Organoselenium(II) and selenium(IV) compounds containing 2-(Me2NCH2)C6H4 moieties: solution behavior and solid state structure

The cleavage of the Se-Se bond in [2-(Me₂NCH₂)C₆H₄]₂Se₂ (1) was achieved by treatment with SO₂Cl₂ (1:1 molar ratio) or elemental halogens to yield [2-(Me₂NCH₂)C₆H₄]SeX [X = Cl (2), Br (3), I (4)]. Oxidation of 1 with SO₂Cl₂ (1:3 molar ratio) gave [2-(Me₂NCH₂)C₆H₄]SeCl₃ (5). [2-(Me₂NCH₂)C₆H₄]SeS(S)CNR₂ [R = Me (6), Et (7)] were prepared by reacting [2-(Me₂NCH₂)C₆H₄]SeBr with Na[S₂CNR₂] · nH₂O (R = Me, n = 2; R = Et, n = 3). The reaction of 3 with K[(SPMe₂)(SPPh₂)N] resulted in isolation of [2-(Me₂NCH₂)C₆H₄]Se-S-PMe₂N-PPh₂S (8). The compounds were characterized by solution NMR spectroscopy (¹H, ¹³C, ³¹P, ⁷⁷Se, 2D experiments). The solid-state molecular structures of 2, 4-8 were established by single crystal X-ray diffraction. All compounds are monomeric, with the N atom of the pendant CH₂NMe₂ arm involved in a three-center-four-electron N?Se-X (X = halogen, S) bond. This results in a T-shaped coordination geometry for the Se(II) atom in 2, 4, 6-8. In 5, the Se(IV) atom achieves a square pyramidal coordination in the mononuclear unit. Loosely connected dimers are formed through intermolecular Se?Cl interactions (3.40 Å); the overall coordination geometry being distorted octahedral. In all compounds hydrogen bonds involving halide or sulfur atoms generate supramolecular associations in crystals.     

Solid state structure and solution behaviour of organoselenium(II) compounds containing 2-{E(CH2CH2)2NCH2}C6H4 groups (E = O, NMe)

Cleavage of the Se-Se bond in [2-{O(CH(2)CH(2))(2)NCH(2)}C(6)H(4)](2)Se(2) (1) and [2-{MeN(CH(2)CH(2))(2)NCH(2)}C(6)H(4)](2)Se(2) (2) by treatment with SO(2)Cl(2), bromine or iodine (1 : 1 molar ratio) yielded [2-{O(CH(2)CH(2))(2)NCH(2)}C(6)H(4)]SeX [X = Cl (3), Br (4), I (5)] and [2-{MeN(CH(2)CH(2))(2)NCH(2)}C(6)H(4)]SeI (6). The compounds were characterized in solution by NMR spectroscopy (1H, 13C, 15N, 77Se, 2D experiments). The solid-state molecular structures of 1-3, 4.HBr, 5 and 6 were established by single crystal X-ray diffraction. In all cases T-shaped coordination geometries, i.e. (C,N)SeSe (1, 2), (C,N)SeX (3, 5, 6; X = halogen) or CSeBr(2) (4.HBr), were found. Supramolecular associations in crystals based on hydrogen contacts are discussed.     

Hypervalent organobismuth(iii) carbonate, chalcogenides and halides with the pendant arm ligands 2-(Me2NCH2)C6H4 and 2,6-(Me2NCH2)2C6H3

R2BiOH (1) [R = 2-(Me2NCH2)C6H4] and (R2Bi)2O (2) are formed by hydrolysis of R2BiCl with KOH. Single crystals of were obtained by air oxidation of (R2Bi)2. The reaction of R2BiCl and Na2CO3 leads to (R2Bi)2CO3 (3). 3 is also formed by the absorption of CO2 from the air in solutions of 1 or 2 in diethyl ether or toluene. (R2Bi)2S (4) is obtained from R2BiCl and Na2S or from (R2Bi)2 and S8. Exchange reactions between R2BiCl and KBr or NaI give R2BiX [X = Br (5), I (6)]. The reaction of RBiCl2 (7) with Na2S and [W(CO)5(THF)] gives cyclo-(RBiS)2[W(CO)5]2 (8). cyclo-(R'BiS)2 (9) [R' = 2,6-(Me2NCH2)2C6H3] is formed by reaction of R'BiCl2 and Na2S. The structures of were determined by single-crystal X-ray diffraction.     

