Ate complexes of Ge(II) and Sn(II) with bidentate ligands [LiE(OCH2CH2NMe2)3]2 (E=Ge, Sn): synthesis and structure

The reaction of equimolar quantities of LiOCH₂CH₂NMe₂ and E¹⁴(OCH₂CH₂NMe₂)₂ (E¹⁴=Ge, Sn) in ether yielded new ate complexes [LiE¹⁴(OCH₂CH₂NMe₂)₃]₂ (E¹⁴=Ge (1), Sn (2)) with bidentate ligands. The compounds 1 and 2 are white crystalline substances which are highly soluble in THF and pyridine and very sensitive to the traces of oxygen and moisture. The structures of these compounds are studied by X-ray diffraction analysis. The ate complexes 1 and 2 are powerful nucleophiles and may be employed as ligands (neutral) in the coordination chemistry of the transition metals. The electronegative O-substituents at the divalent E¹⁴ atoms render them less oxidizable than alkyl- or aryl-substituted derivatives, and the bidentate ligands, owing to intramolecular donor-acceptor interactions, make them more thermodynamically stable compared to monodentate ligands.     

Heteroleptic tin (II) dialkoxides stabilized by intramolecular coordination Sn(OCH2CH2NMe2)(OR) (R = Me, Et, Pr, Bu, Ph). Synthesis, structure and catalytic activity in polyurethane synthesis

A straightforward method of synthesis of heteroleptic tin (II) alkoxides stabilized by one intramolecular coordination bond was developed. Addition of one equivalent of dimethylamino ethanol to diamide Sn(N(SiMe₃)₂)₂ (5) yields alkoxy-amido derivative Sn(OCH₂CH₂NMe₂)(N(SiMe₃)₂) (2). Further addition of alcohol leads to corresponding heteroleptic dialkoxides Sn(OCH₂CH₂NMe₂)(OR) (R = Me (6), Et (7), ⁱPr (8), ^tBu (9), Ph (10)). Catalytic activity of tin (II) compounds in polyurethane formation was tested.     

Reverse Kocheshkov reaction - Redistribution reactions between RSn(OCH2CH2NMe2)2Cl (R = Alk, Ar) and PhSnCl3: Experimental and DFT study

A series of organotin compounds bearing two intramolecular N → Sn coordination bonds RSn(OCH₂CH₂NMe₂)₂Cl (R = Me (4), n-Bu (5), Mes (6)) were synthesized in good yields. These compounds as well as 2 (R = Ph) react with PhSnCl₃ to give redistribution products RPhSnCl₂ and (Me₂NCH₂CH₂O)₂SnCl₂ (3). The direction of redistribution reactions is reverse to Kocheshkov reaction. DFT calculations have shown that the driving force of the reactions is formation of intramolecular N → Sn coordination bonds in (RO)₂SnCl₂ (3), the Lewis acid stronger than RSn(OR)₂Cl (2, 4-6). The mechanism of the redistribution reaction between 2 and PhSnCl₃ consists of two steps: (1) initial exchange of OCH₂CH₂NMe₂ and Cl to give PhSn(OCH₂CH₂NMe₂)Cl₂ (7) followed by (2). Ph and OCH₂CH₂NMe₂ exchange.     

New water-soluble (hydroxymethyl)triphosphine [(HOCH2)2PCH2CH2]2PCH2OH, a derived PdII(triphosphine) complex, and triphosphine trioxide

An aqueous solution of (hydroxymethyl)triphosphine [(HOCH₂)₂P(CH₂)₂]₂PCH₂OH (II) was synthesized in situ by treatment of the triphosphine H₂P(CH₂)₂PH(CH₂)₂PH₂ with formaldehyde. Addition of a CH₂Cl₂ solution of trans-PdCl₂(PhCN)₂ to an in situ aqueous solution of II resulted in the formation of a species thought to be [PdCl{[(HOCH₂)₂P(CH₂)₂]₂PCH₂OH}]⁺Cl⁻. Attempts to isolate the complex were unsuccessful because of conversion to material containing small amounts of phosphine oxide(s) formed via a redox reaction involving water. The triphosphine trioxide [(HOCH₂)₂P(O)(CH₂)₂]₂P(O)CH₂OH was readily isolated from an in situ solution of II by treatment with aqueous H₂O₂.     

