Ciprian I. Raţ

Metallophilic bonding and agostic interactions in gold(I) and silver(I) complexes bearing a thiotetrazole unit.

Gold(I) and silver(I) complexes of 1-methyl-5-thio-tetrazole (1) have been prepared and the coordination chemistry of this ligand toward metal-phosphine frameworks has been explored. As indicated by IR and Raman data, ligand 1 is deprotonated and the resulted anion acts as a bidentate (S,N)-tetrazole-5-thiolato unit in the new gold(I) complexes, [Au(SCN(4)Me)(PPh(3))] (2), [{Au(SCN(4)Me)}(2)(μ-dppm)] (3), and [{Au(SCN(4)Me)}(2)(μ-dppe)] (4), while it is coordinated only through the sulfur atom as its neutral tetrazole-5-thione form in the silver(I) derivative, [Ag(HSCN(4)Me)(PPh(3))](2)(OTf)(2) (5). Further characterization of the new compounds was performed using multinuclear ((1)H, (13)C, (31)P, (19)F) NMR spectroscopy, mass spectrometry, and DSC measurements. Single-crystal X-ray diffraction studies revealed basically linear P-M-S arrangements in complexes 3-5. The bidentate (S,N) coordination pattern results in a T-shaped (S,N)PAu core in 3 and 4, whereas, in 5, a similar coordination geometry is achieved in the dimer association based on S-bridging ligand 1. Herein, weak (C)H···Au and (C)H···Ag agostic interactions were observed. An intramolecular Au···Au contact occurs in 3, while in 4 intermolecular aurophilic bonds lead to formation of a chain polymer. An intermolecular Ag···Ag contact is also present in the dimer unit of 5. Low-temperature (31)P NMR data for 5 evidenced the presence of monomer and dimer units in solution. Theoretical calculations on model of the complexes 2 and 4 are consistent with the geometries found by X-ray diffraction studies.

19-Tungstodiarsenate(III) Functionalized by Organoantimony(III) Groups: Tuning the Structure–Bioactivity Relationship

A family of three discrete organoantimony(III)-functionalized heteropolyanions-[Na{2-(Me2HN(+)CH2)C6H4Sb(III)}As(III)2W19O67(H2O)](10-) (1), [{2-(Me2HN(+)CH2)C6H4Sb(III)}2As(III)2W19O67(H2O)](8-) (2), and [{2-(Me2HN(+)CH2)C6H4Sb(III)}{WO2(H2O)}{WO(H2O)}2(B-β-As(III)W8O30)(B-α-As(III)W9O33)2](14-) (3)-have been prepared by one-pot reactions of the 19-tungstodiarsenate(III) precursor [As(III)2W19O67(H2O)](14-) with 2-(Me2NCH2)C6H4SbCl2. The three novel polyanions crystallized as the hydrated mixed-alkali salts Cs3KNa6[Na{2-(Me2HN(+)CH2)C6H4Sb(III)}As(III)2W19O67(H2O)]·43H2O (CsKNa-1), Rb2.5K5.5[{2-(Me2HN(+)CH2)C6H4Sb(III)}2As(III)2W19O67(H2O)]·18H2O·Me2NCH2C6H5 (RbK-2), and Rb2.5K11.5[{2-(Me2HN(+)CH2)C6H4Sb(III)}{WO2(H2O)}{WO(H2O)}2(B-β-As(III)W8O30)(B-α-As(III)W9O33)2]·52H2O (RbK-3), respectively. The number of incorporated {2-(Me2HN(+)CH2)C6H4Sb(III)} units could be tuned by careful control of the experimental parameters. Polyanions 1 and 2 possess a dimeric sandwich-type topology, whereas 3 features a trimeric, wheel-shaped structure, representing the largest organoantimony-containing polyanion. All three compounds were fully characterized in the solid state via single-crystal X-ray diffraction (XRD), infrared (IR) spectroscopy, and thermogravimetric analysis, and their aqueous solution stability was validated by ultraviolet-visible light (UV-vis) and multinuclear ((1)H, (13)C, and (183)W) nuclear magnetic resonance (NMR) spectroscopy. Effective inhibition against six different types of bacteria was observed for 1 and 2, and we could extract a structure-bioactivity relationship for these polyanions.

Bis(4-pyridyl)mercury – a new linear tecton in crystal engineering: coordination polymers and co-crystallization processes

Three new coordination polymers have been obtained using bis(4-pyridyl)mercury (py2Hg) as a spacer: [Cu(Hmea)2(py2Hg)](ClO4)2·2(py2Hg) (1), [Cu2(pa)2(py2Hg)(ClO4)2]·0.5(py2Hg)·H2O (2), and [Cu2(pa)2(py2Hg)2](BF4)2 (3) (Hmea = monoethanolamine; Hpa = propanolamine). Compounds 1 and 2 are linear coordination polymers with mononuclear and binuclear alkoxo-bridged nodes, respectively. Compound 3 features a 3-D network with a cadmium sulfate topology. The ability of py2Hg to generate supramolecular solid-state architectures is illustrated by three systems obtained from co-crystallization processes: (4,4′-dihydroxybiphenyl)·(py2Hg) (4), (pyrogallol)·(py2Hg) (5), and (phloroglucinol)·2(py2Hg) (6). The convolution of various supramolecular interactions (Hg⋯N, Hg⋯O, π⋯Hg, and π–π) in sustaining the architecture of the crystals is analyzed. A new synthetic method for bis(4-pyridyl)mercury was developed. It consists of a two-step reaction, starting from 4-iodopyridine and using iPrMgCl·LiCl and HgCl2.

