Interaction of polyhedral boron hydride anions [B10H10] and [B12H12] with cyclic copper and silver 3,5-bis(trifluoromethyl)pyrazolate complexes

The interactions of cyclic trinuclear copper {[3,5-(CF₃)₂Pz]Cu}₃ and silver {[3,5-(CF₃)₂Pz]Ag}₃ complexes with polyhedral borate anions [B₁₀H₁₀]²⁻ and [B₁₂H₁₂]²⁻ in solvents of low-polarity were studied using IR spectroscopy (190-290 K). Two types of complexes were found in solution: {[((3,5-CF₃)₂PzM)₃][B_nH_n]}²⁻ and {[((3,5-CF₃)₂PzM)₃]₂[B_nH_n]}²⁻ (M = Ag, Cu; n = 10, 12). The stability constants of these complexes were determined from IR-spectra.     

Synthesis of the 1-hydroxy-closo-decaborate anion [1-B10H9OH]

Reactions of the diazonium derivative of closo-decaborate anion with oxygen nucleophiles were studied. The reaction of [1-B₁₀H₉N₂]⁻ with hydroxide ion gives the corresponding hydroxy derivative [1-B₁₀H₉OH]²⁻ in high yield. The reactions with OR (R = Me, Et, i-Pr, Ph) result in mixture of [1-B₁₀H₉OR]²⁻ and [a²-B₂₀H₁₈]⁴⁻.     

Synthesis and X-ray structural characterisation of the tetramethylene oxonium derivative of the hydrodecaborate anion. A versatile route for derivative chemistry of [B10H10]

The oxonium derivative P(C₆H₅)₄[2-B₁₀H₉O(CH₂)₄] (1) has been prepared from [B₁₀H₁₀]²⁻ by a solvent-addition reaction route, promoted by Et₂O · BF₃. Its structure has been confirmed by single crystal X-ray analysis. 1 is assumed to be a useful synthon for the derivative chemistry of [B₁₀H₁₀]²⁻. As an illustration, ring-opening reaction occurred in presence of the strong nucleophilic agent OH⁻, giving the monoanionic derivative [P(C₆H₅)₄]₂[2-B₁₀H₉O(CH₂)₄OH] (2).     

Ethynylmonocarba-closo-dodecaborates: M[12-HCC-closo-1-CB11H11] and M[7,12-(HCC)2-closo-1-CB11H10] (M = Cs, [Et4N])

Cesium and tetraethylammonium salts of the ethynyl functionalized monocarba-closo-dodecaborate anions [12-HCC-closo-1-CB₁₁H₁₁]⁻ and [7,12-(HCC)₂-closo-1-CB₁₁H₁₀]⁻ were obtained by desilylation of [Et₄N][12-Me₃SiCC-closo-1-CB₁₁H₁₁] and [Et₄N][7,12-(Me₃SiCC)₂-closo-1-CB₁₁H₁₀], respectively. Their thermal properties were examined by differential scanning calorimetry. The compounds were characterized by multi-NMR, IR, and Raman spectroscopy, (−)-MALDI mass spectrometry, and elemental analysis. Single-crystals of Cs[12-HCC-closo-1-CB₁₁H₁₁] and [Et₄N][7,12-(HCC)₂-closo-1-CB₁₁H₁₀] were studied by X-ray diffraction. The discussion of the spectroscopic and structural properties is supported by data derived from theoretical calculations using density functional theory as well as perturbation theory.     

Reactions of oxonium derivatives of [B12H12] with amines: Synthesis and structure of novel B12-based ammonium salts and amino acids

The reactions of oxonium derivatives of [B₁₂H₁₂]²⁻ with various amines were studied. A series of novel B₁₂-species with ammonium group on the side chain was synthesized in high yield. A structure of tetrabutylammonium-[2-(2-morpholinium-ethoxy)-ethoxy]-undecahydro-closo-dodecaborate was determined and the existence of intramolecular N-H?O-B bond was shown. Using these reactions, novel boronated piperazines and amino acids were prepared.     

Synthesis and X-ray structural characterization of the triphenylphosphine derivative of the closo-dodecaborate anion, closo-[B12H11P(C6H5)3][N(n-C4H9)4]

The reaction of a molar excess of closo-[B₁₂H₁₁I][N(n-C₄H₉)₄]₂ (1) with tetrakis(triphenylphosphine)palladium (0), Pd(0)L₄, yields to the formation of the title monoanionic compound, closo-[1-B₁₂H₁₁P(C₆H₅)₃][N(n-C₄H₉)₄] (2). The structure of 2 was determined by X-ray diffraction analysis performed on a single crystal. The mechanism of formation of 2 is also discussed. We suggested a two-step mechanism for the formation of 2 consisting in a oxidative addition of the palladium complex followed by a reductive elimination involving P(C₆H₅)₃ and assisted by Na₂CO₃. To our knowledge, this is the first example of monosubstitution of B₁₂ with formation of boron-phosphorus bond.     

