Cryoscopic Molecular Weight Research Articles

Structure investigation of dimethyl-aluminium, -gallium and -indium O,O′-chelate complexes in solution and the solid state. Molecular structure of five-co-ordinated [Me2M(μ-OC6H4CO2Me-2)]2 adducts

The reaction of trimethyl-aluminium, -gallium and -indium with an equimolar amount of methyl salicylate, 2-(HO)C6H4CO2Me (Hmesal), gives [Me2M(mesal)]n chelate complexes in high yield (where n = 1 or 2, M = Al 1 or Ga 2; n = 2, M = In 3). The resulting compounds have been characterised in solution by NMR and IR spectroscopy as well as by cryoscopic molecular weight determinations in benzene; their molecular structures in the solid state were determined by single-crystal X-ray diffraction techniques. All three compounds are dimeric in the solid state, with five-co-ordinated metal centres. The deformation of the metal centre co-ordination sphere is discussed. In solution compounds 1 and 2 are monomeric, four-co-ordinated chelate complexes while 3 retains its dimeric structure. On the basis of the structural observation resulting from this study and with respect to related compounds the following sequence of the Group 13 metal centre Lewis acidity, in four-co-ordinated diorganometallic O,O′-chelate complexes is proposed: In Al > Ga.

Synthesis and Characterization of the Organoindium Phosphides R2InPPh2 (R = i-Pr, CH2Ph) and the Heterocubane [MesInPMes]4

The reaction of i-Pr2InCl and (PhCH2)2InCl with LiPPh2 in Et2O/THF or Et2O/n-pentane gives the organoindium phosphides i-Pr2InPPh2 (1) and (PhCH2)2InPPh2 (2), respectively. The tetrameric compound [MesInPMes]4 (3) has been prepared by the treatment of MesInCl2 with MesPLi2 in Et2O. 1−3 have been characterized by NMR, IR, and MS techniques as well as by X-ray diffraction. According to cryoscopic molecular weight determinations in benzene, 1 and 2 are present as a monomer−dimer equilibrium mixture, while 3 is tetrameric in solution. The X-ray analyses of 1 and 2 confirm the existence in the solid state of trimers in [i-Pr2InPPh2]3 and [(PhCH2)2InPPh2]3·OEt2 with distorted In3P3 six-membered rings in boat conformations. According to its structural characterization [MesInPMes]4·4.5THF is a heterocubane with an In4P4 core shielded by the bulky organic groups.

Room Temperature Cyclopentadiene Elimination Reaction for the Synthesis of Diethylgallium−Amides, −Phosphides, and −Thiolates. Crystal and Molecular Structures of [Et2GaP(t-Bu)2]2 and [Et2GaS(SiPh3)]2

The compounds [Et2GaNEt2]2, [Et2GaN(H)(Me)]2, [Et2GaN(H)(t-Bu)]2, [Et2GaP(i-Pr)2]2, [Et2GaP(t-Bu)2]2, and [Et2GaS(SiPh3)]2 have been prepared in high yields at room temperature by the elimination of cyclopentadiene from Et2Ga(C5H5) and the corresponding amine, phosphine, or thiol. The three diethylgallium amides and [Et2GaP(i-Pr)2]2 are liquids, whereas the other phosphide and the thiolate are crystalline solids at room temperature. All compounds were fully characterized by elemental analyses, 1H and 31P NMR spectroscopy, and cryoscopic molecular weight studies in benzene, as appropriate, and are dimeric in solution. The crystalline compounds [Et2GaP(t-Bu)2]2, and [Et2GaS(SiPh3)]2 were characterized by X-ray structural studies. Even though [Et2GaN(H)(t-Bu)]2 and [Et2GaS(SiPh3)]2 were prepared at room temperature and isolated in high yield, 1H NMR studies revealed that neither compound was formed in high yield in solution. Removal of the cyclopentadiene by either dimerization or distillation and/or dimerization of the gallium product are necessary to prevent the back-reaction to re-form the reactants.

