Synthesis and Crystal Structures of Alkali and Alkaline Earth Metal Complexes of 3,5-Dinitropyrazolyl-4-carboxylate

The synthesis and crystal structures of 3,5-dinitro-1H-pyrazolyl-4-carboxylic acid (H₂dnpzc) and its four complexes with Ca²⁺, Ba²⁺, Na⁺ and K⁺ are reported in this paper. Ca(dnpzc) · 5H₂O exhibits a 1D polymeric structure, whereas Ba(dnpzc) · 4H₂O possesses a 2D structure. The structure of Na₂(dnpzc) · 4H₂O consists of 2D layers of [Na(dnpzc)]^–_n and 1D chains of [Na(H₂O)₃]⁺_n. K₂(dnpzc) · H₂O has a true 3D structure. It was observed that the doubly deprotonated ligand (dnpzc^2–) can act as a versatile bridge to form polymeric structures by varying combinations of its 8 potential donor atoms (two carboxy O atoms, two pyrazolyl N atoms and four nitro O atoms). Particularly in the structure of K₂(dnpzc) · H₂O, all the 8 donor atoms of dnpzc^2– take part in the coordination and as many as 10 potassium atoms are connected by one ligand.     

Calcium,Strontium, and Barium Acetylides—New Evidence for Bending in the Structures of Heavy Alkaline Earth Metal Derivatives

An unprecedented ligand bending mode is displayed by the acetylide ligands in the first structurally characterized σ‐bound organometallic strontium and barium complexes [M([18]crown‐6)(CCSiPh₃)₂] (M=Sr, Ba). Furthermore, the observed decrease of the angle at the sp‐hybridized C atom on descending Group 2 (see structures depicted) affords new information that will lead to a better understanding of the bonding in alkaline earth metal compounds.     

微波消解-电感耦合等离子体发射光谱(ICP-OES)法测生物质中的碱金属和碱土金属

为研究并解决测试生物质样品中碱金属和碱土金属含量的干扰,采用微波消解-电感耦合等离子体发射光谱(ICP-OES)法对生物质中的碱金属和碱土金属钾、钙、钠、镁元素进行测定,考察了样品消解后不同的酸体系,共存元素干扰对钾、钠、钙、镁含量测定的干扰研究。经过研究表明,接近分析标准曲线酸浓度的样品干扰小,铅、铟、钛、锰元素对钠元素测定造成干扰,砷、铜、镉对钙元素测定干扰,铝对钾元素测定有干扰,镁测定不受共存元素干扰影响,运用干扰系数法可以减少共存元素对测定元素的误差。各待测元素标准曲线相关系数大于0.9996,检出限为0.0014~0.023 mg/L,玉米芯各元素的相对标准偏差为0.98%~1.9%,加标回收率为80.2%~106%;西瓜皮的各元素相对标准偏差为0.91%~2.3%,加标回收率为85.3%~106%。方法用于测定国家标准物质GBW07603,各元素结果均在标准值参考范围内。方法用于测定生物质中碱金属和碱土金属的结果,用t检验法与离子色谱测定值进行比对,结果无显著性差异。     

Are Polar Organometallic Compounds “Carbanions”? The Gegenion Effect on Structure and Energies of Alkali-Metal Compounds

Polar organometallic compounds such as alkyllithium compounds or Grignard reagents often are conceived as “carbanions”, although it is well known from experiments that the metal gegenions may have a strong, and often directing, influence on the reactivity (for example, the basicity vs. the nucleophilicity) of the “carbanion”. This demonstrates that “carbanions” are tightly associated ion pairs, at least in commonly used less polar or nonpolar solvent systems like ethers or hydrocarbons. However, despite about ninety years of widespread application of these organometallic compounds as bases or nucleophilic reagents, the role of the gegenion is not yet understood fully. The focus of this review is on the inherent influences of the metal gegenion on the structures, reaction energies, and activation barriers of some representative alkali-metal compounds. While most comparisons of physical and chemical properties determined experimentally for Group I compounds are precluded due to different substituents, solvents, ligands, etc., ab initio calculations of model compounds can yield intrinsic data that are useful for a better understanding of chemical behavior. For this reason, most of the data reviewed in this article are based on quantum chemical calculations, which are compared with experimental data where available.     

