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.     

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.     

Oxido-pincer complexes of copper(II) - An EXAFS and EPR study of mono- and binuclear [(pydotH2)CuCl2]n (n = 1 or 2)

The oxido-pincer ligand pydotH₂ (2,6-bis(1-hydroxy-1-o-tolyl-ethyl-η²O,O′)pyridine) forms two different Cu^II containing complexes when prepared from anhydrous CuCl₂. A combination of EPR spectroscopy and EXAFS allowed to structurally characterise the light-green dimer of the formula [(pydotH₂)CuCl(μ-Cl)₂ClCu(pydotH₂)] and the penta-coordinate olive-green monomer [(pydotH₂)CuCl₂]. The molecular entities imply that the ligand remains protonated upon coordination. When dissolved in DMF both compounds form monomeric species [(pydotH₂)CuCl₂(DMF)] which could be characterised in detail by EPR, UV-Vis/NIR spectroscopy and electrochemical measurements. The assignments were supported by comparison with Cu^II complexes of the related ligands 2,6-bis(hydroxymethyl)pyridine (pydimH₂) and 2,6-bis(1-hydroxy-1-methyl)pyridine (pydipH₂).     

Synthesis and structures of silicon-, germanium- and tin-containing tungsten imido alkyl complexes (ArN)2W(CH2EMe3)2 (E = Si, Ge, Sn)

The novel silicon-, germanium- and tin-containing imido alkyl complexes of tungsten of the type (ArN)₂W(CH₂EMe₃)₂ (; E = Si (1), Ge (2), Sn (3)) have been prepared by the reactions of (ArN)₂WCl₂(dme) (dme = 1,2-dimethoxyethane) with heteroelement-containing alkyllithium or Grignard reagents Me₃ECH₂Li (E = Si, Ge), Me₃ECH₂MgCl (E = Ge, Sn). The title compounds were isolated in high yields as crystalline solids and characterized by elemental analysis, IR, ¹H, ¹³C, ²⁹Si and ¹¹⁹Sn NMR spectroscopy and X-ray diffraction studies. The geometry of the W atoms in the compounds can be described as a distorted tetrahedron.     

Preparation, crystal structures, EPR and reflectance spectra of two new charge-transfer salts, [CpFeCpCH2N(CH3)3]4[XMo12O40] · nCH3CN (n = 0 for X = P or n = 1 for X = Ge)

Two new charge-transfer salts, [CpFeCpCH₂N(CH₃)₃]₄[PMo₁₂O₄₀] · CH₃CN (1) and [CpFeCpCH₂N(CH₃)₃]₄[GeMo₁₂O₄₀] (2), were synthesized by the traditional solution synthetic method and their structures were determined by single-crystal X-ray analysis. Salt 1 belongs to the triclinic space group P1, and salt 2 belongs to the triclinic space group . There exist the complex interactions of the cationic ferrocenyl donor and Keggin polyanion in the solid state. The solid state UV-Vis diffuse reflectance spectra indicate the presence of a charge-transfer band climbing from 450 nm to well beyond 900 nm for 1, a charge-transfer band from 460 to 850 nm with λ_max = 630 nm for 2.The EPR spectra of salts 1 and 2 at 77 K show a signal at g = 2.0048 and 1.9501, respectively, ascribed to the delocalization of one electron in reduced Keggin ion in salt 1 and the Mo^VI in [GeMo₁₂O₄₀]⁴⁻ is partly reduced to Mo^V owing to the charge-transfer transitions taking place between the ferrocenyl donors and the POM acceptors. The two compounds were also characterized by IR spectroscopy and cyclic voltammetry.     

Bis(silylaminodiarylphosphoranylsilylmethyl-C,N)-tin(II) and -lead(II) complexes and their precursors; structures of H(LL′), H(LL″), Sn(LL″)2 and Pb(LL″)2; [LL′] = [CH(SiMe3)P(Ph)2NSiMe3],

We report a series (a)-(d) of tandem reactions involving the conversion of: (a) 2CH₂(SiMe₃)P(Ph)₂NSiMe₃ [2H(LL′)] (III) into successively [Li(LL′)]₂ (1a) and [Pb(LL′)₂] (3a); (b) 1a in turn into {[Li(LL″)]₂} (2) and [Pb(LL″)₂] (4); (c) 1a successively into Sn(LL′)Cl (5) and [Sn(LL″)₂] (6); (d) (1b) into (3b). Experimental details for the preparation and characterisation (including elemental analysis and multinuclear NMR spectra in C₆D₆ and EI mass spectra) of 1a, 2, 3a, 3b, 4, 6, III (a new synthesis) and IV are provided. The X-ray structures of crystalline 4, 6, III and IV are presented; those of 1a, 2 and 3a were previously published.     