Solid state and solution study of some phosphoramidate derivatives containing the P(O)NHC(O) bifunctional group: Crystal structures of CCl2HC(O)NHP(O)(NCH3(CH2C6H5))2, p-ClC6H4C(O)NHP(O)(NCH3(CH2C6H5))2, CCl2HC(O)NHP(O)(N(CH2C6H5)2)2 and p-BrC6H4C(O)NHP(O)(N(CH2C6H5)2)2

Synthetic methods for several novel phosphoramidate compounds containing the P(O)NHC(O) bifunctional group were developed. These compounds with the general formula R₁C(O)NHP(O)(N(R₂)(CH₂C₆H₅))₂, where R₁ = CCl₂H, p-ClC₆H₄, p-BrC₆H₄, o-FC₆H₄ and R₂ = hydrogen, methyl, benzyl, were characterized by several spectroscopic methods and analytical techniques. The effects of phosphorus substituents on the rotation rate around the P–N_amine bond were also investigated. ¹H NMR study of the synthesized compounds demonstrated that the presence of bulky groups attached to the phosphorus center and electron withdrawing groups in the amide moiety lead to large chemical-shift non-equivalence (Δδ_H) of diastereotopic methylene protons. The crystal structures of CCl₂HC(O)NHP(O)(NCH₃(CH₂C₆H₅))₂, p-ClC₆H₄C(O)NHP(O)(NCH₃(CH₂C₆H₅))₂, CCl₂HC(O)NHP(O)(N(CH₂C₆H₅)₂)₂ and p-BrC₆H₄C(O)NHP(O)(N(CH₂C₆H₅)₂)₂ were determined by X-ray crystallography using single crystals. The coordination around the phosphorus center in these compounds is best described as distorted tetrahedral and the P(O) and C(O) groups are anti with respect to each other. In the compound Br-C₆H₄C(O)NHP(O)(N(CH₂C₆H₅)₂)₂ (with two independent molecules in the unit cell), two conformers are connected to each other via two different N–H?O hydrogen bonds forming a non-centrosymmetric dimer. In the crystalline lattice of other compounds, the molecules form centrosymmetric dimers via pairs of same N–H?O hydrogen bonds. The structure of CCl₂HC(O)NHP(O)(N(CH₂C₆H₅)₂)₂ reveals an unusual intramolecular interaction between the oxygen of CO group and amine nitrogen.     

The structural aspects of organoborane and organoborate compounds containing the (C6H4-2-CH2NMe2) ligand

The new organoborates (ArBMe₃)Li·OEt₂ (I), (ArBEt₃)Li·OEt₂ (II) and [ArPh(BBN)Li·OEt₂ (III) (Ar = C₆H₄-2-(CH₂NMe₂), BBN = 9-borabicyclo[3.3.1]nonyl) were synthesized. The structures of I, II and III and their temperature-dependent dynamic properties were established by means of ¹H, ¹³C and ¹¹B NMR spectroscopy. It was revealed that I, II and III exist in solution as undissociated molecules with the boron and lithium atoms bonded through alkyl and/or aryl bridges.     

Isomers of a dibismuthane, R2Bi-BiR2 [R = 2,6-(Me2NCH2)2C6H3], and unusual reactions with oxygen: formation of [R2Bi]2(O2) and R'R' 'Bi [R' = 2-(Me2NCH2)-6-{Me2N(O)CH2}C6H3; R' ' = 2-(Me2NCH2)-6-{O(O)C}C6H3

R2Bi-BiR2 [1; R = 2,6-(Me2NCH2)2C6H3], a dibismuthane that exists in different forms in the crystalline state, reacts in air with the formation of the peroxide [R(2)Bi]2(O2) (2) and partial oxidation of the pendant (dimethylamino)methyl groups, yielding the mononuclear bismuth complex R'R' 'Bi (3) [R' = 2-(Me2NCH2)-6-{Me2N(O)CH2}C6H3; R' ' = 2-(Me2NCH2)-6-{O(O)C}C6H3].     

