOEt)]_n (1) and [Fe(μ-OOCBu^t)₂]_n (3) with pivalic acid and o-phenylenediamines 1,2-(NH₂)₂C₆H₂R₂ (R = H or Me) were studied. The synthesis of compound 1 performed with a deficiency of pivalate anions affords the antiferromagnetic chloropivalate polymer { (MeCN)(HOOCBu^t)(H₂O)Mn₅Cl(OH)(OOCBu^t)₈·MeCN}_n. The reaction of 1 with an excess of pivalic acid produces the antiferromagnetic polymer [Mn₄(OOCBu^t)₈(HOOCBu^t)₂]_n. The analogous reaction of pivalic acid with polymer 3 gives the mononuclear complex Fe(η ¹-OOCBu^t)₂(η¹-HOOCBu^t)₄ containing the high spin iron(II) atom as the major product. Study of the reactions of 3 with a deficiency (<1: 1) and an excess (>1: 1) of diamines demonstrated that the polymer {[(η²-(NH₂)₂C₆H₄)₂Fe(μ-OOCBu^t)₂][Fe₂(μ-OOCBu^t)₄] · · 2MeCN}_n is generated as the major product in the former case, whereas the mononuclear complexes Fe(η¹-OOCBu^t)₂[η¹-(NH₂)₂C₆H₄]₄ and Fe(η¹-OOCBu^t)₂[η²-(NH₂)₂C₆H₂Me₂][η¹-(NH₂)₂C₆H₂Me₂]₂ are predominantly obtained in the latter case. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 779–792, May, 2006.     

Mono-and polynuclear CoII complexes with 2-hydroxy-6-methylpyridine

The reaction of 2-hydroxy-6-methylpyridine with Co(NO₃)₂·6H₂O or Co(F₃CSO₃)₂·6H₂O in the absence of a deprotonating agent produces the mononuclear complexes Co(HL)₄(NO₃)₂ or Co(HL)₄(F₃CSO₃)₂ (HL is 6-methyl-2-pyridone), respectively. In the presence of triethylamine, the reaction affords the trinuclear complex Co₃(HL)₂(L)₄(NO₃)₂ or the heptanuclear dicationic complex [Co₇L₁₂]·(F₃CSO₃)₂·4MeCN in the case of cobalt nitrate or cobalt trifluoromethanesulfonate, respectively. When HL is deficient, the replacement of the trimethylacetate anions in polymeric cobalt pivalate [Co(OH)_n(OOCCMe₃)_2−n ]_x gives rise to the hexanuclear complex Co₆(μ₃-OH)₂(η²,μ₃-L)₂(μ-OOCCMe₃)₈(HOOCCMe₃)₄, whereas the HLCo₆(μ₃-OH)(η²,μ₃-L)₃(η²,μ-L) (μ₃-L)(μ₃-OOCCMe₃)(μ-OOCCMe₃)₄(η²-OOCCMe₃) complex is generated when HL is present in excess. The structures of the reaction products were established by X-ray diffraction. Dedicated to Academician O. M. Nefedov on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1851–1862, November, 2006.     

Unsymmetrical dinuclear cobalt and nickel trimethylacetate complexes

The reaction of the dinuclear complex Co₂(-OOCCMe₃)₂(²-OOCCMe₃)₂bpy₂ (1) with the polymer [Co(OH) _n (OOCCMe₃)_2–n ] _x afforded the unsymmetrical dinuclear complex bpyCo₂(₂-O,²-OOCCMe₃)(₂-O,O"-OOCCMe₃)₂(²-OOCCMe₃) (2). The reaction of 2,2"-dipyridylamine with [Co(OH) _n (OOCCMe₃)_2–n ] _x gave rise to the analogous complex [(C₅H₄N)₂NH]Co₂(₂-O,²-OOCCMe₃)(-OOCCMe₃)₂(²-OOCCMe₃) (3). The reaction of complex 1 with Ni₄(₃-OH)₂(-OOCCMe₃)₄(OOCCMe₃)₂(MeCN)₂[²-o-C₆H₄(NH₂)(NHPh)]₂ (4) produced an isostructural heterometallic analog of complex 2 with composition bpyM₂(₂-O,²-OOCCMe₃)(₂-O,O"-OOCCMe₃)₂(²-OOCCMe₃) (5) (M = Co, Ni; Co : Ni = 1 : 1) and the dinuclear heterometallic complex bpy(HOOCCMe₃)M(-OH₂)(-OOCCMe₃)₂M(OOCCMe₃)₂[o-C₆H₄(NH₂)(NHPh)] (6) (M = Co, Ni; Co : Ni = 0.15 : 1.85). Compounds 2 and 5 exhibit ferromagnetic spin-spin exchange interactions.     

