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Catalytic cyclotrimerization routes to symmetrical [9]helical indenofluorene were explored by using different transition–metal complexes and thermal conditions. Depending on the reaction conditions, the cyclotrimerizations were accompanied by dehydro‐Diels–Alder reaction giving rise to another type of aromatic compounds. Structures of both symmetrical [9]helical cyclotrimerization product as well as the dehydro‐Diels–Alder product were confirmed by single‐crystal X‐ray diffraction analyses. Limits of enantioselective cyclotrimerization were assessed as well. DFT calculations shed light on the reaction course and the origin of diminished enantioselectivity. [ABSTRACT FROM AUTHOR]

Herein we introduce fully modular synthesis leading to three representative examples of rigid molecular rods that are intended to form sturdy monolayers on various surfaces. These molecules contain two triptycene units that are designed to interlock into a compact "double‐decker" structure. Two of the three final products provided suitable crystals for X‐ray diffraction (analyzed on synchrotron), allowing deeper insight into packing in the 3‐D crystal lattice. The acidity of all three compounds were determined by capillary electrophoresis, and the pKa values ranged between 2.06‐2.53. All three rigid rods easily formed Langmuir‐Blodgett monolayers (LBMs) on the water‐air interfaces, with the area per molecule equal to 55–59 Å2/molecule, suggesting tight intermolecular packing. The thickness of all three films reached ∼19 Å after transfer to a gold (111) surface, meaning that individual molecules are tilted maximally 38° from the axis perpendicular to the surface. The structure of one of these films on a gold (111) surface was visualized by AFM. These geometrically unique molecules represent promising platforms with a wide scope of applicability in the supramolecular architecture. [ABSTRACT FROM AUTHOR]

Introducing a ferrocene moiety into a molecule results in the incorporation of a metal center and a redox active moiety. This contribution describes the synthesis of FcN(CH2PPh2)2 (1; Fc=ferrocenyl), a ferrocene analog of the widely studied bis‐phosphane pincer ligands, RN(CH2PPh2)2. Compound 1 was studied as a ligand in complexes of Group 10 and 11 metal ions. The following compounds were synthesized and characterized using a combination of spectroscopic methods and single‐crystal X‐ray diffraction analysis: the square planar complexes [MX2(1‐κ2P,P')] (M/X=Ni/Cl, Pd/Cl, Pd/Br, Pd/I and Pt/Cl) and the tetrahedral complexes [M(1‐κ2P,P')2]X (M/X=Cu/PF6, Ag/SbF6 and Au/SbF6). Furthermore, a pair of open and cyclic digold(I) complexes containing bis‐phosphane 1 as a P,P‐bridging ligand, viz. [(μ(P,P')‐1)(AuCl)2] and [(μ(P,P')‐1)2Au2][SbF6]2, were isolated. Ligand 1, the corresponding phosphane selenide 1‐Se and all complexes (except for the poorly soluble [(μ(P,P')‐1)2Au2][SbF6] and unstable [Ag(1‐κ2P,P')2][SbF6]) were further analyzed by cyclic voltammetry. [ABSTRACT FROM AUTHOR]

A 17-membered piperazine-based macrocyclic ligand LdiProp (1,5,13,17,22-pentaazatricyclo[15.2.2.17,11]docosa-7,9,11(22)-triene) was resynthesized in high yield by using a linear pump. Its Mn(II), Fe(II), Co(II) and Ni(II) complexes of the general formula [MnLdiProp(ClO4)2] (1), [FeLdiProp(CH3CN)](ClO4)2 (2), [CoLdiProp(CH3CN)](ClO4)2 (3), [NiLdiProp](ClO4)2 (4) were prepared and thoroughly characterized. X-ray diffraction analysis confirmed that Mn(II) complex 1 has capped trigonal prismatic geometry with a coordination number of seven, Fe(II) and Co(II) complexes 2 and 3 are trigonal prismatic with a coordination number of six and Ni(II) complex 4 has square pyramidal geometry with a coordination number of five. The decrease of the coordination number is accompanied by a shortening of M–N distances and an increase of torsion of the piperazine ring from the equatorial plane. Magnetic measurement reveals moderate anisotropy for 4 and rather large magnetic anisotropy for 2 and 3 (axial zero-field splitting parameter D(Ni) = 9.0 cm−1, D(Fe) = −14.4 cm−1, D(Co) = −25.8 cm−1, together with rather high rhombicity). Co(II) complex 3 behaves as a field-induced SMM with a combination of Raman and direct or Orbach and direct relaxation mechanisms. Obtained magnetic data were extensively supported by theoretical CASSCF calculations. The flexibility and rather large 17-membered macrocyclic cavity of ligand LdiProp could be responsible for the variation of coordination numbers and geometries for the investigated late-first row transition metals. [ABSTRACT FROM AUTHOR]

Novel hybrid ligands based on [1,2,3]-diazaphosphole (dap) were prepared and their coordination behaviour toward selected transition metals has been studied. The syntheses and spectroscopic properties of polydentate bis(5-t-butyl-[1,2,3]-diazaphosphol-2-yl)-dimethylsilane (BdapsH,tBu) and bis(4-methyl-5-ethyl-[1,2,3]-diazaphosphol-2-yl)-dimethylsilane (BdapsMe,Et) are reported. In zerovalent compounds of the type [M(CO)4(κ2-P,P′-BdapsR1,R2)] (R1 = Me, R2 = Et, M = Cr, Mo and W; R1 = H, R2 = t-Bu, M = W) and [Ni(κ2-P,P′- BdapsH,tBu)2] the ligand serves as a P,P′-donor, giving rigid six-membered chelate rings. BdapsMe,Et is also capable of behaving as an N,N′-chelator as confirmed by isolation of high-spin chelate complex [CoBr2(κ2-N,N′-BdapsMe,Et)]. The reaction of parent 2H-4-methyl-5-ethyl-[1,2,3]-diazaphosphole with NiBr2·DME yielded paramagnetic compound [NiBr2(κ-N-dap)2], where the dap heterocycle bonds with the nickel(II) centre via a 1-nitrogen donor atom in a distorted tetrahedral environment. All the studied complexes showing different coordination modes of the new ligands were fully characterized, including single-crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