Group IB organometallic chemistry : XXXVII. Complex forming reactions of polynuclear arylcopper compounds: CalkP bond cleavage in 1,2-bis(diphenylphosphino)ethane (diphos) by (2-Me2NCH2C6H4)4Cu4 and crystal structure of [(C6H5)2PCu · diphos]2 · 2 C6H6

Molecular weight measurements and microwave titrations indicate that no interaction occurs between tetrameric 2-Me₂NCH₂C₆H₄Cu (Ar₄Cu₄) and the monodentate ligands PPh₃, CH₃CN or pyridine. However, the tetrameric structure Ar₄Cu₄ breaks down upon interaction (1/1 molar ratio ArCu/L) with the bidentate ligands (L) Diphos or cis-DPPEE to give the monomeric 1/1 complexes ArCu · L.Addition of Diphos to ArCu · Diphos or conducting the reaction of Ar₄Cu₄ with Diphos in a 1/2 ratio (ArCu/Diphos) gives rise to a C_alkP bond cleavage reaction resulting in the formation of dimeric (Ph₂PCu · Diphos)₂ · 2 C₆H₆, ArH and Ph₂PCHCH₂.The molecular structure of (Ph₂PCu · Diphos)₂ · 2 C₆H₆, has been determined by a single-crystal X-ray diffraction study. Crystals are monoclinic, space group P2₁/c and have Z  2 in a unit cell of dimensions a  12.997(6), b  12.669(7), c  22.839(9) Å and β  94.48(4)°. The structure was refined to R  0.048 for 3048 independent reflections. The four copper atoms in the dimer are held together by two Ph₂P bridges. The bonding in the dimer is discussed.     

Raman,infrared and force field studies of K2(12)C2O4 x H2O and K2(13)C2O4 x H2O in the solid state and in aqueous solution,and of (NH4)2(12)C2O4 x H2O and (NH4)2(13)C2O4 x H2O in the solid state

The Raman and infrared spectra of solid K2(12)C2O4 x H2O are reported together with, for the first time, the corresponding Raman and infrared spectra of solid K2(13)C2O4 x H2O. Raman spectra of aqueous solutions of both isotopomers are also reported. In the solid state the oxalate anion is planar with D2h symmetry in this salt, whereas in aqueous solution the Raman spectra of the anion are best interpreted on the basis of D2d symmetry. The Raman spectra of solid (NH4)2(12)C2O4 x H2O and (NH4)2(13)C2O4 x H2O, in which the oxalate anion is twisted from planarity by 28 degrees about the CC bond, have also been recorded. Several reassignments have been made. The harmonic force field for the oxalate anion in the D2h, D2 and D2d geometries has been determined in part, and approximate values of key valence force constants determined. All the observed band wavenumbers and 12C/13C isotopic shifts are well reproduced by the force fields. The potential energy distribution of the totally symmetric normal modes of planar oxalate indicates that each mode consists of extensively mixed symmetry corrdinates and that the labels previously used for the bands seen here at 475 and 879 cm(-1) would better be described as v(CC) and deltaS(CO2), respectively, putting them in the same wavenumber order as v(NN) and deltaS(NO2) for the isoelectronic and isostructural molecule N2O4. The stretching force constants of N2O4 and planar C2O4(2-) are established to be in the order f(NN) < f(CC) and f(NO) > f(CO), consistent with the known relative bond lengths.     

