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1.
Synthesis and Crystal Structure of [(PhCH2)2GaF(tBuNH2)]2 · 2 THF (PhCH2)2GaF reacts with tBuNH2 to the adduct [(PhCH2)2GaF(tBuNH2)] ( 1 ). 1 was characterized by NMR, IR and MS techniques. 1 can be recrystallized from THF forming crystals of [ 1 ]2 · 2 THF. According to an X-ray structure analysis [ 1 ]2 · 2 THF consists of dimers of 1 formed by hydrogen bridges. The THF molecules are coordinated to [ 1 ]2 by hydrogen bridges, too.  相似文献   

2.
Synthesis, Crystal Structures, and Vibrational Spectra of [(Ph3P)2N]2[(W6Cl )I ] · 2 Et2O · 2 CH2Cl2 and [(Ph3P)2N]2[(W6Cl )(NCS) ] · 2 CH2Cl2 By treatment of [(W6Cl)I]2– with (SCN)2 in dichloromethane at –20 °C the hexaisothiocyanato cluster anion [(W6Cl)(NCS)]2– is formed. X‐ray structure determinations have been performed on single crystals of [(Ph3P)2N]2[(W6Cl)I] · 2 CH2Cl2 · 2 Et2O ( 1 ) (triclinic, space group P1, a = 10.324(5), b = 14.908(3), c = 17.734(8) Å, α = 112.78(2)°, β = 99.13(3)°, γ = 92.02(3)°, Z = 1) and [(Ph3P)2N]2[(W6Cl)(NCS)] · 2 CH2Cl2 ( 2 ) (triclinic, space group P1, a = 11.115(2), b = 14.839(2), c = 17.036(3) Å, α = 104.46(1)°, β = 105.75(2)°, γ = 110.59(1)°, Z = 1). The thiocyanate ligands of 2 are bound exclusively via N atoms with W–N bond lengths of 2.091–2.107 Å, W–N–C angles of 173.1–176.9° and N–C–S angles of 178.1–179.3°. The vibrational spectra exhibit characteristic innerligand vibrations at 2067–2045 (νCN), 879–867 (νCS) and 490–482 (δNCS). Based on the molekular parameters of the X‐ray determination of 1 the vibrational spectra of the corresponding (n‐Bu4N) salt of 1 are assigned by normal coordinate analysis. The valence force constants are fd(WW) = 1.61, fd(WI) = 1.23 and fd(WCl) = 1.10 mdyn/Å.  相似文献   

3.
The Oxochlorotantalates (PPh4)2[Ta2OCl9]2 · 2 CH2Cl2, (PPh4)2[Ta2OCl10] · 2 CH3CN, and (K-18-crown-6)4[Ta4O6Cl12] · 12 CH2Cl2 (K-18-crown-6)4[Ta4O6Cl12] · 12 CH2Cl2 was obtained from a reaction of tantalum pentachloride, K2S5 and 18-crwon-6 in dichlormethane. According to its crystal structure analysis it is tetragonal (space group I 4 2d) and contains [Ta4O6Cl12]4– ions that have an adamantane-like Ta4O6 skeleton. Each K+ ion is coordinated by the oxygen atoms of the crown ether molecule from one side and with three Cl atoms of one [Ta4O6Cl12]4– ion from the opposite side. (PPh4)2[Ta2OCl10] · 2 CH3CN was a product from PPh4Cl and TaCl5 in acetonitrile in the presence of Na2S4. Its crystals are monoclinic (space group P21/c) and contain centrosymmetric [Ta2OCl10]2– ions having a linear Ta–O–Ta grouping with short bonds (Ta–O 189 pm). TaCl5 and H2S formed a solid substance (TaSCl3) from which a small amount of (PPh4)2[Ta2OCl9]2 · 2 CH2Cl2 was obtained by the reaction with PPh4Cl in CH2Cl2. The anions in the monoclinic crystals (space group P21/n) consist of two Ta2OCl9 units which are joined by chloro bridges; each Ta2OCl9 unit has a nearly linear Ta–O–Ta group with differing bond lengths (179 and 202 pm). The oxygen in the compounds probably was introduced by traces of water in the crown ether, acetonitrile or H2S, respectively.  相似文献   