Metallorganische verbindungen der lanthanoide CVIII. Synthese und strukturaufklärung monomerer organolanthanoidacetate

LnCl 3 reacts with Na(C 5Me 4 1Bu) in THF to form the organolanthanoid chlorides [(C 5Me 4 1Bu) 2LnCl(THF)] (Ln = La ( 1a), Lu ( 1b)). Compounds 1a and 1b yield in reaction with NaO 2CCH 3 the monomeric organolanthanoid acetates [(C 5Me 4 1Bu) 2LnO 2CCH 3] (Ln = La ( 2a), Lu ( 2b)). The single crystal X-ray structure analysis of 2b as well as the cryoscopic molecular weight investigation of 2a verify the monomeric structure of these complexes.

Synthesis and Spectroscopic Characterization of Novel Heterotermetallic Isopropoxides: X-ray Crystal Structures of ICd{M(2)(OPr(i))(9)} and [{Cd(OPr(i))(3)}Ba{M(2)(OPr(i))(9)}](2) (M = Ti, Hf).

Metathesis reactions between CdI(2) and KM(2)(OPr(i))(9) (M = Ti, Hf) in toluene produce monomeric iodo-heterobimetallic isopropoxides ICdM(2)(OPr(i))(9) (1, M = Ti; 2, M = Hf) which have been characterized by solution ((1)H, (13)C, and (113)Cd) and solid state ((13)C and (113)Cd) CP MAS NMR spectroscopy, microanalysis, cryoscopic molecular weight determination, and single crystal X-ray diffraction study. Both 1 and 2 in the solid state represent the first structurally characterized examples of halide heterobimetallic alkoxides based on {Ti(2)(OPr(i))(9)}(-) and {Hf(2)(OPr(i))(9)}(-) bioctahedral subunits, respectively. The overall molecular geometry of 1 and 2 can be viewed formally as an interaction of the CdI(+) fragment with {M(2)(OPr(i))(9)}(-) substructures via two terminal and two bridging (&mgr;(2)-) isopropoxy groups. Reaction of 1 and 2 with equimolar KBa(OPr(i))(3) in toluene afforded novel heterotermetallic isopropoxides [{Cd(OPr(i))(3)}Ba{M(2)(OPr(i))(9)}](2) (3, M = Ti; 4, M = Hf). Formation of heterotermetallic frameworks involves an interesting rearrangement of the central metal atoms between the two precursor molecules, which is probably commanded by the tendency of barium to achieve higher coordination numbers. The dimeric forms of 3 and 4 as shown by cryoscopy and (113)Cd solution and solid state CP MAS NMR studies are confirmed by crystallography. The X-ray crystal structures of 3 and 4 reveal, as a common feature, a central Ba(&mgr;(2)-OPr(i))(2)Cd(&mgr;(2)-OPr(i))(2)Cd(&mgr;(2)-OPr(i))(2)Ba unit formed by a spirocyclic linking of two LBa(OPr(i))(2) (3, L = Ti(2)(OPr(i))(9); 4, L = Hf(2)(OPr(i))(9)) units to a four membered, Cd(2)(OPr(i))(2), ring. Crystal data: for 1, monoclinic, space group P2(1)/m, a = 11.71(2) Å, b = 15.78(3) Å, c = 12.16(2) Å, beta = 116.69(14) degrees, Z = 2; for 2, triclinic, space group P&onemacr;, a = 9.825(2) Å, b = 11.428 Å, c = 20.619 Å, alpha = 95.619(12) degrees, beta = 99.915(11) degrees, gamma = 111.347(11) degrees, Z = 2; for 3, monoclinic, space group P2(1)/c, a = 22.68(2) Å, b = 12.603(11) Å, c = 19.00(2) Å, beta = 96.83(8) degrees, Z = 2; for 4, monoclinic, space group P2(1)/c, a = 23.197(5) Å, b = 12.886(3) Å, c = 19.378(4) Å, beta = 97.18(3) degrees, Z = 2.

