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Domino reaction of benzo[d]thiazole‐2‐methylamine (S1) has been developed in the presence of MnCl2 ⋅ 4H2O, leading to tetrasubstituted pyrrole coordinated dinuclear Mn(II) complex 1 ([MnClP]2, P−=2,3,4,5‐tetrakis(benzo[d]thiazol‐2‐yl)pyrrol‐1‐ide). The reaction process has been studied by assigning a series of intermediates based on time‐dependent mass spectrometry, control experiments, crystallography, and density functional theory (DFT) theoretical calculation. A plausible mechanism involving an unprecedented divergent‐convergent domino sequence has been proposed. Compound S1 could be activated by MnCl2 ⋅ 4H2O via coordination, which divergently produces two intermediates imine II (1‐(benzo[d]thiazol‐2‐yl)‐N‐(benzo[d]thiazol‐2‐ylmethyl)methanimine) and alkene C (1,2‐bis(benzo[d]thiazol‐2‐yl)ethene) through oxidative self‐condensation and free radical coupling followed by elimination, respectively. They could then react with each other convergently via formal [3+2] cycloaddition to give deprotonated tetrasubstituted pyrrole coordinated intermediate [MnClP] after aromatization. Dimerization of [MnClP] produces the final product 1. Three C−C bonds and one C−N bond are formed through this six‐step domino sequence. The corresponding organic skeleton (HP: 2,2′,2′′,2′′′‐(1H‐pyrrole‐2,3,4,5‐tetrayl)tetrakis(benzo[d]thiazole)) has been obtained from 1 and shows a higher fluorescent quantum yield (52 %) than the reported 3,4‐diphenyl substituted analogue 2,2′‐(3,4‐diphenyl‐1H‐pyrrole‐2,5‐diyl)bis(benzo[d]thiazole) (DPB) (42 %). [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A domino ring‐opening and coupling of imidazolyl annulated heterocycles 1 (1a: 4‐methyl‐1‐(1‐methyl‐1H‐benzo[d]imidazol‐2‐yl)‐4H‐ benzo[d]imidazo[1,5‐a]imidazole, 1b: 1‐(1,5‐dimethyl‐1H‐benzo[d]imidazol‐2‐yl)‐4,7‐dimethyl‐4H‐benzo[d]imidazo[1,5‐a]imidazole) with dioxygen was developed at solvothermal condition, leading to conjugated 1,2‐diamidoalkenes derivatives 2 ((E)‐ArCONHArC=CArNHCOAr (Ar: 1‐methyl‐1H‐benzo[d]imidazolyl (2a), 1,5‐dimethyl‐1H‐benzo[d]imidazolyl (2b))) as single crystals directly. The reaction process was tracked by electrospray ionization mass spectrometry (ESI‐HRMS) and a series of reaction intermediates are detected. 18O2 labeling experiment verified the source of oxygen in 2. Combining evidence from control experiments, nuclear magnetic resonance (NMR) tracking, and crystallography, a seven‐step reaction pathway involving oxygen addition, ring opening, Friedel‐Crafts alkylation, oxidation, and dehydration was proposed and further supported by DFT calculation. [ABSTRACT FROM AUTHOR]

(1-methyl-1H-benzo[d]imidazol-2-yl) methanol (Hmbm) reacts with Mn(ClO4)2·6H2O to form heptanuclear disks [Mn7(mbm)12]·2(ClO4) (1) under ambient conditions. The heptanuclear cluster was previously described as a double calix unit with the hydroxides in the middle. The seven Mn(II) ions are essentially coplanar as expected for all edge-sharing octahedra, which can be intituled as a segment of Mg(OH)2 layer of brucite, so it is a symmetric disk. ESI–MS of crystals showed its stability in solution. Time-dependent mass spectrometry (MS) from solutions at different period of the assembly reveal a hierarchical sequence, [MnIII(mbm)2]+ → [MnII2(mbm)3]+ → [MnII4(mbm)6(ClO4)]+ → [MnIIIMnII6(mbm)12(ClO4)2]+. [ABSTRACT FROM AUTHOR]

