Transmission of electronic effects through the {closo-1-CB9} and {closo-1-CB11} cages: apparent dissociation constants for series of [closo-1-CB9H8-1-COOH-10-X] and [closo-1-CB11H10-1-COOH-12-X] acids

The apparent ionization constants pK(a)' for series of carboxylic acids [closo-1-CB(9)H(8)-1-COOH-10-X](-) (1) and [closo-1-CB(11)H(10)-1-COOH-12-X](-) (2), where X = H, I, n-C(6)H(13), (+)NMe(3), (+)N(2), (+)SMe(2), OC(5)H(11), were measured in EtOH/H(2)O (1/1, v/v) at 24 °C. Correlation analysis of the pK(a)' values using Hammett substituent constants σ(p)(X) gave the reaction constant ρ = 0.87 ± 0.04 for series 1 and ρ = 1.00 ± 0.09 for series 2. These values are higher than for derivatives of PhCH═CHCOOH (ρ = 0.70 ± 0.09 in 55% EtOH) and correspond to 56% and 65% efficiencies in transmission of electronic effects by [closo-1-CB(9)H(10)](-) (E) and [closo-1-CB(11)H(12)](-) (F), respectively, as compared to benzene (A). Experimental results were supported with DFT calculations of relative acidity for series of acids derived from A, E, and F in aqueous medium.     

Reductive degradation of nido-1-CB8H12 into smaller-cage carborane systems via new monocarbaboranes [arachno-5-CB8H13](-) and closo-2-CB6H8

Treatment of the nido-1-CB8H12 (1) carborane with NaBH4 in THF at ambient temperature led to the isolation of the stable [arachno-5-CB8H13]- (2(-)), which was isolated as Na+[5-CB8H13]-.1.5 THF and PPh4 +[5-CB8H13]- in almost quantitative yield. Compound 2(-) underwent a boron-degradation reaction with concentrated hydrochloric acid to afford the arachno-4-CB7H13 (3) carborane in 70 % yield, whereas reaction between 2(-) and excess phenyl acetylene in refluxing THF gave the [closo-2-CB6H7]- (4-) in 66 % yield. Protonation of the Cs+4(-) salt with concentrated H2SO4 or CF3COOH in CH2Cl2 afforded a new, highly volatile 2-CB6H8 (4) carborane in 95 % yield, the deprotonation of which with Et3N in CH2Cl2 leads quantitatively to Et3NH+[2-CB6H7](-) (Et3NH+4(-)). Both compounds 4- and 4 can be deboronated through treatment with concentrated hydrochloric acid in CH2Cl2 to yield the carbahexaborane nido-2-CB5H9 (5) in 60 % yield. New compounds 2-, 3, and 4 were structurally characterised by the ab initio/GIAO/MP2/NMR method. The method gave superior results to those carried out using GIAO-HF when relating the calculated 11B NMR chemical shifts to experimental data.     

A practical synthesis of isomerically pure 1,10-difunctionalized derivatives of the [closo-1-CB9H10] anion

The isomer-free [closo-1-CB9H(8)-1-COOH-10-I]- anion was prepared in four steps and 10% overall yield from B10H14. The key step is the skeletal isomerization of the [closo-2-CB9H8-2-COOH-7-I]- anion to a mixture of the 10- and 6-iodo derivatives of [closo-1-CB9H(9)-1-COOH]- formed in up to a 3:1 ratio. The carboxylic acid 4 was converted to the amine [closo-1-CB9H(8)-1-NH(2)-10-I]- using the Curtius reaction. The relative thermodynamic stability of each product was calculated at the DFT and MP2 levels of theory. The regioselectivity of electrophilic substitution in [closo-CB9H10]- derivatives was briefly investigated using the NBO population analysis of the MP2 wave function.     

Monocarbaborane chemistry. Preparation and characterisation of [4-CB8H9]-, the 'missing' closo-carbaborane anion

Thermolysis in the solid state of Cs+[arachno-CB9H14]-, or of Cs+[nido-CB9H12]-, or the oxidation of nido-1-CB8H12 with I2 in THF at -78 degrees C in the presence of NEt3, gives the first nine-vertex closo monocarbaborane, the stable [closo-4-CB8H9]- anion, in yields of 56, 61 and 75%, respectively.     