4.
[Mo2(O2C–CH3)4 · 1/2 {(CH2)6N4} · 1/2 CH2Cl2] – a Donor‐Acceptor Complex with Supramolecular Structure Yellow single crystals of [Mo2(O2C–CH3)4 · 1/2 {(CH2)6N4} · 1/2 CH2Cl2] ( 1 ) have been obtained by the reaction of the silylated phosphaneimine Me3SiNPEt3 with [Mo2(O2C–CH3)4] in dichloromethane solution. 1 forms a three‐dimensional network with linear N–Mo:Mo–N and tetrahedral (CH2)6N4Mo4 moieties, which is topologically related with the PtS type. Space group P42/nnm, Z = 4, lattice dimensions at –70 °C: a = b = 1121.7(1), c = 1395.0(3) pm, R1 = 0.0413.  相似文献   

5.
Synthesis and Crystal Structure of the Transition Metal Trimetaphosphimates Zn3[(PO2NH)3]2 · 14 H2O and Co3[(PO2NH)3]2 · 14 H2O The transition metal trimetaphosphimates Zn3[(PO2NH)3]2 · 14 H2O and Co3[(PO2NH)3]2 · 14 H2O were obtained by the reaction of an aqueous solution of Na3(PO2NH)3 · 4 H2O with the respective metal nitrate or halide (molar ratio 1 : 4). The structure of Zn3[(PO2NH)3]2 · 14 H2O was solved by single crystal X‐ray methods. The structure of isotypic Co3[(PO2NH)3]2 · 14 H2O was refined from X‐ray powder diffraction data using the Rietveld method (Zn3[(PO2NH)3]2 · 14 H2O ( 1 ): P 1, a = 743.7(2), b = 955.9(2), c = 980.1(2) pm, α = 102.70(3), β = 90.46(3), and γ = 100.12(3)°, Z = 1; Co3[(PO2NH)3]2 · 14 H2O ( 2 ): P 1, a = 746.05(1), b = 957.06(2), c = 988.51(2) pm, α = 102.162(1), β = 90.044(1), and γ = 99.258(1)°, Z = 1). In 1 and 2 the P3N3 rings of the trimetaphosphimate ions attain a conformation which can be described as a combination of an ideal boat and an ideal twist conformation. The trimetaphosphimate ions act as bridging ligands. Thus chains of alternating M2+ and (PO2NH)33– ions are formed which are interconnected by additional M2+ ions forming electro‐neutral double chains. In the solid these double chains are connected by hydrogen bonds.  相似文献   

6.
Yb3F4S2: A mixed‐valent Ytterbium Fluoride Sulfide according to YbF2 · 2 YbFS Attempts to synthesize ytterbium(III) fluoride sulfide (YbFS) from 2 : 3 : 1‐molar mixtures of ytterbium metal (Yb), elemental sulfur (S) and ytterbium trifluoride (YbF3) after seven days at 850 °C in silica‐jacketed gastight‐sealed arc‐welded tantalum capsules result in the formation of the mixed‐valent ytterbium(II,III) fluoride sulfide Yb3F4S2 (tetragonal, I4/mmm; a = 384,61(3), c = 1884,2(4) pm; Z = 2) instead. The almost single‐phase product becomes even single‐crystalline and emerges as black shiny platelets with square cross‐section when equimolar amounts of NaCl are present as fluxing agent. Its crystal structure can be described as a sheethed intergrowth arrangement of one layer of CaF2‐type YbF2 followed by two layers of PbFCl‐type YbFS parallel (001). Accordingly there are two chemically and crystallographically different ytterbium cations present. One of them (Yb2+) is surrounded by eight fluoride anions in a cubic fashion, the other one (Yb3+) exhibits a capped square‐antiprismatic coordination sphere consisting of four F and five S2– anions. In spite of being structurally very plausible, the obvious ordering of the differently charged ytterbium in terms of a localized mixed valency can only be fictive because of the black colour of Yb3F4S2 which rather suggests charge delocalization coupled with polaron activity.  相似文献   

