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1.
DFT‐calculations of the geometries of the closo‐anion [B11H11]2– in its ground state and in the transition state of its skeletal rearrangement and of the protonated species [B11H12]– in its ground state were performed at the B3LYP/6‐31++G(d,p) level. The corresponding NMR shifts were computed on the basis of the optimized geometry by the GIAO method at the same level. Calculated and observed NMR data are in good agreement and thus prove the structure of [B11H12]–, previously deduced from 2 D‐NMR spectra. The addition of water, ethanol, and pyridine to [B11H12]– at low temperature gave the nido‐species [B11H13(OH)]–, [B11H13(OEt)]–, and [B11H12(py)]–, respectively. The structures of these anions were investigated by NMR methods and the last two of them by crystal structure analyses of appropriate salts. The course of the addition reactions can be rationalized on the basis of the structurally characterized reaction components. 相似文献
2.
The Lewis base SMe2 in 7‐B11H13(SMe2) ( 1a ) can be replaced by the amines L = NH2(CH2tBu), NH2Cy, NH2Ph, NH2(4‐C6H4Me), py, chinoline or the phosphanes L = PPh3, PMePh2, yielding 7‐B11H13L ( 1b ‐ i ). The borane 1a can be deprotonated by certain amines, alkanides, or hydrides to give the anion 7‐B11H12(SMe2)‐ ( 2a ). Replacing the base SMe2 in the anion 2a by weak bases gives B11H12L‐ (L = PPh3, MeCN; 2h , j ). Upon reaction of 1a with the amine NH2(CH2tBu) in the ratio 1:2, a deprotonation and the substitution of SMe2 by the amine are observed, 7‐B11H12[NH2(CH2tBu)]‐ ( 2b ) being formed. At 170 °C, the 7‐isomers 1b , f are isomerized into a mixture of the corresponding 1‐ and 2‐isomers ( 1b′ , f′ and 1b″ , f″ , respectively). 相似文献
3.
The Lanthanum Dodecahydro‐closo‐Dodecaborate Hydrate [La(H2O)9]2[B12H12]3·15 H2O and its Oxonium‐Chloride Derivative [La(H2O)9](H3O)Cl2[B12H12]·H2O By neutralization of an aqueous solution of the free acid (H3O)2[B12H12] with basic La2O3 and after isothermic evaporation colourless, face‐rich single crystals of a water‐rich lanthanum(III) dodecahydro‐closo‐dodecaborate hydrate [La(H2O)9]2[B12H12]3·15 H2O are isolated. The compound crystallizes in the trigonal system with the centrosymmetric space group (a = 1189.95(2), c = 7313.27(9) pm, c/a = 6.146; Z = 6; measuring temperature: 100 K). The crystal structure of [La(H2O)9]2[B12H12]3·15 H2O can be characterized by two of each other independent, one into another posed motives of lattice components. The [B12H12]2− anions (d(B–B) = 177–179 pm; d(B–H) = 105–116 pm) are arranged according to the samarium structure, while the La3+ cations are arranged according to the copper structure. The lanthanum cations are coordinated in first sphere by nine oxygen atoms from water molecules in form of a threecapped trigonal prism (d(La–O) = 251–262 pm). A coordinative influence of the [B12H12]2− anions on La3+ has not been determined. Since “zeolitic” water of hydratation is also present, obviously the classical H–Oδ–···+δH–O‐hydrogen bonds play a significant role in the stabilization of the crystal structure. During the conversion of an aqueous solution of (H3O)2[B12H12] with lanthanum trichloride an anion‐mixed salt with the composition [La(H2O)9](H3O)Cl2[B12H12]·H2O is obtained. The compound crystallizes in the hexagonal system with the non‐centrosymmetric space group (a = 808.84(3), c = 2064.51(8) pm, c/a = 2.552; Z = 2; measuring temperature: 293 K). The crystal structure can be characterized as a layer‐like structure, in which [B12H12]2− anions and H3O+ cations alternate with layers of [La(H2O)9]3+ cations (d(La–O) = 252–260 pm) and Cl− anions along [001]. The [B12H12]2− (d(B–B) = 176–179 pm; d(B–H) = 104–113 pm) and Cl− anions exhibit no coordinative influence on La3+. Hydrogen bonds are formed between the H3O+ cations and [B12H12]2− anions, also between the water molecules of [La(H2O)9]3+ and Cl− anions, which contribute to the stabilization of the crystal structure. 相似文献
4.