Alkaline earth metal poly(hydrogen fluorides) hexafluoroarsenates(V) and hexafluorophosphate(V): M2(H2F3)(HF2)2(AF6) (M = Ca, A = As; M = Sr, A = As, P)

New compounds of the type M₂(H₂F₃)(HF₂)₂(AF₆) with M = Ca, A = As and M = Sr, A = As, P) were isolated. Ca₂(H₂F₃)(HF₂)₂(AsF₆) was prepared from Ca(AsF₆)₂ with repeated additions of neutral anhydrous hydrogen fluoride (aHF). It crystallizes in a space group P4₃22 with a = 714.67(10) pm, c = 1754.8(3) pm, V = 0.8963(2) nm³ and Z = 4. Sr₂(H₂F₃)(HF₂)₂(AsF₆) was prepared at room temperature by dissolving SrF₂ in aHF acidified with AsF₅ in mole ratio SrF₂:AsF₅ = 2:1. It crystallizes in a space group P4₃22 with a = 746.00(12) pm, c = 1805.1(5) pm, V = 1.0046(4) nm³ and Z = 4. Sr₂(H₂F₃)(HF₂)₂(PF₆) was prepared from Sr(XeF₂)_n(PF₆)₂ in neutral aHF. It crystallizes in a space group P4₁22 with a = 737.0(3) pm, c = 1793.7(14) pm, V = 0.9744(9) nm³ and Z = 4. The compounds M₂(H₂F₃)(HF₂)₂(AF₆) gradually lose HF at room temperature in a dynamic vacuum or during being powdered for recording IR spectra or X-ray powder ray diffraction patterns. All compounds are isotypical with coordination of nine fluorine atoms around a metal center forming a distorted Archimedian antiprism with one face capped. This is the first example of the compounds in which H₂F₃⁻ and HF₂⁻ anions simultaneously bridge metal centers forming close packed three-dimensional network of polymeric compounds with low solubility in aHF. The HF₂⁻ anions are asymmetric with usual F?F distances of 227.3-228.5 pm. Vibrational frequency (ν₁) of HF₂⁻ is close to that in NaHF₂. The anion H₂F₃⁻ exhibits unusually small F?F?F angle of 95.1°-97.6° most probably as a consequence of close packed structure.     

Synthesis, characterization and study of the chromogenic properties of the hybrid polyoxometalates [PW11O39(SiR)2O] (R = Et, (CH2)nCHCH2 (n = 0, 1, 4), CH2CH2SiEt3, CH2CH2SiMe2Ph)

Reaction of Cl₃SiR or (EtO)₃SiR with [PW₁₁O₃₉]⁷⁻ affords the disubstituted hybrid anions [PW₁₁O₃₉(SiR)₂O]³⁻. These species have been characterized by IR spectroscopy in the solid state and by multinuclear NMR (¹H, ²⁹Si, ³¹P and ¹⁸³W) and cyclic voltammetry in solution. The hydrosilylation of [PW₁₁O₃₉(Si-CHCH₂)₂O]³⁻ has been achieved with Et₃SiH and PhSiMe₂H. These are the first examples of hydrosilylation on a hybrid tungstophosphate core. The chromogenic behaviour of hybrid species has been demonstrated in solution.     

[Cu(men)2(BF4)2] (men = N-methyl-1,2-diaminoethane): Preparation, crystal structure, spectroscopic and magnetic properties

Single crystals of [Cu(men)₂(BF₄)₂] (men = N-methyl-1,2-diaminoethane) (1) were isolated from an aqueous-ethanolic system Cu²⁺-men-BF₄⁻. The crystal structure of 1 consists of [Cu(men)₂(BF₄)₂] molecules. Copper ion exhibits usual distorted octahedral coordination; there are two coordinated men ligands in the equatorial plane with Cu-N bonds of 2.0451(12) and 2.0035(12) Å, while the axial positions are occupied by fluorine atoms from BF₄⁻ anions with Cu-F bond of 2.5091(11) Å. The packing of the [Cu(men)₂(BF₄)₂] molecules is governed by N-H?F type hydrogen bonds. The measured ESR spectrum corroborated the presence of Jahn-Teller anisotropy of Cu(II) with g_|| = 2.20 and g_⊥ = 2.06. The magnetic studies in the temperature range 300-2 K reveal that 1 follows the Curie-Weiss law with parameters g = 2.1612(1) and θ = −0.233(1) K suggesting the presence of weak antiferomagnetic interactions.     