Arsenic (III) alkoxides containing 2,2,2-trifluoroethoxy and 1,1,1,3,3,3-hexafluoroisopropoxy ligands

The metathesis of arsenic (III) chloride with 3 mol each of NaOCH 2CF 3 and NaOCH(CF 3) 2 in n-hexane yields As(OR) 3 [R = CH 2CF 3 and CH(CF 3) 2]. The reaction of As(OR) 3 with 1 or 2 mol of acetyl chloride in n-hexane affords AsCl(OR) 2/AsCl 2(OR). All these compounds are liquids with the exception of As(OCH 2CF 3) 3 which is a low melting solid. Their cryoscopic molecular weights show them to be monomeric. The compounds have been characterised by elemental analysis, IR, NMR spectra and mass spectrometry. Their reaction with pyridine yields 1:1 solid adducts.

Syntheses, Characterization, Crystal and Molecular Structures, and Solution Properties of Et2Ga(C5H5) and EtGa(C5H5)2

Abstract : The compounds Et2Ga(C5H5) and EtGa(C5H5)2 have been prepared by ligand redistribution reactions in pentane solution between appropriate quantities of GaEt3 and Ga(C5H5)3. Both compounds have been fully characterized by elemental analyses, X-ray structural studies, cryoscopic molecular weight studies in benzene solution, mass spectroscopic studies, 1H NMR studies of solutions and 1H NMR studies of the melts. Both compounds exist as pure single compounds in the solid state. jg

Synthesis and Characterization of a Series of Organoindium Phosphides, Including Molecular Structures of [(Me3CCH2)2InPEt2]2 and [(Me3CCH2)2InP(H)(C6H11)

Abstract : A series of organoindium-phosphides including (Me3CCH2)2InPRR' (R = R' =Et, C6H11; R = C6H11, R' = H; R = Me, R' = Ph) and (Me3SiCH2)2InP(Me)Ph have been prepared and characterized. The characterization data include partial elemental analyses (C, H), 1H and 31P NMR and IR spectral studies, physical properties, cryoscopic molecular weight studies (with the exception of Me3CCH2)2InP(C6H11)2), and X-ray structural studies of ((Me3CCH2)2InPEt2)2 and ((Me3CCH2)2InP(H)(C6H11))3. The compound (Me3CCH2)2InPEt2 is observed to be a dimer in benzene solution; (Me3CCH2)2InP(H)(C6H11) exists as a dimer-trimer equilibrium mixture whereas (Me3CCH2)2InP(Me)(Ph) and (Me3SiCH2)2InP(Me)(Ph) are trimers. NMR studies are consistent with (Me3CCH2)2InP(C6H11)2 being a dimer in benzene solution but the concentration was too low to confirm the conclusion by cryoscopic molecular weight studies. jg

Behaviour of differently produced methylalumoxanes in the phase separation with diethyl ether and molecular weight estimations

AbstractCryoscopic molecular weight estimations and phase separation experiments of differently produced methylalumoxanes showed diverse behaviour. The cryoscopic molecular weight estimations showed higher molecular weights caused by increasing methyl conversion. The average molecular weight in benzene lay between 1000 to 2000 while the solvent 1, 4‐dioxane delivered smaller molecular weights (factor 2 to 4). Molecular weights in trimethylaluminium were similar to those in benzene. In phase separation experiments we obtained an increasing volume portion of lower phase with increasing methyl conversion during production. There was a decisive influence of circulation circumstances at the ice surface and the trimethylaluminium concentration at production according to the behaviour in phase separation experiments.

