Strontium- und Barium-bis[N,N′ -bis(trimethylsilyl)benzamidinate] aus der Additionsreaktion der Erdalkalimetall-bis[bis(trimethylsilyl)amide] mit Benzonitril

Strontium and Barium Bis[N,N′-bis(trimethylsilyl)benzamidinates] from the Addition Reaction of the Alkaline Earth Metal Bis[bis(trimethylsilyl)amides] and Benzonitrile The reaction of strontium bis[bis trimethylsilyl)amide] with benzonitrile yields strontium bis[N,N′- bis(trimethylsilyl)benzamidinate] · 2THF, which crystallizes in the orthorhombic space group Pbcn (a = 1845.4(3); b = 131 1,3(2); c = 1838,(3) pm; Z = 4). During the similar reaction of barium bis[bis(trimethylsilyl)amide] with benzonitrile the benzonitrile adduct barium bis[N,N′-bis(trimethylsilyl)benzamidinate] · 2 THF · benzonitrile is formed. After the addition of diphenylacetylene to the strontium di(benzamidinate) in diglyme a clathrate of the composition strontium bis[N,N′-bis(trimethylsilyl)benzamidinate] · diglyme · diphenylacetylene could be isolated; the spectroscopic data as well as the X-ray structure (monoclinic, C2/c, a = 1492.2(2); b = 1539.1(2); c = 2337.8(3)pm; Z = 4) confirm the isolated appearance of the acetylene molecule without interaction to the metal center in solution and in the solid state, respectively.     

Synthese von Magnesium-bis[N,N′-bis(trimethylsilyl)benzamidinat] als Bis(THF)- und Benzonitril-Addukt

Synthesis of Magnesium Bis[N,N′ -bis(trimethylsilyl)benzamidinate] as both Bis(THF) and Benzonitrile Adduct Magnesium bis[bis(trimethylsilyl)amide] 1 , reacts with benzonitrile in toluene at room temperature to yield magnesium bis[N,N′-bis(trimethylsilyl)benzamidinate]-benzonitrile(1/1) 2 . Addition of THF leads to a quantitative substitution of the benzonitrile ligand by two THF molecules. The performance of the addition reaction in THF yields magnesium bis[N,N′-bis(trimethylsilyl)benzamidinate] · THF(1/2) 3 . The upper benzonitrile complex 2 , crystallizes in the orthorhombic space group Pbcn with {a = 1383.2(2); b = 2589.1(4); c = 1133.7(1) pm; Z = 4}. The magnesium atom is coordinated distorted trigonal-bipyramidal, where the benzonitrile ligand lies within the equatorial plane. The axial bound nitrogen atom of the benzamidinate substitution shows with a value of 213 pm a slightly longer bond distance to the metal center than the one in the equatorial plane (210 pm). The steric strain within the benzamidinate ligand leads to an elongation of the silicon atoms out of the 1,3-diazaallylic moiety under an enlargement of the C? N? Si angle to 131°.     

Metallderivate von Molekülverbindungen. IV. Synthese,Struktur und Reaktivität des Lithium-[tris-(trimethylsilyl)silyl]tellanids · DME

Metal Derivatives of Molecular Compounds. IV Synthesis, Structure, and Reactivity of Lithium [Tris(trimethylsilyl)silyl]tellanide · DME Lithium tris(trimethylsilyl)silanide · 1,5 DME [3] and tellurium react in 1,2-dimethoxyethane to give colourless lithium [tris(trimethylsilyl)silyl]tellanide · DME ( 1 ). An X-ray structure determination {-150 · 3·C; P2₁/c; a = 1346.6(4); b = 1497.0(4); c = 1274.5(3) pm; β = 99.22(2)·; Z = 2 dimers; R = 0.030} shows the compound to be dimeric forming a planar Li? Te? Li? Te ring with two tris(trimethylsilyl)silyl substituents in a trans position. Three-coordinate tellurium is bound to the central silicon of the tris(trimethylsilyl)silyl group and to two lithium atoms; the two remaining sites of each four-coordinate lithium are occupied by the chelate ligand DME {Li? Te 278 and 284; Si? Te 250; Li? O 200 pm (2X); Te? Li? Te 105°; Li? Te? Li 75°; O? Li? O 84°}. The covalent radius of 154 pm as determined for the DME-complexed lithium in tellanide 1 is within the range of 155 ± 3 pm, also characteristic for similar compounds. In typical reactions of the tellanide 1 [tris(trimethylsilyl)silyl]tellane ( 2 ), methyl-[tris(trimethylsilyl)silyl]tellane ( 4 ) and bis[tris(trimethylsilyl)silyl]ditellane ( 5 ) are formed.     