Polyhedral monocarbaborane chemistry : Reactions of the [6-Ph-nido-6-CB9H11] anion with two-electron donors to yield a series of neutral arachno and closo ten-vertex monocarbaborane derivatives

Reaction of the ten-vertex [6-Ph-nido-6-CB₉H₁₁]⁻ anion (1) with two-electron donor ligands L, where L is SMe₂, NH₂Ph, NC₅H₅, NC₅H₄-para-CH₂Ph, NC₅H₄-para-Ph or NC₉H₇ (where NC₉H₇ is quinoline) in the presence of {FeCl₃(OH₂)₆} gives the six neutral arachno ten-vertex monocarbaboranes [6-Ph-9-L-arachno-6-CB₉H₁₂], compounds 2, 3, 4, 7, 9 and 11, respectively, isolatable in yields of up to 63%. On prolonged treatment with {FeCl₃(OH₂)₆} oxidative cluster closure of the four compounds 4, 7, 9 and 11 that have pyridine-type ligands gives the neutral closo ten-vertex monocarbaboranes [1-Ph-6-L-closo-1-CB₉H₈], compounds 6, 8, 10 and 12, respectively, in yields of 49-92%. All new species 2, 3, 4, 6, 7, 8, 9, 10, 11 and 12 are characterised by single-crystal X-ray diffraction analysis and NMR spectroscopy. [This paper is an annotated exposition of parts of an oral presentation at the Third Pan-European Meeting of Boron Chemists, EUROBORON-3, Pruhonice, The Czech Republic, September 2004, of which the proceedings constitute this volume of Journal of Organometallic Chemistry.]     

The preparation of [closo-1-CB9H8-1-COOH-10-(4-C3H7C5H9S)] as intermediate to polar liquid crystals

The preparation of iodo acid [closo-1-CB₉H₈-1-COOH-10-I]⁻ (1) is optimized and scaled from 1 to 40 g of B₁₀H₁₄. The improved preparation of the [arachno-6-CB₉H₁₃-6-COOH]⁻ (5) uses four times smaller volume and can be run conveniently in up to 40 g scale in a 3-L vessel. The optimized oxidation of 5 to [closo-2-CB₉H₉-2-COOH]⁻ (4) requires less oxidant, 12 times smaller volume, and significantly shorter reaction time. The overall yields of the iodo acid 1 as the [NMe₄]⁺ salt are typically 8-10% (10-12 g) for 40 g of B₁₀H₁₄. The iodo acid 1 was transformed to amino acid 8, then to dinitrogen acid 10, and finally to sulfonium acid 2[3] in overall yield of about 13%. The search for a more efficient phosphine ligand for the Pd-catalyzed amination process was not fruitful. Three routes to the sulfonium acid 2[n] were investigated, and the best yield of about 47% was obtained for Cs₂CO₃-assisted cycloalkylation. Liquid crystalline ester of acid 2[3] and 4-butoxyphenol was prepared and investigated.     

[1-B<Subscript>10</Subscript>H<Subscript>9</Subscript>N<Subscript>2</Subscript>]<Superscript>−</Superscript> and [1-CB<Subscript>9</Subscript>H<Subscript>10</Subscript>]<Superscript>−</Superscript> anions: an attempt of quantum chemical calculations

Comparative quantum chemical calculations of structural parameters, chemical shifts of ¹¹B NMR spectra, and atomic charges in 10-vertex boron hydride anions [1-CB₉H₁₀]⁻ and [1-B₁₀H₉N₂]⁻ were performed using the restricted Hartree-Fock method with the 6-31++G(D,P) basis set. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1853–1855, September, 2007.     

Synthesis and structure of halogen derivatives of 9-dimethylsulfonium-7,8-dicarba-nido-undecaborane [9-Me2S-7,8-C2B9H11]

Halogenation of 9-dimethylsulfonium-7,8-dicarba-nido-undecaborane [9-SMe₂-7,8-C₂B₉H₁₁] with N-chlorosuccinimide, bromine and iodine gave the expected corresponding halogen derivatives [9-SMe₂-11-X-7,8-C₂B₉H₁₀], where X = Cl (1), Br (2), I (3). In the bromination reaction, [9-SMe₂-6-Br-7,8-C₂B₉H₁₀] (4) was isolated as a minor product being the first example of substitution at a “lower” belt of the 7,8-dicarba-nido-undecaborate cage. The use of excess of bromine resulted in dibromo derivative [9-SMe₂-6,11-Br₂-7,8-C₂B₉H₉] (5). Structures of the compounds prepared were determined using ¹¹B-¹¹B COSY NMR spectroscopy (for all halogen derivatives) and single crystal X-ray diffraction (for compounds 2, 3, and 5).     