During the reaction of an aqueous solution of (H3O)2[B12H12] with Tl2CO3 anhydrous thallium(I) dodecahydro‐closo‐dodecaborate Tl2[B12H12] is obtained as colorless, spherical single crystals. It crystallizes in the cubic system with the centrosymmetric space group Fm$\bar{3}$ (a = 1074.23(8) pm, Z = 4) in an anti‐CaF2 type structure. Four quasi‐icosahedral [B12H12]2– anions (d(B–B) = 180–181 pm, d(B–H) = 111 pm) exhibit coordinative influence on each Tl+ cation and provide a twelvefold coordination in the shape of a cuboctahedron (d(Tl–H) = 296 pm). There is no observable stereochemical activity of the non‐bonding electron pairs (6s2 lone pairs) at the Tl+ cations. By neutralization of an aqueous solution of the acid (H3O)2[B12H12] with PbCO3 and after isothermic evaporation colorless, plate‐like single crystals of lead(II) dodecahydro‐closo‐dodecaborate hexahydrate Pb(H2O)3[B12H12] · 3H2O can be isolated. This compound crystallizes orthorhombically with the non‐centrosymmetric space group Pna21 (a = 1839.08(9), b = 1166.52(6), c = 717.27(4) pm, Z = 4). The crystal structure of Pb(H2O)3[B12H12] · 3H2O is characterized as a layer‐like arrangement. The Pb2+ cations are coordinated in first sphere by only three oxygen atoms from water molecules (d(Pb–O) = 247–248 pm). But a coordinative influence of the [B12H12]2– anions (d(B–B) = 173–181 pm, d(B–H) = 93–122 pm) on lead has to be stated, too, as three hydrogen atoms from three different hydroborate anions are attached to the Pb2+ cations (d(Pb–H) = 258–270 pm) completing their first‐sphere coordination number to six. These three oxygen and three hydrogen ligands are arranged as quite irregular polyhedron leaving enough space for a stereochemical lone‐pair activity (6sp) at each Pb2+ cation. Since additional intercalating water of hydration is present as well, both classical H–Oδ– ··· +δH–O‐ and unconventional B–Hδ– ··· +δH–O hydrogen bonds play a significant role in the stabilization of the entire crystal structure. 相似文献
5.
Syntheses,Crystal Structures,and Properties of the Isotypic Pair [Cr(H2O)6]2[B12H12]3·15H2O and [In(H2O)6]2[B12H12]3·15H2O
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Single crystals of [Cr(H2O)6]2[B12H12]3 · 15H2O and [In(H2O)6]2[B12H12]3 · 15H2O were obtained by reactions of aqueous solutions of the acid (H3O)2[B12H12] with chromium(III) hydroxide and indium metal shot, respectively. The title compounds crystallize isotypically in the trigonal system with space group R$\bar{3}$ c (a = 1157.62(3), c = 6730.48(9) pm for the chromium, a = 1171.71(3), c = 6740.04(9) pm for the indium compound, Z = 6). The arrangement of the quasi‐icosahedral [B12H12]2– dianions can be considered as stacking of two times nine layers with the sequence …ABCCABBCA… and the metal trications arrange in a cubic closest packed …abc… stacking sequence. The metal trications are octahedrally coordinated by six water molecules of hydration, while another fifteen H2O molecules fill up the structures as zeolitic crystal water or second‐sphere hydrating species. Between these free and the metal‐bonded water molecules, bridging hydrogen bonds are found. Furthermore, there is also evidence of hydrogen bonding between the anionic [B12H12]2– clusters and the free zeolitic water molecules according to B–Hδ– ··· δ+H–O interactions. Vibrational spectroscopy studies prove the presence of these hydrogen bonds and also show slight distortions of the dodecahydro‐closo‐dodecaborate anions from their ideal icosahedral symmetry (Ih). Thermal decomposition studies for the example of [Cr(H2O)6]2[B12H12]3 · 15H2O gave no hints for just a simple multi‐stepwise dehydration process. 相似文献
6.
