Synthesis and Structure of Heterospin Compounds Based on the [Mn₆(O)₂Piv₁₀]-Cluster Unit and Nitroxide

Reaction of [Mn6(O)2Piv10(Thf)4]·Thf with 2,4,4,5,5-pentamethyl-4,5-dihydro-1H-imidazolyl-3-oxide-1-oxyl (NIT-Me) produces different heterospin compounds depending of the solvent used in the synthesis. Among the latter a new molecular magnet [Mn6(O)2Piv10(Thf)2(NIT-Me)Mn6(O)2Piv10(Thf)(CH2Cl2)(NIT-Me)] with Tc = 3.5 K has been found

Redox-Induced Change in the Ligand Coordination Mode

The reaction of cobalt­(II) pivalate with a spin-labeled Schiff base (HL1) in organic solvents formed trinuclear complex [Co3(Piv)2L12L22]·Solv (Solv is Me2CO and/or C7H16 and CH3CN) containing both nitroxide L1 and the product of its single-electron reduction, nitrone L2. The formation of [Co3(Piv)2L12L22] was a consequence of an unusual phenomenon, which we called “redox-induced change in the ligand coordination mode”. A reduction of L1 to L2 led to a change in the set of donor atoms and even in the size of the metallocycle. This phenomenon was also found for mononuclear [CrL12L2] and [FeL12L2]·Me2CO

Synthesis, Structure, and Magnetic Properties of (6−9)-Nuclear Ni(II) Trimethylacetates and Their Heterospin Complexes with Nitroxides

New polynuclear nickel trimethylacetates [Ni6(OH)4(C5H9O2)8(C5H10O2)4] (6), [Ni7(OH)7(C5H9O2)7(C5H10O2)6(H2O)]·0.5C6H14·0.5H2O (7), [Ni8(OH)4(H2O)2(C5H9O2)12] (8), and [Ni9(OH)6(C5H9O2)12(C5H10O2)4]·C5H10O2·3H2O (9), where C5H9O2 is trimethylacetate and C5H10O2 is trimethylacetic acid, have been found. Their structures were determined by X-ray crystallography. Because of their high solubility in low-polarity organic solvents, compounds 6−9 reacted with stable organic radicals to form the first heterospin compounds based on polynuclear Ni(II) trimethylacetate and nitronyl nitroxides containing pyrazole (L1−L3), methyl (L4), or imidazole (L5) substituent groups, respectively, in side chain [Ni7(OH)5(C5H9O2)9(C5H10O2)2(L1)2(H2O)]·0.5C6H14·H2O (6+1a), [Ni7(OH)5(C5H9O2)9(C5H10O2)2(L2)2(H2O)]·H2O (6+1b), [Ni7(OH)5(C5H9O2)9(C5H10O2)2(L3)2(H2O)]·H2O (6+1c), [Ni6(OH)3(C5H9O2)9(C5H10O2)4(L4)]·1.5C6H14 (6‘ ‘), and [Ni4(OH)3(C5H9O2)5(C5H10O2)4(L5)]·1.5C7H8 (4). Their structures were also determined by X-ray crystallography. Although Ni(II) trimethylacetates may have varying nuclearity and can change their nuclearity during recrystallization or interactions with nitroxides, this family of compounds is easy to study because of its topological relationship. For any of these complexes, the polynuclear framework may be derived from the [Ni6] polynuclear fragment {Ni6(μ4-OH)2(μ3-OH)2(μ2-C5H9O2−O,O‘)6(μ2-C5H9O2−O,O)(μ4-C5H9O2−O,O,O‘,O‘)(C5H10O2)4}, which is shaped like an open book. On the basis of this fragment, the structure of 7-nuclear compounds (7 and 6+1a−c) is conveniently represented as the result of symmetric addition of other mononuclear fragments to the four Ni(II) ions lying at the vertexes of the [Ni6] open book. The 9-nuclear complex is formed by the addition of trinuclear fragments to two Ni(II) ions lying on one of the lateral edges of the [Ni6] open book. This wing of the 9-nuclear complex preserves its structure in another type of 6-nuclear complex (6‘ ‘) with the boat configuration. If, however, two edge-sharing Ni(II) ions are removed from [Ni6] (one of these lies at a vertex of the open book and the other, on the book-cover line), we obtain a 4-nuclear fragment recorded in the molecular structure of 4. Twinning of this 4-nuclear fragment forms highly symmetric molecule 8, which is a new chemical version of cubane

Redox-Induced Change in the Ligand Coordination Mode

The reaction of cobalt­(II) pivalate with a spin-labeled Schiff base (HL1) in organic solvents formed trinuclear complex [Co3(Piv)2L12L22]·Solv (Solv is Me2CO and/or C7H16 and CH3CN) containing both nitroxide L1 and the product of its single-electron reduction, nitrone L2. The formation of [Co3(Piv)2L12L22] was a consequence of an unusual phenomenon, which we called “redox-induced change in the ligand coordination mode”. A reduction of L1 to L2 led to a change in the set of donor atoms and even in the size of the metallocycle. This phenomenon was also found for mononuclear [CrL12L2] and [FeL12L2]·Me2CO

Redox-Induced Change in the Ligand Coordination Mode

The reaction of cobalt­(II) pivalate with a spin-labeled Schiff base (HL¹) in organic solvents formed trinuclear complex [Co₃(Piv)₂L¹₂L²₂]·Solv (Solv is Me₂CO and/or C₇H₁₆ and CH₃CN) containing both nitroxide L¹ and the product of its single-electron reduction, nitrone L². The formation of [Co₃(Piv)₂L¹₂L²₂] was a consequence of an unusual phenomenon, which we called “redox-induced change in the ligand coordination mode”. A reduction of L¹ to L² led to a change in the set of donor atoms and even in the size of the metallocycle. This phenomenon was also found for mononuclear [CrL¹₂L²] and [FeL¹₂L²]·Me₂CO