Metallderivate von Molekülverbindungen. III. Molekül- und Kristallstruktur des Lithium-bis (trimethylsilyl)-phosphids · DME und des Lithium-dihydrogenphosphids · DME

Metal Derivatives of Molecular Compounds. III. Molecular and Crystal Structure of Lithium bis(trimethylsilyl)phosphide · DME and of Lithium dihydrogenphosphide · DME Lithium bis(trimethylsilyl)phosphide · DME 1 prepared from tris(trimethylsilyl)-phosphine and lithium methanide [2, 4] in 1,2-dimethoxyethane

1 1,2-Dimethoxyethan (DME); Tetrahydrofuran (THF); Bis[2-(dimethylamino)ethyl]methyl-amin (PMDETA).

, crystallizes in the orthorhombic space group Pnnn {a = 881.1(9); b = 1308.5(9); c = 1563.4(9) pm at ?120 ± 3°C; Z = 4 formula units}, lithium dihydrogenphosphide · DME 2 [10] prepared from phosphine and lithium- n -butanide in the same solvent, in P2 ₁ 2 ₁ 2 ₁ {a = 671.8(1); b = 878.6(1); c = 1332.2(2) pm at ?120 ± 3°C; Z = 4 formula units}. X-ray structure determinations (R _w = 0.036/0.045) show the bis(trimethylsilyl) derivative 1 to be dimeric with a planar P? Li? P? Li ring (P? Li 256 pm; Li? P? Li 76°; P? Li? P 104°), and the dihydrogenphosphide 2 to be polymeric with a linear Li? P? Li fragment (P? Li 254 to 260 pm; Li? P? Li 177°; P? Li? P 118°). The shortened P? Si distance (221 pm) of compound 1 and the structure of the PH ₂ group in 2 are discussed in detail. Lithium obtains its preferred coordination number 4 by a chelation with one molecule of 1,2-dimethoxyethane (Li? O 202 to 204 pm).     

Molekül- und Kristallstruktur von Magnesium-bis[bis(trimethylsilyl)phosphanid] · DME

Molecular and Crystal Structure of Magnesium Bis[bis(trimethylsilyl)phosphide] · DME Magnesium bis[bis(trimethylsilyl)phosphide] crystallizes in the tetragonal space group I4 c2 with a = 1652.9(2); c = 2282.6(5) pm and Z = 8. The magnesium atom is distorted tetrahedrally surrounded by two oxygen and two phosphorus atoms with Mg? P- and Mg? O-bond lengths of 248.7(2) and 204.7(5) pm, respectively. The phosphorus atom displays a trigonal pyramidal coordination.     

Synthese und Struktur von Lithium-tris(trimethylsilyl)silanid · 1,5 DME

Synthesis and Structure of Lithium Tris(trimethylsilyl)silanide · 1,5 DME Lithium tris(trimethylsilyl)silanide · 1,5 DME 2a synthesized from tetrakis(trimethylsilyl)silane 1 [6] and methyllithium in 1,2-dimethoxyethane , crystallizes in the monoclinic space group P2₁/c with following dimensions of the unit cell determined at a temperature of measurement of ?120 ± 2°C: a = 1 072.9(3); b = 1 408.3(4); c = 1 775.1(5) pm; β = 107.74(2)°; 4 formula units (Z = 2). An X-ray structure determination (R_w = 0.040) shows the compound to be built up from two [lithium tris(trimethylsilyl)silanide] moieties which are connected via a bridging DME molecule. Two remaining sites of each four-coordinate lithium atom are occupied by a chelating DME ligand. The Li? Si distance of 263 pm is considerably longer than the sum of covalent radii; further characteristic mean bond lengths and angles are: Si? Si 234, Li? O 200, O? C 144, O?O (biß) 264 pm; Si? Si? Si 104°, Li? Si? Si 107° to 126°; O? Li? O (inside the chelate ring) 83°. Unfortunately, di(tert-butyl)bis(trimethylsilyl)silane 17 prepared from di(tert-butyl)dichlorsilane 15 , chlorotrimethylsilane and lithium, does not react with alkyllithium compounds to give the analogous silanide.     

