Carbon–Carbon Bond Formation Reactivity of a Four-Coordinate NHC-Supported Iron(II) Phenyl Compound

The preparation and characterization of a NHC-coordinated (NHC = N-heterocyclic carbene) ferrous phenyl complex [(IPr₂Me₂)₂FePh₂] (<b>1</b>; IPr₂Me₂ = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) as well as its C–C bond formation reactivity have been studied. The four-coordinate iron­(II) phenyl complex was prepared from the reaction of ferrous chloride with PhMgBr and IPr₂Me₂. It reacts with nonactivated primary and secondary alkyl bromides and chlorides to furnish cross-coupling products and the iron­(II) monophenyl species (IPr₂Me₂)₂FePhX (X = Br (<b>2</b>), Cl). When it is treated with cyclooctatetraene (cot) or [Cp₂Fe]­[BAr^F₄] in the presence of PMe₃, it undergoes coordination or one-electron oxidation induced reductive elimination of biphenyl to form the corresponding iron(0) or iron­(I) species [(IPr₂Me₂)₂Fe­(η⁴-cot)] (<b>3</b>) or [(IPr₂Me₂)₂Fe­(PMe₃)₂]­[BAr^F₄] (<b>4</b>). All of these iron-containing products have been fully characterized by various spectroscopic methods. Complex <b>1</b> and (IPr₂Me₂)₂FeCl₂ catalyze the reaction of <i>n</i>-C₈H₁₇Br with (<i>p</i>-tolyl)­MgBr to afford the cross-coupling product in moderate yields (49% and 47%), whereas the reactions employing <b>4</b> and <b>1</b>/PMe₃ as catalysts give the cross-coupling product in very low yields. The results reflect the complexity of the reaction mechanism of iron-catalyzed coupling reactions

Carbon–Carbon Bond Formation Reactivity of a Four-Coordinate NHC-Supported Iron(II) Phenyl Compound

The preparation and characterization of a NHC-coordinated (NHC = N-heterocyclic carbene) ferrous phenyl complex [(IPr₂Me₂)₂FePh₂] (<b>1</b>; IPr₂Me₂ = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) as well as its C–C bond formation reactivity have been studied. The four-coordinate iron­(II) phenyl complex was prepared from the reaction of ferrous chloride with PhMgBr and IPr₂Me₂. It reacts with nonactivated primary and secondary alkyl bromides and chlorides to furnish cross-coupling products and the iron­(II) monophenyl species (IPr₂Me₂)₂FePhX (X = Br (<b>2</b>), Cl). When it is treated with cyclooctatetraene (cot) or [Cp₂Fe]­[BAr^F₄] in the presence of PMe₃, it undergoes coordination or one-electron oxidation induced reductive elimination of biphenyl to form the corresponding iron(0) or iron­(I) species [(IPr₂Me₂)₂Fe­(η⁴-cot)] (<b>3</b>) or [(IPr₂Me₂)₂Fe­(PMe₃)₂]­[BAr^F₄] (<b>4</b>). All of these iron-containing products have been fully characterized by various spectroscopic methods. Complex <b>1</b> and (IPr₂Me₂)₂FeCl₂ catalyze the reaction of <i>n</i>-C₈H₁₇Br with (<i>p</i>-tolyl)­MgBr to afford the cross-coupling product in moderate yields (49% and 47%), whereas the reactions employing <b>4</b> and <b>1</b>/PMe₃ as catalysts give the cross-coupling product in very low yields. The results reflect the complexity of the reaction mechanism of iron-catalyzed coupling reactions

Calix[4]arene-Supported Mononuclear Lanthanide Single-Molecule Magnet

Three new single paramagnetic lanthanide-based complexes, [Ln­(L)­(L_OEt)] (Ln³⁺ = Dy³⁺, Tb³⁺, and Ho³⁺), are synthesized with the multidentate calix[4]­arene ligand H₂L (H₂L = 5,11,17,23-tetrakis­(1,1-dimethylethyl)-25,27-dihydroxy-26,28-dimethoxycalix[4]­arene) and Kläui’s tripodal ligand L_OEt^– (L_OEt^– = (η⁵-cyclopentadienyl)­tris­(diethylphosphito-<i>p</i>)­cobaltate­(III)). All of the complexes have been characterized by single crystal X-ray diffraction analysis, thermal stability, absorption spectra, and magnetization measurements. The magnetic properties and magnetostructural correlation in this seven-coordinated system are investigated. The dysprosium complex <b>1</b> shows typical single-molecule magnetic behavior with characteristic magnetic hysteresis loops and the slow relaxation of magnetization