New polynuclear cobalt trimethylacetate complexes: synthesis and structure

Extraction of polymer (1), formed in the reaction of CoCl₂ with KOOCBu^t, with boiling hexane gives crystals of hexamer Co₆(μ₃-OH)₂(OOCBu¹)₁₀(HOOCBu¹)₄ (2). According to data of X-ray study, four Co¹¹ atoms in the hexanuclear molecule2 have an octahedral ligand environment and two Co¹¹ atoms have a tetrahedral one. Dissolution of polymer1 in EtOH results in its splitting into Co₄(μ₃-OH)₂(OOCBu¹)₆(HOEt)₆ tetramers (3). In molecule3, two asymmetric dimeric (η²-OOCBu^t)(EtOH)Co(μ-OOCBu^t)Co(HOEt)₂ fragments are bound by two tridentate bridging OH groups. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1773–1778, September, 1999.     

Thermal decomposition of dinuclear complexes LM(μ-OOCR)<Subscript>4</Subscript>ML (L is α-substituted pyridine)

The solid-state thermal decomposition of the tetrabridged dinuclear Mn^II, Fe^II, Co^II, Ni^II, and Cu^II pivalate complexes with apical α-substituted pyridine ligands containing different substituents (2,3-dimethylpyridine or quinoline) was studied by differential scanning calorimetry and thermogravimetry. The decomposition of the Co^II complexes is accompanied by the aggregation to form the volatile octanuclear complex Co₈(μ₄-O)₂(μ_n-OOCCMe₃)₁₂, where n = 2 or 3, whereas the thermolysis of the Mn^II, Fe^II, Ni^II, and Cu^II complexes is accompanied by the degradation of the starting compounds, the phase composition of the decomposition products being substantially dependent on the nature of metal and the apical organic ligand. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1650–1659, September, 2007.     

Crystal structure and spectroscopic properties of polymeric adducts of the tetra-μ-haloaspirinate-dicopper(II)

Eight new copper(II) complexes with halo-aspirinate anions have been synthesized: [Cu₂(Fasp)₄(MeCN)₂]?·?2MeCN (1), [Cu₂(Clasp)₄(MeCN)₂]?·?2MeCN (2), [Cu₂(Brasp)₄(MeCN)₂]?·?2MeCN (3), {[Cu₂(Fasp)₄(Pyrz)]?·?2MeCN} _n (4), {[Cu₂(Clasp)₄(Pyrz)]?·?2MeCN} _n (5), [Cu₂(Brasp)₄(Pyrz)] _n (6), [Cu₂(Clasp)₄(4,4′-Bipy)] _n (7), and [Cu₂(Brasp)₄(4,4′-Bipy)] _n (8) (Fasp: fluor-aspirinate; Clasp: chloro-aspirinate; Brasp: bromo-aspirinate; MeCN: acetonitrile; Pyrz: pyrazine; 4,4′-Bipy: 4,4′-bipyridine). The crystal structure of two 2 and 4 have been determined by X-ray diffraction methods. All compounds have been studied employing elemental analysis, IR, and UV-Visible spectroscopic techniques. The results have been compared with previous data reported for complexes with similar structures.     

Formation of bi- and tetranuclear cobalt(ii) trimethylacetate complexes with 2-amino-5-methylpyridine and 2,6-diaminopyridine

The reactions of the polymeric complex [Co(OH)_n(OOCCMe₃)_2–n ]_x (1) with 2-amino-5-methylpyridine (L₁) and 2,6-diaminopyridine (L₂) under anaerobic conditions at the ratio M : L = 1 : 1 afforded the binuclear complexes Co₂(-OOCCMe₃)₄[-MeC₅H₃N(NH₂)]₂ (2) and Co₂(-OOCCMe₃)₄[-C₅H₃N(NH₂)₂]₂ (3), respectively, with Chinese-lantern-like structures. The reaction of the tetranuclear cobalt(ii) complex Co₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆ (4) with 2,6-diaminopyridine under anaerobic conditions at the ratio M : L₂ = 2 : 1 gave rise to the antiferromagnetic tetranuclear complex Co₄(₄-O)[-C₅H₃N(NH₂)₂]₂(-OOCCMe₃)₄(²-OOCCMe₃)₂ (5) with tetradentate-bridging coordination of the oxygen atom. The structures of the compounds synthesized were established by X-ray diffraction analysis.     

