Phenylchloroantimon(III)ates; their preparations, and the crystal structures of Me4N[PhSbCl3], [Hpy]2[PhSbCl4], and Me4N[Ph2SbCl2]

Affinity of Telluronium Chalcogen Bond Donors for Lewis Bases in Solution: A Critical Experimental-Theoretical Joint Study

Telluronium salts [Ar2 MeTe]X were synthesized, and their Lewis acidic properties towards a number of Lewis bases were addressed in solution by physical and theoretical means. Structural X-ray diffraction analysis of 21 different salts revealed the electrophilicity of the Te centers in their interactions with anions. Telluroniums' propensity to form Lewis pairs was investigated with OPPh3 . Diffusion-ordered NMR spectroscopy suggested that telluroniums can bind up to three OPPh3 molecules. Isotherm titration calorimetry showed that the related heats of association in 1,2-dichloroethane depend on the electronic properties of the substituents of the aryl moiety and on the nature of the counterion. The enthalpies of first association of OPPh3 span -0.5 to -5 kcal mol-1 . Study of the affinity of telluroniums for OPPh3 by state-of-the-art DFT and ab-initio methods revealed the dominant Coulombic and dispersion interactions as well as an entropic effect favoring association in solution. Intermolecular orbital interactions between [Ar2 MeTe]+ cations and OPPh3 are deemed insufficient on their own to ensure the cohesion of [Ar2 MeTe ⋅ Bn ]+ complexes in solution (B=Lewis base). Comparison of Grimme's and Tkatchenko's DFT-D4/MBD-vdW thermodynamics of formation of higher [Ar2 MeTe ⋅ Bn ]+ complexes revealed significant molecular size-dependent divergence of the two methodologies, with MBD yielding better agreement with experiment.

Binding, Sensing, And Transporting Anions with Pnictogen Bonds: The Case of Organoantimony Lewis Acids

Motivated by the discovery of main group Lewis acids that could compete or possibly outperform the ubiquitous organoboranes, several groups, including ours, have engaged in the chemistry of Lewis acidic organoantimony compounds as new platforms for anion capture, sensing, and transport. Principal to this approach are the intrinsically elevated Lewis acidic properties of antimony, which greatly favor the addition of halide anions to this group 15 element. The introduction of organic substituents to the antimony center and its oxidation from the + III to the + V state provide for tunable Lewis acidity and a breadth of applications in supramolecular chemistry and catalysis. The performances of these antimony-based Lewis acids in the domain of anion sensing in aqueous media illustrate the favorable attributes of antimony as a central element. At the same time, recent advances in anion binding catalysis and anion transport across phospholipid membranes speak to the numerous opportunities that lie ahead in the chemistry of these unique main group compounds.

Activation of an Au-Cl Bond by a Pendent SbIII Lewis Acid: Impact on Structure and Catalytic Activity

With the objective of identifying new coordination modes of ambiphilic ligands, we have investigated the bidentate Sb/P ligands (o-(Ph₂ P)C₆ H₄ )SbCl₂ (L^Cl ) and (o-(Ph₂ P)C₆ H₄ )SbPh₂ (L^Ph ). Reaction of these ligands with (tht)AuCl affords the monoligated species L^Cl AuCl (1) and L^Ph AuCl (2), respectively, in which the antimony centers are only weakly engaged with the coordinated gold atom. Treatment of 1 with PPh₃ induces an intramolecular transfer of a chloride ligand from gold to antimony to form the zwitterionic species o-(Cl₃ Sb)C₆ H₄ (Ph₂ P)Au(PPh₃ ) (3). Natural bond orbital (NBO) calculations show that the antimony and gold centers are involved in weak Sb→Au and Au→Sb interactions, the latter reflecting the Lewis acidity of the pendent antimony group. Finally, we demonstrate that the ability of the antimony center in 1 to abstract a gold-bound chloride in the presence of a Lewis basic substrate may be utilized to activate the gold center for the electrophilic cycloisomerization of propargylic amides.

σ-Donor/acceptor-confused ligands: the case of a chlorostibine

In search for new examples of σ-acceptor ligands, we have investigated the tridentate ligands (o-(iPr2P)C6H4)2SbPh) (L(Ph)) and (o-(iPr2P)C6H4)2SbCl) (L(Cl)) which react with (tht)AuCl (tht = tetrahydrothiophene) to afford L(Ph)AuCl (1) and L(Cl)AuCl (2), respectively. As suggested by the structure of these complexes, which confirm complexation of the SbP2 ligands to the gold chloride fragment, and in agreement with the results of the density functional theory (DFT) and natural bond orbital (NBO) calculations, the gold and antimony atom of 1 and 2 are involved in a Au→Sb donor-acceptor interaction. The magnitude of this interaction is higher in complex 2 which possesses a chlorinated and thus more Lewis acidic antimony center. We have also compared the strength of the Au→Sb interaction present in 2 with the Au→Bi interaction observed in the newly prepared bismuth analogue [(o-(iPr2P)C6H4)2BiCl]AuCl (3). This comparison reveals that 2 possesses a stronger Au→Pn bond (Pn = pnictogen), an observation reconciled by invoking the greater Lewis acidity of antimony(III) halides. Finally, complexes 1 and 2 undergo a clean antimony-centered oxidation when treated with ortho-chloranyl. These oxidation reactions afford complexes [(o-(iPr2P)C6H4)2(o-C6Cl4O2)SbPh]AuCl (5) and [(o-(iPr2P)C6H4)2(o-C6Cl4O2)SbCl]AuCl (6). Structural and computational studies of 5 show that the Au→Sb bond becomes shorter and more covalent upon oxidation of the antimony atom. Although the structure of 6 has not been experimentally determined, spectroscopic and computational results show a similar effect in this complex. Complex 5 and 6 constitute rare examples of metalated six coordinate antimony compounds.

