Chang-Neng Chen

Reactions of manganese benzoate dihydrate and lanthanide nitrate hexahydrate with 2‐(hydroxymethyl)pyridine (hmpH) as ligand in the mixture solutions of acetonitrile and ethanol according to different molar ratios of NEt₃ generated two kinds of Mn‐Ln compounds [Mn^III₄La^III₂(O)₂(hmp)₇(PhCO₂)₂(NO₃)₅] ·5H₂O (1) and [Mn^III₂Gd^III₂(hmp)₆(PhCO₂)₄(NO₃)₂] ·3CH₃CN·3C₂H₅OH·2H₂O (2). By comparison of the two compounds, there exist considerable effects of reaction alkalinity on the structures and magnetic properties of products. Compound 1 possesses a core of [Mn^III₄La^III₂(μ₄‐O)(μ₃‐O)(μ₃‐OR)(μ₂‐O)₇]²⁻, which comprises three face‐sharing defected cubane units. The core topology represents a new core type of Mn‐Ln clusters. Compound 2 has a planar‐butterfly structure. The solid‐state dc magnetic susceptibility analyses indicate the antiferromagnetic interactions within compound 1 and ferromagnetic interactions within compound 2. Compound 1 has an S = 0 ground state, while compound 2 possesses an S = 11 ground state, fitting of the dc data for the tetranuclear Mn₂Gd₂ with the Magpack program gives parameters of J_Mn‐Mn = 3.11 cm⁻¹, J_Mn‐Gd = 0.02 cm^—1 and g = 1.96.

Reactions of manganese nitrate and lanthanide nitrate hexahydrate with 2-(hydroxymethyl)pyridine (hmpH) and sodium propionate as co-ligands in the mixed solutions of acetonitrile and ethanol generated two hexanuclear Mn–Ln compounds [Mn₄Ln₂O₂(OH)(hmp)₅(EtCO₂)₃(MeCN)(NO₃)₅(H₂O)] [Ln = La (1), Nd (2)]. Compounds 1 and 2 are isostructural and possess a core of [Mn^III ₄Ln^III ₂(μ₃-OR)₃(μ₃-O)₂(μ₂-O)₃]⁵⁺, which comprises three face-sharing defect cubane units. The core topology represents a new core type of Mn–Ln cluster. The soild-state dc magnetic susceptibility analyses indicate antiferromagnetic interactions within the two compounds. Compound 1 possesses an S = 0 ground state spin, fitting of the dc data for a tetranuclear Mn^III ₄ with the Magpack program gives parameters of J₁ = −0.50 cm⁻¹, J₂ = −5.03 cm⁻¹, J₃ = 3.77 cm⁻¹ and g = 1.95.

Dodenuclear Mn/Ln clusters with 2-(hydroxymethyl)pyridine as a ligand have been synthesized. Complexes 1 and 5 showed a frequency-dependent decrease in χ ′ _M T and an out-of-phase χ ′′ _M peak maximum, indicating slow magnetic relaxation and potential SMM behaviour.

Four novel manganese phosphonate clusters, namely Cl@[Mn₆(t-BuPO₃)₈(H₂O)₂(CH₃OH)₄][OH] (1), Br@[Mn₆(t-BuPO₃)₈(H₂O)₂(CH₃OH)₄][OH]·4H₂O (2), [Mn₁₃O₆(t-BuPO₃)₁₀(OH)₆(CH₃OH)₆][Mn₁₃O₆(t-BuPO₃)₁₀(OCH₃)₆(t-BuPO₃H₂)₂(H₂O)₄]·2CH₃OH·10H₂O (3) and [Mn₁₅K₂O₈(t-BuPO₃)₁₀(CH₃O)₄(C₆H₅COO)₄(H₂O)₈]·6H₂O (4), have been successfully synthesized in the presence of tert-butylphosphonic acid, carboxylic acid, NBuⁿ ₄MnO₄ and different manganese sources. These clusters were characterized by elemental analyses, IR spectroscopy, thermogravimetric (TG) analyses and single-crystal X-ray diffraction. Single-crystal structure analyses reveal that the structures of 1–4 are diverse. The structure of cluster 1 is analogous to that of cluster 2, which displays a cage-like arrangement with one halide ion (Cl⁻, Br⁻) lying inside the centre of the cave. Cluster 3 is a carboxylate-free manganese phosphonate cluster consisting of two similar Mn₁₃ structural units. Moreover, there exist two potassium ions and fifteen manganese ions in the heterometallic cluster 4. In addition, solid-state DC magnetic susceptibility measurements indicate the existence of overall antiferromagnetic (AF) exchange interactions between the Mn ions in all clusters.