A series of six indenyl molybdenum compounds bearing a thiophenyl function in the side chain were prepared and characterized by analytical and spectroscopic methods. The structures of [(η5-C9H6CH2C4H3S)(η3-C3H5)Mo(CO)2] and [(η5-C9H6CH2C4H3S)Mo(CO)2(bpy)][BF4] were determined by single-crystal X-ray diffraction. The compounds bearing N,N-chelating ligands exhibit increased cytotoxic activity against human leukemia cell lines MOLT-4; up to two orders of magnitude lower IC50 values were observed compared to analogues with unsubstituted indenyl, which clearly demonstrates the strong effect of the indenyl ligand modification on the biological activity of the molybdenum(ii) compounds. The highest cytostatic potential was observed for the complex bearing 4,7-diphenyl-1,10-phenanthtoline [(η5-C9H6CH2C4H3S)Mo(CO)2(Ph2phen)][BF4] with IC50 (MOLT-4) = 0.19 ± 0.02 μM. Detailed regulation of the molecular and cellular mechanism by this derivative was investigated on the lung carcinoma cell line A549 and compared with the lung fibroblast cell line MRC-5. Rather unusual differences in the effects on tumor and non-tumor cell lines provide a unique insight into the cytostatic action of molybdenum(ii) complexes. [ABSTRACT FROM AUTHOR]

Four dipicolylamine (DPA) derivatives bearing methylphosphonic or methylphosphinic acid (P–R; R = H, Me, CH2PO2H2) groups were synthesized. Their acid–base and coordination properties were studied by potentiometry, UV-Vis and NMR measurements. The phosphonate derivative shows increased basicity (log K1 = 8.39), whereas the phosphinate derivatives show decreased basicity (log K1 = 6–7) compared to the parent dipicolylamine. Consequently, the stability constants of the phosphonate complexes are 3 to 4 orders of magnitude higher than those of the phosphinate complexes. All ligands show excellent selectivity for Zn(ii) over Ca(ii) and Mg(ii) ions. The structures of several Cu(ii) and Ni(ii) complexes in the solid state were determined by X-ray diffraction analysis. The complexes mostly show dimeric or polymeric structures and the two metal ions induce a different coordination geometry of the DPA group. The coordination geometry is always (pseudo)octahedral. The DPA fragment is bound in mer geometry in the Cu(ii) complexes, whereas the Ni(ii) complexes have fac geometry. In conclusion, the phosphonate and phosphinate derivatives of DPA are efficient complexing agents for divalent transition metal ions and the DPA-phosphinate grouping is a suitable fragment for sensing Zn(ii) ions. [ABSTRACT FROM AUTHOR]

Reaction of anti-B18H221 with pyridine in neutral solvents gives sparingly soluble B16H18-3′,8′-Py23a as the major product (ca. 53%) and B18H20-6′,9′-Py22 (ca. 15%) as the minor product, with small quantities of B18H20-8′-Py 4 (ca. 1%) also being formed. The three new compounds 2, 3a and 4 are characterized by single-crystal X-ray diffraction analyses and by multinuclear multiple-resonance NMR spectroscopy. Compound 2 is of ten-vertex nido:ten-vertex arachno two-atoms-in-common architecture, long postulated for a species with borons-only cluster constitution, but previously elusive. Compound 3a is of unprecedented ten-vertex nido:eight-vertex arachno two-atoms-in-common architecture. The single-crystal X-ray diffraction analysis for the picoline derivative B16H18(NC5H4Me)23b, similarly obtained, is also presented. B18H20Py 4 is also previously unreported but is of known ten-vertex nido:ten-vertex nido two-atoms-in-common architecture of anti configuration, but now with the pyridine ligand positioned differently to other reported examples of B18H20L compounds. Factors behind the remarkably low solubility of 3a and 3b are elucidated in terms of electrostatic potential (ESP) calculations, polarity, and van der Waals complementarities. In view of contemporary developing high interest in the fluorescent properties of macropolyhedral boron-containing species, a detailed assessment of the photophysical characteristics of 3a and 4 is also presented. In contrast to the thermochromic fluorescence of 2 (from 620 nm brick-red at room temperature to 585 nm yellow at 8 K, quantum yield 0.15), compound 3a is only weakly phosphorescent in the yellow region (590 nm, quantum yield 0.01), whereas compound 4 exhibits no luminescence. The far more photoactive nature of compound 2 is associated with S1 excited-state minima structures that differ from each other only by the relative rotational positions of the pyridine substituents on its disubstituted ten-vertex {arachno-B10Py2}-subcluster. The wavelength and relative intensity of fluorescence from these structures depends on the rotational positions of the pyridine ligands, which in turn are influenced by temperature and/or rotational inhibition in the solid-state. [ABSTRACT FROM AUTHOR]

The preparation, X-ray single-crystal structure determination and vibrational spectroscopic characterisation of five novel salts, i.e. bis(4,6-diaminopyrimidinium (1+)) oxalate tetrahydrate; 4,6-diaminopyrimidinium (1+) hydrogen malonate monohydrate; bis(4,6-diaminopyrimidinium(1+)) succinate octahydrate; bis(4,6-diaminopyrimidinium(1+)) glutarate dihydrate and bis(4,6-diaminopyrimidinium (1+)) adipate octahydrate, are presented. It is the first crystallographic study with the title cation. All the structures are centrosymmetric. The oxalate, succinate and adipate anions are situated about inversion centres in their respective structures. The dependence on the parity of the number of carbon atoms in the anions is apparent in the interplanar angles of the carboxylate or carboxylic groups. In all of the structures, there are intermolecular N-H · · · N, N-H · · · Oacid, N-H · · · Owater, Owater-H · · · Oacid and Owater-H · · · Owater hydrogen-bonds of moderate strength. The most common graph set motif, R2 2(8), describes the arrangement of the involved carboxylic as well as of the primary- and secondary-amine groups. There is a growing complexity of arrangement of water molecules in the structures with longer anionic molecules. In 4,6-diaminopyrimidinium (1+) hydrogen malonate monohydrate, there is an intramolecular Oacid-H · · · Oacid bond, and the conformation of the hydrogen malonate ions with non-parallel carboxylic and carboxylate groups is not often observed. The structural parameters of the carboxylic or carboxylate groups in the dicarboxylic acids or their derivatives found in the Cambridge Structural Database (CSD) are compared with the title structures. [ABSTRACT FROM AUTHOR]