Structural diversity of lithium sulfenamides: 7Li NMR studies in solution and crystal structures of [Li2(eta2-(CH3)3C-NS-C6H4CH(3)-4)2(THF)2] and [Li2(eta1-4-CH3C6H4-NS-C6H4CH(3)-4)2(THF)4

Two lithium sulfenamides were prepared by reaction of (CH(3))(3)C-N(H)-S-C(6)H(4)CH(3)-4 (1) and 4-CH(3)C(6)H(4)-N(H)-S-C(6)H(4)CH(3)-4 (2) with an alkyllithium. The unsolvated sulfenamide Li[(CH(3))(3)C-NS-C(6)H(4)CH(3)-4] (3) was soluble enough for variable-temperature (VT) (7)Li NMR to provide evidence of a dynamic exchange of oligomers in solution. The crystal structures of the solvated sulfenamides of [Li(2)(eta(2)-(CH(3))(3)C-NS-C(6)H(4)CH(3)-4)(2)(THF)(2)] (4) and of [Li(2)(eta(1)-4-CH(3)C(6)H(4)-NS-C(6)H(4)CH(3)-4)(2)(THF)(4)] (6) consisted of dimers in which the anions display different hapticities. The VT (7)Li NMR spectra of 4 suggest that the two different structures exist in equilibrium in toluene-THF mixtures. These compounds are easily oxidized to the neutral thioaminyl radicals as identified by EPR spectroscopy.     

An experimental and theoretical investigation on hypervalent organoselenium(II) halides: Case study of [2-(Et2NCH2)C6H4]SeX (X = Cl,Br, I)

Cleavage of the Se–Se bond in [2-(Et₂NCH₂)C₆H₄]₂Se₂ (1) with SO₂Cl₂ (1:1 molar ratio) yielded the organoselenium(II) chloride [2-(Et₂NCH₂)C₆H₄]SeCl (2). Treatment of 2 with excess of KX yielded the organoselenium(II) halides [2-(Et₂NCH₂)C₆H₄]SeX [X = Br (3), I (4)]. The new compounds 2–4 were characterized by solution NMR spectroscopy (¹H, ¹³C, ⁷⁷Se, 2D experiments). The solid-state molecular structures of 2, 2·HCl and 3 were established by single crystal X-ray diffraction. Distorted T-shaped coordination geometries of type (C,N)SeX (X = Cl, Br) and CSeCl₂ were found for the neutral halides 2 and 3, and the zwitterionic species [2-{Et₂N⁺(H)CH₂}C₆H₄]SeCl₂￣ (2·HCl), respectively. DFT calculations were performed on 2–4 and the related tellurium compounds [2-(Et₂NCH₂)C₆H₄]TeX [X = Cl (5), Br (6) and I (7)] in order to elucidate the bond nature and FT-Raman features of this class of organochalcogen(II) derivatives.     

Diorganotin(IV) complexes with 2-benzoylpyridine and 2-acetylpyrazine N(4)-phenylthiosemicarbazones: Synthesis, crystal structures and biological activities

Four diorganotin(IV) complexes [(Me)₂Sn(L¹)(CH₃COO)]·CH₃CH₂OH (1), [(Ph)₂Sn(L¹)(CH₃COO)]·CH₃CH₂OH (2), [(Me)₂Sn(L²)Cl] (3) and [(Ph)₂Sn(L²)(CH₃COO)] (4) where HL¹ = 2-benzoylpyridine N(4)-phenylthiosemicarbazone and HL² = 2-acetylpyrazine N(4)-phenylthiosemicarbazone have been synthesized and characterized by elemental analysis, IR MS, ¹H NMR and single-crystal X-ray diffraction studies. Schiff bases in their deprotonated forms coordinate to tin(IV) via pyridine/pyrazine nitrogen atom and the nitrogen atom and sulfur atoms of the thiosemicarbazone moiety. The tin atom is seven-coordinated in 1, 2 and 4 containing one acetato group, respectively, and six-coordinated in 3 containing one chloride ion. Biological studies, carried out in vitro against selected bacteria and K562 leukaemia cells, respectively, have shown that different substituted groups attached at the thiosemicarbazone moieties and different diorganotin(IV) groups showed distinctive differences in the biological property.     