Coordination Chemistry of Lanthanides at “High” pH: Synthesis and Structure of the Pentadecanuclear Complex of Europium(III) with Tyrosine

A five-coordinate chloride ion is believed to template the assembly of a pentadecanuclear lanthanide complex of europium(III ). This cluster (see picture) has been prepared by coordination of europium(III ) perchlorate with tyrosine at about pH 6. Single crystal X-ray analysis established an unprecedented structure in which 15 constituent europium(III ) ions are organized into three parallel pentagonal layers.     

“Self-Assembly” in Organolanthanide Chemistry: Formation of Rings and Clusters

Highly symmetrical arrangements of the lanthanide metals Ln including the S₆-symmetrical chair conformations of the [Sm(CN)]₆ ring in 1 or an icosahedron as in 2 (see picture) are found in novel multinuclear cyclopentadienyl complexes. The formation of different structural motifs is directed by ionic bonding criteria such as the nature of the bridging heteroligands and the Cp/Ln ratio. [{(C₅Me₅)₂Sm(µ-CN)}₆] 1 [(C₅Me₅)₁₂Sm₁₂(µ₃-Cl)₂₄] 2     

Synthesis and Comprehensive Characterization of Hydrated Alkaline Earth Metal Salts of 5‐Amino‐1H‐tetrazole

Hydrated alkaline earth metal salts of 5‐amino‐1H‐tetrazole ( B ) were synthesized by reaction of B with a suitable metal hydroxide in water. All compounds were fully characterized by analytical (elemental analysis and mass spectrometry) and spectroscopic (IR, Raman, ¹H and ¹³C NMR) methods. Additionally, the crystal structures of the magnesium [ 1· 4H₂O: triclinic, P$\bar {1}$ , a = 5.940(1) Å, b = 7.326(1) Å,c = 7.383(1) Å, α = 106.10(1)°, β = 106.51(1)°, γ = 111.85(1)°, V = 258.0(1) ų], calcium [ 2· 6H₂O: monoclinic, P2₁/m, a = 6.904(1) Å,b = 6.828(1) Å, c = 10.952(2) Å, β = 94.50(2)°, V = 514.6(1) ų], and strontium [ 3· 6H₂O: orthorhombic, Cmcm, a = 6.987(1) Å, b = 28.394(2) Å, c = 7.007(1) Å, V = 1390.3(2) ų] were determined by low temperature X‐ray diffraction. Additionally, the (gas phase) structure of the 5‐amino‐1H‐tetrazole anion ([ B ]^–) was also studied by natural bond orbital (NBO) analysis [B3LYP/6‐31+G(d,p)]. Lastly, standard tests were used to determine the sensitivity towards impact, friction, and electrostatic discharge of the compounds and the thermal stability was assessed by differential scanning calorimetry (DSC) analysis.     

Multiple Bonds between Transition Metals and “Bare” Main Group Elements: Links between Inorganic Solid State Chemistry and Organometallic Chemistry

The last two decades have seen a dramatic development in the study of metal-metal multiple bonds, particular successes being recorded in the field of organometallic chemistry. Syntheses designed to produce novel transition metal complexes with single, double, triple and quadruple metal-metal bonds occupy a most important place in such research, as also do reactivity studies. A striving to establish general principles has provided much of the motivation for such work, but one less obvious goal—the commercial application of the catalytic properties of metal-metal multiple bonding systems, in the medium and long term—should not be overlooked. All aspects of the investigations of metal-metal multiple bonds also apply to a particular class of compound that has, however, enjoyed little lime-light and thus deserves the present review: complexes with multiple bonds between transition metals and substituent-free (“bare”) main group elements. Although based mostly on accidental discoveries, the few noteworthy examples are now beginning to unfold general concepts of synthesis that are capable of being extended and thus are deserving of exploitation in preparative chemistry. The availability of further structural patterns exhibiting multiple bonds between transition metals and ligand-free main group elements might enable preparative organometallic chemistry to expand in a completely new direction (for instance by the stabilizing or activation of small molecules at the metal complex). This essay discusses the chemistry of complexes of bare carbon, nitrogen, and oxygen ligands (carbido-, nitrido-, and oxo-complexes) and their relationships to higher homologues from both a synthetic and a structural point of view.     