The S1 ← S0 vibronic spectra and structure of the (CH3)2 CHCHO and (CH3)2 CHCDO 2-methylpropanal molecules

A multipass cell with an optical path up to 120 m long was used to measure the vibronic absorption spectra of 2-methylpropanal-h₁ (MPA-h₁, (CH₃)₂CHCHO)) and 2-methylpropanal-d₁ (MPA-d₁, (CH₃)₂CHCDO)) over the frequency range 28200–31600 cm⁻¹. The most intense spectral lines were assigned to transitions from vibrational levels of the cis and gauche MPA-h₁ and MPA-d₁ conformers in the ground electronic state (S ₀) to vibrational levels of conformers 1 and 3 in the lowest singlet excited electronic state (S ₁). According to our estimates, the origins (0 ₀ ⁰ ) of the 1 S ₁) ← cis(S ₀) and 3(S ₁) ← cis(S ₀) and also 1(S ₁) ← gauche(S ₀) and 3(S ₁) ← gauche(S ₀) electronic transitions were situated at 29147 and 29177, 29391 and 29417 cm⁻¹, respectively, for MPA-h₁ and at 29226 and 29240, 29480 and 29500 cm⁻¹ for MPA-d₁. The structure of conformers 1 and 3 in the S ₁ state was shown to differ from the structure of the cis and gauche conformers in the S ₀ state by the angle of rotation of the (CH₃)₂CH-isopropyl top and “pyramidal distortion” of the CCHO/CCDO carbonyl fragment. A series of fundamental frequencies of MPA conformers in different electronic states were found. The potential functions of inversion were determined for the conformer 1-conformer 3 pairs of MPA-h₁ and MPA-d₁ from the experimental energy levels of inversion vibrations. The potential barriers to inversion and equilibrium displacements of the CH/CD bond out of the CCO plane were found to be 735/675 cm⁻¹ and ±34°/±32° for MPA-h₁ and MPA-d₁, respectively. Original Russian Text ? I.A. Godunov, S.L. Lur’e, N.N. Yakovlev, V.A. Bataev, 2007, published in Zhurnal Fizicheskoi Khimii, 2007, Vol. 81, No. 1, pp. 52–62.     

One-step synthesis of pentavalent triphenylantimony derivatives Ph3Sb(OSiR3)2, Ph3Sb(OCH2CH2)2NH and Ph3Sb(OCH2CH2NMe2)2: X-ray molecular structure of Ph3Sb(OSiMe3)2

Pentavalent bis(triorganosiloxy)triphenylantimony derivatives, Ph₃Sb(OSiR₃)₂ (R = Me, Ph), were synthesized by reaction of triphenylantimony with trimethyl- or triphenylsilanol in the presence of tert-butylhydroperoxide by the mild reaction conditions (0-5 °C, 2 h). The reaction of triphenylantimony with diethanolamine in the presence of tert-butylhydroperoxide gave the cyclic compound Ph₃Sb(OCH₂CH₂)₂NH. The mixture of Ph₃SbO and Ph₃Sb(OCH₂CH₂NMe₂)₂ was obtained by the reaction of triphenylantimony with 2-(N,N-dimethylamino)ethanol in the presence of tert-butylhydroperoxide.     

New stable germylenes, stannylenes, and related compounds. 5. Germanium(II) and tin(II) azides [N3-E-OCH2CH2NMe2]2 (E = Ge, Sn): synthesis and structure

New stable azido derivatives of divalent germanium and tin [N₃-E¹⁴-OCH₂CH₂NMe₂]₂ (E¹⁴ = Ge (1), Sn (2)) have been synthesized by use of the β-dimethylaminoethoxy ligand that forms the intramolecular E¹⁴ ← N coordination bond. Their crystal structures have been determined by X-ray diffraction analysis. Compounds 1 and 2 are centrosymmetric dimers via two intermolecular dative E¹⁴ ← O interactions with essentially linear monodentate azide ligands. The dominant canonical form of the E¹⁴-azide moieties is E¹⁴-N-NN.     