On the Crystal Structures of the Transition‐Metal(II) Dodecahydro‐closo‐Dodecaborate Hydrates Cu(H2O)5.5[B12H12]·2.5 H2O and Zn(H2O)6[B12H12]·6 H2O By neutralization of an aqueous solution of the free acid (H3O)2[B12H12] with basic copper(II) carbonate or zinc carbonate, blue lath‐shaped single crystals of the octahydrate Cu[B12H12]·8 H2O (≡ Cu(H2O)5.5[B12H12]·2.5 H2O) and colourless face‐rich single crystals of the dodecahydrate Zn[B12H12]·12 H2O (≡ Zn(H2O)6[B12H12]·6 H2O) could be isolated after isothermic evaporation. Copper(II) dodecahydro‐closo‐dodecaborate octahydrate crystallizes at room temperature in the monoclinic system with the non‐centrosymmetric space group Pm (Cu(H2O)5.5[B12H12]·2.5 H2O: a = 768.23(5), b = 1434.48(9), c = 777.31(5) pm, β = 90.894(6)°; Z = 2), whereas zinc dodecahydro‐closo‐dodecaborate dodecahydrate crystallizes cubic in the likewise non‐centrosymmetric space group F23 (Zn(H2O)6[B12H12]·6 H2O: a = 1637.43(9) pm; Z = 8). The crystal structure of Cu(H2O)5.5[B12H12]·2.5 H2O can be described as a monoclinic distortion variant of the CsCl‐type arrangement. As characteristic feature the formation of isolated [Cu2(H2O)11]4+ units as a condensate of two corner‐linked Jahn‐Teller distorted [Cu(H2O)6]2+ octahedra via an oxygen atom of crystal water can be considered. Since “zeolitic” water of hydratation is also present, obviously both classical H–Oδ?···+δH–O and non‐classical B–Hδ?···+δH–O hydrogen bonds play a significant role for the stabilization of the structure. A direct coordinative influence of the quasi‐icosahedral [B12H12]2? anions on the Cu2+ cations has not been determined. The zinc compound Zn(H2O)6[B12H12]·6 H2O crystallizes in a NaTl‐type related structure. Two crystallographically different [Zn(H2O)6]2+ octahedra are present, which only differ in their relative orientation within the packing of the [B12H12]2? anions. The stabilization of the crystal structure takes place mainly via H–Oδ?···+δH–O hydrogen bonds, since again the hydrogen atoms of the [B12H12]2? anions have no direct coordinative influence on the Zn2+ cations. 相似文献
7.
Synthesis and Crystal Structure of Cadmium Dodecahydro closo‐Dodecaborate Hexahydrate, Cd(H2O)6[B12H12] Through neutralization of the aqueous free acid (H3O)2[B12H12] with cadmium carbonate (CdCO3) and after isothermic evaporation of the resulting solution, colourless lath‐shaped single crystals of Cd(H2O)6[B12H12] are obtained. Cadmium dodecahydro closo‐dodecaborate hexahydrate crystallizes at room temperature in the monoclinic system (space group: C2/m) with the lattice constants a = 1413.42(9), b = 1439.57(9), c = 749.21(5) pm and β = 97.232(4)° (Z = 4). The crystal structure of Cd(H2O)6[B12H12] can be regarded as a monoclinic distortion variant of the CsCl‐type structure. Two crystallographically different [Cd(H2O)6]2+ octahedra (d(Cd–O) = 227–230 pm) are present which only differ in their relative orientation. The intramolecular bond lengths for the quasi‐icosahedral [B12H12]2? cluster anions range in the intervals usually found for dodecahydro closo‐dodecaborates (d(B–B) = 177–179 pm, d(B–H) = 103–116 pm). The hydrogen atoms of the [B12H12]2? clusters have no direct coordinative influence on the Cd2+ cations. Due to the fact that no “zeolitic” crystal water molecules are present, a stabilization of the lattice takes place mainly via the B–Hδ?···+δH–O hydrogen bonds. 相似文献
8.
