Bulky Polyfluorinated Terphenyldiphenylboranes: Water Tolerant Lewis Acids.

Protocols for the synthesis of the bulky polyfluorinated triarylboranes 2,6-(C6 F5 )2 C6 F3 B(C6 F5 )2 (1), 2,6-(C6 F5 )2 C6 F3 B[3,5-(CF3 )2 C6 H3 ] (2), 2,4,6-(C6 F5 )3 C6 H2 B(C6 F5 )2 (3), 2,4,6-(C6 F5 )3 C6 H2 B[3,5-(CF3 )2 C6 H3 ] (4) were developed. All boranes are water tolerant and according to the Gutmann-Beckett method, 1-3 display Lewis acidities larger than that of the prominent B(C6 F5 )3 .

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.

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-ß-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-ß-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.

(2,4,6-Trimethyl-phen-yl)boronic acid-triphenyl-phosphine oxide (1/1).

In the crystal structure of the title compound, C(9)H(13)BO(2)·C(18)H(15)OP, there are O-H⋯O hydrogen bonds between the O atom of triphenyl-phosphine oxide and one hy-droxy group of the boronic acid. Boronic acid mol-ecules form inversion-related hydrogen-bonded dimers in an R(2) (2)(8) motif. The structure is consolidated by inter-molecular C-H⋯O bonds and C-H⋯π inter-actions.

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.

2'-Iodo-2,2'',3,3'',4,4'',5,5'',6,6''-deca-methyl-1,1':3',1''-terphenyl chloro-form monosolvate.

The title compound, C(28)H(33)I·CHCl(3), forms dimers through C-I⋯π inter-actions. The crystal structure is consolidated by the presence of C-H⋯π inter-actions between the chloro-form solvent and the main mol-ecule.

3,5-Dibromo-2',3',4',5',6'-penta-methyl-1,1'-biphen-yl.

In the crystal structure of the title compound, C(17)H(18)Br(2), the benzene rings are almost perpendicular [dihedral angle = 84.0 (3)°]. The crystal structure is consolidated by the presence of C-Br⋯π inter-actions.

[2-(4-Methyl-piperazin-1-ylmeth-yl)phen-yl]diphenyl-phosphane.

In the title compound, C(24)H(27)N(2)P, the P atom is bonded to three C atoms in a trigonal-pyramidal geometry. The overall Ψ-trigonal-bipyramidal coordination of the P atom is established when the contribution of the electron lone pair and of the N-P donor-acceptor distance of 3.051 (3)Å are considered. The 4-methyl-piperazinyl ring adopts a chair conformation. Intra- and inter-molecular C-H⋯π hydrogen bonding leads to the consolidation of the structure.

Chloridobis{2-[(dimethyl-amino)-meth-yl]phen-yl}anti-mony(III).

In the title compound, [Sb(C(9)H(12)N)(2)Cl], the Sb atom adopts a Ψ-trigonal-bipyramidal geometry. The two 2-[(dimethyl-amino)-methyl]-phenyl ligands are coordinated asymmetrically to the Sb atom. The carbon atoms of one of the ligands are disordered over sets of sites with equal occupancy, resulting in two conformational isomers in the crystal. The Sb-C and Sb-N distances in the ordered ligand are: 2.153 (4) and 3.326 (5) Å, respectively. The corresponding distances in the disordered ligand are: 2.103 (5)/2.188 (5) and 2.454 (3) Å, respectively. The structure displays intra-molecular C-H⋯Cl hydrogen bonding.

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.

A general route to monoorganopnicogen(III) (M = Sb, Bi) compounds with a pincer (N,C,N) group and oxo ligands.