Three polymorphic modifications of bis( N -phenylbiguanidium(1+)) oxalate are reported, and their characterization is discussed in this paper. The non-centrosymmetric bis( N -phenylbiguanidium(1+)) oxalate (I), which was obtained from an aqueous solution at 313 K, belongs to the monoclinic space group Cc ( a = 6.2560(2) Å, b = 18.6920(3) Å, c = 18.2980(5) Å, β = 96.249(1)°, V = 2127.0(1) Å 3 , Z = 4, R = 0.0314 for 4738 observed reflections). The centrosymmetric bis( N -phenylbiguanidium(1+)) oxalate (II) was obtained from an aqueous solution at 298 K and belongs to the monoclinic space group P 2 1 / n ( a = 6.1335(3) Å, b = 11.7862(6) Å, c = 14.5962(8) Å, β = 95.728(2)°, V = 1049.90(9) Å 3 , Z = 4, R = 0.0420 for 2396 observed reflections). The cooling of the centrosymmetric phase (II) leads to the formation of bis( N -phenylbiguanidium(1+)) oxalate (III) ( a = 6.1083(2) Å, b = 11.3178(5) Å, c = 14.9947(5) Å, β = 93.151(2)°, V = 1035.05(8) Å 3 , Z = 4, R = 0.0345 for 2367 observed reflections and a temperature of 110 K), which also belongs to the monoclinic space group P 2 1 / n . The crystal structures of the three characterized phases are generally based on layers of isolated N -phenylbiguanidium(1 +) cations separated by oxalate anions and interconnected with them by several types of N-H ... O hydrogen bonds. The observed phases generally differ not only in their crystal packing but also in the lengths and characteristics of their hydrogen bonds. The thermal behaviour of the prepared compounds was studied using the DSC method in the temperature range from 90 K up to a temperature near the melting point of each crystal. The bis( N -phenylbiguanidium(1+)) oxalate (II) crystals exhibit weak reversible thermal effects on the DSC curve at 147 K (heating run). Further investigation of this effect, which was assigned to the isostructural phase transformation, was performed using FTIR, Raman spectroscopy and X-ray diffraction analysis in a wide temperature range. [ABSTRACT FROM AUTHOR]

Ferrocene P,N-ligands have been extensively studied due to their favorable catalytic properties. This contribution focuses on a pair of new, isomeric ferrocene phosphinoamines, FcNHCH 2 CH 2 PPh 2 (1) and FcN(Me)CH 2 PPh 2 (2), which were prepared from aminoferrocene, converted to the respective phosphine selenides (1-Se and 2-Se) and further studied as ligands in Pd(II) complexes containing the 2-(dimethylamino-κ N)phenyl-κ C 1 auxiliary (LNC) ligand. Thus, cleavage of the dimeric precursor [(LNC)Pd(μ-Cl)] 2 with the phosphinoamines afforded the corresponding phosphine complexes [(LNC)PdCl(1 -κ P)] (5) and [(LNC)PdCl(2 -κ P)] (6) with trans -P,N configuration. The subsequent removal of the chloride ligand with AgClO 4 from 5 produced the cationic bis-chelate complex [(LNC)PdCl(1 -κ2 P,N)]ClO 4 (7), whereas an analogous reaction with 6 gave no defined product. The phosphinoamines and their complexes were characterized by elemental analysis and common spectroscopic methods, and the crystal structures of 1, 2 , and 7 were determined by single-crystal X-ray diffraction analysis. A cyclic voltammetry study, supported by DFT calculations, revealed that the primary electrochemical oxidation of these compounds occurs at the ferrocene unit. [ABSTRACT FROM AUTHOR]

The title structures of biuret-cyanuric acid (2/2) monohydrate, C10H18N12O11, 1 [ P1̅, Z=2, a=8.2598(4) Å, b=10.8795(5) Å, c=11.9138(6) Å, α=67.036(1)°, β= 79.842(2)°, γ=69.859(2)°, V=924.38(8) Å3], and of biuret-glutaric acid (1/1), C7H13N3O6, 2 [ P1̅, Z=2, a=5.0044(3) Å, b=7.0832(3) Å, c=14.9803(10) Å, α=102.860(4)°, β= 91.899(3)°, γ=102.202(4)°, V=504.20(5) Å3], show usual features both in constitution and intermolecular contacts except for a slightly longer C=O bond length in one of the carbonyl groups in 2. The biuret molecules have conformations with anti-parallel arrangement of the carbonyl groups. In each structure O-H...O and N-H...O hydrogen bonds of the moderate strength are present. The new results are compared with other structures which contain biuret molecules. The influence of the hydrogen bonding on the bond length of the carbonyl group C=O in the fragment NH2-(C=O)-NH with amine and hydroxyl donors has also been investigated. It transpires that the C=O...H angle of about 120° favors a slight elongation of the C=O bond length. The elongation of the C=O bond is more susceptible to the relative orientation of the C=O group with regard to amine over hydroxyl groups. This is the likely explanation why one of the C=O bonds in 2 is slightly longer than usual because this carbonyl group is simultaneously involved in two hydrogen bonds where C=O...H-O and C=O...H-N satisfy the 120° condition. Vibrational spectra of the title structures were also recorded and assigned. [ABSTRACT FROM AUTHOR]

Here it is reported that crystals of an enantiopure [7]helquat salt undergo reversible thermal solid-solid phase transition at 404 K. Differential scanning calorimetry (DSC), capillary electrophoresis (CE), and X-ray diffraction analysis were used to unravel the mechanistic details of this process. The single-crystal-to-single-crystal course enabled direct monitoring of the structural changes by in situ variable-temperature X-ray diffraction, thus providing the first direct evidence of a solid phase transition in a helicene-like compound. [ABSTRACT FROM AUTHOR]

{[Tris(hydroxymethyl)methylamino]carbonyl}ferrocene ( 1 ) reacts with phosphorus(III) chloride in the presence of pyridine or triethylamine to afford a ferrocenyl-substituted bicyclic phosphite, {[(2,6,7-trioxa-1-phosphabicyclo[2.2.2]oct-4-yl)amino]carbonyl}ferrocene ( 2 ), in a moderate yield. (4,5-Dihydro-4,4-bis(chloromethyl)-2-oxazolyl)ferrocene ( 3 ) is found to be formed in some experiments as a minor side-product, resulting presumably via halogenation of 1 and base-induced cyclization of an intermediate chloromethyl derivative. The reaction of 2 with [W(CO) 4 (cod)] (cod = cycloocta-1,5-diene) at elevated temperature produces bis-phosphite complex cis -[W(CO) 4 ( 2 -κ P ) 2 ] ( 4 ) as the major product. All newly prepared compounds have been characterized by spectroscopic methods (IR, NMR and mass spectrometry) and elemental analysis. The crystal structures of 2 , 3 ·1/2H 2 O and 4 ·Me 2 CO·H 2 O were determined by single-crystal X-ray diffraction and the redox behaviour of phosphite 2 and the W(0) complex 4 was studied by cyclic voltammetry. [ABSTRACT FROM AUTHOR]