Dodecahydro‐ closo ‐dodecaborates of the Heavy Alkaline‐Earth Metals from Aqueous Solution: Ca(H2O)7[B12H12] · H2O, Sr(H2O)8[B12H12], and Ba(H2O)6[B12H12] The crystalline hydrates of the heavy alkaline earth metal dodecahydro‐closo‐dodecaborates (M[B12H12] · n H2O, n = 6–8; M = Ca, Sr, Ba) are easily accessible by reaction of an aqueous (H3O)2[B12H12] solution with an alkaline earth metal carbonate (MCO3). By isothermic evaporation of the respective aqueous solution we obtained colourless single crystals which are characterized by X‐ray diffraction at room temperature. The three compounds Ca(H2O)7[B12H12] · H2O (orthorhombic, P212121; a = 1161.19(7), b = 1229.63(8), c = 1232.24(8) pm; Z = 4), Sr(H2O)8[B12H12] (trigonal, R3; a = 1012.71(6), c = 1462.94(9) pm; Z = 3) and Ba(H2O)6[B12H12] (orthorhombic, Cmcm; a = 1189.26(7) pm, b = 919.23(5) pm, c = 1403.54(9) pm; Z = 4) are neither formula‐equal nor isostructural. The structure of Sr(H2O)8[B12H12] is best described as a NaCl‐type arrangement, Ba(H2O)6[B12H12] rather forms a layer‐like and Ca(H2O)7[B12H12] · H2O a channel‐like structure. In first sphere the alkaline earth metal cations Ca2+ and Sr2+ are coordinated by just seven and eight oxygen atoms from the surrounding water molecules, respectively. A direct coordinative influence of the quasi‐icosahedral [B12H12]2– cluster anions becomes noticeable only for the Ba2+ cations (CN = 12) in Ba(H2O)6[B12H12]. The dehydratation of the alkaline earth metal dodecahydro‐closo‐dodecaborate hydrates has been shown to take place in several steps. Thermal treatment leads to the anhydrous compounds Ca[B12H12], Sr[B12H12] and Ba[B12H12] at 224, 164 and 116 °C, respectively. 相似文献
9.
Structural Investigations on Cs2[B12H12] The crystal structure of Cs2[B12H12] has been determined from X‐ray single‐crystal data collected at room temperature. Dicesium dodecahydro‐closo‐dodecaborate crystallizes as colourless, face‐rich crystals (cubic, Fm 3; a = 1128.12(7) pm; Z = 4). Its synthesis is based on the reaction of Na[BH4] with BF3(O(C2H5)2) via the decomposition of Na[B3H8] in boiling diglyme, followed by subsequent separations, precipitations (with aqueous CsOH solution) and recrystallizations. The crystal structure is best described as anti‐CaF2‐type arrangement with the Cs+ cations in all tetrahedral interstices of the cubic closest‐packed host lattice of the icosahedral [B12H12]2–‐cluster dianions. The intramolecular bond lengths are in the range usually found in closo‐hydroborates: 178 pm for the B–B and 112 pm for the B–H distance. Twelve hydrogen atoms belonging to four [B12H12]2– icosahedra provide an almost perfect cuboctahedral coordination sphere to the Cs+ cations, and their distance of 313 pm (12 ×) attests for the salt‐like character of Cs2[B12H12] according to {(Cs+)2([B12H12]2–)}. The 11B{1H}‐NMR data in aqueous (D2O) solution are δ = –12,70 ppm (1JB–H = 125 Hz), and δ = –15,7 ppm (linewidth: δν1/2 = 295 Hz) for the solid state 11B‐MAS‐NMR. 相似文献
10.
Investigations on the Crystal Structure of Lithium Dodecahydro‐closo‐dodecaborate from Aqueous Solution: Li2(H2O)7[B12H12] By neutralization of an aqueous solution of the acid (H3O)2[B12H12] with lithium hydroxide (LiOH) and subsequent isothermic evaporation of the resulting solution to dryness, it was possible to obtain the heptahydrate of lithium dodecahydro‐closo‐dodecaborate Li2[B12H12] · 7 H2O (≡ Li2(H2O)7[B12H12]). Its structure has been determined from X‐ray single crystal data at room temperature. The compound crystallizes as colourless, lath‐shaped, deliquescent crystals in the orthorhombic space group Cmcm with the lattice constants a = 1215.18(7), b = 934.31(5), c = 1444.03(9) pm and four formula units in the unit cell. The crystal structure of Li2(H2O)7[B12H12] can not be described as a simple AB2‐structure type. Instead it forms a layer‐like structure analogous to the well‐known barium compound Ba(H2O)6[B12H12]. Characteristic feature is the formation of isolated cation pairs [Li2(H2O)7]2+ in which the water molecules form two [Li(H2O)4]+ tetrahedra with eclipsed conformation, linked to a dimer via a common corner. The bridging oxygen atom (∢(Li‐ O ‐Li) = 112°) thereby formally substitutes Ba2+ in Ba(H2O)6[B12H12] according to (H2 O )Li2(H2O)6[B12H12]. A direct coordinative influence of the [B12H12]2— cluster anions to the Li+ cations is not noticeable, however. The positions of the hydrogen atoms of both the water molecules and the [B12H12]2— units have all been localized. In addition, the formation of B‐Hδ—···δ+H‐O‐hydrogen bonds between the water molecules and the hydrogen atoms from the anionic [B12H12]2— clusters is considered and their range and strength is discussed. The dehydratation of the heptahydrate has been investigated by DTA‐TG measurements and shown to take place in two steps at 56 and 151 °C, respectively. Thermal treatment leads to the anhydrous lithium dodecahydro‐closo‐dodecaborate Li2[B12H12], eventually. 相似文献
11.