Synthesis and characterization of the [Cu(Cin2bda)2]ClO4 and [Cu(Ncin2bda)2]ClO4 complexes: Crystal structure of [Cu(Ncin2bda)2]ClO4

Two copper(I) complexes [Cu(Cin₂bda)₂]ClO₄ (I) and [Cu(Ncin₂bda)₂]ClO₄ (II) have been prepared by the reaction of the ligands N²,N²′-bis(3-phenylallylidene)biphenyl-2,2′-diamine (L¹) and N²,N²′-bis[3-(2-nitrophenyl)allylidene]biphenyl-2,2′-diamine (L²) and copper(I) salt. These compounds were characterized by CHN analyses, ¹H NMR, IR, and UV-Vis spectroscopy. The C=N stretching frequency in the copper(I) complexes shows a shift to a lower frequency relative to the free ligand due to the coordination of the nitrogen atoms. The crystal and molecular structure of II was determined by X-ray single-crystal crystallography. The coordination polyhedron about the copper(I) center in the complex is best described as a distorted tetrahedron. A quasireversible redox behavior was observed for complexes I and II. The article is published in the original.     

Soluble Ni alkoxides based on dimethylaminoisopropoxide ligands: molecular structure of [Li(PrOH)Ni (η-OR)2Cl]2 and of cis-NiCl2(ROH)2 (R = CHMeCH2NMe2)

Various routes to Ni^II aminoalkoxides have been investigated. A nickel isopropoxide derivative 1 was prepared by anodic dissolution of the metal in the presence of LiCl as electrolyte. Alcoholysis reactions of 1 with 1-dimethylamino-2-propanol afforded the homoleptic nickel(II) aminoalkoxide 2 together with a NiLi species 3. 2 was also obtained by metathesis reactions between sodium alkoxide and the nickel hexammine complex whereas the reaction between the latter and the aminoalcohol led to an halide solvate, cis-NiCl₂(η²-ROH)₂, 4. The various compounds were characterized by elemental analysis, FT-IR and UV-vis spectroscopies as well as by X-ray diffraction for 3 and 4. 3 corresponds to [Li(PrⁱOH)Ni(η²-OCHMeCH₂NMe₂)Cl]₂ and the overall structure can be seen as two [Ni(η²-OCHMeCH₂NMe₂)₂Cl]⁻ moieties assembled by Li(PrⁱOH)⁺. The lithium atom is 4-coordinate due to its interaction with the oxygen atoms of the aminoalkoxide ligands. Nickel is 5-coordinate with a distorted tetragonal pyramidal stereochemistry, one nitrogen being in the apical position. The metal displays a distorted octahedral surrounding for the NiCl₂ adduct 4. The bond distances vary in the order NiOR < NiN ≈ NiO(H)R < NiCl for 3 and 4. The various compounds (except 1) are soluble in organic media.     

Darstellung und charakterisierung von verbindungen des typs (CH3)3ME(CF3)2 (M = Si,Ge, Sn; E = P,As)

Various preparative routes for the synthesis of (CH₃)₃SiP(CF₃)₂ are discussed. The most favourable method, reaction of (CH₃)₃MPH₂ with HE(CF₃)₂, provides a good yield of (CH₃)₃ME(CF₃)₂ compounds (M = Si, Ge, Sn; E = P, As). The reaction rate is dependent on M (Si < Ge <Sn) und E (P < As). The stability and reactivity of the (CH₃)₃ME(CF₃)₂ compounds are discussed. The new compounds were characterized by NMR and IR spectra and by cleavage reactions of the M-E bond. ¹H, ¹⁹F NMR and IR spectral data are reported.     