Palladium(II) complexes with chiral organoantimony(III) ligands. Solution behaviour and solid state structures

The chiral compound (2-Me2NCH2C6H4)PhSbCl (1) was obtained from (2-Me2NCH2C6H4)Li and PhSbCl2 in 1:1 molar ratio, while (2-Me2NCH2C6H4)Mes2Sb (2) was prepared from (2-Me2NCH2C6H4)SbCl2 and MesMgBr in 1:2 molar ratio. The compounds 1 and 2 were used to obtain the Pd(II)/stibine complexes: [Me2NHCH2C6H5]+[PdCl3{SbCl(Ph)(C6H4CH2NMe2-2)-Sb}]− (3) and [PdCl2{SbMes2(C6H4CH2NMe2-2)-N,Sb}] (4). All the compounds were characterized by multinuclear NMR spectroscopy in solution, elemental analysis, mass spectrometry and single-crystal X-ray diffraction studies. In compounds 1–3 the coordination geometry around the antimony atom is pseudo-trigonal bipyramidal, while in compound 4 a tetrahedral geometry around the antimony atom is observed. Theoretical calculations at the DFT level on compounds 1–4 were used in order to gain insight into the nature of the coordinative bonds.

Hypervalent diorganoantimony(III) fluorides via diorganoantimony(III) cations – a general method of synthesis

Novel diorganoantimony(III) fluorides containing ligands with pendant arms, R2SbF (5), (R)PhSbF (6) [R = 2-(2′,6′-iPr2C6H3NCH)C6H4], R′′2SbF (7) and (R′′)PhSbF (8) [R′′ = 2-(Me2NCH2)C6H4], were prepared via the ionic derivatives [R2Sb]+[PF6]− (1), [(R)PhSb]+[PF6]− (2), [R′′2Sb]+[SbF6]− (4) and [(R′′)PhSb]+[SbF6]− (obtained in situ) by treatment with [Bu4N]F·3H2O. The ionic species used as starting materials as well as [R′2Sb]+[PF6]− (3) [R′ = 2-(2′,4′,6′-Me3C6H2NCH)C6H4] were obtained from the corresponding bromides or chlorides and Tl[PF6] or Ag[SbF6]. The compounds were investigated by multinuclear NMR spectroscopy in solution, MS and IR spectroscopy in the solid state. The molecular structures of the ionic species 1·2CH2Cl2 and 3·2CHCl3 as well as of the fluorides 5–8 were determined by single-crystal X-ray diffraction.

(2,4,6-Trimethyl­phen­yl)boronic acid–triphenyl­phosphine oxide (1/1)

In the crystal structure of the title compound, C9H13BO2·C18H15OP, there are O—H⋯O hydrogen bonds between the O atom of triphenylphosphine oxide and one hydroxy group of the boronic acid. Boronic acid molecules form inversion-related hydrogen-bonded dimers in an R 2 2(8) motif. The structure is consolidated by intermolecular C—H⋯O bonds and C—H⋯π interactions.

The Complex BiCl3 · CH3C6H5

Single crystals of BiCl3 ·CH3C6H5 (1) formed from BiCl3 and toluene have been analysed by X-ray crystallography (triclinic, P1̄, Z = 4, a = 7.308(2), b = 12.013(3), c = 12.284(2) Å , α = 75.02(2), β = 84.23(2), γ = 88.86(2)°, T = 173(2) K).

1,1,1,1,4,4,4,4-Octacarbonyl-2,2,3,3,5,5,6,6-octamethyl-cyclo-2,3,5,6-tetraantimony-1,4-dichromium.

The structure of the title compound, alternatively called bis(mu-tetramethyldistibinediyl)bis(tetracarbonylchromium), [Cr2Sb4(CH3)8(CO)8], consists of two Me4Sb2 bridging units between Cr(CO)4 complex fragments. The centre of the molecule is located on a special position of 2/m symmetry. This is the first characterized Sb4Cr2 heterocycle.

Mapping the Trajectory of Nucleophilic Substitution at Silicon Using a peri-Substituted Acenaphthyl Scaffold

The second-order nucleophilic substitution (SN 2) reaction at a silicon atom is scrutinized by means of snapshots along a pseudoreaction coordinate. Phosphine and fluoride represent both attacking and leaving groups in the modeled SN 2 reaction. In the experimentally obtained 5-diphenylphosphinoacenaphth-6-yl-dimethylfluorosilane, 1, the phosphine and fluorosilane moieties are forced into immediate proximity through an acenaphthyl scaffold, that is, they exhibit peri interactions that serve as the model of the reactant ion-molecule complex and starting point for a theoretical potential-energy surface (PES) scan. Upon dissociation of fluoride, the experimentally obtained silylphosphonium cation 2 serves as a model of the product and end point of the PES scan. The pseudoreaction pathway is studied using geometric, energetic, spectroscopic, molecular-orbital, and topological real-space bonding indicators. It becomes evident that it is crucial to combine such methods to understand the pseudoreaction because they reveal different aspects based on different sensitivity to dispersive, electrostatic, and polar-covalent contributions to bonding, as shown by the reduced density gradient analysis. For example, atoms-in-molecules theory describes a late topological catastrophe, whereas the electron localizability indicator describes an early concerted reaction and natural resonance theory describes a more gradual change of properties. This case study encourages the use of a well-balanced toolbox equipped with complementary methods to emphasize different aspects of bonding.

Formation and Structure of [(CO)4Mo(Et4Sb2)]2

The formation and the structure of [(CO)4Mo(Et4Sb2)]2 (1) and of a complex with distibane and distibane oxide ligands (2) are reported. Graphical Abstract Formation and Structure of [(CO)4Mo(Et4Sb2)]2