Bis(tetramethylammonium) dodecahydrododecaborate, [(CH3)4N]2[B12H12], and bis(tetramethylammonium) dodecahydrododecaborate acetonitrile, [(CH3)4N]2[B12H12] · CH3CN, were synthesized and characterized via Infrared, 1H and 11B NMR spectroscopy. [(CH3)4N]2[B12H12] crystallizes isopunctual to the alkali metal dodecaborates. The crystal structure of [(CH3)4N]2[B12H12] · CH3CN was determined from single crystal data and refined in the orthorhombic crystal system (Pcmn, no. 62, a = 898.68(8), b = 1312.85(9) c = 1994.5(1) pm, R(|F| , 4σ) = 5.9%, wR(F2) = 18.3%). Here, the geometry of the dodecaborate anion is that of an almost ideal icosahedron, less distorted than most other dodecaborates known. By low‐temperature Guinier‐Simon diffractometry phase transitions were detected for [(CH3)4N]2[B12H12] and [(CH3)4N]2[B12H12] · CH3CN at –70 and –15 °C, respectively. 相似文献
12.
Synthesis, Crystal Structure, and Thermal Decomposition of Mg(H2O)6[B12H12] · 6 H2O By reaction of an aqueous solution of the free acid (H3O)2[B12H12] with MgCO3 and subsequent isothermic evaporation of the resulting solution to dryness, colourless, bead‐shaped single crystals of the dodecahydrate of magnesium dodecahydro closo‐dodecaborate Mg(H2O)6[B12H12] · 6 H2O (cubic, F4132; a = 1643.21(9) pm, Z = 8) emerge. The crystal structure is best described as a NaTl‐type arrangement in which the centers of gravity of the quasi‐icosahedral [B12H12]2— anions (d(B—B) = 178—180 pm, d(B—H) = 109 pm) occupy the positions of Tl— while the Mg2+ cations occupy the Na+ positions. A direct coordinative influence of the [B12H12]2— units at the Mg2+ cations is however not noticeable. The latter are octahedrally coordinated by six water molecules forming isolated hexaaqua complex cations [Mg(H2O)6]2+ (d(Mg—O) = 206 pm, 6×). In addition, six “zeolitic” water molecules are located in the crystal structure for the formation of a strong O—Hδ+···δ—O‐hydrogen bridge‐bonding system. The evidence of weak B—Hδ—···δ+H—O‐hydrogen bonds between water molecules and anionic [B12H12]2— clusters is also considered. Investigations on the dodecahydrate Mg[B12H12] · 12 H2O (≡ Mg(H2O)6[B12H12] · 6 H2O) by DTA/TG measurements showed that its dehydration takes place in two steps within a temperature range of 71 and 76 °C as well as at 202 °C, respectively. Thermal treatment eventually leads to the anhydrous magnesium dodecahydro closo‐dodecaborate Mg[B12H12]. 相似文献
13.