Synthesis of a Tyr-octreotate conjugated closo-carborane [HC2B10H10]: a potential compound for boron neutron capture therapy

A novel Tyr³-octreotate conjugated closo-carborane as a potential compound for boron neutron capture therapy was obtained via Fmoc solid phase peptide synthesis. The boron cluster [C₂B₁₀H₁₁] was introduced through the reaction of 6,9-bis(acetonitrile)decaborane and 5-hexynoic acid yielding a new closo-carborane conjugated carboxylic acid which was coupled subsequently with solid phase conjugated Tyr³-octreotate. The final boron-containing peptide was purified by preparative reverse phase HPLC and structural identity was proved applying MALDI-TOF mass spectrometry.     

Synthesis and characterization of hetero-binuclear Co-Rh complexes [CpCoS2C2(B9H10)][Rh(COD)] and [CpCoSe2C2(B10H10)][Rh(COD)]

Two hetero-binuclear complexes [Cp^∗CoS₂C₂(B₉H₁₀)][Rh(COD)] (2a) and [Cp^∗CoSe₂C₂(B₁₀H₁₀)][Rh(COD)] (2b) [Cp^∗ = η⁵-pentamethylcyclopentadienyl, COD = cyclo-octa-1,5-diene (C₈H₁₂)] were synthesized by the reactions of half-sandwich complexes [Cp^∗CoE₂C₂(B₁₀H₁₀)] [E = S (1a), Se (1b)] with low valent transition metal complexes [Rh(COD)(OEt)]₂ and [Rh(COD)(OMe)]₂. Although the reaction conditions are the same, the structures of two products for dithiolato carborane and diselenolato carborane are different. The cage of the carborane in 2a was opened; However, the carborane cage in 2b was intact. Complexes 2a and 2b have been fully characterized by ¹H, ¹¹B NMR and IR spectroscopy, as well as by elemental analyses. The molecular structures of 2a and 2b have been determined by single-crystal X-ray diffraction analyses and strong metal-metal interactions between cobalt and rhodium atoms (2.6260 Å (2a) and 2.7057 Å (2b)) are existent.     

The transition-metal assisted synthesis of the anti-octadecaborate Anion [B18H21] from the Nido-dodecahydrononaborate anion [B9H12]

When heated under reflux in CH₂Cl₂ solution with [Os(CO)₃Cl₂]₂, two nido-[B₉H₁₂]⁻ units edge-fuse to form anti-[B₁₈H₂₁]⁻.     

Practical synthesis of 1,4-dioxane derivative of the closo-dodecaborate anion and its ring opening with acetylenic alkoxides

Practical method of synthesis of the 1,4-dioxane derivative of the closo-dodecaborate anion was developed. The cleavage of the dioxonium ring in [B₁₂H₁₁O(CH₂CH₂)₂O]⁻ with acetylenic alcohols gave rise to the preparation of closo-dodecaborate derivatives with terminal acetylene group. These compounds can be introduced into click reactions with phenylazide leading to the corresponding triazoles. The structures of (Bu₄N)[B₁₂H₁₁O(CH₂CH₂)₂O] and (Bu₄N)₂[B₁₂H₁₁(OCH₂CH₂)₂OCH₂CCH] · 0.5HOCH₂CCH were determined by single-crystal X-ray diffraction.     

Synthesis and characterization of 11-vertex platinaborane compounds having nido-PtB10H12 and nido-Pt2B9H10 skeletons

The reaction of closo-[B₁₀H₁₀]²⁻ with [PtCl₂(PPh₃)₂] in MeOH at reflux affords the B-methoxy substituted 11-vertex nido-platinaborane compound [(PPh₃)₂PtB₁₀H₁₀-8-H_0.5(OCH₃)_0.5-10-(OCH₃)] (1) and the known species [(PPh₃)₂PtB₁₀H₁₁-8-(OCH₃)] (2) and 1,6-(PPh₃)₂B₁₀H₈ (3). The same reaction under solvothermal condition gives the partially degraded diplatinaborane [(PPh₃)₂(μ-PPh₂)Pt₂B₉H₇-3,9,11-(OMe)₃] (4) with a novel nido-Pt₂B₉H₁₀ skeleton. The new metallaborane compounds have been characterized by spectroscopic methods and single-crystal X-ray analyses. In particular, computational/theoretical chemistry supports the ultimate structural confirmation of 4. The structures of these metallaboranes exhibit interesting intra- and/or intermolecular C-H?O hydrogen bonding interactions.     