Synthesis,Spectroscopy and Crystal Structures of Chiral Organic Ammonium Tetrathiometalates Showing N‐H···S and C‐H···S Interactions

The reaction of ammonium tetrathiometalate (NH₄)₂[MS₄] (M = W or Mo) with the R(+) or S(?) forms of the organic amine α‐methylbenzylamine [PhCH(CH₃)NH₂] results in the formation of the corresponding non‐centrosymmetric bis(α‐methylbenzylammonium) tetrathiometalate complexes [PhCH(CH₃)NH₃]₂[MS₄] (R‐ammonium M = W 1 ; R‐ammonium M = Mo 2 ; S‐ammonium M = W 3 , S‐ammonium M = Mo 4 ) which were characterized by elemental analysis, IR, Raman, UV‐Vis and CD spectra, X‐ray powder diffractometry and single crystal X‐ray crystallography. Compounds 1 ‐ 4 crystallize in the chiral space group P2₁ and constitute the first examples of structurally characterized chiral organic ammonium group VI tetrathiometalates. The structures of 1 ‐ 4 consist of two crystallographically independent chiral organic ammonium cations and a tetrahedral tetrathiometalate dianion. The N‐H···S and C‐H···S interactions between the anions and cations organise them such that the organic ammonium ions always point towards the S atoms of [MS₄]^2?.     

Synthese und Kristallstruktur von [WNCl3 · NC–Ph]4 · 3 CH2Cl2

Synthesis and Crystal Structure of [WNCl₃ · NCPh]₄ · 3 CH₂Cl₂ The adduct of tungsten nitride trichloride with benzonitrile, [WNCl₃ · NCPh]₄, is formed by the reaction of N,N,N'-tris(trimethylsilyl)benzamidine and tungsten hexachloride in CCl₄ solution. It forms red crystal needles and was characterized by its IR spectrum and an X-ray crystal structure determination (1983 unique observed reflexions, R = 0.075). Crystal data: a = 1464.8, b = 1902.6, c = 2033.8 pm, β = 102.27°, space group C2/c, Z = 4. In the [WNCl₃ · NCPh]₄ molecule the tungsten atoms were located at the vertices of a square and are linked with one another via linear W?N? W nitrido bridges with alternating short and long bonds having average lengths of 166 and 211 pm. The N atoms of the benzonitrile ligands are in the positions trans to the W?N bonds at distances of 237 pm.     

New Fluoromanganate(III) Hydrates: Mn3F8 · 12H2O and AgMnF4 · 4H2O

Single crystals of fluoride hydrates Mn₃F₈ · 12 H₂O and AgMnF₄ · 4 H₂O have been prepared and characterized by X-ray methods. Mn₃F₈ · 12 H₂O crystallizes in the space group P1 (a = 623.0(3), b = 896.7(4), c = 931.8(4) pm, α = 110.07(2)°, β = 103.18(2)°, γ = 107.54(2)°, Z = 1); AgMnF₄ · 4 H₂O crystallizes in the space group P2₁/m (a = 700.9(2), b = 726.1(1), c = 749.4(3) pm, β = 107.17(3)°, Z = 2). Both structures contain Jahn-Teller-distorted [Mn(H₂O)₂F₄]^? anions as well as crystal water molecules and exhibit a complex hydrogen bond network between anions and cations, i. e. [Mn(H₂O)₆]²⁺ for the first and a polymeric [Ag(H₂O)₂]^? cation for the second compound.     