Four strains of the fungus Quambalaria cyanescens (Basidiomycota: Microstromatales), were used for the determination of secondary metabolites production and their antimicrobial and biological activities. A new naphthoquinone named quambalarine A, (S)-(+)-3-(5-ethyl-tetrahydrofuran-2-yliden)-5,7,8-trihydroxy-2-oxo-1,4-naphthoquinone (1), together with two known naphthoquinones, 3-hexanoyl-2,5,7,8-tetrahydroxy-1,4-naphthoquinone (named here as quambalarine B, 2) and mompain, 2,5,7,8-tetrahydroxy-1,4-naphthoquinone (3) were isolated. Their structures were determined by single-crystal X-ray diffraction crystallography, NMR and MS spectrometry. Quambalarine A (1) had a broad antifungal and antibacterial activity and is able inhibit growth of human pathogenic fungus Aspergillus fumigatus and fungi co-occurring with Q. cyanescens in bark beetle galleries including insect pathogenic species Beauveria bassiana. Quambalarine B (2) was active against several fungi and mompain mainly against bacteria. The biological activity against human-derived cell lines was selective towards mitochondria (2 and 3); after long-term incubation with 2, mitochondria were undetectable using a mitochondrial probe. A similar effect on mitochondria was observed also for environmental competitors of Q. cyanescens from the genus Geosmithia. [ABSTRACT FROM AUTHOR]

The reactions of 1′-(diphenylphosphino)-1-cyanoferrocene ( 1 ) and silver(I) salts with common oxoanions, viz. AgNO 3 , AgNO 2 and Ag 2 SO 4 , led to defined products only in the case of AgNO 3 and AgNO 2 . Whereas the reactions involving silver(I) nitrate produced the phosphine complex [Ag(NO 3 -κ 2 O , O ′)( 1 -κ P ) 2 ] ( 2 ) irrespective of the metal-to-ligand ratio, those with AgNO 2 gave rise to the coordination polymer [Ag{μ(P,N)- 1 }(NO 2 -κ 2 O , O ′)] n ( 3 ) and the discrete monosilver complex [Ag(NO 2 -κ O , O ′)( 1 -κ P ) 2 ] ( 4 ) at the Ag: 1 molar ratios 1:1 and 1:2, respectively. Compounds 2 – 4 were structural characterized by spectroscopic methods and by single-crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

1'-Diphenylphosphino-1-{[(2-(methylthio)ethyl)amino]carbonyl}ferrocene (1), accessible via amidation of 1'-(diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) with 2-(methylthio)ethylamine, reacts with [PdCl2(cod)] (cod = cycloocta-1,5-diene) at a 1 : 1 metal-to-ligand ratio to give trans-[PdCl2(1-κ2P,S)] (trans-2) as the sole product. A similar reaction with [PtCl2(cod)] affords a mixture of cis- and trans- [PtCl2(1-κ2P,S)] (cis- and trans-3), which can be separated by fractional crystallisation. Complexation reactions performed with 2 equiv. of the ligand are less selective, yielding mixtures of the expected bis-phosphine complexes (i.e., trans-[PdCl2(1-κP)2], or a mixture of cis- and trans-[PtCl2(1-κP)2]) with the respective monophosphine complexes. The structures of 1, trans-2, cis-3 and trans-3 determined by X-ray diffraction demonstrate the ability of the title ligand to act as a flexible cis- or trans-P,S-chelate donor (the ligand bite angles are 174.03(2)/173.05(2)° for trans-2/3 and 92.86(2)° for cis-3). [ABSTRACT FROM AUTHOR]

The chloride and l-tartrate salts of the 2,4-diaminoquinazolinium(1+) were prepared and characterized by both X-ray diffraction and infrared spectroscopy. The potential of the 2,4-diaminoquinazolinium(1+) cation as a building block for materials for nonlinear optics was assessed using quantum mechanical computations. Both 2,4-diaminoquinazolinium(1+) chloride dihydrate ( a = 7.2121(1) Å, b = 8.0105(2) Å, c = 18.6157(5) Å, β = 92.493(1)°, V = 1074.46(4) Å, Z = 4, R = 0.0305 for 4605 observed reflections) and 2,4-diaminoquinazolinium(1+) l-tartrate dihydrate ( a = 7.2899(2) Å, b = 11.9508(2) Å, c = 13.4183(3) Å, β = 92.375(2)°, V = 1168.00(5) Å, Z = 2, R = 0.0367 for 4761 observed reflections) belong to the monoclinic space group P2. They are stable, non-hygroscopic, colorless and exhibit non-zero SHG efficiency for powdered samples. Graphical Abstract: Two novel non-centrosymmetric salts of 2,4-diaminoquinazolinium(1+) were prepared and thoroughly characterized during the search for materials for the second harmonic generation. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The stannylene {2-[(CH3)2NCH2]C6H4}2Sn (1) was reacted with oxygen, sulfur, selenium, tellurium, and carbon disulfide. The reactions with heavier chalcogens led to the rapid formation of 1:1 dinuclear adducts which were characterized by elemental analysis, ESI-MS measurements, 1H NMR spectroscopy, and structurally characterized by X-ray diffraction (in the case of reaction products with S8 (3) and Te (5)). The reaction of 1 with carbon disulfide and elemental sulfur yields the remarkable compound {{2-[(CH3)2NCH2]2C6H4}Sn}2(μ2-S2C＝CS2) (3a). The stability and reactivity of compounds 1–5 were rationalized at DFT/TZ2P level. [Copyright &y& Elsevier]

Abstract: Binuclear titanocene complexes [Cp2Ti(tcm)]2O (4), [Cp2Ti(dca)]2O (5) and [Cp2Ti(dcnm)]2O (6) (tcm− =tricyanomethanide, dca− =dicyanamide and dcnm− =dicyanonitrosomethanide) were synthesized in moderate yields by the reaction of Cp2TiCl2 (1) with respective alkali metal pseudohalide salts in the aqueous solution. When the reaction was carried out in dry organic solvents, mononuclear compounds Cp2Ti(tcm)2 (2) and Cp2Ti(dca)2 (3) were isolated. Preparation of dipseudohalide complex Cp2Ti(dcnm)2 by this manner was unsuccessful due to decomposition of dcnm ligand resulting in formation of oxygen-bridged compound 6. All prepared compounds were characterized by elemental analysis, NMR, Raman, infrared and UV–Vis spectroscopy. Molecular structures of 2, 4 and 6 (two polymorphs) have been determined by single-crystal X-ray diffraction analysis. [Copyright &y& Elsevier]