Heteroatomic deltahedral clusters: synthesis and structures of closo-[Bi3Ni(4)(CO)6]3-, closo-[Bi4Ni4(CO)6]2-, the open cluster [Bi3Ni6(CO)9]3-, and the intermetalloid closo-[Nix@[Bi6Ni6(CO)8)]4-

Reactions of ethylenediamine solutions of K4Bi5 with Ni(PPh3)2(CO)2 yielded four novel hetero-atomic Bi/Ni deltahedral clusters. Three of them, the 7-atom pentagonal bipyramidal [Bi3Ni4(CO)6]3-, the 8-atom dodecahedral [Bi4Ni4(CO)6]2-, and the Ni-centered or empty 12-atom icosahedral [Nix@[Bi6Ni6(CO)8]4-, are closo-species according to both electron count and shape. The centered icosahedral cluster resembles packing in intermetallic compounds and belongs to the emerging class of intermetalloid clusters. The shape of the fourth cluster, [Bi3Ni6(CO)9]3-, can be derived from the icosahedral Ni-centered [Ni@[Bi6Ni6(CO)8]4- by removal of three Bi- and one Ni-atoms of two neighboring triangular faces. The clusters were structurally characterized by single-crystal X-ray diffraction in compounds with potassium cations sequestered by 2,2,2-crypt or 18-crown-6 ether. They were also characterized in solution by electrospray mass spectrometry.     

Monocarbaborane anion chemistry. The elusive C-arylated [PhCB11H11]-, [PhCB9H9]- and [PhCB8H8]- anions

B10H14 and PhCHO yield [6-Ph-nido-6-CB9H11]- (94%), from which the nine-vertex C-phenyl monocarbaborane anion [4-Ph-closo-4-CB8H8]- (68%) can be obtained by heating at 200 degrees C, and from which the twelve- and ten-vertex analogues [1-Ph-closo-1-CB11H11]- (50%) and [4-Ph-closo-4-CB9H9]- (25%) can be obtained by heating at 210 degrees C with BH3(NEt3).     

Anion driven ionic liquid crystals: The effect of the connecting group in [closo-1-CB9H10]- derivatives on mesogenic properties

Replacement of the connecting CH₂ group in ionic liquid crystal 1a[Pyr] with an oxygen atom in 1b[Pyr] resulted in significant destabilisation of the nematic and, to a greater extent, smectic A (SmA) phases, as established from binary mixture studies in 2a[Pyr]. Density functional theory (DFT) modelling of both anions suggests that the destabilisation results from the difference in charge distribution rather than conformational changes. Binary mixture studies demonstrated that all three ionic liquid crystals are compatible with a non-ionic benzoate nematic host 3a.     

Unusual interaction of alkynes with nine-vertex arachno-monocarbaboranes 4-CB8H14 and [4-CB8H13]-

Alkynes R(1)R(2)C(2) react with the neutral monocarbaborane arachno-4-CB(8)H(14) (1) at elevated temperatures (115-120 degrees C) under the formation of the derivatives of the ten-vertex dicarbaborane nido-5,6-C(2)B(8)H(12) (2) of general formula 9-Me-5,6-R1,R2-nido-5,6-C(2)B(8)H(9) (where R1,R2 = H,H 2a; Me,Me 2b; Et,Et 2c, H,Ph 2d, and Ph,Ph 2e) in moderate yields (26-52%). Side reaction with PhC(2)H also yields 1-Ph-6-Me-closo-1,2-C(2)B(8)H(8) (3d). In contrast, the reaction between [arachno-4-CB(8)H(13)](-) anion ((-)) and PhC(2)H produces a mixture of the closo anions [1-CB7H8]- (4-) and [1-CB6H7]- (5-) (yields 32 and 24%, respectively). Individual compounds were isolated and purified by liquid chromatography and characterized by NMR spectroscopy ((11)B, (1)H and (13)C) combined with two-dimensional [(11)B-(11)B]-COSY and (1)H-{(11)B(selective)}NMR techniques.     