7.
Novel tetrameric rhenium(V) complexes have been prepared from [ReNCl2(PPh3)2] and [ReN(PMe2Ph)(S2CNEt)2], respectively. [ReNCl2(PPh3)2] reacts with 1.5 equivalents of KS2CNEt2 in methanol to yield the unusual dark red species [{cyclo-ReN}4(S2CNEt2)6(MeOH)2(PPh3)2][BPh4]2 · CH2Cl2 · 2 H2O ( 1 ). The crystal structure of the tetramer (triclinic, space group P1, a = 13.842(2), b = 15.213(2), c = 16.796(3) Å, α = 67.88(1), β = 70.90(1), γ = 88.05(1)°, U = 3080.2(8) Å3, Z = 1) shows four rhenium atoms in a square configuration which are bridged via linear asymmetric Re≡N–Re groups with bond lengths of about 169 and 203 pm. The molecule contains a centre of symmetry with two distinct octahedral rhenium environments. The first rhenium environment contains two bidentate dithiocarbamate ligands which complete the octahedral geometry and the second contains a bidentate dithiocarbamate ligand, coordinated methanol and has retained a single phosphine coligand. A symmetric compound containing the {cyclo-ReN}4 core is obtained from the reaction of [ReN(PMe2Ph)(S2CNEt2)2] with Al2Cl6 in acetone. [{cyclo-ReN}4(S2CNEt2)4Cl4(PMe2Ph)4] · 2 acetone ( 2 ) forms red crystals (monoclinic, space group C2/c, a = 21.432(6), b = 13.700(3), c = 28.060(9) Å, β = 102.37(1)°, U = 8048(4) Å3, Z = 4) with each rhenium atom coordinated by a bidentate dithiocarbamato, a phosphine and a chloro ligand. The non-planar 8-membered {ReN}4 ring contains asymmetric Re≡N–Re bridges (mean values: 1.69 Å and 2.029 Å, respectively). In contrast, reaction of [ReNCl(S2CNEt2)(PMe2Ph)2] with one equivalent of K[S2CN(Me)CH2CH2NMe3]I gave the mixed dithiocarbamato-cation [ReN(S2CNEt2)(S2CN(Me)CH2CH2NMe3)(PMe2Ph)]+ ( 3 ) which was isolated as a tetraphenylborate salt.  相似文献   

8.
Carbonate Hydrates of the Heavy Alkali Metals: Preparation and Structure of Rb2CO3 · 1.5 H2O und Cs2CO3 · 3 H2O Rb2CO3 · 1.5 H2O and Cs2CO3 · 3 H2O were prepared from aqueous solution and by means of the reaction of dialkylcarbonates with RbOH and CsOH resp. in hydrous alcoholes. Based on four‐circle diffractometer data, the crystal structures were determined (Rb2CO3 · 1.5 H2O: C2/c (no. 15), Z = 8, a = 1237.7(2) pm, b = 1385.94(7) pm, c = 747.7(4) pm, β = 120.133(8)°, VEZ = 1109.3(6) · 106 pm3; Cs2CO3 · 3 H2O: P2/c (no. 13), Z = 2, a = 654.5(2) pm, b = 679.06(6) pm, c = 886.4(2) pm, β = 90.708(14)°, VEZ = 393.9(2) · 106 pm3). Rb2CO3 · 1.5 H2O is isostructural with K2CO3 · 1.5 H2O. In case of Cs2CO3 · 3 H2O no comparable structure is known. Both structures show [(CO32–)(H2O)]‐chains, being connected via additional H2O forming columns (Rb2CO3 · 1.5 H2O) and layers (Cs2CO3 · 3 H2O), respectively.  相似文献   

9.
Syntheses and Crystal Structures of the Nitrido‐chloro‐molybdates [Mg(THF)4{NMoCl4(THF)}2] · 4 CH2Cl2 and [Li(12‐Crown‐4)(NMoCl4)]2 · 2 CH2Cl2 Both the title compounds as well as [Li(12‐crown‐4)2]+MoNCl4 were made from MoNCl3 and the chlorides MgCl2 and LiCl, respectively, in dichloromethane suspensions in the presence of tetrahydrofuran and 12‐crown‐4, respectively. They form orange‐red moisture‐sensitive crystals, which were characterized by their IR spectra and partly by crystal structure analyses. [Mg(THF)4{NMoCl4(THF)}2] · 4 CH2Cl2 ( 1 ): space group C2/m, Z = 2, lattice dimensions at –50 °C: a = 1736.6(1), b = 1194.8(1), c = 1293.5(2) pm; β = 90.87(1)°; R1 = 0.037. In 1 the magnesium ion is coordinated octahedrally by the oxygen atoms of the four THF molecules and in trans‐position by the nitrogen atoms of the two [N≡MoCl4(THF)] ions. [Li(12‐crown‐4)(NMoCl4)]2 · 2 CH2Cl2 ( 2 ): space group P 1, Z = 1, lattice dimensions at –70 °C: a = 930.4(1), b = 957.9(1), c = 1264.6(1) pm; α = 68.91(1)°, β = 81.38(1)°, γ = 63.84(1)°; R1 = 0.0643. 2 forms a centrosymmetric ion ensemble in the dimeric cation of which, i. e. [Li(12‐crown‐4)]22+, the lithium ions on the one hand are connected to the four oxygen atoms each of the crown ether molecules in a way not yet known; and in addition, each of the lithium ions enters into a intermolecular Li–O bond with neighboring crown ether molecules under formation of a Li2O2 four‐membered ring. The two N≡MoCl4 counterions are loosely coordinated to one oxygen atom each of the crown ether molecules with Mo–O distances of 320.2 pm.  相似文献   