Crystal and molecular structure of (NH4)2[UO2(NO3)4] and [(NH4)(18C6)]2[UO2(NO3)4]

Single crystals of diammonium tetranitratouranylate (NH₄)₂[UO₂(NO₃)₄] (I) and a new diammonium tetranitratouranylate complex with 18-crown-6 [(NH₄)(18C6)]₂[UO₂(NO₃)₄] (II) have been synthesized by the reaction of diaquadinitratouranyl tetrahydrate with ammonium nitrate in a nitric acid solution and the reaction of the same reagents with 18C6 in an ethanol solution, respectively. The X-ray diffraction analysis of compounds I and II has been performed. Crystals of compounds I and II are monoclinic, Z = 2, space group P2₁/n, a = 6.4075(5) ?, b = 7.7851(7) ?, c = 12.4461(12) ?, β = 101.239(1)°, V = 608. 94(9) ?³ for compound I and a = 10.542(9) ?, b = 8.590(8) ?, c = 22.5019(19) ?, β = 101.632(1)°, V = 2058.3(3) ?³ for compound II. The [UO₂(NO₃)₄]²⁻ complex anion in compounds I and II contains two monodentate and two bidentate cyclic nitrato groups, and the coordination number of uranyl is 6. The 18C6 molecule in the structure of compound II has the classic crown conformation and combined with the ammonium ion by three hydrogen bonds. Compounds I and II formed by electrostatic attraction forces between counterions are stabilized by (NH₄⁺)NH...O(NO₃⁻) interionic hydrogen bonds.     

Synthesis and X-ray diffraction study of R[UO2(CH3COO)3] (R = H3O+ or NH(C2H5) 3+ )

Single crystals of (H₃O)[UO₂(CH₃COO)₃] (I) and (NH(C₂H₅)₃)[UO₂(CH₃COO)₃] (II) are synthesized, and their structures are studied by X-ray crystallography. Compound I crystallizes in the tetragonal crystal system with the unit cell parameters a = 13.70640(10) ?, c = 27.5258(5) ?, V = 5171.14(11) ?³, space group I4₁/a, Z = 16, R = 0.0238. The crystals of compound II are orthorhombic with the parameters a = 13.3685(3) ?, b = 10.6990(3) ?, c = 12.2616(3) ?, V = 1753.77(8) ?³, space group Pna2₁, Z = 4, R = 0.0228. The uranium-containing structural units of crystals I and II are [UO₂(CH₃COO)₃]⁻ island mononuclear groups belonging to the A B₃⁰¹(A = UO₂²⁺, B⁰¹ = CH₃COO⁻) crystal-chemical group of uranyl complexes. [UO₂(CH₃COO)₃]⁻ complexes are linked into a three-dimensional framework by electrostatic interactions with the outer-sphere cations and by hydrogen bonds involving the hydrogen atoms of hydroxonium (I) or triethylammonium (II) with the oxygen atoms of the acetato groups.     

1,2-Eliminations from (CH3)2NH+CH2CH3 and (CH3)2NH 2+ : Guided dissociations

1,2-Eliminations are a varied and extensive set of dissociations of ions in the gas phase. To understand better such dissociations, elimination of CH₂=CH₂ and CH₃CH₃ from (CH₃)₂NH⁺CH₂CH₃ (1) and of CH₄ from (CH₃)₂NH₂⁺ are characterized by quantum chemical calculations. Stretching of the CN bond to ethyl is followed by shift of an H from methyl to the bridging position in ethyl and then to N to reach (CH₃)₂NH₂⁺ + CH₂=CH₂ from 1. CH₃CH₃ elimination by H-transfer to C₂H₅⁺ to form CH₃NH⁺=CH₂ + CH₃CH₃ also takes place. (CH₃)₂NH₂⁺ eliminates methane by CN bond extension followed by β-H-transfer to give CH₂=NH⁺ + CH₄. Low-energy reactions resembling complex-mediated 1,2-eliminations occur and constitute a hitherto largely unrecognized type of reaction. As in many complex-mediated reactions, these reactions transfer H between incipient fragments. They are distinguished from complex-mediated processes by the fragments not being able to rotate freely relative to each other near the transition state for reaction, as they do in complexes. Most 1,2-eliminations are ion-neutral complex-mediated, occur by the just described lower energy reactions, have 1,1-like transition states, or utilize highly asynchronous 1,2 transition states. All of these avoid synchronized 1,2-transition states that would violate conservation of orbital symmetry.     