Diphosphacarbollide analogues of the C5H5- anion: isolation of the nido-di- and triphosphacarboranes 7,8,9-P2CB8H10, [7,8,9-P2CB8H9]-, [7,8,10-P2CB8H9]-, and 7,8,9,10-P3CB7H8

Treatment of a solution of excess PCl(3) and PS (PS = "proton sponge" = 1,8-dimethylamino naphthalene) with arachno-4-CB(8)H(14) (1) in CH(2)Cl(2), followed by hydrolysis of the reaction mixture, resulted in the isolation of the eleven-vertex diphosphacarbaborane nido-7,8,9-P(2)CB(8)H(10) (2) (yield 34%) as the main product. Other products isolated from this reaction were the phosphacarboranes nido-7,8,9,10-P(3)CB(7)H(8) (3) (yield 5%) and closo-2,1-PCB(8)H(9) (4) (yield 15%). Compound 2 can be deprotonated by PS in CH(2)Cl(2) or NaH in diethyl ether to give the [nido-7,8,9-P(2)CB(8)H(9)](-) (2(-)()) anion, which gives back the original compound, 2, upon re-protonation. Thermal rearrangement of anion 2(-) (Na(+) salt) at 350 degrees C for 2 h produced the isomeric [nido-7,8,10-P(2)CB(8)H(9)](-) (5(-)()) anion, which was isolated as a PPh(4)(+) salt (yield 86%). Multinuclear ((1)H, (11)B, (31)P, and (13)C), two-dimensional [(11)B-(11)B] COSY, (1)H{(11)B(selective)}, (1)H{(31)P(selective)}, and gradient-enhanced ([(1)H-(13)C] HSQC) magnetic resonance measurements led to complete assignments of all resonances which are in excellent agreement with the structures proposed. Coupling constants, (1)J((31)P,(13)C), (2)J((31)P,C,(1)H), and (1)J((31)P,(31)P), were calculated using the DFT method B3LYP/6-311+G(d,p). The molecular geometries of all compounds were optimized ab initio at a correlated level of theory (RMP2(fc)) using the 6-31G basis set, and their correctness was assessed by comparison of the experimental (11)B and (13)C chemical shifts with those calculated by the GIAO-SCF/II//RMP2(fc)/6-31G method. The computations also include the structures and chemical shieldings of the still unknown isomers [nido-7,10,8-P(2)CB(8)H(9)](-) (6(-)) and [nido-7,9,8-P(2)CB(8)H(9)](-) (7(-)).     

Synthesis and Structure of 6'-Diethylamino-2'-phenacylami nospiro-[isobenzofuran- 1 (3H), 9'- [9H]xanthen]-3-one

1mTRODUCTIONWehavereportedsomenuorancomPoundswithdifferentsubstitutedgroups"~'>.Thispaperdescribesacontinuationofourinvestigationonthenuoranderivatives.ThecrystalstructureofthecomPOundC,zHzsNzo'(I)(whereRl-NEt2,R2=H,R3=NHCHzCoCeHs,R`=H)wasdeterminedbyX-raydiffractionmethod.Inaddition,wealsocomparethetitlecomPOundwithotherfluorancomPounds.2EXPERIMENTAL2.1SynthesisAmixtureof2'-carboxy-4-diethylamino-2-hydrzophenoneandP-hydroxy-acetanilide(molarratio1:l)insulfuricacidwasheated…     

Salts of the Lewis-acidic dianion [Hg(closo-1-CB11F11)2]2-: coordination of acetonitrile and water

The coordination of acetonitrile and water to the Hg atom in [Hg(closo-1-CB(11)F(11))(2)](2-) (1) reveals the Lewis acidity of the Hg(II) center, which is unprecedented, since 1 is a dianion. Both coordination compounds were characterized by single-crystal X-ray diffraction, vibrational spectroscopy, and differential scanning calorimetry (DSC). In contrast, the Hg atom in [PhHg(closo-1-CB(11)F(11))](-) (2) does not coordinate to CH(3)CN and H(2)O, although it has only a single negative charge.     

Synthesis of monohalogeno derivatives of closo-[B9H9]2-. Crystal structures of (Ph4P)2[1-XB9H8].CH3CN (X = Cl, Br, I)

By reaction of Na2[B9H9] with the appropriate N-halogenosuccinimide, the monohalogenated anion [1-XB9H8]2- (X = Cl, Br, or I) is formed. The X-ray diffraction analyses performed on single crystals of (Ph4P)2[1-XB9H8].CH3CN (X = Cl, Br, I) reveal that the tricapped trigonal prismatic geometry of the cluster is retained after substitution in the 1-position. Crystallographic data are as follows for (Ph4P)2[1-XB9H8].CH3CN. X = Cl, Br: monoclinic, space group P2(1), a = 10.7 A, b = 32.9 A, c = 13.8 A, beta = 96 degrees, Z = 4, R1 = 0.038 and R1 = 0.036, respectively. X = I: monoclinic, space group P2(1)/n, a = 10.5 A, b = 13.6 A, c = 33.4 A, beta = 94 degrees, Z = 4, R1 = 0.094. The compounds have been characterized by vibrational and 11B NMR spectroscopy as well.     