The combination of a new cobalt complex with a cyclometalated iridium photosensitizer gives an efficient system for H ₂ evolution.

A family of novel Mn₃Ln₄ clusters: single-molecule magnets and the first structurally characterized 3d/4f clusters containing the 3-methyloxysalicylaldoximate ligand.

The pyrene-functionalized cobaloxime–g-C ₃ N ₄ system was active for hydrogen production in CH ₃ CN–H ₂ O mixed solvent with a highest TON of 281.

The trinuclear title compound, [Fe₃(C₃H₆S₂)₂(CO)₇], is a mixed-valent Fe^I/Fe^IIcomplex and crystallizes with two molecules of similar configuration in the asymmetric unit. The three Fe atoms in each molecule display a bent arrangement [Fe—Fe—Fe = 156.22 (4) and 157.06 (3)°]. Both outer Fe^Iatoms are six-coordinated in a distorted ocahedral coordination geometry defined by the bridging Fe^IIatom, three carbonyl C atoms and two bridging S atoms. The coordination number of the central Fe^IIatom is seven and includes bonding to the two outer Fe^Iatoms, four bridging S atoms and one carbonyl C atom. The resulting coordination polyhedron might be described as a highly distorted monocapped trigonal prism. In the crystal packing, the molecules exhibit a chain-like arrangement parallel to [100] and [001], and the resulting layers are stacked along [010]. The cohesion of the structure is dominated by van der Waals interactions.

A series of platinum(II) complexes bearing 1,3‐bis(2‐pyridylimino)isoindoline (BPI) derivatives as ligand have been prepared by substitution of the coordinated Cl in precursors [Pt(L)Cl] [L = L1 (1), L2 (2), L3 (3)] by a monodentate strong‐field ligand such as CN^–, CN‐cyclohexyl, PPh₃, NCS^–, PhS^–, or N(CN)₂^–. Most of these compounds display orange‐to‐red luminescence in both the solid state and solution at ambient temperature. Compared with precursors 1–3, both low‐energy absorption and emission bands in ligand‐substituted platinum(II) complexes 4–13 exhibit distinct blueshifts. The emission of platinum(II) complexes with CN‐containing monodentate ligands shows progressive blueshifts with increasing ligand field strength: 609 (10, NCS^–) → 603 [12, N(CN)₂^–] → 590 (4, CN^–) → 581 nm (7, C≡N‐cyclohexyl). The emission of complexes 4–9 originates mainly from the ³[π → π*(BPI)] ³IL triplet excited state, mixed with some ³[dπ(Pt) → π*(BPI)] ³MLCT character. In contrast, the emission of 10–13 arises from a clearly increased ³[π(L) → π*(BPI)] ³LLCT state with reduced ³[π → π*(BPI)] ³IL and ³[5d(Pt) → π*(BPI)] ³MLCT character. Noticeably, dicyanamido‐linked dinuclear complex 13 displays a significant ligand–ligand electronic interaction between the two BPI across the Pt–N≡C–N–C≡N–Pt bridge with remarkable LLCT character from one BPI to the other.

Exploration of the complex Ni₂(MBD)₄ (MBD = 2-mercaptobenzimidazole) (C1) having different coordinated Ni atoms as a photocatalyst for hydrogen evolution is made. For comparison, the bimetallic Ni₂(MBT)₄ (MBT = 2-mercaptobenthiazole) (C2) complex with the same coordinated Ni atoms was synthesized. Both of the complexes have been successfully constructed for photo-induced hydrogen production using organic dyes as photosensitizers and triethanolamine (TEOA) as the effective electron donor by visible light (>400 nm) in acetonitrile–water solution. The time-dependence of H₂ generation and DFT computational studies demonstrate that the complex C1 is more active than C2 for H₂ evolution. The mechanisms of photocatalytic hydrogen generation for C1 and C2 involve different protonation sites resulting from the differences between the two structures.