Synthesis and coordinating properties of the facultative Sb2O- and As2O-donor ligands O{(CH2)2ER2}2 (E = Sb or As; R = Ph or Me)

The new mixed Sb₂O-donor ligands O{(CH₂)₂SbR₂}₂ (R = Ph, 1; R = Me, 2) with flexible backbones have been prepared in good yields as air-sensitive oils from reaction of NaSbR₂ with 0.5 mol equivalents of O(CH₂CH₂Br)₂ in thf solution. The As₂O-donor analogues, O{(CH₂)₂AsR₂}₂ (R = Ph, 3; R = Me, 4) were obtained similarly from LiAsPh₂ or NaAsMe₂, respectively and O(CH₂CH₂Br)₂, although ligand 4 appears to be considerably less stable with respect to C-O bond fission under some conditions than the other ligands. Using O(CH₂CH₂Cl)₂ leads only to partial substitution by the SbPh₂⁻ or AsPh₂⁻ nucleophile. These ligands behave as bidentate chelating Sb₂- or As₂-donors in the distorted tetrahedral [M(L-L)₂]BF₄ (M = Cu or Ag; L-L = 1-4) on the basis of solution ¹H and ⁶³Cu NMR spectroscopic studies, mass spectrometry and microanalyses. Crystal structures of three representative examples with Cu(I) and Ag(I) confirm the distorted tetrahedral Sb₄ or As₄ coordination at the metal and allow comparisons of geometric parameters. The crystallographic identification of an unexpected Cu(I)-Cu(I) complex, [Cu₂{Me₂As(CH₂)₂OH}₃](BF₄)₂, obtained as a by-product via C-O bond fission within ligand 4 is also reported. The distorted octahedral [RhCl₂(L-L)₂]Cl and the distorted square planar cis-[PtCl₂(L-L)] (L-L = 1 or 2) are also described. The ether O atoms are not involved in coordination to the metal ion in any of the late transition metal complexes isolated.     

Synthesis and characterisation of [AlMen{Si(SiMe3)3}3−n(thf)] (n = 1 or 2)

The crystalline compounds [AlMe_n{Si(SiMe₃)₃}_3−n(thf)] [n = 2 (1) or 1 (2)] were prepared from the lithium sisyl [Li{Si(SiMe₃)₃}(thf)₃] (A) and the appropriate methylaluminium chloride [AlCl_3−nMe_n] in thf. The X-ray structure of 1 is reported. Unlike A or a magnesium sisyl [Mg{Si(SiMe₃)₃}₂(thf)₂] (B), neither 1 nor 2 underwent an insertion reaction with an α-H-free nitrile.     

Novel octahedral nickel(II) dithiocarbamates with bi- or tetradentate N-donor ligands: X-ray structures of [Ni(Bzppzdtc)(phen)2]ClO4 · CHCl3 and [Ni(Bz2dtc)2(cyclam)]

A series of novel octahedral nickel(II) dithiocarbamate complexes involving bidentate nitrogen-donor ligands (phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) or a tetradentate ligand (cyclam = 1,4,8,11-tetraazacycloteradecane) of the composition [Ni(BzMetdtc)(phen)₂]ClO₄ (1), [Ni(Pe₂dtc)(phen)₂]ClO₄ (2), [Ni(Bzppzdtc)(phen)₂]ClO₄ · CHCl₃ (3), [Ni(Bzppzdtc)(phen)₂](SCN) (4), [Ni(BzMetdtc)(bpy)₂]ClO₄ · 2H₂O (5), [Ni(Pe₂dtc)(cyclam)]ClO₄ (6), [Ni(BzMetdtc)₂(cyclam)] (7), [Ni(Bz₂dtc)₂(cyclam)] (8) and [Ni(Bz₂dtc)₂(phen)] (9) (BzMetdtc = N,N-benzyl-methyldithiocarbamate(1-) anion, Pe₂dtc = N,N-dipentyldithiocarbamate(1-) anion, Bz₂dtc = N,N-dibenzyldithiocarbamate(1-) anion, Bzppzdtc = 4-benzylpiperazinedithiocarbamate(1-) anion), have been synthesized. Spectroscopic (electronic and infrared), magnetic moment and molar conductivity data, and thermal behaviour of the complexes are discussed. Single crystal X-ray analysis of 3 and 8 confirmed a distorted octahedral arrangement in the vicinity of the nickel atom with a N₄S₂ donor set. They represent the first X-ray structures of such type complexes. The catalytic influence of complexes 2, 3, 6, and 7 on graphite oxidation was studied and discussed.     