Two Three‐Dimensional Metal‐Organic Frameworks Constructed from Alkaline Earth Metal Cations (Sr and Ba) and 5‐Nitroisophthalicacid – Synthesis,Charaterization, and Thermochemistry

Two MOFs of [Sr^II(5‐NO₂‐BDC)(H₂O)₆] ( 1 ) and [Ba^II(5‐NO₂‐BDC)(H₂O)₆] ( 2 ) have been synthesized in water using alkaline earth metal salts and the rigid organic ligand 5‐NO₂‐H₂BDC. The compounds were characterized by elemental analysis, infrared spectrum, thermal analysis, and X‐ray crystallography. Crystal structure analyses have shown that the two complexes are isostructural as evidenced by IR spectra and TG‐DTA. Both compounds present three‐dimensional frameworks built up from infinite chains of edge‐sharing twelve‐membered rings through O–H···O hydrogen bonds. The specific heat capacities of the title complexes have been determined by an improved RD496‐III microcalorimeter with the values of (109.29 ± 0.693) J mol⁻¹ K⁻¹ and (81.162 ± 0.858) J mol⁻¹ K⁻¹ at 298.15 K, and the molar enthalpy changes of the formation reactions of complexes at 298.15 K were calculated as (4.897 ± 0.008) kJ mol⁻¹ and (2.617 ± 0.009) kJ mol⁻¹, respectively.     

Synthesis,Structures, and Magnetic Properties of New Thiocyanato Coordination Polymers with 4‐(3‐Phenylpropyl)pyridine as Ligand

The reaction of different metal salts with 4‐(3‐phenylpropyl)pyridine (ppp) lead to the formation of compounds of composition M(NCS)₂(ppp)₄ [M = Mn ( Mn‐1 ); Fe ( Fe‐1 ), Ni ( Ni‐1 ); Cd ( Cd‐1 )], M(NCS)₂(ppp)₂(H₂O)₂ [M = Mn ( Mn‐2 ); Ni ( Ni‐2 )] and [M(NCS)₂(ppp)₂]_n [M = Mn ( Mn‐3 ); Ni ( Ni‐3 ); Cd ( Cd‐3 )]. On heating compounds M‐1 decompose without the formation of any ppp deficient intermediate. In contrast, on heating, Ni‐2 transforms into a compound of composition M(NCS)₂(ppp)₂ that does not correspond to Ni‐3 . Unfortunately, this compound is of low crystallinity and therefore, its structure cannot be determined. The crystal structures of compounds M‐1 and M‐2 consist of discrete complexes, in which the metal cations are octahedrally coordinated. In compounds M‐3 the metal cations are linked by pairs of μ‐1,3‐bridging anions into chains. IR spectroscopic investigations show, that the value of the asymmetric CN stretching vibration depend on the coordination mode of the anionic ligand as well as on the nature of the metal cation. Magnetic measurements reveal that Ni‐3 shows only Curie‐Weiss behavior without any magnetic anomaly. A similar behavior is also found for Ni‐3 . Comparison of the magnetic properties of Ni‐3 with those of similar compounds indicates that the magnetic properties are only minor influenced by the Co‐ligand.     

Synthesis,Structures, and Luminescent Properties of Three Alkaline Earth Metal‐based MOFs Assembled from 3‐(3‐Carboxyphenoxy) Phthalic Acid Ligand

Three two‐dimensional (2D) coordination complexes, namely [Ca₂(HL)₂(H₂O)₅]_n · 2nH₂O ( 1 ), [Sr(HL)(H₂O)₃]_n · nH₂O ( 2 ), and [Ba(HL)(H₂O)₃]_n · nH₂O ( 3 ) [H₃L = 3‐(3‐carboxy‐phenoxy) phthalic acid], were synthesized by using the ligand H₃L and alkaline earth metals. Structural analysis reveals that the structures of complexes 1 – 3 can be described as 2D networks with the point (Schälfli) symbol for net: {3¹² · 4¹⁴ · 5²} topology. Additionally, the thermal stability and solid‐state luminescent properties of compounds 1 – 3 were investigated at room temperature. The quantum yield (QY) of compound 2 is 10.75 %, which is much higher than the QY of the free H₃L ligand (QY_H3L < 1 %).     