10.
UO2(H2AsO4)2 · H2O was synthesized by dissolving elemental uranium in arsenic acid (80.5%) for twelve weeks at room temperature. The resulting small crystals were transparent and of yellow‐green color. The crystal structure was refined from single‐crystal X‐ray data: C2/c, a = 1316.4(3) pm, b = 886.2(2) pm, c = 905.0(3) pm, β = 124.41(3)°, R1 = 0.023, wR2 = 0.060, 981 structure factors, and 65 variable parameters. The uranium atoms of this new structure type are coordinated by two very close oxygen atoms in linear arrangement. Four further oxygen atoms which belong to four different AsO4 tetrahedra and the oxygen atom of the water molecule complete the 7‐fold coordination of the uranium atoms. [UO2(H2O)]2+ and two H2AsO4 units form infinite electroneutral chains which are the main building units of the structure and which are interconnected by hydrogen bridging bonds. IR heating experiments show that dehydration around 500 K leads to a complete decomposition of the structure. Magnetic measurement gave a diamagnetic behavior with a susceptibility of χ = –8.68 10–9 m3/mol in good agreement with the diamagnetic increment of the compound (χ = –8.20 10–9 m3/mol) calculations with U6+.  相似文献   

11.
Reaction of MnSO4 · H2O, 2,2′‐bipyridine (bpy), suberic acid and Na2CO3 in CH3OH/H2O yielded a mixture of [Mn2(H2O)4(bpy)2(C8H12O4)2] · 2 H2O ( 1 ) and [Mn(H2O)2‐ (bpy)(C8H12O4)2/2] · H2O ( 2 ). In both complexes, the Mn atoms are octahedrally coordinated by two N atoms of one bpy ligand and four O atoms of two trans positioned H2O molecules and two suberato ligands (d(Mn–O) = 2.107–2.328 Å; d(Mn–N) = 2.250–2.330 Å). The bis‐monodentate suberato ligands bridge Mn atoms to form dinuclear [Mn2(H2O)4(bpy)2(C8H12O4)2] complex molecules in 1 and 1D [Mn(H2O)2(bpy)(C8H12O4)2/2] chains in 2 . Via the intermolecular hydrogen bondings and π‐π stacking interactions, the dinuclear molecules in 1 are assembled into 2D networks parallel to (100), between which the crystal H2O molecules are sandwiched. The polymeric chains in 2 are linked together by interchain hydrogen bonding and π‐π stacking interactions into 3D networks with the crystal H2O molecules located in tunnels along [010]. Crystal data for 1 : P21/c (no. 14), a = 10.092(1) Å, b = 11.916(2) Å, c = 17.296(2) Å, β = 93.41(1)° and Z = 2. Crystal data for 2 : P21/c (no. 14), a = 11.176(2) Å, b = 9.688(1) Å, c = 37.842(6) Å, β = 90.06(1)° and Z = 8.  相似文献   