Abstract: Thermolysis of [TiMe2(η5-C5Me4Ph)2] (4) at 145°C for 5h afforded the singly tucked-in paramagnetic titanocene [Ti(III)(η5-C5Me4Ph){η5:η1-C5Me3Ph(CH2)}] (9). In distinction to the singly tucked-in permethyltitanocene [Ti(III)(η5-C5Me5){η5:η1-C5Me4(CH2)}] (1) which was found crystallographically disordered [J.M. Fischer, W.E. Piers, V.G. Young, Jr., Organometallics 15 (1996) 2410] the single crystal X-ray diffraction analysis of 9 afforded molecular parameters with nearly by one order better precision as measured by esd-values. [Copyright &y& Elsevier]

The novel functionalized ferrocene alkyne Ph2P(S)fcC≡CH (1; fc=ferrocene-1,1′-diyl) was synthesized from Ph2P(S)fcCHO (6) via the Corey–Fuchs reaction. It was further reacted with K2[HgI4]/KOH to give mercury(II) acetylide Hg{C≡CfcP(S)Ph2}2 (8), and with [Co2(CO)8] to afford the trimetallic Co2Fe complex [(μ-η2:η2-1){Co(CO)3}2](Co–Co) (9). All compounds were characterized by spectral methods (IR, NMR, and MS) and by combustion or high-resolution MS elemental analyses. In addition, the crystal structures of 1, Ph2PfcBr (5), 6, Ph2P(S)fcCH=CBr2 (7), and 9 were determined by single-crystal X-ray diffraction. [Copyright &y& Elsevier]

2-(Ferrocenylmethyl)amino-2-methylpropan-1-ol was synthesized and converted to the respective ammonium bromide ([1H]Br ≡ 2) and dihydrogenphosphate ([1H]H2PO4 ≡ 3). The solid-state structures of 1, 2 and the solvated salt 3 · 1/6Et2O (3a) have been determined by X-ray diffraction. The solid-state assemblies of 1 and 2 are dominated by infinite ladder-like arrays interconnected by hydrogen bonds whereas the solid-state structure of 3a is built up from linear hydrogen-bonded dihydrogenphosphate chains, which are interlinked via hydrogen bonds to the cations [1H]+ into a complicated three-dimensional network. Compound 1 and its interactions with Bu4NBr and Bu4NH2PO4 in solution were further studied by electrochemical methods and NMR titrations. [Copyright &y& Elsevier]

Synthesis of unsymmetrical [7]-helical compounds possessing the dispiro[2,1- c ]indenofluorene motif was achieved for the first time in good yields. The crucial step of the whole reaction sequence was catalytic intramolecular [2 + 2 + 2] cycloaddition of triynediols by using various transition metal compounds (Co, Ni, etc.). The cyclotrimerizations were accompanied by dehydro-Diels-Alder reaction giving rise to other types of aromatic compounds depending on the respective reaction conditions. Limits of enantioselective cyclotrimerization were assessed. The subsequent transformations of the cyclotrimerization products provided the respective dispiroindenofluorenes. Structures of both unsymmetrical [7]helical cyclotrimerization products as well as three dehydro-Diels-Alder products were unequivocally confirmed by single-crystal X-ray diffraction analyses. Photophysical properties of selected products were determined as well. [Display omitted] • Catalytic [2 + 2 + 2]cyclotrimerization route to unsymmetrical [7]helical indenofluorenes. • Competition of cyclotrimerization with thermal dehydro-Diels-Alder reaction. • Catalytic enantioselective cyclotrimerization. • Photophysical and structural properties of products were determined. [ABSTRACT FROM AUTHOR]

The effect of modification of benzoylferrocene periphery on catalytic activity toward drying of alkyd resins has been investigated by the combination of experimental techniques. A series of substituted ferrocenes have been synthesized and characterized by analytical and spectroscopic tools including X-ray diffraction analysis on single crystals. The electrochemical behavior of the ferrocene derivatives has been elucidated by cyclic voltammetry and rotation disk voltammetry. The activity toward room temperature curing of alkyd resin has been evaluated by standard mechanical tests on coated plates, which enabled to establish a structure/catalytic activity relationship. Fast drying of test coatings has been observed for formulations of (3-methoxybenzoyl) ferrocene. Time-resolved infrared spectroscopy in combination with attenuated total reflectance sampling technique enabled to reveal the kinetic origin of the improved performance for this ferrocene derivative. [ABSTRACT FROM AUTHOR]

The azo–hydrazo tautomerism of four model azo dyes in the solid state is investigated by multinuclear solid-state nuclear magnetic resonance (SS-NMR) spectroscopy, X-ray diffraction and quantum-chemical calculations. The measurement of 15N SS-NMR spectra is the most straightforward way to determine the tautomeric state of solid azo compounds. Unfortunately, the sensitivity of these nuclei for SS-NMR is very low and the acquisition of 15N spectra in a reasonable time may be challenging. It is demonstrated that a natural abundance of almost 100% of another nitrogen isotope, 14N, can be exploited for the investigation of the tautomerism. Indirect detection of 14N nuclei via protons is an elegant approach for the rapid and unequivocal determination of the tautomeric form. Furthermore, a comparison of experimental carbon SS-NMR chemical shifts with those obtained in solution or by quantum-chemical computations can be used for the same purpose. Image 1 • The azo–hydrazo tautomerism of azo dyes in the solid state is studied by solid-state NMR spectroscopy. • 1H, 13C, 14N and 15N NMR experiments are used for the determination of the tautomeric form. • Indirect detection of 14N nuclei via 1H provides a rapid determination of the tautomeric form. • Quantum-chemical computations of NMR parameters help to determine the tautomeric form. [ABSTRACT FROM AUTHOR]

We describe syntheses of six triptycene-containing molecular rotors with several single-crystal X-ray diffraction analyses. These rod-shaped molecules carrying an axial rotator are designed to interleave on an aqueous surface into Langmuir–Blodgett (LB) monolayers containing a two-dimensional trigonal array of dipoles rotatable about an axis normal to the surface. Monolayer formation was verified with the simplest of the rotor structures. On an aqueous subphase containing divalent cations (Mg2+, Ca2+, Zn2+, Sr2+, or Cd2+), the LB isotherm yielded an area of 53 ± 3 Ų/molecule (monolayer of type A), compatible with the anticipated triangular packing of axes normal to the surface. On pure water, the area is 30 ± 3 Ų/molecule, and it is proposed that in this monolayer (type B), the molecular axes are tilted by 40–45° to a structure similar to those observed in single crystals of related triptycenes. After transfer to a gold surface, ellipsometry and PM IRRAS yield tilt angles of 29 ± 4° (monolayers of type A) and 38 ± 4° (type B). A full-scale examination of monolayers from all the rotors on a subphase and after transfer is underway and will be reported separately. [ABSTRACT FROM AUTHOR]