Tetra(diethyl)amide-p-tert-butyl-thiacalix[4]arene in Cone Conformation: Synthesis and Binding Properties with Alkali,Alkaline Earth,Heavy and Transition Metal Ions

Tetra(diethyl)amide-p-tert-butylthiacalix[4]arene 1a in the cone conformation was synthesized and its binding properties towards a large variety of metal ions were established on the basis of liquid–liquid and solid–liquid extraction as well as complexation experiments. This compound is a less efficient and selective compound than the “classical” tetra(diethyl)amide-p-tert-butylcalix[4]arene 3 in the cone conformation for alkali and alkaline earth metal ions. However, Pb²⁺ is selectively extracted and complexed within heavy and transition metal ions.     

Surprisingly Different Reaction Behavior of Alkali and Alkaline Earth Metal Bis(trimethylsilyl)amides toward Bulky N‐(2‐Pyridylethyl)‐N′‐(2,6‐diisopropylphenyl)pivalamidine

N‐(2,6‐Diisopropylphenyl)‐N′‐(2‐pyridylethyl)pivalamidine (Dipp‐N=C(tBu)‐N(H)‐C₂H₄‐Py) ( 1 ), reacts with metalation reagents of lithium, magnesium, calcium, and strontium to give the corresponding pivalamidinates [(tmeda)Li{Dipp‐N=C(tBu)‐N‐C₂H₄‐Py}] ( 6 ), [Mg{Dipp‐N=C(tBu)‐N‐C₂H₄‐Py}₂] ( 3 ), and heteroleptic [{(Me₃Si)₂N}Ae{Dipp‐N=C(tBu)‐N‐C₂H₄‐Py}], with Ae being Ca ( 2 a ) and Sr ( 2 b ). In contrast to this straightforward deprotonation of the amidine units, the reaction of 1 with the bis(trimethylsilyl)amides of sodium or potassium unexpectedly leads to a β‐metalation and an immediate deamidation reaction yielding [(thf)₂Na{Dipp‐N=C(tBu)‐N(H)}] ( 4 a ) or [(thf)₂K{Dipp‐N=C(tBu)‐N(H)}] ( 4 b ), respectively, as well as 2‐vinylpyridine in both cases. The lithium derivative shows a similar reaction behavior to the alkaline earth metal congeners, underlining the diagonal relationship in the periodic table. Protonation of 4 a or the metathesis reaction of 4 b with CaI₂ in tetrahydrofuran yields N‐(2,6‐diisopropylphenyl)pivalamidine (Dipp‐N=C(tBu)‐NH₂) ( 5 ), or [(thf)₄Ca{Dipp‐N=C(tBu)‐N(H)}₂] ( 7 ), respectively. The reaction of AN(SiMe₃)₂ (A=Na, K) with less bulky formamidine Dipp‐N=C(H)‐N(H)‐C₂H₄‐Py ( 8 ) leads to deprotonation of the amidine functionality, and [(thf)Na{Dipp‐N=C(H)‐N‐C₂H₄‐Py}]₂ ( 9 a ) or [(thf)K{Dipp‐N=C(H)‐N‐C₂H₄‐Py}]₂ ( 9 b ), respectively, are isolated as dinuclear complexes. From these experiments it is obvious, that β‐metalation/deamidation of N‐(2‐pyridylethyl)amidines requires bases with soft metal ions and also steric pressure. The isomeric forms of all compounds are verified by single‐crystal X‐ray structure analysis and are maintained in solution.     

New Azo Chromophore‐Containing Conjugated Polymers: Facile Synthesis by Using “Click” Chemistry and Enhanced Nonlinear Optical Properties Through the Introduction of Suitable Isolation Groups

A new series of azobenzene‐containing polyfluorenes have been successfully prepared through polymer reactions by the utilization of “click” chemistry. All the polymers were well characterized and soluble in common solvents. By the application of the concept of “suitable isolation group”, the macroscopic nonlinear optical (NLO) properties of the polymers could be boosted to as large as three times that of the polymer without isolation moieties. Also, all the polymers were thermally stable, and demonstrated good procesability, coupled with improved optical transparency. Thus, they are good candidates for the practical applications as new photonic materials.

