Magnesium-Stabilised Transition Metal Formyl Complexes: Structures, Bonding, and Ethenediolate Formation

Herein we report the first comprehensive series of crystallographically characterised transition metal formyl complexes. In these complexes, the formyl ligand is trapped as part of a chelating structure between a transition metal (Cr, Mn, Fe, Co, Rh, W, and Ir) and a magnesium (Mg) cation. Calculations suggest that this bonding mode results in significant oxycarbene-character of the formyl ligand. Electron-rich late-transition metal complexes have the highest oxycarbene-character to the bonding and are the most stable in solution. Further reaction of a heterometallic Cr---Mg formyl complex results in a rare example of C–C coupling and formation of an ethenediolate complex. These results show that well-defined transition metal formyl complexes are potential intermediates in the homologation of carbon monoxide.

Crystal structure of the two-dimensional coordination polymer poly[di-μ-bromido-bis(μ-tetrahydrothiophene)dicopper(I)]

The polymeric title compound, [Cu2Br2(C4H8S)2] n , CP1, represents an example of a two-dimensional coordination polymer resulting from reaction of CuBr with tetrahydrothiophene (THT) in MeCN solution. The two-dimensional layers consist of two different types of rhomboid-shaped dinuclear Cu(μ2-Br)2Cu secondary building units (SBUs); one with a quite loose Cu...Cu separation of 3.3348 (10) Å and a second one with a much closer intermetallic contact of 2.9044 (9) Å. These SBUs are interconnected through bridging THT ligands, in which the S atom acts as a four-electron donor bridging each Cu(μ2-Br)2Cu unit in a μ2-bonding mode. In the crystal, the layers are linked by very weak C—H...·Br hydrogen bonds with H...Br distances of 2.95 Å, thus giving rise to a three-dimensional supramolecular network.

The Filler Effect on Compressive Strength of Sulfur Concrete

The sulfur concrete samples were prepared by the optimized process, which were mixed with cement, fly ash and slag, respectively. The influence of the type and content of filler on the compressive strength of sulfur concrete was studied. The phase and micromorphology of filler and sulfur mixture were characterized by X-ray diffraction and scanning electron microscope, and the bonding mode was studied. The results show: the cement filler has the best effect on the compressive performance of sulfur concrete,and the compressive strength is 87.2 MPa by adding cement filler with the same quality as sulfur; there is no chemical reaction between filler and sulfur, and the filler is physically bonded to sulfur matrix.

Intramolecular π-conjugated channel expansion achieved by doping cross-linked dopants into carbon nitride framework towards propelling photocatalytic hydrogen evolution and mechanism insight

Developing the modified carbon nitride (CN) with multi-bonding mode remains a pivotal challenge for the high-efficiency photocatalytic hydrogen evolution (PHE). Here, we fabricate a PYM-CN photocatalyst by doping pyrimethamine (PYM)...

Fluxional chloro-pyrrole-Pd(II) complex to cationic η2-Pyrrole-Pd(II) complex: subtlety in structure-directed bonding mode

Fluxionality in η1-aromatic carbocyclic ligated Pd(II) complexes is retained if the η1-carbon is replaced with N atom through “hemilabile” palladium−carbon η1-pyrrole ligation. Herein, We report and characterize tetra coordinated neutral...

A sandwich-type cluster containing Ge@Pd3 planar fragment flanked by aromatic nonagermanide caps

Sandwich-type clusters with the planar fragment containing a heterometallic sheet have remained elusive. In this work, we introduce the [K(2,2,2-crypt)]4{(Ge9)2[η6-Ge(PdPPh3)3]} complex that contains a heterometallic sandwich fragment. The title compound is structurally characterized by means of single-crystal X-ray diffraction, which reveals the presence of an unusual heteroatomic metal planar fragment Ge@Pd3. The planar fragment contains a rare formal zerovalent germanium core and a peculiar bonding mode of sp2-Ge@(PdPPh3)3 trigonal planar structure, whereas the nonagermanide fragments act as capping ligands. The chemical bonding pattern of the planar fragment consists of three 2c-2e Pd-Ge σ-bonds attaching Pd atoms to the core Ge atom, while the binding between the planar fragment and the aromatic Ge9 ligands is provided by six 2c-2e Pd-Ge σ-bonds and two delocalized 4c-2e σ-bonds. The synthesized cluster represents a rare example of a sandwich compound with the heteroatomic metal planar fragment and inorganic aromatic capping ligands.

Investigating the effect of different bonding areas on the lateral resistance of polyurethane-mixed ballast using the discrete element method

In order to investigate the characteristics of the lateral resistance of the polyurethane-mixed ballast with different bonding areas, a sleeper–ballast model was established using the discrete element method. The lateral resistance of the polyurethane-mixed ballast with single and combined bonding modes was analyzed. The results show that the lateral resistance increases with the increase of the bonding depth of the shoulder ballast. After the bonding depth of the crib ballast and the base ballast reaches 5 cm and 15 cm below the bottom of the sleeper, respectively, there is no significant development of the lateral resistance. The lateral resistance cannot be improved efficiently by bonding the slope ballast. The combined bonding of the crib ballast and the base ballast is an effective method to improve the lateral resistance. With the gradual failure of the bonding contact points between the sleeper and the ballast, the average value of the lateral resistance decreases linearly and the lateral resistance presents a greater randomness under the more complex bonding mode.

Crystal structure of the coordination polymer catena-poly[[[(acetonitrile-κN)copper(I)]-μ3-1,3-dithiolane-κ3 S:S:S′] hexafluoridophosphate]

The polymeric title compound, [Cu2(C2H3N)2(C3H6S2)2](PF6)2, represents an example of a one-dimensional coordination polymer resulting from the reaction of [Cu(MeCN)4][PF6] with 1,3-dithiolane. The cationic one-dimensional ribbon consists of two copper(I) centers each ligated by one acetonitrile molecule and interconnected through two bridging 1,3-dithiolane ligands. One S-donor site of each ligand is κ1-bound to Cu, whereas the second S atom acts as a four-electron donor, bridging two Cu atoms in a κ4-bonding mode. The positive charge of each copper cation is compensated for by a hexafluoridophosphate counter-ion. In the crystal, the polymer chains are linked by a series of C—H...F hydrogen bonds, forming a supramolecular framework.

Nitrosalicylatocopper(II) complexes with chelating pyridine derivatives

Three new nitrosalicylatocopper(II) complexes have been prepared and characterized. Compounds of the composition Cu(5-NSal)2(2-ampy)2 (1), Cu(5-NSal)2(2-hmpy)2 (2) and Cu(3,5-DNSal)2(2-hmpy)2 (3), where 2-ampy = (2-aminomethyl)pyridine, 2-hmpy = (2-hydroxymethyl)pyridine, 5-NSal = 5-nitrosalicylate anion and 3,5-DNSal = 3,5-dinitrosalicylate anion, were characterized by elemental analyses, EPR and IR spectroscopy. EPR spectra are consistent with the dx2-y2ground electronic state. Spectral properties have shown “classic” monodentate coordination of 5-nitrosalicylate anion. Similarly, bonding mode of the 3,5‑dinitrosalicylate anion in (3) is assumed to be unidentate via the carboxyl group, which is surprising compared with the previously studied complex, where the preferred coordination via the phenolate group anion was observed.