In[NC5H3(CO2)2](OH2)F: A new layered indium-organic framework material (NC5H3(CO2)2=2,6-pyridinedicarboxylate)

A new layered indium-organic framework material, In[NC₅H₃(CO₂)₂](OH₂)F has been synthesized by a hydrothermal reaction using In₂O₃, NH₄F, 2,6-NC₅H₃(CO₂H)₂ (2,6-pyridinedicarboxylic acid), HF, and water at 200 °C. Single-crystal X-ray diffraction was used to determine the structure of the reported material. In[NC₅H₃(CO₂)₂](OH₂)F has a novel layered structure consisting of InO₅NF polyhedra and the pyridinedicarboxylate organic linker. Detailed structural analyses with full characterization including infrared spectrum, thermogravimetric analysis, elemental analysis, exchange reactions for the coordinated water molecule, and gas adsorption experiments are reported.     

Crystal structure of [Mn(1,10-C12H8N2)3](B6H7)2

A new compound [MN^II(Phen)₃]²⁺(B₆H₇)₂⁻ is synthesized; its crystal structure is studied by XRD at 100 K. Crystallographic data: C₃₆H₃₈B₁₂N₆Mn, M = 739.39, triclinic symmetry, space group P , unit cell parameters: a = 10.3131(3) ?, b = 13.4839(4) ?, c = 15.1132(4) ?; α = 97.696(1)°, β = 108.324(1)°, γ = 102.211(1)°; V = 1903.9(1) ?³, Z = 2, d _calc = 1.290 g/cm³. The structure is solved by direct and Fourier methods and refined by full-matrix LSM in the anisotropic (isotropic for hydrogen atoms) approximation to the final factor R ₁ = 0.036 for 10169 I _hkl ≥ 2σ _I (Bruker-Nonius X8 APEX CCD diffractometer, λMoK _α). The structure contains two crystallographically different anions. Original Russian Text Copyright ? 2009 by T. M. Polyanskaya, M. K. Drozdova, V. V. Volkov, and K. G. Myakishev __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 381–385, March–April, 2009.     

Solvothermal synthesis and characterisation of new one-dimensional indium and gallium sulphides: [C10N4H26]0.5[InS2] and [C10N4H26]0.5[GaS2]

Two new main group metal sulphides, [C₁₀N₄H₂₆]_0.5[InS₂] (1) and [C₁₀N₄H₂₆]_0.5[GaS₂] (2) have been prepared solvothermally in the presence of 1,4-bis(3-aminopropyl)piperazine and their crystal structures determined by single-crystal X-ray diffraction. Both compounds are isostructural and crystallise in the monoclinic space group P2₁/n (Z=4), with a=6.5628(5), b=11.2008(9), c=12.6611(9) Å and β=94.410(4)° (wR=0.035) for compound (1) and a=6.1094(5), b=11.2469(9), c=12.7064(10) Å and β=94.313(4)° (wR=0.021) for compound (2). The structure of [C₁₀N₄H₂₆]_0.5[MS₂] (M=In,Ga) consists of one-dimensional [MS₂]⁻ chains which run parallel to the crystallographic a axis and are separated by diprotonated amine molecules. These materials represent the first example of solvothermally prepared one-dimensional gallium and indium sulphides.     

Hydrothermal synthesis, crystal structure, and characterization of a new pseudo-two-dimensional uranyl oxyfluoride, [N(C2H5)4]2[(UO2)4(OH2)3F10]

A new uranyl oxyfluoride, [N(C₂H₅)₄]₂[(UO₂)₄(OH₂)₃F₁₀] has been synthesized by a hydrothermal reaction technique using (C₂H₅)₄NBr, UO₂(OCOCH₃)₂·2H₂O, and HF as reagents. The structure of [N(C₂H₅)₄]₂[(UO₂)₄(OH₂)₃F₁₀] has been determined by a single-crystal X-ray diffraction technique. [N(C₂H₅)₄]₂[(UO₂)₄(OH₂)₃F₁₀] crystallizes in the monoclinic space group P2₁/n (No. 14), with , , , β=98.88(3)°, , and Z=4. [N(C₂H₅)₄]₂[(UO₂)₄(OH₂)₃F₁₀] reveals a novel pseudo-two-dimensional crystal structure that is composed of UO₂F₅, UO₃F₄, and UO₄F₃ pentagonal bipyramids. Each uranyl pentagonal bipyramid shares edges and corners through F atoms to form a six-membered ring. The rings are further interconnected to generate infinite strips running along the b-axis. [N(C₂H₅)₄]₂[(UO₂)₄(OH₂)₃F₁₀] has been further characterized by elemental analysis, bond valence calculations, Infrared and Raman spectroscopy, and thermogravimetric analysis.