Reactivity of ZrCl4 and HfCl4 with silylamines and thermal decomposition of the compounds [MCl4{NH(R)(SiR′3)}] (M = Zr,Hf, R = tBu,R′ = Me; R = SiR′3 = SiMe3, SiMe2H)

The Lewis acid/base adducts [MCl₄{NH(R)(SiR′₃)}] (M = Zr, Hf; R = tBu, R′ = Me; R = SiR′₃ = SiMe₃, SiMe₂H) were synthesized by the 1:1 reaction of MCl₄ with NH(R)(SiR′₃) in dichloromethane solution at room temperature. The decomposition of [MCl₄{NH(R)(SiR′₃)}] proceeds with the elimination of R′₃SiCl, as shown by thermogravimetric analysis. Pyrolysis of the compounds at 620 °C under inert conditions (N₂, vacuum) afforded powders of composition [ClMN] or [Cl₂MNH]. Preliminary low pressure chemical vapour deposition experiments show that [MCl₄{NH(R)(SiR′₃)}] deposits thin films of metal nitride contaminated with metal oxide.     

A series of three-dimensional coordination polymers with general formula [{Ln(H2O)n}{Re6Te8(CN)6}] · xH2O (Ln = Eu,Gd, Tb,Dy, Ho,Er, Tm,Yb; n = 3, 4, x = 0, 2.5)

A series of new compounds containing rare earth cations (Eu to Yb) and paramagnetic cluster anion [Re₆Te₈(CN)₆]³⁻ was prepared and investigated. The X-ray structural analyses have revealed that the compounds [{Ln(H₂O)₄}{Re₆Te₈(CN)₆}] · 2.5H₂O; Ln = Eu (1), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), [{Gd(H₂O)₃}{Re₆Te₈(CN)₆}] · 2.5H₂O (2) and [{Yb(H₂O)₄}{Re₆Te₈(CN)₆}] (8) are three-dimensional polymers based on Re–CN–Ln interactions. Measurements of magnetic susceptibility for 2 and 5 showed that effective magnetic moment (at 300 K) was 8.13 μ_B for compound 2 and 10.79 μ_B for compound 5 with weak antiferromagnetic ordering appeared at low temperatures.     

Ti(II)-mediated domino cyclization of 2-functionalized 1-halo-2,n-enynes (n = 7, 8) to bicyclic compounds

The reaction of 2-functionalized 1-halo-2,n-enynes (n = 7 or 8) with a divalent titanium reagent, Ti(O-i-Pr)₄/2i-PrMgCl, proceeded in a domino fashion to afford bicyclic compounds in good yields.     

Random exchange in the spin ladder Cu(quinoxaline)X2 (X = Cl, Br)

Mixed halide versions of the spin ladder copper quinoxaline dihalide (X = Cl, Br) have been synthesized. X-ray crystallographic analysis shows the structures of the mixed halide versions are the same as those as the pure halide compounds; in the mixed-halide compounds, the larger bromide ions are preferentially found in the terminal, rather than the bridging, sites of the Cu₂X₄ dimeric units. Susceptibility studies show the rung interactions (within the dimeric units) remain unchanged upon mixing but the rail interactions (through the quinoxaline molecules) change systematically.     

Metal complexes of 2-aza-2-benzyl-5,10,15,20-tetraphenyl-21-carbaporphyrin: M(2-NCH2C6H5NCTPP) (M = Ni, Pd) and Mn(2-NCH2C6H5NCTPP)Br (NCTPP = N-confused 5,10,15,20-tetraphenyl porphyrinate)

The crystal structures of (2-aza-2-benzyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N′,N″) nickel(II) methylene chloride solvate [Ni(2-NCH₂C₆H₅NCTPP); 4], (2-aza-2-benzyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N′,N″) palladium(II) [Pd(2-NCH₂C₆H₅NCTPP); 5] and bromo(2-aza-2-benzyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N′,N″) manganese(III) toluene solvate [Mn(2-NCH₂C₆H₅NCTPP)Br·C₆H₅CH₃; 3·C₆H₅CH₃] have been established. The coordination sphere around the Ni²⁺ ion in 4 (or Pd²⁺ ion in 5) is distorted square planar (DSP), whereas for Mn³⁺ in 3·C₆H₅CH₃, it is a square-based pyramid with the Br atom lying in the axial site. The g value of 11.34, measured from parallel polarization of the X-band EPR spectra at 4 K, is consistent with a high spin mononuclear manganese(III) centre (S = 2) in 3. The magnitude of the axial (D) zero-field splitting (ZFS) for the mononuclear Mn(III) centre in 3 was determined approximately to be 1.4 cm⁻¹ by paramagnetic susceptibility measurements and conventional EPR spectroscopy.     