The reaction of RMCl2 [R = 2,6-[MeN(CH2CH2)2NCH2]2C6H3; M = Sb (1), Bi (2)] with KOH affords the isolation of the oxides cyclo-R2M2O2 [M = Sb (3), Bi (4)]. Treatment of 3 with trifluoroacetic acid produced an ionic species (5) with a dinuclear cation that contains organic ligands protonated partially at one of the pendant arms. The cyclic oxides 3 and 4 are able to trap gaseous CO2 to give "RMCO3" [M = Sb (6), Bi (7)], the degree of these organometallic carbonates' oligomerization being under investigation. The reactivity of the dinuclear oxide 3 was also investigated towards oxalic acid or dopamine hydrochloride and pure mononuclear compounds could be isolated, i.e. RSb[O(O)CC(O)O] (8) and RSb[O2-1,2-C6H3-3-(CH2)2NH3]Cl (9). The reaction of the dichlorides 1 and 2 with ethylene glycol, pinacol or catechol, in the presence of KOH, led to 2-organo-1,3,2-dioxastibolanes or -bismolanes RM(OCH2)2 [M = Sb (10), Bi (11)], RM(OCMe2)2 [M = Sb (12), Bi (13)] and 2-organo-1,3,2-dioxastibole or -bismole RM(O2-1,2-C6H4) [M = Sb (14), Bi (15)], respectively. The compounds were investigated by NMR spectroscopy, including variable temperature experiments, providing evidence for the presence of the intramolecular N→M interactions in solution. Single crystal X-ray diffraction studies were performed for most compounds and revealed an organic group R acting as a pincer ligand resulting in a distorted square pyramidal (N,C,N)MO2 core with cis intramolecular N→M interactions placed trans to M­O bonds. This is in contrast to the N→M interactions trans to each other as found in the RMCl2 used as starting materials. The crystals of the oxides 3 and 4·4H2O contain different geometric isomers with anti and syn orientation of the M­C bonds, respectively, with respect to the planar M2O2 ring. In the supramolecular polymeric architecture established in the crystal of 4·4H2O an important finding is the experimental observation of water hexamer units with a [tetramer + 2] structure (water molecules connected to opposite corners of a square water tetramer) fixed between 1D-chains of the type (syn-R2Bi2O2·H2O)n through additional hydrogen bonds to oxygen atoms of the dinuclear organobismuth(III) moieties. Theoretical calculations were carried out on 2­6 and 8­15 in order to gain insight into the stabilization energy produced by intramolecular coordination of the pendant arms, association degrees and formation energies of the organopnicogen compounds with chelating ligands.

Organoantimony(III) compounds containing (imino)aryl ligands of the type 2-(RN=CH)C6H4 (R = 2',4',6'-Me3C6H2, 2',6'-(i)Pr2C6H3): bromides and chalcogenides.

The reaction of 2-(RN=CH)C(6)H(4)MgBr [R = 2',4',6'-Me(3)C(6)H(2) (R(1)), 2',6'-(i)Pr(2)C(6)H(3) (R(2))] [prepared from 2-(R(1)N=CH)C(6)H(4)Br (1) or 2-(R(2)N=CH)C(6)H(4)Br (2) and Mg] with SbCl(3) in a 2 : 1 and 1 : 1 molar ratio followed by treatment with an aqueous KBr solution gave [2-(R(1)N=CH)C(6)H(4)](2)SbBr (3) and [2-(R(2)N=CH)C(6)H(4)](2)SbBr (4) as well as [2-(R(1)N=CH)C(6)H(4)]SbBr(2) (6) and [2-(R(2)N=CH)C(6)H(4)]SbBr(2) (7). Treatment of 4 with Na(2)S·9H(2)O provided the dinuclear [{2-(R(2)N=CH)C(6)H(4)}(2)Sb](2)S (5). Heterocyclic species, i.e. the oxide cyclo-[{2-(R(2)N=CH)C(6)H(4)}SbO](3) (8) and the sulfides cyclo-[{2-(R(1)N=CH)C(6)H(4)}SbS](2) (9) and cyclo-[{2-(R(2)N=CH)C(6)H(4)}SbS](2) (10), were obtained by reacting dibromides 6 and 7 with KOH and Na(2)S·9H(2)O, respectively, in a water-toluene solvent mixture. The sulfide 10 reacted with [W(CO)(5)(thf)] to yield the heterometallic complex cyclo-[{2-(R(2)N=CH)C(6)H(4)}SbS](2)[W(CO)(5)] (11). The compounds were characterised by multinuclear NMR spectroscopy in solution, mass spectrometry and IR spectroscopy in the solid state. The molecular structures of 4, 5, 6·CHCl(3), 7, 9·CH(2)Cl(2), 10 and 11·0.25CH(3)OH were established by single-crystal X-ray diffraction. Theoretical calculations using DFT methods were carried out on bromide 7 and the geometrical isomers of its dimer association as well as the geometrical isomers of sulfide 10 and its monomer.