catena-Poly[[[dichlorido(pyridin-1-ium-3-yl)arsenic(III)]-μ-chlorido] mono-hydrate]

The crystal structure of the title compound, {[AsCl3(C5H5N)]·H2O} n , is characterized by polymeric chains consisting of alternating arsenic and chlorine atoms running parallel to the a axis. O-H⋯Cl and N-H⋯O hydrogen bonds mediated by non-coordinating water mol-ecules assemble these chains into a three-dimensional framework. The As(III) atom, the atoms of the pyridinium ring and the water O atom have m site symmetry and the bridging Cl atom has site symmetry 2. This is the first reported organotrichloro-arsenate(III) in which arsenic adopts a ψ-octa-hedral fivefold coordination.

[Tetra(n-butyl)ammonium] [di(μ-bromo) bis{dichloro(p-tolyl)antimonate(III)}]: Synthesis and crystal structure

The crystal structure of a salt of mixed trihalo(aryl)antimonate(III) anion, [ n-Bu4N]2[( p-tol)Cl2Sb(μ-Br)2SbCl2( p-tol)] ( p-tol = p-tolyl) reveals that the anion is dimeric in nature and two Sb atoms of the dimer are asymmetrically bridged by bromide ions (Sb-Br(bridging) = 2.985(2) / 3.373(1) Å).

Synthesis and Structures of Intramolecularly Base-Coordinated Group 15 Aryl Halides

Four group 15 monochlorides of the type EAr(2)Cl [Ar = 2-[(dimethylamino)methyl]phenyl, 2-(Me(2)NCH(2))C(6)H(4) (C(9)H(12)N), E = Sb (4), E = Bi (5); Ar = 8-(dimethylamino)-1-naphthyl, 8-(Me(2)N)C(10)H(6) (C(12)H(12)N), E = Sb (6), E = Bi (7)] have been prepared via the salt elimination reactions of 2 equiv of either 2-(Me(2)NCH(2))C(6)H(4)Li or 8-(Me(2)N)C(10)H(6)Li with ECl(3). Four related group 15 dihalides of the type EArX(2) [Ar = 8-(Me(2)N)C(10)H(6), X = Cl, E = As, (8), E = Sb (9); Ar = 2-(Me(2)NCH(2))C(6)H(4), X = Cl, E = Bi (10); X = I, E = Bi (11)] have been prepared via the salt elimination reactions of equimolar amounts of 8-(Me(2)N)C(10)H(6)Li or 2-(Me(2)NCH(2))C(6)H(4)Li with EX(3). The X-ray crystal structures of 4-6, 8, 9, and 11 are described, and the observed trends in the degree of intramolecular coordination of the nitrogen atoms are consistent with the view that the Lewis acidity of these complexes is associated with the E-X sigma orbitals. Crystal data for 4: triclinic, space group P&onemacr;, a = 9.1483(1) Å, b = 9.4868(1) Å, c = 12.9776(2) Å, alpha = 70.614(8) degrees, beta = 85.738(9) degrees, gamma = 83.094(9) degrees, V = 1054.0(2) Å(3), Z = 2, R = 0.0420. Crystal data for 5: monoclinic, space group P2(1)/c, a = 11.9498(1) Å, b = 11.4695(1) Å, c = 13.9456(8) Å, beta = 104.536(6) degrees, V = 1850.2(3) Å(3), Z = 4, R = 0.0375. Crystal data for 6: monoclinic, space group P2(1)/n, a = 9.4991(8) Å, b = 23.455(4) Å, c = 9.726(1) Å, beta = 100.629(8) degrees, V = 2129.8(4) Å(3), Z = 4, R = 0.0406. Crystal data for 8: orthorhombic, space group P2(1)2(1)2(1), a = 9.713(3) Å, b = 9.835(4) Å, c = 13.310(3) Å, V = 1273.8(5) Å(3), Z = 4, R = 0.0695. Crystal data for 9: orthorhombic, space group P2(1)2(1)2(1), a = 9.7140(3) Å, b = 10.0196(1) Å, c = 13.444(3) Å, V = 1308.5(3) Å(3), Z = 4, R = 0.0320. Crystal data for 11: monoclinic, space group P2(1)/c, a = 7.9455(7) Å, b = 19.3949(3) Å, c = 8.6226(9) Å, beta = 93.338(9) degrees, V = 1326.5(2) Å(3), Z = 4, R = 0.0379.