New antiferromagnetic tetranuclear pivalate complex containing Fe<Superscript>III</Superscript> and Fe<Superscript>II</Superscript> atoms

The interaction of [K₂Fe^III ₄(O)₂(OOCCMe₃)₁₀(HOOCCMe₃)₂(H₂O)₂]_n with 2-pyridinecarboxaldehyde results in a mixed-valence complex Fe^IIFe^III ₃(μ₃-O)₂(μ₂-OOCCMe₃)₇L₂··2.5MeCN·3H₂O (L = 2-NC₅H₄COOH_0.75K_0.25). The structure of the complex was established by X-ray analysis. The magnetic properties of the complex were studied. Dedicated to Academician A. L. Buchachenko on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2145–2148, September, 2005.     

Chemical assembly of a new heterometallic trimethylacetate cluster with the Co6Ni2 core

Co-thermolysis of the tetranuclear trimethylacetate clusters M₄(₃-OH)₂(OOCCMe₃)₆(HOEt)₆ (M = Co or Ni; the reagent ratio was 1 : 1) in decalin (2 h, 170 °C) afforded the octanuclear heterometallic cluster Co₆Ni₂(₄-O)₂(₂-OOCCMe₃)₆(₃-OOCCMe₃)₆, which exhibits ferromagnetic properties at 10—8 K.     

Polynuclear iron(III) pivalates

The formation of magnetically active polynuclear Fe^III pivalates in the FeSO₄·7H₂O-KOOCCMe₃ system was studied. The reaction of FeSO₄·7H₂O (1) with KOOCCMe₃ in EtOH in air afforded the antiferromagnetic trinuclear complex [Fe₃O(OOCCMe₃)₆(H₂O)₃]⁺[OOCCMe₃]^–·3EtOH. A change of the solvent (EtOH) in this system to a 40:1 benzene—THF mixture resulted in the formation of the antiferromagnetic hexanuclear cluster [Fe₆(O)₂(OH)₂(OOCCMe₃)₁₂(HOOCCMe₃)(THF)]·1.5C₆H₆. The addition of trimethylacetic acid to EtOH and recrystallization from hexane gave rise to the antiferromagnetic coordination polymer [K₂Fe₄(O)₂(OOCCMe₃)₁₀(HOOCCMe₃)₂(H₂O)₂]_n (7). Recrystallization of the latter from acetonitrile afforded the antiferromagnetic tetranuclear complex K₂Fe₄(O)₂(OOCCMe₃)₁₀(HOOCCMe₃)₂(MeCN)₂. The structures of these compounds were established by X-ray diffraction analysis, and their magnetic susceptibilities and thermal decomposition were investigated.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2403–2413, November, 2004.     

New cobalt and iron pivalate complexes with 2,2′:6′,2″-terpyridine: synthesis, structure, and magnetic properties

The mononuclear complexes (η³-terpy)M(Piv)²·MeCN (M = Fe ⁱⁱ (3) and Co ⁱⁱ (4), and Piv is the pivalate anion) were synthesized by the reactions of polymeric iron(ii) and cobalt(ii) pivalates with 2,2′:6′,2″-terpyridine (terpy). The oxidation of compound 3 affords the pentanuclear heterospin iron(ii,iii) complex (η³-terpy)Fe₅(μ₄-O)(μ₃-OH)(μ-OH)₂(μ-Piv)₇(η¹-Piv)₂ (5). All compounds were characterized by X-ray diffraction. Dedicated to the 90th anniversary of the L. Ya. Karpov Institute of Physical Chemistry. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1186–1190, June, 2008.     

Replacement of carboxylate bridges in polynuclear nickel pivalates with 2-hydroxy-6-methylpyridine anions

The reaction of 2-hydroxy-6-methylpyridine (HL, 1) with nonanuclear nickel trimethyl-acetate Ni₉(OH)₆(OOCCMe₃)₁₂(HOOCCMe₃)₄ (2) in MeCN with a ratio M: L = 1: 1 under mild conditions (20 °C, 15 min) led to degradation of the metal core to form the hexanuclear complex (HL)₂(μ ₂-HL)₂Ni₆(μ₃-OH)₂(μ₂-H₂O)₂(μ-OOCCMe₃)₈(η-OOCCMe₃)₂ (3). Further heating of 3 in acetonitrile at 80 °C for 4 h afforded the (HL)Ni₆(μ ₃-OH)(μ₃,η²-L)₃(μ,η²-L)(μ₃-L)(μ ₃-OOCCMe₃)(μ-OOCCMe₃)₄(η²-OOCCMe₃) complex. The reaction with the use of a 2: 1 THF-EtOH mixture instead of acetonitrile at 50 °C gave the decanuclear complex [Ni₁₀(μ ₃-O)₂(μ₃-OH)₄(μ-OOCCMe₃)₆(μ₃,η ²-L)₆(EtOH)₆](H₂O)₂, which is also produced from compounds 1 and 2 in ethanol. The structures of the resulting complexes were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 908–917, May, 2007.