The closo‐dodecaborate [B12H12]2? is degraded at room temperature by oxygen in an acidic aqueous solution in the course of several weeks to give B(OH)3. The degradation is induced by Ag2+ ions, generated from Ag+ by the action of H2S2O8. Oxa‐nido‐dodecaborate(1?) is an intermediate anion, that can be separated from the reaction mixture as [NBzlEt3][OB11H12] after five days in a yield of 18 %. The action of FeCl3 on the closo‐undecaborate [B11H11]2? in an aqueous solution gives either [B22H22]2? (by fusion) or nido‐B11H13(OH)? (by protonation and hydration), depending on the concentration of FeCl3. In acetonitrile, however, [B11H11]2? is transformed into [OB11H12]? by Fe3+ and oxygen. The radical anions [B12H12] ˙ ? and [B11H11] ˙ ? are assumed to be the primary products of the oxidation with the one‐electron oxidants Ag2+ and Fe3+, respectively. These radical anions are subsequently transformed into [OB11H12]? by oxygen. The crystal structure analysis shows that the structure of [OB11H12]? is derived from the hypothetical closo‐oxaborane OB12H12 by removal of the B3 vertex, leaving a non‐planar pentagonal aperture with a three‐coordinate O vertex, as predicted by NMR spectra and theory. 相似文献
14.
Jonathan Bould Raikko Kiveks Reijo Sillanp Francesc Teixidor Clara Vias 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(5):o271-o273
Tetraethylammonium 7‐dimethylsulfanyl‐nido‐dodecahydroundecaborate, [Et4N][7‐Me2S‐nido‐B11H12] or C8H20N+·C2H18B11S−, is a product of the deprotonation of [7‐Me2S‐nido‐B11H13] with KHBEt3 and precipitation with tetraethylammonium chloride. The effect of removing one endo‐terminal H atom is to cause a general contraction of the open‐face B—B distances. 相似文献
15.
The potassium salt of the [1‐H2N‐2‐F‐closo‐1‐CB11H10]– anion ( 1 ) was obtained from an insertion reaction of Li3[7‐H2N‐nido‐7‐CB10H10] with BF3 · OEt2. Anion 1 was protonated to the neutral species 1‐H3N‐2‐F‐closo‐1‐CB11H10 (H 1 ) and it was iodinated with ICl to the [1‐H2N‐2‐F‐closo‐1‐CB11I10]– anion ( 2 ). All species were characterized by multinuclear NMR, IR, and Raman spectroscopy as well as by elemental analysis. The structure of H 1· (CH3)2CO was studied by single‐crystal X‐ray diffraction and the experimentally determined bond lengths are compared to values derived from density functional calculations. 相似文献
16.
Colourless, lath‐shaped single crystals of Cs2[B12I12] · 2 CH3CN (monoclinic, C2/m; a = 1550.3(2), b = 1273.2(1), c = 1051.5(1) pm, β = 120.97(1)°; Z = 2) are obtained by the reaction of Cs2[B12H12] with an excess of I2 and ICl (molar ratio: 1 : 2) in methylene iodide (CH2I2) at 180 °C (8 h) and recrystallization of the crude product from acetonitrile (CH3CN). The crystal structure contains quasi‐icosahedral [B12I12]2– anions (d(B–B) = 176–182 pm, d(B–I) = 211–218 pm) which arrange in a cubic closest‐packed fashion. All octahedral interstices are filled with centrosymmetric dimer‐cations {[Cs(N≡C–CH3)]2}2+ containing a diamond‐shaped four‐membered (Cs–N–Cs–N) ring of Cs+ cations and nitrogen atoms of the solvating acetonitrile molecules (d(Cs–N) = 321 pm, 2 ×). The cesium cations themselves actually reside in the distorted tetrahedral voids of the cubic [B12I12]2– packing (d(Cs–I) = 402–461 pm, 10 ×) if one ignores the solvent particles. 相似文献
17.
18.