• Platinum complexes with cyclometalated carbene and metallocene bisphosphine ligands were prepared. • The compounds were characterized by spectroscopic methods and cyclic voltammetry. • Structures of two representatives were determined by X-ray diffraction analysis. • DFT calculations were used to described the bonding situation in these componds. Four cycloplatinated complexes of the type [Pt(C^C*){M(η5-C 5 H 4 PPh 2) 2 -κ2 P,P '}][PF 6 ] n (M = Fe, n = 1; M = Co, n = 2), where C^C* is 2-(3-methylimidazol-2- ylidene-1-yl-κC2)phenyl-κC1 and similar cyclometalated ligands bearing an additional aromatic ring and phenyl substituents at the imidazol-2-ylidene unit, were prepared and structurally characterized by spectroscopic methods (NMR and ESI MS), elemental analysis, cyclic voltammetry and DFT calculations. Experimental structural parameters and DFT calculations consistently indicate differentiation of the Pt-bound phosphine groups due to unlike trans influence of the phenyl and carbene donor moieties at the cyclometalated ligand in these compounds [Display omitted] [ABSTRACT FROM AUTHOR]

Rich supergene mineral association with prevalence of Pb was found in a shallow gallery of the Rovnost mine, the Jachymov (St. Joachimsthal) ore district, western Bohemia (Czech Republic). Mimetite occurs as colourless transparent flexible fibres up to 1 mm in length and up to 10 urn in diameter. The fibres form greyish white aggregates (up to 1 cm² in area) grown on the surface of gangue strongly affected by supergene alteration. The results of the single crystal X-ray diffraction study of mimetite with R1 = 0.0381 are fully consistent with data reported previously for this mineral phase. According to electron microprobe study, interesting are namely elevated contents of SiO4 (up to 0.16 apfu). Among the supergene minerals, cerussite, anglesite, wulfenite, philipsbornite-segnitite minerals, pyromorphite and metazeunerite were determined based on powder X-ray diffraction and electron microprobe analyses. The presence of U (~ 4 wt. % UO3) and As (up to 4 wt. % As2O5) in wulfenite is particularly noteworthy. Characteristic of the studied mineral association are elevated and omnipresent contents of F-. This mineral assemblage is considered to be a result of a long-term in-situ weathering in near-surface conditions. [ABSTRACT FROM AUTHOR]

Abstract: Two series of vanadocene complexes of the type (Cp′= η 5-C5H5, η 5-C5H4Me; X=dicyanamide, tricyanomethanide, dicyanonitrosomethanide) were prepared by the reaction of appropriate vanadocene dichloride complex with alkali salt of non-linear pseudohalide. The bonding mode of pseudohalide ligands was determined by spectroscopic measurements and X-ray diffraction analyses. [Copyright &y& Elsevier]

(Ferrocenylmethyl)(2-hydroxyethyl)amine (1) reacts with mono- (CH3CO2H and PhCO2H) and dicarboxylic acids (HO2C(CH2)nCO2H (n=0–2), (E)- and (Z)-HO2CCH=CHCO2H) to give the respective carboxylates, viz [1H](RCO2) (2, R=CH3; 3, R=Ph), [1H]2(O2C(CH2)nCO2) (4, n=0; 5, n=1; 6, n=2), [1H]2((E)-O2CCHCHCO2) (7) and [1H]2((Z)-HO2CCH=CHCO2) (8), as defined crystalline solids. Crystal structures of 2–8 have been determined by single-crystal X-ray diffraction analysis, revealing extensive hydrogen bonding interactions based predominantly on charge-supported N+–H···O− and O–H···O− hydrogen bonds, and on C–H···O contacts. Whereas the crystal assemblies of the monocarboxylate salts propagate preferentially in one dimension (2: cross-linked chains, 3: columnar stacks), those of the salts prepared from the dicarboxylic acids (including hydrogenmaleate 8) are best described as layered composite arrays resulting via alternation of polar, hydrogen-bonded layers and of non-polar sheets constituted by the ferrocenyl substituents. [Copyright &y& Elsevier]

Abstract: The preparation and characterization of organolithium O,C,O-pincer compound [2,6-(tBuOCH2)2C6H3]-Li (1) is described. The X-ray diffraction techniques revealed the dimeric structure of 1 consisting of two lithium atoms Li(1) and Li(2) and two monoanionic chelating aryl ligands in the solid state, where each lithium atom is coordinated by two oxygen atoms of two different ligands. The NMR spectroscopy and cryoscopy measurements established monomer–dimer equilibrium of 1 in concentrated solutions of non-coordinated solvents, while the diluted solutions of 1 consist of monomer only. [Copyright &y& Elsevier]

Two types of vanadocene complexes with carboxylic acids have been synthesized from the aqueous solution, Cp2V(OOCR)2 (R=H, CCl3 and CF3) and Cp2V(OOC–A–COO) (A= – and CH2), and characterized by EPR, IR, and Raman spectroscopy and X-ray diffraction analysis. Monocarboxylic and dicarboxylic acids form monodentate and chelate complexes, respectively. Both bonding types were evidenced by X-ray diffraction analysis. Structures and EPR HFC tensors were also calculated at the DFT level. Correlation between the complex structure and HFC tensor was established. HFC tensors are characteristic for the type of bond of carboxylic acid on vanadocene fragment. It is shown that the structure of complexes can be determined by the combination of theoretical method with experimental EPR spectra. [Copyright &y& Elsevier]