Organomercury(II) and tellurium(II) compounds with the "pincer" ligand 2,6-[O(CH2CH2)2NCH2]2C6H3--stabilization of an unusual organotellurium(II) cationic species.

The reaction of RH (1) with Hg(OAc)(2), in EtOH, gave the acetate RHgOAc (2) [R = 2,6-[O(CH(2)CH(2))(2)NCH(2)](2)C(6)H(3)]. The corresponding RHgCl (3) was obtained from 2 and LiCl. The reaction of 3 with TeCl(4) (1:1 molar ratio), in anhydrous 1,4-dioxane, resulted in the transfer of the organic ligand from mercury to tellurium and the isolation of the unexpected ionic compounds [RTe](2)[Hg(2)Cl(6)] (4) and [RH(3)][HgCl(4)] (5). The molecular structures of 1-4 and 5·H(2)O were established by single-crystal X-ray diffraction. The acetate 2 and the chloride 3 are monomeric in solid state. In both mercury and tellurium organometallic compounds the organic group acts as an (N,C,N) "pincer" ligand. This coordination pattern provided stability for the rare [RTe](+) cation. Weak cation-anion interactions [Te···Cl 3.869(3) Å] are present between [RTe](+) and the dinuclear anion [Hg(2)Cl(6)](2-) in the crystal of 4. Theoretical calculations with DFT methods were performed for models of 3 and 4. The results show that in the cation of 4 the coordination of the nitrogen atoms play an important role for the stabilization of the structure found in the crystal whereas in 3 the coordination of the nitrogen atoms to the metal centre stabilizes to a less extent the structure found in solid state.

New chiral organoantimony(III) compounds containing intramolecular N --> Sb interactions--solution behaviour and solid state structures.

Hypervalent organoantimony(III) compounds of the type [2-(Me2NCH2)C6H4]PhSbCl (1), [2-(Me2NCH2)C6H4]MesSbBr (7) and [2-(Me2NCH2)C6H4]nAr(3-n)Sb [n = 1, Ar = Ph (4), Mes (9); n = 2, Ar = Ph (5), Mes (10)] were prepared via salt elimination reactions between [2-(Me2NCH2)C6H4]Li and MesMgBr and PhnSbCl(3-n), [2-(Me2NCH2)C6H4]SbBr2 or [2-(Me2NCH2)C6H4]nSbCl(3-n) (n = 1, 2), in appropriate molar ratios. Halogen exchange reactions with aqueous KBr or KI gave [2-(Me2NCH2)C6H4]ArSbX [Ar = Ph, X = Br (2), I (3); Ar = Mes, X = I (8)]. Metathesis reaction between 1 and MesMgBr affords [2-(Me2NCH2)C6H4]PhMesSb (6). Compounds 1-10 were investigated by means of NMR (1H, 13C) in solution and by mass spectrometry. The investigation of the molecular structures of 2-8 by single-crystal X-ray diffraction revealed that the nitrogen atoms of the pendant CH2NMe2 arms are strongly coordinated to the antimony atoms. All compounds exhibit chirality and crystallize as racemic mixtures.

Polynuclear titanocene complexes with antimony ligands: [(Cp2Ti)2(SbR2)2] (R=Et), [(Cp2Ti)3(SbR)3Sb] [R=2-(Me2NCH2)C6H4] and [(Cp2Ti)5(SbR)2Sb7] (R=Me3SiCH2).

The formation and crystal structure of [(Cp2Ti)2(SbR2)2] (1, R=Et), [(Cp2Ti)3(SbR)3Sb] [2, R=2-(Me2NCH2)C6H4], and [(Cp2Ti)5(SbR)2Sb7] (3, R=Me3SiCH2) is reported.