Low Oxidation State Gallium Compounds Synthesis and Characterization of [Ga(CH2CMe3)

Abstract : The new organogallium(I) compound (Ga(CH2CMe3))n has been prepared by the reduction of Ga(CH2CMe3)2Cl by using either sodium or lithium with naphthalene in THF. When the reagents were combined at -78 deg C, a yellow intermediate, a neopentylgallium(III) derivative of dihydronaphthalene C10H8(Ga(CH2CMe3)2)2 (dot) 2 MCl (M = Li, Na) was formed. Warming of the solution to 0-25 deg C resulted in decomposition of the yellow intermediate and formation of a reddish brown solution of Ga(CH2CMe3))n, Ga(CH2CMe3)3, C10H8, and either NaCl or LiCl. The gallium(I) product was a vitreous solid and was characterized by complete elemental analyses, hydrolyses with HC1/H20 and with DCl/D20, oxidation with HgCl2 and with I2, cryoscopic molecular weight studies in benzene solution and IR and NMR spectroscopic studies. All data support the conclusion that (Ga(CH2CMe3))n exists as a mixture of species which are gallium cages. The numbers of gallium atoms in these cages might range from 6 to 12 atoms. Gallium, Low oxidation state gallium compounds, Gallium clusters.

Mono- and bis-ortho-chelated lithium and sodium phenolates. Molecular structures of the first lithium phenolate with a stable, trinuclear structure and of a tetranuclear sodium analog, [MOC6H2(CH2NMe2)2-2,6-Me-4]x (M = Li, x = 3; M = Na, x = 4)

The lithium and sodium phenolates of 2-[(dimethylamino)methyl]phenol, 1a and 2a, 2- [(dimethylamino)methyl]4,6-dimethylphenol, 1b and 2b, and 2,6-bis[(dimethylamino)methyl]-4-methylphenol, 1c and 2c, respectively, have been synthesized. The structures of these complexes in solution were studied by variable-temperature 1 H and 13 C NMR spectroscopy and cryoscopic molecular weight measurements. The solid-state structures of complexes 1c and 2c derived from 2,6-bis[(dimethylamino)methyl]-4-methylphenol, were determined by X-ray diffraction

Gallium and indium compounds containing three different substituents. Crystal and molecular structure of [(Me 3CCH 2)ClGaPPh 2

Three new heavier group 13 element compounds containing three different substituents, (Me 3CCH 2)ClGaPPh 2, (Me 3CCH 2)BrGaPPh 2 and (Me 3CCH 2)ClInPPh 2, have been prepared and characterized. All compounds were characterized by partial elemental analysis, cryoscopic molecular weight studies in benzene solution, and NMR and IR spectroscopic data. All three compounds exist as trimeric molecules in solution. NMR spectral data were consistent with the presence of multiple isomers of the trimers. The compound [(MC 3CCH 2)ClGaPPh 2] 3 crystallizes in the acentric space group Pn2 1 a with a = 17.741(9) Å, b = 13.942(6) Å and c = 21.574(8) Å. Diffraction data were collected on an Enraf-Nonius CAD-4 diffractometer, and the structure was refined to R = 4.6% and R w = 6.0% for those 2971 reflections with [ F o >s- 5σ( F o)]. The GaP six-membered ring has a typical chair conformation with the bulky neopentyl groups occupying the E,A,A, positions. Distances of interest include GaCl = 2.209(4), 2.219(4) and 2.220(4) Å and GaP(bridging) which range from 2.414(3) Å to 2.433(4) Å.

Use of Me2Ga(C5H5) to prepare (Me2GaERR')n (E = N, P) at or below room temperature and the crystal and molecular structure of [Me2GaP(Me)(Ph)

Abstract : The organogallium compound, Me2Ga(C5H5) has been observed to react at room temperature or below with primary and secondary amines and phosphines to form Me2GaNH23, Me2GaN(H)(Me)3, Me2GaN(H)(t-Bu)2, Me2GaN(H)(C6H11)2, Me2GaNEt22, Me2GaN(Me)(C6H11)2, Me2GaN(Me)(Ph)2, Me2GaN(Et)(Ph)2, Me2GaP(C6H11)22, Me2GaP(Me)(Ph)3 or Me2GaPPh22 and cyclopentadiene. All new compounds have been fully characterized by their melting points, partial elemental analyses (C and H), 1H NMR, 31P NMR (as appropriate) and IR spectroscopic data and cryoscopic molecular weight studies. The compound Me2GaP(Me)(Ph)3 crystallizes in the trigonal space group R3 with a = 16.526(5)A, c = 10.242(2)A, V = 2421(1)A(3), and Z = 3 (trimeric molecules). The molecule contains a Ga3P3 ring in the chair conformation with phenyl groups in axial positions. The Ga-P distances range from 2.407(4)A to 2.413(6). Gallium-nitrogen and -phosphorus chemistry, X-ray structural study.