12.
Crystal Structure, Vibrational Spectra, and Normal Coordinate Analysis of ( n ‐Bu4N)2[{Ru(NO)ClI2}2(μ‐I2)] · 2 I2 By treatment of (n‐Bu4N)2[Ru(NO)I5] with (n‐Bu4N)Cl in dichloromethane (n‐Bu4N)2[{Ru(NO)ClI2}2(μ‐I2)] is formed. The X‐Ray structure determination on a single crystal of (n‐Bu4N)2[{Ru(NO)ClI2}2(μ‐I2)] · 2 I2 (monoclinic, space group I 2/a, a = 20.446(6), b = 11.482(8), c = 27.225(3) Å, β = 107.51(4)°, Z = 4) reveals a dinuclear iodine bridged structure, in which the chlorine atoms are trans positioned to the nitrosyl groups. The low temperature IR and Raman spectra have been recorded of (n‐Bu4N)2[{Ru(NO)ClI2}2(μ‐I2)] · 2 I2 and are assigned by normal coordinate analysis. A good agreement between observed and calculated frequencies is achieved. The valence force constants are fd(NO) = 14.08, fd(RuN) = 5.58, fd(RuCl) = 1.52, fd(RuIt) = 0.90 and fd(RuIb) = 0.76 mdyn/Å.  相似文献   

13.
Synthesis, Structure, and Properties of Some Selenidostannates. II. [(C2H5)3NH]2Sn3Se7 · 0,25 H2O and [(C3H7)2NH2]4Sn4Se10 · 4 H2O The new selenidostannate hydrates [(C2H5)3NH]2Sn3Se7 · 0.25 H2O ( I ) and [(C3H7)2NH2]4Sn4Se10 · 4 H2O ( II ) were synthesized from an aqueous suspension of triethylammonium (tripropylammonium), tin, selenium I and in addition sulfur II at 130 °C. I crystallizes at ambient temperature in the monoclinic space group P21/n (a = 2069,3(4) pm, b = 1396,6(3) pm, c = 2342,8(5) pm, β = 114,68(3)°, Z = 8) and is characterized by two different anions, chains from edge‐sharing [Se3Se7]2– units and nets from trigonal SnSe5 bipyramids. II crystallizes at ambient temperature in the tetragonal space group I41/amd (a = 2150,0(3) pm, c = 1174,4(2) pm, Z = 4) and contains adamantane like [Sn4Se10]4–‐cages. The UV‐VIS spectra of the selenidostannates demonstrate that the absorption edges red shift as the dimensionality of the compounds is increased.  相似文献   

14.
Preparation and Crystal Structures of Silver(I) Mixed Ligand Complexes with Bibenzimidazole and Triphenylphosphane: [Ag(PPh3)2(bbimH2)](COOCH3) · 2 CH2Cl2 and [{Ag(PPh3)2}2(μ-bbim)] · 4 CH2Cl2 The title compounds are obtained from silver acetate, 2,2′-bibenzimidazole and PPh3. They are characterized by their IR, 1H-NMR, 31P-NMR spectra and crystal structure determinations. [Ag(PPh3)2(bbimH2)](COOCH3) · 2 CH2Cl2: Reaction in CH2Cl2. Space group C2/c, Z = 4, 3129 observed unique reflections, R = 0.033. Lattice parameters at 203 K: a = 1450.8; b = 1556.2; c = 2316.4 pm; β = 99.69°. The crystal structure is built up by monomeric molecules with distorted tetrahedral coordination of the silver atom (AgP2N2) and bibenzimidazole as a bidentate ligand. The acetate ion is linked to the NH-groups of the bibenzimidazole by hydrogen bonds. [{Ag(PPh3)2}2(μ-bbim)] · 4 CH2Cl2: Reaction in fused PPh3 at 180 °C. Space group P 1, Z = 1. 9227 observed unique reflections, R = 0.051. Lattice parameters at 203 K: a = 1276.5; b = 1352.1; c = 1408.1 pm; α = 96.97; β = 115.87; γ = 96.84°. The crystal structure is built up by centrosymmetric molecules with distorted tetrahedral coordination of the silver atoms (AgN2P2) and bibenzimidazolate(2–) as tetradentate bridging ligand.  相似文献   

15.
Cleavage reactions of the dinuclear [{Ni(′S2C ′)}2] · DMF (′S2C ′ 2– = 1,3‐imidazolidinyl‐N,N′‐bis(2‐benzenethiolate)(2–)) with HNPiPr3 or HNSPh2 yielded the mononuclear complexes [Ni(NHPiPr3)(′S2C ′)] ( 1 ) and [Ni(NHSPh2)(′S2C ′)] ( 2 ) which have been completely characterized. The nickel‐carbene‐dithiolate [Ni(′S2C ′)] moiety is one of the very rare complex fragments that are able to coordinate both HNPR3 or HNSR2. IR spectra and X‐ray structure determinations show that 1 and 2 exhibit intramolecular N–H…S(thiolate) hydrogen bonds. Geometric parameters and NMR spectroscopic data of 1 and 2 are compatible with N–X single bonds and ylidic structures of the HNPiPr3 and HNSPh2 ligands. Comparison of Ni–N distances in diamagnetic and paramagnetic [Ni(NHSPh2)] complexes was rendered possible through the X‐ray structure determination of the homoleptic [Ni(NHSPh2)6]Cl2 ( 3 ) which formed as minor by‐product in the synthesis of 2 .  相似文献   