Novel structures of cyclometallated complexes of palladium(II) derived from terdentate ligands. Crystal and molecular structure of [Pd{C6H4C(H)=NCH2CH2CH2NMe2}(X)] (X=Cl, Br, I)

Treatment of N-(2-chlorobenzylidene)-N,N-dimethyl-1,3-propanediamine (1) and N-(2-bromo-3,4-(MeO)₂-benzylidene)-N,N-dimethyl-1,3-propanediamine (20) with tris(dibenzylideneacetone)dipalladium(0) in toluene gave the mononuclear cyclometallated complexes [Pd{C₆H₄C(H)=NCH₂CH₂CH₂NMe₂}(Cl)] (2) and [Pd{3,4-(MeO)₂C₆H₂C(H)=NCH₂CH₂CH₂NMe₂}(Br)] (21), respectively, via oxidative addition reaction with the ligand as a C,N,N terdentate ligand. Reaction of 2 with sodium bromide or iodide in an acetone–water mixture gave the cyclometallated analogues of 2, [Pd{C₆H₄C(H)=NCH₂CH₂CH₂NMe₂}(Br)] (3) and [Pd{C₆H₄C(H)=NCH₂CH₂CH₂NMe₂}(I)] (4), by halogen exchange. The X-ray crystal structures of 2, 3 and 4 were determined and discussed. Treatment of 2, 3, 4 and 21 with tertiary monophosphines in acetone gave the mononuclear cyclometallated complexes [Pd{C₆H₄C(H)=NCH₂CH₂CH₂NMe₂}(L)(X)] (6: L=PPh₃, X=Cl; 7: L=PPh₃, X=Br; 8: L=PPh₃, X=I; 9: L=PMePh₂, X=Cl; 10: L=PMe₂Ph, X=Cl) and [Pd{3,4-(MeO)₂C₆H₂C(H)=NCH₂CH₂CH₂NMe₂}(L)(Br)] (22: L=PPh₃; 23: L=PMePh₂; 24: L=PMe₂Ph). A fluxional behaviour due to an uncoordinated CH₂CH₂CH₂NMe₂ could be determined by variable temperature NMR spectroscopy. Treatment of 2, 3 and 4 with silver trifluoromethanesulfonate followed by reaction with triphenylphosphine gave the mononuclear complex [Pd{C₆H₄C(H)=NCH₂CH₂CH₂NMe₂}(PPh₃)][F₃CSO₃] (11) where the Pd–NMe₂ bond was retained. Reaction of 2, 3 and 4 with ditertiary diphosphines in a cyclometallated complex–diphosphine 2:1 molar ratio gave the binuclear complexes [{Pd[C₆H₄C(H)=NCH₂CH₂CH₂NMe₂](X)}₂(μ-L–L)][L–L=PPh₂(CH₂)₄PPh₂(dppb) (13, X=Cl; 14, X=Br; 15, X=I; L–L=PPh₂(CH₂)₅PPh₂(dpppe): 16, X=Cl; 17, X=Br; 18, X=I) with palladium–NMe₂ bond cleavage. Treatment of 2, 3 and 4 with ditertiary diphosphines, in a cyclometallated complex–diphosphine 2:1, molar ratio and AgSO₃CF₃ gave the binuclear cyclometallated complexes [{Pd[C₆H₄C(H)=NCH₂CH₂CH₂NMe₂]}₂(μ-L–L)][F₃CSO₃]₂ (11: L–L=PPh₂(CH₂)₄PPh₂(dppb), X=Cl; 12: L–L=PPh₂(CH₂)₅PPh₂ (dpppe), X=Cl). Reaction of 2 with the ditertiary diphosphine cis-dppe in a cyclometallated complex–diphosphine 1:1 molar ratio followed by treatment with sodium perchlorate gave the mononuclear cyclometallated complex [Pd{C₆H₄C(H)=NCH₂CH₂CH₂NMe₂}(cis-PPh₂CH=CHPPh₂–P,P)][ClO₄] (19).