Maik Finze Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(4):947-962
The first primary 2‐aminocarba‐closo‐dodecaborates [1‐R‐2‐H2N‐closo‐CB11H10]? (R=H ( 1 ), Ph ( 2 )) have been synthesized by insertion reactions of (Me3Si)2NBCl2 into the trianions [7‐R‐7‐nido‐CB10H10]3?. The difunctionalized species [1,2‐(H2N)2‐closo‐CB11H10] ( 3 ) and 1‐CyHN‐2‐H3N‐closo‐CB11H10 (H‐ 4 ) have been prepared analogously from (Me3Si)2NBCl2 and 7‐H3N‐7‐nido‐CB10H12. In addition, the preparation of [Et4N][1‐H2N‐2‐Ph‐closo‐CB11H10] ([Et4N]‐ 5 ) starting from PhBCl2 and 7‐H3N‐7‐nido‐CB10H12 is described. Methylation of the [1‐Ph‐2‐H2N‐closo‐CB11H10]? ion ( 2 ) to produce 1‐Ph‐2‐Me3N‐closo‐CB11H10 ( 6 ) is reported. The crystal structures of [Et4N]‐ 2 , [Et4N]‐ 5 , and 6 were determined and the geometric parameters were compared to theoretical values derived from DFT and ab initio calculations. All new compounds were studied by NMR, IR, and Raman spectroscopy, MALDI mass spectrometry, and elemental analysis. The discussion of the experimental NMR chemical shifts and of selected vibrational band positions is supported by theoretical data. The thermal properties were investigated by differential scanning calorimetry (DSC). The pKa values of 2‐H3N‐closo‐CB11H11 (H‐ 1 ), 1‐H3N‐closo‐CB11H10 (H‐ 7 ), and 1,2‐(H3N)2‐closo‐CB11H10 (H2‐ 3 ) were determined by potentiometric titration and by NMR studies. The experimental results are compared to theoretical data (DFT and ab initio). The basicities of the aminocarba‐closo‐dodecaborates agree well with the spectroscopic and structural properties. 相似文献
19.
Colourless octahedral single crystals of solvent‐free Ag2[B12Cl12] (cubic, Pa3¯; a = 1238.32(7) pm, Z = 4) are obtained by the metathesis reaction of Cs2[B12Cl12] with an aqueous solution of silver nitrate (AgNO3) and recrystallization of the crude product from water. The crystal structure is best described as a distorted anti‐CaF2‐type arrangement in which the quasi‐icosahedral [B12Cl12]2— anions (d(B—B) = d(B—Cl) = 177—180 pm) are arranged in a cubic closest‐packed fashion. The tetrahedral interstices are filled with Ag+ cations which are strongly displaced from their ideal positions. Thereby each silver atom gets coordinated by six chlorine atoms from the edges of three [B12Cl12]2— anions providing a distorted octahedral coordination sphere to the Ag+ cations (d(Ag—Cl) = 283—285 pm, CN = 6). 相似文献
20.
One of the two bridging protons of the aza‐nido‐decaboranes RNB9H10X can be removed by certain bases to give nido‐anions [RNB9H9X]– [R/X = H/H ( 1 a ), Ph/H ( 1 b ), p‐MeC6H4/H ( 1 c ), Bzl/H ( 1 d ), H/N3 ( 1 ′ a )]; the stericly demanding base 1,8‐bis(dimethylamino)naphthalene (“proton sponge”, ps) is ideal. In the case of tBu anion, the deprotonation (→ C4H10) may be accompanied by a hydridation (→ C4H8), yielding the arachno‐anions [RNB9H11X]– ( 2 a , b , d , 2 ′ a ); these are the main products, when stericly non‐demanding bases like H– are applied. The Lewis acid BH3 is added to 1 a and 1 ′ a to give the aza‐arachno‐undecaborates HNB10H12X [X = H ( 3 a ), N3 (in position 2) ( 3 ′ a )]. Thia‐ and selenaaza‐arachno‐undecaborates, [S(RN)B9H10]– ( 4 b , c ) and [Se(RN)B9H10]– ( 4 ′ b , c ), are obtained from 1 b , c by the addition of sulfur or selenium, respectively. The methylation of the anions 4 c and 4 ′ c gives the thia‐ and selenaazaarachno‐undecaboranes (MeS)(RN)B9H10 ( 5 c ) and (MeSe)(RN)B9H10 ( 5 ′ c ), respectively. The action of HBF4 on the arachno‐borates [HNB10H12X]– ( 3 a , 3 ′ a ) leads to a mixture of nido‐HNB9H10X and nido‐HNB10H11X by the elimination of BH3 or H2, respectively; the aza‐nido‐decaborane predominates in the case of 3 ′ a and the aza‐nido‐undecaborane in the case of 3 a . The action of HBF4 on the anion 4 c yields the hypho‐undecaborate [S(RN)B9H10F2]– ( 6 c ). The structures of the products are elucidated on the basis of 1H and 11B NMR spectra, supported by 2D COSY and HMQC techniques. Two types of 11‐vertex‐arachno structures and an 11‐vertex‐hypho structure are found for the products. The crystal structures of 5 c and [Hps] 6 c · CH2Cl2 are reported. 相似文献