Calix[4]arene-Supported Mononuclear Lanthanide Single-Molecule Magnet

Three new single paramagnetic lanthanide-based complexes, [Ln­(L)­(L_OEt)] (Ln³⁺ = Dy³⁺, Tb³⁺, and Ho³⁺), are synthesized with the multidentate calix[4]­arene ligand H₂L (H₂L = 5,11,17,23-tetrakis­(1,1-dimethylethyl)-25,27-dihydroxy-26,28-dimethoxycalix[4]­arene) and Kläui’s tripodal ligand L_OEt^– (L_OEt^– = (η⁵-cyclopentadienyl)­tris­(diethylphosphito-<i>p</i>)­cobaltate­(III)). All of the complexes have been characterized by single crystal X-ray diffraction analysis, thermal stability, absorption spectra, and magnetization measurements. The magnetic properties and magnetostructural correlation in this seven-coordinated system are investigated. The dysprosium complex <b>1</b> shows typical single-molecule magnetic behavior with characteristic magnetic hysteresis loops and the slow relaxation of magnetization

Magnetic Anisotropy from Trigonal Prismatic to Trigonal Antiprismatic Co(II) Complexes: Experimental Observation and Theoretical Prediction

A family of trigonal antiprismatic Co­(II) complexes was synthesized, which exhibited field-induced Raman process dominated single-molecule magnet behavior. Despite the coordination environment of Co­(II) being of similar symmetry, the four complexes exhibit distinct dynamic magnetic properties owing to their packing arrangements and dipole–dipole interactions. On the basis of computational results we have demonstrated that the <i>g</i>_<i>z</i> and <i>g</i>_iso values follow a cosine relation with respect to the rotated angle φ (twist angle φ defined as the rotation angle of one coordination square away from the eclipse conformation to the other)

Electrochemical Synthesis and Magnetic Properties of [Cu₉W₆]: The Ultimate Member of the Quindecanuclear Octacyanometallate-Based Transition-Metal Cluster?

[Cu₉W₆], synthesized by the electrochemical method, may be the ultimate member of the quindecanuclear octacyanometallate-based transition-metal cluster. Its single-crystal structure and magnetic properties were characterized

Structural Conversion and Magnetic Studies of Low-Dimensional Ln^III/Mo^V/IV(CN)₈ (Ln = Gd–Lu) Systems: From Helical Chain to Trinuclear Cluster

The slow diffusion reaction of octacyanometallate [Mo^V(CN)₈]^3–, lanthanide ions (Gd–Lu), and 1,10-phenanthroline (phen) in CH₃CN/H₂O has yielded eight isostructural one-dimensional chains, [Ln^III(phen)₂­(H₂O)­Mo^V(CN)₈]₂­[(<i>n</i>-C₄H₉)₄N]­(NO₃)­·2CH₃CN·4H₂O (Ln = Gd­(<b>1</b>), Tb­(<b>2</b>), Dy­(<b>3</b>), Ho­(<b>4</b>), Er­(<b>5</b>), Tm­(<b>6</b>), Yb­(<b>7</b>), Lu­(<b>8</b>)), in which [Ln^III(phen)₂(H₂O)]³⁺ and [Mo^V(CN)₈]^3– units are linked alternatively through cyanide groups, generating left- and right-handed helices. Interestingly, <b>1</b>–<b>8</b> undergo a resolvation–recrystallization process upon prolonging the diffusion-reaction time, together with the valence change from V to IV of Mo center and structural dimensionalities switching from helical chains to trinuclear clusters, (Hphen)_2.5­[Ln^III_0.5(phen)­(H₂O)]­[Mo^IV(CN)₈]­·1.5CH₃CN (Ln = Gd­(<b>9</b>), Tb­(<b>10</b>), Dy­(<b>11</b>), Ho­(<b>12</b>), Er­(<b>13</b>), Tm­(<b>14</b>), Yb­(<b>15</b>), Lu­(<b>16</b>)). Magnetic studies of <b>1</b>–<b>16</b> revealed the typical effects induced by single-ion magnetic anisotropy and/or the population of low-lying excited states, and <b>11</b> and <b>13</b> showed extraordinary field-induced slow magnetic relaxations

Family of Mixed 3d–4f Dimeric 14-Metallacrown‑5 Compounds: Syntheses, Structures, and Magnetic Properties