An organoindium compound containing an indium-selenium bond: synthesis, properties, and molecular structure of [(Me3CCH2)2InSePh

Abstract : An organoindium compound with a In-Se bond, has been synthesized, characterized by elemental analyses, IR, 1H NMR and 13 C NMR spectroscopies, cryoscopic molecular weight studies and an X-ray structural study. The dimeric molecule crystallizes in the centrosymmetric monoclinic space-group P21/c (No, 14). Diffraction data were collected on a Siemens R3m/V automated four circle diffractometer, and the structure was solved and refined. The four-membered In2Se2 ring has a butterfly arrangement with the phenyl groups in the anti position relative to the ring. The In-C (neopentyl) distances range from 2. 135(11) to 2.168(10) while In-Se bond distances range from 2.748(1) to 2.756(1). There is some rotational disorder of the methyl groups within (at least) one of the neopentyl (-CH2 CMe3) groups.

The chemistry of copper(I)β-diketonate compounds. Part 4. Syntheses and characterization of CuXLn(X =β-diketonate or Cl, L = PMe3, n= 2 or 4; L = PEt3, n= 2)

The salts [Cu(PMe3)4]+[CuCl2]– and [Cu(PMe3)4]+[β-diketonate]–[β-diketonate = 1,1,1,5,5,5-hexafluoroacetylacetonate (hfacac), 1,1,1-trifluoroacetylacetonate (tfacac) or acetylacetonate (acac)] were prepared by the displacement of the co-ordinating anions Cl– and β-diketonate from the copper(I) complexes [CuX(PMe3)](X = Cl or β-diketonate) by addition of an excess of PMe3. These species were characterized by a variety of spectroscopic methods including 31P NMR spectroscopy which revealed coupling between 31P and 63,65Cu in the cation. Two examples were characterized in the solid state by single-crystal X-ray diffraction: [Cu(PMe3)4]+[CuCl2]–, space group P213, a= 13.584(1)A and Z= 12; [Cu(PMe3)4]+[hfacac]–, space group Pmmn, a= 10.703(2), b= 15.077(3), c= 8.997(2)A and Z= 2. The cations exhibit an approximately tetrahedral co-ordination environment and the anion [CuCl2]– is linear. The addition of excess of PEt3 to [CuX(PEt3)] resulted in formation of [CuX(PEt3)2] in contrast to the PMe3 analogues. The compound [CuCl(PEt3)2] was found to be monomeric in benzene solution by cryoscopic molecular weight determination and has high volatility.

Methylene-bridged Group 13-15 compounds, R2MCH2PPh2 (R = CH2CMe3, CH2SiMe3; M = Ga,In). Crystal structure of [(Me3CCH2)2InCH2PPh2]2.cntdot.C6D6, a molecule containing an In-C-P-In-C-P ring in a chair conformation

Abstract : A series of compounds of the type R2MCH2PPh2 (R = CH2CMe3, CH2SiMe3; M = Ga, In) have been prepared by metathetical reactions between the appropriate diorganometal halide and LiCH2PPH2 in pentane or Et2O at -78 C. All compounds were characterized by physical properties, partial elemental analyses (C, H), cryoscopic molecular weight measurements in benzene solution as well as IR, H NMR and P NMR spectroscopic data. All appropriate data support the existence of dimeric molecules. The monomeric species dimerize by apparent Lewis acid-base interactions. These interactions are sufficiently strong that the compounds do not form stable adducts with oxygen- or nitrogen-containing Lewis bases.