Ten new vanadocene complexes bearing N , N ′-chelating ligands were prepared, characterized, and their cytotoxicity toward a panel of cancer cells was measured. Structures of four vanadocene compounds were determined by single crystal X-ray diffraction analysis. Complexes containing 1,2-bis(phenylimino)acenaphthene (bian) and 1,2-bis(4-methoxyphenylimino)acenaphthene (4-MeO-bian) exhibit higher cytotoxicity than those with dipyrido[3,2- a :2′,3′- c ]phenazine (dppz) and (E)- N -((pyridin-2-yl)methylene)benzenamine (pyma). In light of the finding, cytotoxic mechanisms of two highly effective complexes [(η5-C 5 H 4 Me) 2 V(bian)][OTf] 2 (3b) and [(η5-C 5 H 4 Me) 2 V(4-MeO-bian)][OTf] 2 (4b) against human A549 lung adenocarcinoma cells were investigated by following membrane leakage of intracellular lactate dehydrogenase, Trypan Blue staining and activation of tumor protein p53 (p53). Evaluated complexes have a potent dose-dependent antiproliferative activity, causing cell cycle redistribution by the increased accumulation of cells in the G2 and S phase. In accord with the observed cell cycle deceleration, cyclin-dependent kinase inhibitor-interacting protein 1 (p21WAF1/Cip1), extracellular signal–regulated kinases 1 and 2 (ERK1/2), Checkpoint kinase 1 (Chk1), Checkpoint kinase 2 (Chk2) and their phosphorylated forms Chk1 at serine 345 and Chk2 at threonine 68 increased. In the cells exposed to complexes, dose- and time-dependent apoptotic process is initiated by the activation of the initiator caspase 8, followed by activation of effector caspase 3/7 and phosphatidylserine externalization. Moreover, because of treatment, A549 cells activate prosurvival mitogen-activated protein kinases (MAPK) signaling and up-regulate antiapoptotic protein B-cell lymphoma (Bcl-2), thereby promoting evasion of cell death. Both complexes exhibited considerably higher cytotoxic effect than the reference anticancer drug cis -platin and the cytotoxicity was more pronounced at higher treatment time. The newly synthetized vanadocene complexes bearing N , N′ -ligands were tested on the cancer cell line. Experimental methods showed that the complexes of bis(phenylimino)acenaphthenes have higher cytotoxic effect than cis -platin but mechanism of the effect is similar to cis -platin. Unlabelled Image • Newly synthetized N , N′ -vanadocene complexes were tested for anti-cancer activity. • Their cytotoxic effect is higher than cis -platin. • Molecular action is based on the block cell cycle. • Tumor protein p53 (p53) and mitogen-activated protein kinases (MAPK) are activated. [ABSTRACT FROM AUTHOR]

Two novel ternary Cu(II) coordination polymers with formulas {[Cu(μ 2 -AZPY)(H 2 BTC) 2 ]} n ( 1 ) and {[Cu(μ 2 -AZPY)(μ 2 -HBTC)(H 2 O)]·AZPY} n ( 2 ) (AZPY – trans-4,4′-azobis(pyridine), BTC – benzene-1,3,5-tricarboxylate) have been synthesized using the solvothermal or diffusion techniques, respectively. Compounds were characterized by single crystal X-ray diffraction, thermogravimetry, infrared spectroscopy, elemental analysis and AAS. Removal of water and AZPY from the framework of 2 was investigated by wide-angle X-ray scattering measurements during in-situ heating. A magnetic study showed on antiferromagnetic coupling in 1 and 2 and magnetic properties may be influenced by both crystal field (CF) and inter-molecular interactions. The effective magnetic moment decreases from the values μ eff = 4.97 μ B for 1 and μ eff = 3.39 μ B for 2 at T = 290 K to the values of μ eff = 1.41 μ B for 1 and μ eff = 1.27 μ B for 2 at T = 2 K. The origin of the observed behavior is discussed. [ABSTRACT FROM AUTHOR]

The cobalt bis(dicarbollide) anion [(1,2-C2B9H11)2-3,3'-Co]- (1-) is an increasingly important building block for the design of new biologically active compounds. Here we report the reactions of lithiated 1- with N-(ω-bromoalkyl)phthalimides Br-(CH2)n-N(CO)2NC6H4 (where n = 1 to 3) that give a number of new compounds substituted at dicarbollide carbon atom positions. For n = 2 and 3, substitution of the cobalt bis(dicarbollide) anion is accompanied by cyclocondensation of the organic moieties to give polycyclic ring structures attached to the cage. Predominant products correspond to oxazolo[2,3-a]isoindol-5(9bH)-1,2,3-dihydro-9b-yl)-(1-cobalt(III) bis(1,2-dicarbollide)(1-) (2-) and 1-(2H-[1,3]-oxazino[2,3-a]isoindol-6(10bH)-1,3,4-dihydro-10b-yl)-(1-cobalt(III) bis(1,2-dicarbollide)(1-) (4-) ions with isoindolone functions containing either five- or six-membered lateral oxazine rings. Additionally, products (tetrahydro-2-benzo[4,5]furan-1(3H)-1-[3,3]-yl-)-1,1'-μ-cobalt(III) bis(1,2-dicarbollide)(1-) (3-) and (2-(azetidin-yl-carbonyl)benzoyl-)-1-cobalt(III) bis(1,2-dicarbollide)(1-) (5-) were isolated, which display unusual cyclic structures featuring a bicyclic benzofuranone ring attached in a bridging manner by a quarternary carbon to two skeletal carbon atoms and a ketobenzoic acid amide substituent with a side azetidine ring. However, in the case of n = 1, only the anticipated methylene amine derivative [(1-NH2CH2-1,2-C2B9H11)(1',2'-C2B9H11)2-3,3'-Co]- (6-) was isolated in low yield after cleavage of the phthalimide intermediate species. The molecular structures of all isolated cyclic products 2- to 5- were confirmed by single-crystal X-ray diffraction studies, and the structure of cobalt bis(dicarbollide)-1-CH2NH2 6- was delineated using density functional theory applied at BP86/AE1 level in combination with NMR spectroscopy. Thus, the synthetic method described herein presents a facile route to new cobalt bis(dicarbollide) derivatives substituted by polycyclic structural motifs with potential biological activity. [ABSTRACT FROM AUTHOR]