An isomorphous family of mixed 3d–4f dodenuclear aggregates, {[Mn^III₈Ln₄(Clshi)₈(OAc)₆(μ₃-OCH₃)₂(μ₃-O)₂(CH₃OH)₁₂(H₂O)₂]·4CH₃OH·<i>x</i>H₂O)} (where Ln = Eu^III (<b>1</b>), Gd^III (<b>2</b>), Tb^III (<b>3</b>), and Dy^III (<b>4</b>); ClshiH₃ = 5-chlorosalicylhydroxamic acid; <i>x</i> = 5 for <b>1</b> and <b>3</b>; <i>x</i> = 6 for <b>2</b>; <i>x</i> = 2 for <b>4</b>), were synthesized and characterized. They were obtained from the reaction of ClshiH₃ with Mn­(OAc)₂·4H₂O and Ln­(NO₃)₃·6H₂O. These isomorphous mixed 3d–4f compounds represent a family of novel structures with lanthanide ions in the metallacrown (MC) ring. Each dodecanuclear aggregate contains two offset stacked 14-MC-5 units with M–N–O–M–N–O–Ln–O–N–M–O–N–M connectivity to capture one Ln^III ion in the core of each MC. Two 14-MC-5 units are connected through O ions with four Mn ions and six O atoms arranged in a double Mn₄O₆ cubane. Magnetic measurement indicates that antiferromagnetic interactions are present between the metal ions. The Dy^III analogue with high anisotropy and large spin shows slow magnetization relaxation at a direct-current field of 2 kOe

Syntheses, Structures, and Magnetic Properties of seven-coordinate Lanthanide Porphyrinate or Phthalocyaninate Complexes with Kläui’s Tripodal Ligand

A series of seven-coordinate mononuclear lanthanide­(III) complexes of the general formula [(TPP)­Ln­(L_OEt)]·0.25H₂O and [(Pc)­Ln­(L_OEt)] (Ln³⁺ = Dy³⁺, Tb³⁺, Ho³⁺, and Gd³⁺; TPP = 5,10,15,20-tetraphenylporphyrinate; Pc = phthalocyaninate; L_OEt^– = [(η⁵-C₅H₅)­Co­(P­(=O)­(OEt)₂)₃]⁻) are synthesized on the basis of the tripodal ligand L_OEt^– and either porphyrin or phthalocyanine ligands. All of the complexes are characterized by X-ray crystallography and by static and dynamic magnetic measurements. The Dy and Tb complexes show the field-induced slow relaxation of magnetization, and they are interesting seven-coordinate single-lanthanide-based SMMs. The magnetic relaxation properties of these double-decker sandwich complexes are influenced by the local molecular symmetry and are sensitive to subtle distortions of the coordination geometry of the paramagnetic lanthanide ions, such as metal-to-plane distances, plane center distances, and bending angles

Family of Mixed 3d–4f Dimeric 14-Metallacrown‑5 Compounds: Syntheses, Structures, and Magnetic Properties

An isomorphous family of mixed 3d–4f dodenuclear aggregates, {[Mn^III₈Ln₄(Clshi)₈(OAc)₆(μ₃-OCH₃)₂(μ₃-O)₂(CH₃OH)₁₂(H₂O)₂]·4CH₃OH·<i>x</i>H₂O)} (where Ln = Eu^III (<b>1</b>), Gd^III (<b>2</b>), Tb^III (<b>3</b>), and Dy^III (<b>4</b>); ClshiH₃ = 5-chlorosalicylhydroxamic acid; <i>x</i> = 5 for <b>1</b> and <b>3</b>; <i>x</i> = 6 for <b>2</b>; <i>x</i> = 2 for <b>4</b>), were synthesized and characterized. They were obtained from the reaction of ClshiH₃ with Mn­(OAc)₂·4H₂O and Ln­(NO₃)₃·6H₂O. These isomorphous mixed 3d–4f compounds represent a family of novel structures with lanthanide ions in the metallacrown (MC) ring. Each dodecanuclear aggregate contains two offset stacked 14-MC-5 units with M–N–O–M–N–O–Ln–O–N–M–O–N–M connectivity to capture one Ln^III ion in the core of each MC. Two 14-MC-5 units are connected through O ions with four Mn ions and six O atoms arranged in a double Mn₄O₆ cubane. Magnetic measurement indicates that antiferromagnetic interactions are present between the metal ions. The Dy^III analogue with high anisotropy and large spin shows slow magnetization relaxation at a direct-current field of 2 kOe