16.
Synthesis and Structure of two Mixed Substituted Dialanes Al2X2{Si(SiMe3)3}2 · 2 THF (X = Cl, Br) The syntheses of tris(trimethylsilyl)silyl (hypersilyl) and halide substituted dialanes Al2X2{Si(SiMe3)3}2 · 2 THF (X = Cl, Br) are presented. The results of the X‐ray diffraction experiments are presented and discussed in comparison to the AlIII compounds AlBr2Si(SiMe3)3 · THF and AlBr3 · OPh2.  相似文献   

17.
Synthesis and Crystal Structures of the Complexes trans ‐[CoIII(py)4F2][H2F3] and [Pd(py)4]F2 · 1.5 HF · 2 H2O The cobalt complex trans‐[Co(III)(py)4F2][H2F3] ( 1 ) has been prepared by electrochemical oxidation of CoF2 in a pyridine/HF mixture and the palladium complex [Pd(py)4]F2 · 1.5 HF · 2 H2O ( 2 ) has been obtained via halogen exchange between Pd(py)2Cl2 and AgF2 in pyridine. 1 and 2 crystallize in the space group C2/c with a = 27.928(14), b = 9.019(3), c = 18.335(8) Å, β = 113.41(3)° for 1 and a = 28.183(9), b = 9.399(3), c = 17.397(6) Å, β = 104.66(3)° for 2 , respectively. Concerning the shape and location of the M(py)4 fragments 1 and 2 are isostructural. The metal atoms occupy special positions in their unit cells with the result that four complex atoms have C2 symmetry and four complex cations have Ci symmetry giving a total of Z = 8. In 1 two F ions complete an octahedral coordination around the Co atoms (Co–F 1.820(2) to 1.834(3) Å). In 2 the shortest Pd–F distance is 3.031(2) Å. This precludes the existence of Pd–F bonds. In 1 one can identify H2F3 groups. In 2 there are larger aggregates, consisting of F, HF, and H2O subunits, connected by H‐bridges. In spite of these differences, both complexes belong to the same type of structure, which may be of a common type Mx+(py)4Fx · y HF · z H2O.  相似文献   

18.
19.
Oxalato‐ and Squarato‐Bridged Threedimensional Networks: The Crystal Structures of La2(C2O4)(C4O4)2(H2O)8 · 2.5 H2O and K[Bi(C2O4)2] · 5 H2O The title compounds have been formed by hydrolysis of amino‐ and thioderivatives of squaric acid in the presence of LaIII and BiIII ions. Both compounds are threedimensional coordination polymers in the solid state, as shown by single crystal X‐ray crystallography. In La2(C2O4)(C4O4)2(H2O)8 · 2.5 H2O oxalato‐bridged pairs of LaO9 polyhedra are connected with identical neighbouring polyhedra by squarate ions. In K[Bi(C2O4)2] · 5 H2O each Bi atom is fourfold linked to other Bi atoms by the oxalate ions. The resulting 3D network shows a diamond‐like topology with square‐shaped channels. In both structures the channels are partially filled by water molecules.  相似文献   

20.
The crystal structures of uncharged tetrahedral dithiocyanato zinc complexes with N-methylated ethylenediamines have been determined with a view to a study of intermolecular hydrogen-bonding interactions in these compounds. It is found that the H(N) hydrogen atoms are exhaustively engaged in N–H(N) … S bonds. The majority of these bonds are branched (bifurcated or trifurcated), and the hydrogen-bond systems they form all contain one of the two characteristic primitive core motifs: either a discrete centrosymmetric […S…H…]2 dimer or an infinite […S…H…] helix about a 21 or pseudo-21 axis. The hydrogen bonding is analyzed in detail, with particular attention to the existence of correlations between the N–H(N)–S angles and the H(N) … S distances as well as between the corresponding N–H(N)–S/H(N)…S pairs in the bifurcated N–H(N)…2 S bonds.  相似文献   

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