The salts {[Ln2Ln*(Hhmq)3(OAc)3(hfac)2]+ [Ln*(hfac)3(OAc)(MeOH)]−} (Hhmq=2‐methanolquinolin‐8‐oxide, hfac=hexafluoroacetylacetonate; Ln, Ln*=Er, Gd, Yb) feature a discrete heteronuclear cation consisting of two types of lanthanide atoms. The quinolinoxy O‐atom serves as a μ2‐bridge to two Ln atoms and as a μ3‐bridge to all three atoms, with metal⋅⋅⋅metal distances being around 3.7 Å. For 1 ([Yb2Er]+), near‐infrared downshifted luminescence is switched to competitive upconversion luminescence upon irradiation by a 980 nm laser under an extremely low excitation power (0.288 W cm−2) through introduction of fluoride ions. The stability of 1 after addition of fluoride was confirmed by powder X‐ray diffraction and multistage mass spectrometry, associated with the 1H NMR of 6 ([La2Eu]+). More importantly, the at least 20‐fold enhancement of the quantum yield in non‐deuterated solvents at room temperature under low power densities (2 W cm−2) is the highest among the few molecular examples reported. [ABSTRACT FROM AUTHOR]

Herein, the reaction of (1‐methyl‐1 H‐benzo[d]imidazol‐2‐yl)methanamine (L1) with Co(H2O)6Cl2, in CH3CN at 120 °C, leading to the 2,3,5,6‐tetrakis(1‐methyl‐1 H‐benzo[d]imidazol‐2‐yl)pyrazine (3), isolated as a dimeric cluster {[CoII2(3)Cl4]⋅2 CH3CN} (2), is reported. When O2 and H2O are present, (1‐methyl‐1 H‐benzo[d]imidazole‐2‐carbonyl)amide (HL1′) is first formed and crystallized as [CoIII(L1)2(L1′)]Cl2⋅2 H2O (4) before fusion of HL1′ with L1, giving 1‐methyl‐N‐(1‐methyl‐1 H‐benzo[d]imidazol‐2‐carbonyl)‐1 H‐benzo[d]imidazol‐2‐carboxamide (HL2′′) forming a one‐dimensional (1D) chain of [CoII3(L2′′)2Cl4]n (5). The combination of crystallography and mass spectrometry (ESI‐MS) of isolated crystals and the solutions taken from the reaction as a function time reveal seven intermediate steps leading to 2, but six steps for 5, for which a different sequence takes place. Control and isotope labeling experiments confirm the two carbonyl oxygen atoms in 5 originate from both air and water. The dependence on the metals, compared with FeCl3⋅6 H2O leading to a stable triheteroarylmethyl radical, is quite astounding, which could be attributed to the different oxidation states of the metals and coordination modes confirmed by DFT calculations. This metal and valence dependent process is a very useful way for selectively obtaining these large molecules, which are unachievable by common organic synthesis. [ABSTRACT FROM AUTHOR]

An unexpected dominance of the coordination affinity of the sulfate anion over those of two organic chelating ligands, (1-methyl-1H-benzo[d]imidazol-2-yl)methanol (Hmbm) and pyridin-2-ylmethanamine (pma), was observed during the study of the solvothermal assembly of [Co11(mbm)6(pma)2(SO4)8(H2O)6(CH3OH)6]·5CH3OH (1), from CoSO4·7H2O at 100 °C in methanol. ESI-MS of solutions at different periods of the assembly reveal a hierarchical sequence, [Co1] → [Co2] → [Co3] → [Co4] → [Co5] → [Co9], where the lower nuclearity species are richer in Co2+ and SO42− before the inclusion of more mbm ligands at the last step. Its crystal structure consists of an almost symmetrical wheel of nine cobalt atoms, [Co9(mbm)6(SO4)8(H2O)6] in edge-sharing octahedral coordination arranged in triangles with two peripheral dangling [Co(pma)(CH3OH)3]. The sulfate ions exhibit three different coordination modes, two in μ6-, two in μ3- and four as μ2-bridging. Its thermal, optical and magnetic properties are also reported. [ABSTRACT FROM AUTHOR]

Dehydration of (S,S)‐1,2‐bis(1H‐benzo[d]imidazol‐2‐yl)ethane‐1,2‐diol (H4L) to (Z)‐1,2‐bis(1H‐benzo[d]imidazol‐2‐yl)ethenol) (H3L′) was found to be metal‐assisted, occurs under solvothermal conditions (H2O/CH3OH), and leads to [MnII4(H3L)4Cl2]Cl2⋅5 H2O⋅5 CH3OH (Mn4L4) and [MnII4(H2L′)6(μ3‐OH)]Cl⋅4 CH3OH⋅H2O (Mn4L′6), respectively. Their structures were determined by single‐crystal XRD. Extensive ESI‐MS studies on solutions and solids of the reaction led to the proposal consisting of an initial stepwise assembly of Mn4L4 from the reactants via [MnL] and [Mn2L2] below 80 °C, and then disassembly to [MnL] and [MnL2] followed by ligand modification before reassembly to Mn4L′6 via [MnL′], [MnL′2], and [Mn2L′3] with increasing solvothermal temperature up to 140 °C. Identification of intermediates [Mn4LxL′6−x] (x=5, 4, 3, 2, 1) in the process further suggested an assembly/disassembly/in situ reaction/reassembly transformation mechanism. These results not only reveal that multiple phase transformations are possible even though they were not realized in the crystalline state, but also help to better understand the complex transformation process between coordination clusters during "black‐box" reactions. [ABSTRACT FROM AUTHOR]