Abstract: The efficient catalytic dehydropolymerization of phenylsilane by homogeneous zirconocene bissilanolates ([{(c-C5H9)7Si8O12O}2Zr(η5-C5H5)2] (1a); [{(c-C5H9)7Si8O12O}2Zr(η5-C5H4Bu)2] (1b) [{(c-C5H9)7Si7O9(OSiMe3)O2}Zr(η5-C5H5)2] (4); [{(Me3CO)3SiO}2Zr(η5-C5H5)2] (5)) and chlorosilanolates ([{(c-C5H9)7Si8O12O}ZrCl(η5-C5H4Bu)2] (2); ([{(c-C5H9)7Si7O9O3}Zr2Cl(η5-C5H5)4] (3a); [{(c-C5H9)7Si7O9O3}Zr2Cl(η5-C5H4Bu)4] (3b)) has been demonstrated. The presence of at least one silanol ligand in the zirconocene moiety was found essential for high catalytic performance. Solid state structure of complex 1a was determined by single crystal X-ray diffraction analysis. A series of nine zirconocene-siliceous catalysts were prepared by grafting of zirconocene moiety onto silica using three general methods: (a) reaction of [(η5-C5H5)2ZrCl2] with silica in the presence of NEt3; (b) reaction of [(η5-C5H5)2ZrMe2] with silica; (c) reaction of solely [(η5-C5H5)2ZrCl2] with silica. Supported catalysts were characterized by ICP-MS, FT-IR, TGA and selected examples by XPS analysis. Those catalysts prepared by method (a) and (b) were found efficient in the phenylsilane polymerization although a higher Zr/monomer ratio had to be used in comparison with homogeneous analogues. The low concentration of residual silanol groups in supported catalysts was found essential for their high catalytic performance. Advantageous reusability of supported catalysts was demonstrated using SiO2(500)/Cp2ZrCl2/NEt3(5.8). The catalytic performance was retained in three consecutive cycles producing polymers with almost identical properties. [Copyright &y& Elsevier]

Abstract: The cytotoxic effect of vanadocene dichloride (Cp2VCl2, 1) and its ring-substituted, (η5-C5H4Me)2VCl2 (2), (η5-C5Me5)2VCl2 (3), (η5-C5H4R)2VCl2 (4: R=MeOCH2CH2–, 5: R=2-MeOC6H4CH2–, 6: R=4-MeOC6H4CH2–) and ansa-bridged analogs Me2C(η5-C5H4)2VCl2 (7) and Me4C2(η5-C5H4)2VCl2 (8) was investigated. Synthesis of two new methoxy-functionalized compounds (4 and 5) is described. They were characterized by spectroscopic methods and X-ray diffraction analysis. The cytotoxicity studies were performed with leukemic cells MOLT-4. [Copyright &y& Elsevier]

The macropolyhedral [B19H22]-monoanion 1 and the dianion [B18H21]2- 2 are synthesized in consistent 86-92% yields by the reaction ot [PSH]+[syn-B18H21] with BH3(SMe2) in 1,2-CI2C2H4 at 72°C ['PS' is an abbreviation tor 'Proton Sponge', 1,8-bis-(dimethylamino)naphthalene. 'PSH' is its protonated derivative.] The molecular structures ot 1 and 2 were elucidated as their [PS(BH2)]+ and [PS(BH2)]2- salts 1a and 2a by single-crystal X-ray diffraction studies, in which all atoms were located, and supported by mass spectrometric analyses together with calculations of the cluster molecular geometries (ab ignitio and/or DFT) and of 1 B chemical shifts based on GIAO-DFT shielding tensors. Aciditication ot dianion 2 with CF3COOH in acetonitrile, H2SO4 in dichloromethane, or aqueous HCI results in the clean tormation ot the monoanion [B19H22]- 1. Conversely, shaking a concentrated acetonitrile solution ot 1 in 0.5 M aqueous NaOH cleanly yields the [B19H21]2- dianion 2. Reaction of a dichloromethane solution ot 1 with a 36% aqueous solution ot HCHO in the presence ot H2SO4 quantitatively converts 1 at room temperature to a 1:1 mixture ot the syn- and anti-isomers ot B18H22. This cluster dismantling process is the first example of a syn- to anti-B16H22 isomer conversion. [ABSTRACT FROM AUTHOR]

A series of novel diphosphinoazine rhodium amido carbonyl complexes [{R2PCHᆖC(But)–NNᆖC(But)CH2PR2}Rh(CO)] (R = Ph, Pri, c-C6H11, But) was prepared by deprotonation of cationic diphosphinoazine rhodium amino carbonyl complexes. The complexes were characterized by NMR as were also their precursors. The crystal structures of two cationic and one neutral deprotonated complex were determined by X-ray diffraction showing the complexes to be essentially planar with mutual trans arrangement of phosphine groups and nitrogens trans to carbonyl ligands. Measurement of valence vibration frequencies of carbonyl groups in the complexes allowed to estimate the electron density on the rhodium centre. The ene-hydrazone ligand backbone (nitrogen covalently bonded) is more electron donating than the azine backbone (nitrogen bonded by electron pair donation) as expected. In the neutral series of complexes electron donation increases with phosphine substitution in the order Ph < Pri = c-C6H11 < But with the corresponding decrease of carbonyl valence vibration frequency. The tert-butyl cationic complex undergoes in a low yield an unusual diphosphinoazine bond cleavage with simultaneous oxidation of the metal resulting in a binuclear bis(iminophosphine)dirhodium complex [{(But)2PCH2C(But)ᆖNH}Rh(Cl)2(μ-Cl)]2 the structure of which was also determined by X-ray diffraction. [Copyright &y& Elsevier]

Abstract: The synthesis of a new, paramagnetic closo-[(8-(-CH2CH2O)2-1,2-C2B9H10)(1′,2′-C2B9H11)-3,3′-Fe]0 (3) is reported. This compound can serve as a versatile building block for construction of both anionic and zwitterionic derivatives, as exemplified by the synthesis of a series of compounds of general formula closo-[(8-X-(CH2CH2O)2-1,2-C2B9H10)(1′,2′-C2B9H11)-3,3′-Fe], bearing organic end groups (X=NC5H5 (4), (C6H5)3P (5), OH (6), and 2-O(1-CH3O–C6H4) (7)) attached to the cluster by a diethyleneglycol spacer. Molecular structures of 3, 4, 5 and 7 were determined by single-crystal X-ray diffraction analysis and by the long-time neglected method of paramagnetic, high field NMR (1H, 13C and 11B) spectroscopy. [Copyright &y& Elsevier]

Abstract: Using solid benzohydroxamic acid (BHA) as a model compound for its salts, a broad absorption at 2730cm−1 was generally agreed to represent the ν(OH) band of the bonds. The absence of ν(OH) band in the IR region 3600–1700cm−1 was taken to indicate the absence of OH groups in the solid salts. The same argument and conclusion was erroneously accepted for lithium (LiBHA) and potassium (KBHA) salts of BHA which are not “normal” but acid salts and do contain OH groups. X-ray diffraction results allow explanation of this discrepancy. The lithium and potassium acid salts have much shorter bridges ( distances of 247 and 245pm, respectively) than the model compound (258pm). Accordingly, the ν() bands in the acidic salts are shifted into the crowded 1600–700cm−1 interval. Obviously, interpretation of a missing spectral band in terms of molecular structure can be misleading when the models do not include all possible structural variations. [Copyright &y& Elsevier]