Diphenylphosphide derivatives of dineopentylgallium and -indium. Crystal and molecular structures of [(Me3CCH2)2GaPPh2]2 and [(Me3CCH2)2InPPh2

Abstract : The two compounds, (Me3CCH2) 2MPPh2 (M=Ga, In) have been prepared by metathetical reactions between (Me3CCH2)2MCl and KPPh2 and fully characterized. The characterization data include elemental analyses (C,H), melting points, IR, H and P NMR spectral studies, cryoscopic molecular weight studies in benzene solution and single crystal X-ray structural studies. The gallium compound exists as a dimer in benzene solution and in the solid state.

Reduction of Cl 2Sn[Fe(CO) 2(η 5-C 5H 5)] 2 with lithium to form {:Sn[Fe(CO) 2(η 5-C 5H 5)] 2}

The reduction of Cl 2Sn[Fe(CO) 2(η 5-C 5H 5)] 2 ( 1) with lithium has been investigated. A species with one tin-tin bond, as shown by 119Sn NMR spectroscopy, believed to be [(η 5-C 5H 5)(CO) 2Fe]ClSn SnCl[Fe(CO) 2(η 5-C 5H 5) ( 2), is formed as an intermediate. Further reduction results in the formation of {:Sn[Fe(CO) 2(η 5-C 5H 5)] 2} ( 3), which has been characterized by spectroscopic and analytical methods and is monomeric in benzene solution, as determined by cryoscopic molecular weight determination. The reactivity of 2 and 3 are discussed.

Synthesis and characterization of four-membered gallium-arsenic ring compounds containing a bridging As(SiMe 3) 2 group: crystal structures of Ph 2[formula omitted]l and Ph 2[formula omitted

The first organogallium four-membered ring compounds with arsenic, halogen mixed bridging to be characterized completely, Ph 2 GaAs(SiMe 3) 2Ga(Ph) 2X (X = Cl ( 1) and X = Br ( 2)) were prepared by the reaction of (Me 3Si) 3As ( 3) with Ph 2GaCl and Ph 2GaBr, respectively. X-ray crystallographic analyses show the compounds to be isostructural with each containing a non-planar Ga-As-Ga-X four membered ring. Isomorphous crystals of 1 and 2 belong to the monoclinic system, space group P2 1/ c ( C 5 2 h ), with four molecules in unit cells of dimensions: a 10.560(3), b 15.797(3), c 20.591(4) Å, β 92.17(2)°, V 3433(2) Å 3 for 1, and a 10.653(1), b 15.777(2), c 20.517(2) Å, β 91.97(1)°, V 3446(1) Å 3 for 2. The non-planarity of the rings is manifested in the halogen atom displacements of 0.256 Å in 1 and 0.293 Å in 2 from the respective Ga-As-Ga′ planes. Deviations from overall C 2 v symmetry serve to relieve unfavorable intramolecular bulky ring substituent interactions present in such a symmetric form. The dimer [Ph 2GaAs(SiMe 3) 2] 2 ( 4), obtained from the reaction of Ph 2GaCl and LiAs(SiMe 3) 2, has been characterized by partial elemental analysis, NMR spectroscopy and cryoscopic molecular weight determination. An alternative route to the synthesis of 1 by reaction of 4 and Ph 2GaCl was investigated via NMR spectroscopy.

Chemical Vapor Deposition of Copper From Metal-Organic Copper(I) Phosphine Complexes

AbstractA series of new, molecular copper(I) compounds with the general formula (β-diketonate)Cu(PMe3) have been prepared which are specifically designed as precursors for the CVD of copper. These species have been designed such that the effects of systematic ligand variations on the CVD process can be examined. The series of derivatives where β-diketonate is one of hexafluoroacetylacetonate, 3, trifluoroacetylacetonate, 4, or acetylacetonate, 5, have been prepared in high yield and are described here. A solid state X-ray diffraction study of 3 reveals that it is monomeric. Cryoscopic molecular weight determination and gas phase FTIR spectroscopy are also consistent with a monomeric structure in liquid and gas phases. Hot-wall CVD of copper from these precursors has been examined under various conditions. Auger electron spectroscopy indicates that the films all exhibit some degree of carbon contamination, but little contamination by oxygen, fluorine or phosphorus.