Analyses of the structural information of molecular fragments from the mass spectra of the solid-state products and their reaction solutions allow for the understanding of their formation and of their diverse properties. The reaction of CuCl2 and (1-methyl-1H-benzo[d]imidazole-2-yl)methanol (HL) led only to crystals containing molecular dimers of [Cu2(L)2Cl2] (Cu2). The CuII–CuII distance and Cu–OR–Cu angle in the structure are 3.044 Å and 104.8°, respectively. The magnetic susceptibility (3–400 K) is characterized by a very strong intradimer antiferromagnetic interaction of J = −465 and interdimer zj = −0.83 cm−1. But mass spectrometry of a dissolved single crystal in different source energies identifies both its fragmentation and oligomerization to [Cu II3 ] and [Cu II4 ]. DFT calculations give the relative stabilization energies of the fragments observed in ESI-MS to provide a formation process. [ABSTRACT FROM AUTHOR]

A new free carbon radical was obtained in a microwave‐assisted solvothermal reaction of the primary amine (1‐methyl‐1H‐benzo[d]imidazol‐2‐yl)methanamine with FeCl3⋅6 H2O in methanol at 140 °C. Through a combination of crystallography and electrospray ionization mass spectrometry, the reaction process was studied. The longest domino reaction includes 14 steps and forms up to 12 new covalent bonds (9 C−N and 3 C−C bonds) and 3 five‐membered heterocycles. For the first time, the homolytic cleavage of a C−O bond was used to synthesize a triarylmethyl radical. A free carbon radical was obtained in a domino reaction of a primary amine with FeCl3⋅6 H2O in methanol under solvothermal conditions. In this process, which was studied by crystallography and ESI mass spectrometry, the longest domino reaction features 14 steps, and methanol is sequentially activated; in addition, the homolytic cleavage of a C−O bond is proposed. [ABSTRACT FROM AUTHOR]

Two zinc clusters Zn4(H3L)4(NO3)4⋅5H2O (Zn4, H4L=(1,2‐bis(1H‐benzo[d]imidazol‐2‐yl)ethane‐1,2‐diol) and [Zn5(H2L′)6](NO3)4]⋅8H2O⋅2CH3OH (Zn5, H3L′=(1,2‐bis(benzo[d] imidazol‐2‐yl)‐ethenol) have been obtained by the reaction of Zn(NO3)2⋅6H2O with H4L at 80 °C or 140 °C under solvothermal condition. Powder X‐ray Diffraction (PXRD) of precipitate and Electrospray Ionization Mass Spectrometry (ESI‐MS) of reaction solution revealed the existence of transformation behavior from Zn4 to Zn5 by increasing the temperature from 80 °C to 140 °C, or directly heating Zn4 at 140 °C via solvothermal reaction. Here we proposed a possible mechanism involves split process of Zn4 and reassembly to form Zn5. ESI‐MS for single crystals revealed [Zn4(H3L)4−3H]+ splits to [Zn(H3L)]+ via [Zn2(H3L)2−H]+. Time dependent ESI‐MS of reaction solution revealed the [Zn(H2L′)]+→[Zn2(H2L′)2−H]+→[Zn5(H2L′)6−H]3+ stepwise assembly. It also has been captured the in situ reaction mainly occurs in the step of [Zn(H3L)]+ to [Zn(H2L′)]+. [ABSTRACT FROM AUTHOR]