New stable germylenes, stannylenes, and related compounds: 6. Heteroleptic germanium(II) and tin(II) compounds [(SiMe3)2N-E-OCH2CH2NMe2]n (E = Ge, n = 1; Sn, n = 2): synthesis and structure

New stable heteroleptic germanium(II) and tin(II) compounds [(SiMe₃)₂N-E¹⁴-OCH₂CH₂NMe₂]_n (E¹⁴ = Ge, n = 1 (1), Sn, n = 2 (2)) have been synthesized and their crystal structures have been determined by X-ray diffraction analysis. While compound 1 is monomer stabilized by intramolecular Ge ← N coordination, compound 2 is associated to dimer via intermolecular dative Sn ← O interactions.     

New organogermanium cations [RGe(OCH2CH2NME2)2]+ with intramolecular N→Ge coordination bonds

New organohalogermanes RGe(OCH₂CH₂NMe₂)₂X (R = Ph, X = I (5); R = Me, X = Cl (6) or I (7)) with an intramolecular N→Ge coordination bond were synthesized. According to the ¹H and ¹³C NMR spectroscopic data, iodides 5 and 7 exist in solution as ionic compounds with the pentacoordinated germanium atom. In solution of compound 4 (R = Ph, X = Cl), there is an equilibrium between the ionic and covalent forms. The equilibrium shifts toward the ionic form with increasing solvent polarity or temperature. In solution, chloride 6 is a covalent compound. The structures and relative stabilities of different isomers of compounds 4–7 were studied by quantum chemical calculations at the density functional level of theory. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 892–900, May, 2007.     

Synthesis and reaction chemistry of 4-nitrile-substituted NCN-pincer palladium(II) and platinum(II) complexes (NCN = [NC-4-C6H2(CH2NMe2)2-2,6])

Nitrile-functionalized NCN-pincer complexes of type [MBr(NC-4-C₆H₂(CH₂NMe₂)₂-2,6)] (6a, M = Pd; 6b, M = Pt) (NCN = [C₆H₂(CH₂NMe₂)₂-2,6]⁻) are accessible by the reaction of Br-1-NC-4-C₆H₂(CH₂NMe₂)₂-2,6 (2b) with [Pd₂(dba)₃ · CHCl₃] (5a) (dba = dibenzylidene acetone) and [Pt(tol-4)₂(SEt₂)]₂ (5b) (tol = tolyl), respectively. Complex 6b could successfully be converted to the linear coordination polymer {[Pt(NC-4-C₆H₂(CH₂NMe₂)₂-2,6)](ClO₄)}_n (8) upon its reaction with the organometallic heterobimetallic π-tweezer compound {[Ti](μ-σ,π-CCSiMe₃)₂}AgOClO₃ (7) ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti).The structures of 6a (M = Pd) and 6b (M = Pt) in the solid state are reported. In both complexes the d⁸-configurated transition metal ions palladium(II) and platinum(II) possess a somewhat distorted square-planar coordination sphere. Coordination number 4 at the group-10 metal atoms M is reached by the coordination of two ortho-substituents Me₂NCH₂, the NCN ipso-carbon atom and the bromide ligand. The NC group is para-positioned with respect to M.     

Novel sandwich complexes of zirconium [C9H5(SiMe3)2](C5Me4R)ZrCl2 (R = CH3, CH2CH2NMe2): Synthesis and reduction behavior

Novel half-sandwich [C₉H₅(SiMe₃)₂]ZrCl₃ (3) and sandwich [C₉H₅(SiMe₃)₂](C₅Me₄R)ZrCl₂ (R = CH₃ (1), CH₂CH₂NMe₂ (2)) complexes were prepared and characterized. The reduction of 2 by Mg in THF lead to (η⁵-C₉H₅(SiMe₃)₂)[η⁵:η²(C,N)-C₅Me₄CH₂CH₂N(Me)CH₂]ZrH (7). The structure of 7 was proved by NMR spectroscopy data. Hydrolysis of 2 resulted in the binuclear complex ([C₅Me₄CH₂CH₂NMe₂]ZrCl₂)₂O (6). The crystal structures of 1 and 6 were established by X-ray diffraction analysis.     