     

Hexatellurium Rings in Coordination Polymers and Molecular Clusters: Synthesis and Crystal Structures of [M(Te6)]X3 (M = Rh,Ir; X = Cl,Br, I) and [Ru2(Te6)](TeBr3)4(TeBr2)2

The reaction of an electron‐rich transition metal M (M = Ru, Rh, Ir), tellurium and TeX₄ (X = Cl, Br, I) resulted in black crystals of five ternary coordination polymers with the general composition [M^III(Te₆)]X₃ (M = Rh, Ir) and of the molecular cluster compound [Ru^II₂(Te₆)](Te^IIBr₃)₄(Te^IIBr₂)₂. X‐ray diffraction on single‐crystals revealed that the compounds [M(Te₆)]X₃ crystallize isostructurally in the trigonal space group type R$\bar{3}$ c. In their crystal structures linear, positively charged [M^III(Te₆)] chains form the motif of a hexagonal rod packing. In the chain, each of the formally uncharged Te₆ molecules with chair conformation acts as a bis‐tridentate bridging ligand to two M atoms. The octahedrally coordinated M atoms are spiro atoms in the chain of trans vertices sharing heterocubane fragments. Including the isolated halide ions, which provide charge balance, the entire arrangement resembles a cut‐out of the α‐polonium structure type.In the monoclinic compound Ru₂Te₁₂Br₁₆ (space group P2₁/n), the ruthenium atoms of the hetero‐cubane core of the molecular cluster [Ru₂(Te₆)](TeBr₃)₄(TeBr₂)₂ are saturated by terminal bromidotellurate(II) groups. Again, the Te₆ ring is formally uncharged. With the tellurium atoms acting as electron‐pair donors the 18 electron rule is fulfilled for the M atoms in all compounds.     

“One‐Step” Synthesis of Ionic Ferrocenyl Compounds of Ferrocenylmethyldimethylamine. Characterization,Migration, and Catalytic Properties During Combustion

Alkylferrocene‐based burning rate catalysts exhibit high migration tendency and volatility during prolonged storage and fabrication process of the solid propellants. To retard the migration problems, eight ionic compounds composed of ferrocenylmethyldimethylammonium cation paired with a common energetic anion, were synthesized by “one‐step” procedure. The compounds were characterized by FT‐IR, NMR, and UV/Vis spectroscopy as well as elementary analysis. Their crystal structures were confirmed by single‐crystal X‐ray diffraction. The TG and DSC analyses indicated that they exhibit high thermal stability. Cyclic voltammetry studies suggested that most of them show reversible or quasi‐reversible redox waves. The anti‐migration results revealed that 1 – 4 are low‐migratory compounds, but 5 exhibits high migration trends. The TG curves at 70 °C for 24 h showed that all of them have low volatility. They have from high to low impact sensitivity depending on the anions of the compounds. They all exhibit significant effect on the thermal decomposition of ammonium perchlorate (AP) and some of them accelerate the thermal degradation of 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX). Among them 4 is the best one. Unexpectedly, compound 5 , with 1H‐tetrazolate as anion, can decompose into its original reactants at the temperature just higher than its melting point and could show smart‐material functionality in solid propellants.     

Study of Six Green Insensitive High Energetic Coordination Polymers Based on Alkali/Alkali‐Earth Metals and 4,5‐Bis(tetrazol‐5‐yl)‐2 H‐1,2,3‐triazole

Constructing insensitive high‐performance energetic coordination polymers (ECPs) with alkali/alkali‐earth metal ions and a nitrogen‐rich organic backbone has been proved to be a feasible strategy in this work. Six diverse dimensional novel ECPs (compounds 1 – 6 ) were successfully synthesized from Na^I, Cs^I, Ca^II, Sr^II, Ba^II ions and a nitrogen‐rich triheterocyclic 4,5‐bis(tetrazol‐5‐yl)‐2 H ‐1,2,3‐triazole (H₃BTT). All compounds show outstanding stability and low sensitivity, the thermal stability of these ECPs are significantly improved as the structural reinforcement increases from 1D to 3D, in which the decomposition temperature of 3D Ba^II based compound 6 is as high as 397 °C. Long‐term storage experiments show that compounds 5 and 6 are stable enough at high temperature. Moreover, the six compounds hold considerable detonation performances, in which Ca^II based compound 5 possesses the detonation velocity of 9.12 km s⁻¹, along with the detonation pressure of 34.51 GPa, exceeding those of most energetic coordination polymers. Burn tests further certify that the six compounds can be versatile pyrotechnics.