Carbonyl-metal fragment insertion into eight-vertex [closo-1-CB7H8]-. Facile synthesis of ten-vertex metalladicarbollide complexes [2,2,2-(CO)3-1-OH-closo-2,1,10-MC2B7H8]n-{M = Fe, Ru (n= 0), Mn, Re (n= 1)}

Insertion of {M(CO)4} fragments (M = Fe, Ru, Mn, Re) into the eight-vertex monocarborane anion [closo-1-CB7H8]- affords ten-vertex metal-dicarbollide complexes.     

Synthesis of uridine diphosphate [1-3H]glucose and uridine diphosphate [6-3H]glucose

Information is given on the synthesis of tritium-labeled UDPG by the successive transformation of D-[1-³H]glucose or D-[6-³H]glucose by the action of the enzymes hexokinase (EC 2.7.1.1), phosphoglucomutase (EC 2.7.5.1), and UDPG-pyrophosphorylase (EC 2.7.7.9) under conditions ensuring the retention of the tritium label. Methods of obtaining tritium-labelled substrates and intermediate products of their enzymatic transformations in the synthesis of [³H]UDPG are discussed.V. G. Khlopin Radium Institute, Leningrad. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 125–128, January–February, 1987.     

"Water-stable boron-iodinated dicarbollide dianions [7,8-nido-C2H2B9I9]2- and [7,8-nido-C2H2B9I8H]2-"

The reaction of 3,4,5,7,8,9,10,11,12-I(9)-1,2-closo-C(2)B(10)H(3) with KOH/EtOH gave a mixture of the boron periodinated [1,2,3,4,5,6,9,10,11-I(9)-7,8-nido-C(2)B(9)H(2)](2-) and the highly iodinated on boron [1,2,4,5,6,9,10,11-I(8)-7,8-nido-C(2)B(9)H(3)](2-) in approximately 50% each. Moreover, 3,4,5,6,7,8,9,10,11,12-I(10)-1,2-closo-C(2)B(10)H(2) was reacted with KOH/EtOH to purely produce [1,2,3,4,5,6,9,10,11-I(9)-7,8-nido-C(2)B(9)H(2)](2-). It is the first dinegative dicarbollide stable in water or protic solvent reported in literature.     

Crown compounds for anions: sandwich and half-sandwich complexes of cyclic trimetric perfluoro-o-phenylenemercury with polyhedral closo-[B10H10]2- and closo-[B12H12]2- anions

It has been shown by IR and NMR spectroscopy that cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4-Hg)3 (1) is capable of binding closo-[B10H10]2- and closo-[B12H12]2- anions to form complexes [[(o-C6F4Hg)3](B10-H10)]2- (2), [[(o-C6F4Hg)3]2(B10H10)]2-(3), [[(o-C6F4Hg)3](B12H12)]2- (4), and [[(o-C6F4Hg)3]2(B12H12)]2- (5). According to IR data, the bonding of the [B10H10]2- and [B12H12]2- ions to the macrocycle in these complexes is accomplished through the formation of B-H-Hg bridges. Complexes 2, 3, and 5 have been isolated in analytically pure form and have been characterized by spectroscopic means. X-ray diffraction studies of 3 and 5 have revealed that these compounds have unusual sandwich structures, in which the polyhedral di-anion is located between the planes of two molecules of 1 and is bonded to each of them through two types of B-H-Hg bridges. One type is the simultaneous coordination of a B-H group to all three Hg atoms of the macrocycle. The other type is the coordination of a B-H group to a single Hg atom of the cycle. According to X-ray diffraction data, complex 2 has an analogous but half-sandwich structure. The obtained complexes 2-5 are quite stable; their stability constants in THF/acetone (1:1) at 20 degrees C have been determined as 1.0 x 10(2)Lmol(-1), 2.6 x 10(3)L(2)mol(2), 0.7 x 10(2)Lmol(-1), and 0.98 x 10(3)L(2)mol(-2), respectively.