Oxime-substituted NCN-pincer palladium and platinum halide polymers through non-covalent hydrogen bonding (NCN = [C6H2(CH2NMe2)2-2,6])

The oxime-substituted NCN-pincer molecules HONCH-1-C₆H₃(CH₂NMe₂)₂-3,5 (2a) and HONCH-4-C₆H₂(CH₂NMe₂)₂-2,6-Br-1 (2b) were accessible by treatment of the benzaldehydes H(O)C-4-C₆H₃(CH₂NMe₂)₂-3,5 (1a) and H(O)C-4-C₆H₂(CH₂NMe₂)₂-2,6-Br-1 (1b) with an excess of hydroxylamine. In the solid state both compounds are forming polymers with intermolecular O-H?N connectivities between the Me₂NCH₂ substituents and the oxime entity of further molecules of 2a and 2b, respectively. Characteristic for 2a and 2b is a helically arrangement involving a crystallographic 2₁ screw axis of the HONCH-1-C₆H₃(CH₂NMe₂)₂-3,5 and HONCH-4-C₆H₂(CH₂NMe₂)₂-2,6-Br-1 building blocks.The reaction of 2b with equimolar amounts of [Pd₂(dba)₃ · CHCl₃] (3) (dba = dibenzylidene acetone) or [Pt(tol)₂(SEt₂)]₂ (4) (tol = 4-tolyl) gave by an oxidative addition of the C-Br unit to M coordination polymers with a [(HONCH-4-C₆H₂(CH₂NMe₂)₂-2,6)MBr] repeating unit (5: M = Pd, 6: M = Pt). Complexes 5 and 6 are in the solid state linear hydrogen-bridged polymers with O-H?Br contacts between the oxime entities and the metal-bonded bromide.     

Polynuclear complexes of gold(III) of the composition ([Au(S2CNR2)2][AuCl4])n (R = C4H9, R2 = (CH2)5): Synthesis, supramolecular structures, and thermal behavior

The interaction of binuclear cadmium dialkyldithiocarbamates [Cd₂(S₂CNR₂)₄] with solutions of AuCl₃ in 2M HCl gives polynuclear gold(III) complexes ([Au(S₂CNR₂)₂][AuCl₄]) _n , where R = C₄H₉ (I) and R₂ = (CH₂)₅ (II). The structures of the synthesized compounds solved by X-ray diffraction analysis are char-acterized by a complicated organization at the supramolecular level. The structures are based on polymer chains (I) and layers (II) involving isomeric cations [Au(S₂CNR₂)₂]⁺ and anions [AuCl₄]⁻. The thermal behavior of the synthesized complexes is studied by simultaneous thermal analysis including thermogravimetry and differential scanning calorimetry. The final product of the thermal transformations of the studied complexes is shown to be reduced metallic gold.     

Reaction of tris(2-hydroxyethyl)amine hydrochloride with zinc diacetate and bis(2-methylphenoxy)acetate

Reaction of tris(2-hydroxyethyl)amine hydrochloride Cl⁻ N⁺H(CH₂CH₂OH)₃ with zinc diacetate and bis(2-methylphenoxy)acetate in the molar ratio 2: 1 results in complexes 2[Cl⁻ N⁺H(CH₂CH₂OH)₃]^· Zn (OCOR)₂ (I, II) R= Me (I), 2-MeC₆H₄OCH₂ (II), which contain two protatrane cations linked with zinc diacylate by two coordination bonds HO → Zn. Complexes I and II are also formed by the reaction of the corresponding tris(2-hydroxyethyl)amine hydrochloride acylate RCOO⁻N⁺H(CH₂CH₂OH)₃ with ZnCl₂. The structure of complexes I, II is proved by elemental analysis, IR and ¹H, ¹³C, ¹⁵N NMR spectroscopy.