Abstract: Two heptanuclear discs, [Co7(L1)6(CH3O)6]2+ (Co7‐L1) and [Co7(L2)12](ClO4)2 (Co7‐L2), have been prepared by the reaction of [Co(H2O)6](ClO4)2 with Schiff base HL1 (HL1=2‐methoxy‐6‐[(methylimino)methyl]phenolate) or benzimidazole derivative HL2 (HL2=(1H‐benzo[d]imidazol‐2‐yl)methanolate), respectively, at room temperature. In contrast, the reaction of [Co(H2O)6](ClO4)2 with a mixture of the two ligands, having similar coordination ability but different shapes, resulted in the butterfly‐structured tetranuclear cobalt cluster [Co4(L1)2(L2)4](ClO4)2⋅2H2O (Co4). Electrospray ionization mass spectrometry (ESI‐MS) analysis in real time revealed the {Co1}→{Co2}→{Co4}→{Co7} stepwise assembly when a single ligand was employed, but when both ligands were used only {Co4} was obtained, an intermediate of the former reactions. Interestingly, ligand competition was evidenced in the assembly process of the reaction with two ligands; for example, [Co4(L1)4(L2)2]2+ and [Co4(L1)3(L2)3]2+ were the primary clusters observed at the beginning of the reaction, but [Co4(L1)2(L2)4]2+ was the final product. This observation suggests ligand exchange is taking place, and DFT calculations confirmed that these transformations were possible. By varying the ratio of ligands, the abundance of a certain species in the competitive reaction could be controlled. [ABSTRACT FROM AUTHOR]

The square-planar monomer NiL2 ( Ni1), L=2-ethoxy-6-( N-methyl-iminomethyl)phenolate, reacts with M(H2O)6(ClO4)2, M=Ni or Co, to form heptanuclear disks [Co xNi7− x(OH)6(L)6](ClO4)2 ⋅2 CH3CN ( Co x Ni7− x, x=0-7) and the co-crystal [Co xNi7− x(OH)6L6][NiL2](ClO4)2 ⋅2 CH3CN ( Co x Ni7− x -Ni1) under ambient conditions. It has proved possible to explore the bottom-up assembly process of Co x Ni7− x and Co x Ni7− x -Ni1 in real time. The final products have been characterized by thermogravimetric analysis, IR, elemental analysis, ICP-MS, and single-crystal X-ray diffraction. Time-dependent mass spectrometry (MS) revealed the following reaction steps: Ni1→[M2L3]+→[M4(OH)2L4]2+→[M7(OH)6L6]2+. In contrast, the reaction of Ni1 with Zn2+ only reaches halfway, and crystallographic evidence indicates a butterfly structure for [Zn2Ni2(OH)2Cl2] ( Zn2Ni2), an intermediate that is difficult to isolate in the above Ni-Co series. A summation method has been used to analyze the MS of bimetallic clusters with very similar atomic masses, as is the case for Co and Ni. The results provide ample information on the distribution of Co and Ni within each cluster and their statistical distribution within selected crystals. [ABSTRACT FROM AUTHOR]

Domino Reactions. In their Communication on page 3748 ff., M.‐H. Zeng et al. describe the synthesis of a free carbon radical through the domino reaction of a primary amine with FeCl3⋅6 H2O in methanol under solvothermal conditions. [ABSTRACT FROM AUTHOR]

Trinuclear nickel thiolate cluster [Ni 3 (μ 3 -S)(L) 3 ]NO 3 (HL = (1-methyl-1 H -benzo[ d ]imidazol-2-yl)methanethiol) (1) has been synthesized from Ni(NO 3) 2 ·6H 2 O and HL at solvothermal condition at 80 °C using methanol as solvent. It has been characterized by X-ray single crystal diffraction, elemental analysis, electrospray ionization mass spectrometry (ESI-MS), and thermogravimetric analysis. The stability of the cluster in methanol is reflected by the fact that the molecular ion peak of [Ni 3 (μ 3 -S)(mbms) 3 ]+ is dominant in ESI-MS. Furthermore, the release of H 2 S from 1 was observed at elevated in source energy condition and in tandem mass spectrometry. The H 2 S fragment was also detected during the destruction of 1 by thermogravimetric analysis combined with mass spectrometry (TG-MS). Key fragments [NiLS]+ and [Ni 2 L 2 ]+ were percepted in solution by ESI-MS during the reaction, which have also been detected at elevated in source energy condition. A plausible stepwise assembly process including [NiL]+ to the mixture of [NiLS]+ and [Ni 2 L 2 ]+ which then combined to give the product [Ni 3 L 3 S]+ was proposed. A nickel thiolate cluster [Ni 3 L 3 S]NO 3 (HL = (1-methyl-1 H -benzo[ d ]imidazol-2-yl)methanethiol) was synthesized and its formation process was studied by mass spectrometry. Unlabelled Image • A new nick thiolate cluster with Ni3S4 mode was synthesized at relatively mild reaction condition • The stepwise assembly process was studied by utilizing ESI-MS technique. • The release of H 2 S was detected for the first time in the thermal decomposition process of nickel thiolate cluster. [ABSTRACT FROM AUTHOR]