Group IB organometallic chemistry: XXXV. Crystal and molecular structure of [Cu4(4-MeC6H4)-MeC-C(C6H4NMe2-2)2(C6H4NMe2-2)2], a tetranuclear organocopper compound containing bridging alkenyl and aryl groups

The crystal and molecular structure of the title compound has been determined by a single crystal X-ray diffraction study using standard Patterson and Fourier methods. The structure was refined by a block-diagonal least-square procedure to a finalR value of 0.16 for 3454 reflections. Crystals are monoclinic, space groupP2₁/c, witha 14.007(5), b 12.224(5), c 28.358(8)A?, β 99.60(1)°, andZ - 4.The molecule consists of a central rhombus-type core of copper atoms to which the alkenyl and aryl groups are bound in a bridging fashion (two electron-three center bonding). The two alkenyl and the two aryl groups each occupy adjoining edges of the Cu₄ core. The dimethylamino groups of the alkenyl ligand coordinate to copper, whereas those of the bridging aryl ligand are free. As a result the copper core is made up of copper atoms which are alternatingly two- and three-coordinate.The structure is discussed in terms of structural information now available for organocopper compounds. The geometry of the Cu₂C (bridge) moiety in organocopper cluster compounds as expected varies little with the nature of the bridging one-electron organo ligand (alkyl, alkenyl, alkynyl or aryl).     

The protonation of Co(C5Me4Et)(C2H4)2

Reversible protonation of the bis-ethylene complex, Co(C₅Me₄Et)(C₂H₄)₂ yields [Co(C₅Me₄Et)(C₂H₄)₂H][BF₄], which readily exchanges its hydridic and olefinic protons stereospecifically at low temperatures; subsequent protonation at room temperature yields cobalt(III) complexes, C₂H₄ and C₂H₆.     

Non-oxo vanadium(IV) alkoxide chemistry: solid state structures, aggregation equilibria and thermochromic behaviour in solution

The reversible thermochromic behaviour of homoleptic [{V(OR)(4)}(n)] complexes in solution [R = Pr(i) (product I), Bu(s) (B(s)), Nep (N) and Cy (C)] is accounted for the existence of an aggregation equilibrium involving dimeric and monomeric species in which vanadium(iv) is respectively five- and four-coordinate. Bulky R groups such as Bu(t) and Pe(t) (tert-pentoxide) prevent aggregation and therefore give rise to exclusively mononuclear compounds (B(t) and P(t), respectively) that are not thermochromic. The complexes and their temperature-dependent interconversion were characterised by single crystal X-ray diffractometry, magnetic susceptibility measurements and electronic, FTIR and EPR spectroscopies in a wide temperature range. Equilibrium constants and enthalpy and entropy changes for the dimerization reactions have been determined and compared with literature data.     

Crystal and Molecular Structure of [2,6‐(Me2NCH2)2C6H3]2SnF2, an Intramolecularly Coordinated Diorganotin Difluoride

Single‐crystal X‐ray diffraction analysis of [2,6‐(Me₂NCH₂)₂C₆H₃]₂SnF₂ reveals that only one of the two dimethylaminomethyl groups of each pincer‐type ligands [2,6‐(CH₂NMe₂)₂C₆H₃]^? is coordinated to the tin atom at Sn‐N distances of 2.576(2) and 2.470(2) Å, inducing chirality of the latter. The tin atom exhibits a distorted octahedral trans(C,C)cis(N,N)cis(F,F) configuration. Extensive intra‐ and intermolecular C‐H···F hydrogen bonding is observed with the latter giving rise to formation of polymeric chains.     

Hydrothermal Synthesis and Crystal Structure of a New Phosphonate： {[Cu（1,10-phen）]2-（H2O3PCH2C6H4C6H4CH2PO3H）2-（HO3PCH2C6H4C6H4CH2PO3H） }n

1 INTRODUCTION Metal organophosphonates have attracted considerable attention for over three decades due to their potential or practical applications, include- ing ion exchanges[1, 2], molecular sensors[3] and optics[4, 5]. Recently, a number of porous m…