Synthese und Charakterisierung heterobimetallischer Bis(trimethylsilyl)phosphanide von Barium und Zinn

Synthesis and Characterization of Hetero-bimetallic Bis(trimethylsilyl)phosphanides of Barium and Tin The reaction of barium bis[bis(trimethylsilyl)amide] with one equivalent of bis(trimethylsilyl)phosphane in 1,2-dimethoxyethane (dme) yields the heteroleptic dimeric (dme)barium bis(trimethylsilyl)amide bis(trimethylsilyl)phosphanide. This colorless compound crystallizes in the monoclinic space group P2₁/n with a = 1 259.1(3), b = 1 822.7(4), c = 1 516.1(3) pm, β = 110.54(3)° and Z = 4. The central moiety of the centrosymmetric molecule is the planar Ba₂P₂-cycle with Ba? P-bond lengths of 329 and 334 pm. In the presence of bis[bis(trimethylsilyl)amino]stannylene hetero-bimetallic bis(trimethylsilyl)phosphanides of tin(II) and barium are isolated. If the reaction of Ba[N(SiMe₃)₂]₂ and Sn[N(SiMe₃)₂]₂ in the molar ratio of 1:2 with six equivalents of HP(SiMe₃)₂ is performed in toluene, barium bis{tin(II)-tris[bis(trimethylsilyl)phosphanide]} can be isolated. This compound crystallizes in the orthorhombic space group P2₁2₁2₁ with a = 1 265.1(1), b = 2 290.1(3), c = 2 731.9(3) pm and Z = 4. The anions {Sn[P(SiMe₃)₂]₃}^? bind as two-dentate ligands to the barium atom which shows the extraordinary low coordination number of four. The addition of tetrahydrofuran (thf) to the above mentioned reaction solution leads to the elimination of tris(trimethylsilyl)phosphane and the formation of thf complexes of barium bis{tin(II)-bis(trimethylsilyl)phosphanide-trimethylsilylphosphandiide}. The derivative crystallizes from toluene in the monoclinic space group P2₁/c with a = 1 301.9(2), b = 2 316.3(3), c = 3 968.7(5) pm, β = 99.29(1)° and Z = 8.     

Octahedral and Cyclic [Ag6] Cluster Cores Stabilized by {Ag3(Spz)3(N‐triphos)3} Motifs [HSpz = Pyrazine‐2‐thiolate,N‐triphos = Tris((diphenylphosphanyl)methyl)amine]: Ag···Ag Interactions

The complexes [Ag₁₂(Spz)₁₂(N‐triphos)₂][Ag₃(Spz)₃(N‐triphos)]₂ · (DMF)₆ ( 1 ) and [Ag₁₈(Spz)₁₂(N‐triphos)₄(CF₃CO₂)₆] ( 2 ) were synthesized and structurally characterized by X‐ray diffraction [HSpz = pyrazine‐2‐thiolate, N‐triphos = tris((diphenylphosphanyl)methyl)amine]. The central [Ag₆] ring with chair‐conformation in 1 and the ideally octahedral [Ag₆] cluster core in 2 are both stabilized by the tripodal building units of neutral [Ag₃(Spz)₃(N‐triphos)] compound. The Ag ··· Ag distances of the [Ag₆] moieties in 1 and 2 are 3.07 and 2.81 Å, respectively, exhibiting intermetallic interactions, which can enhance the stability of [Ag₆] conformations. In addition, the π ··· π interactions between parallel pyrazine rings could impose on the building and the Ag ··· Ag interactions of these Ag–S clusters.     

Reaktionen silylierter Phosphanimine mit Iodmonochlorid und Iodtrichlorid. Die Kristallstrukturen von [Me3SiNPMe3 · ICl], [Ph3PNCl · ICl] und [Me3PN(H)PMe3] [ICl2]2

Reactions of Silylated Phosphorane Imines with Iodine Monochloride and Iodine Trichloride. The Crystal Structures of [Me₃SiNPMe₃ · ICl], [Ph₃PNCl · ICl], and [Me₃PN(H)PMe₃][ICl₂]₂ The donor-acceptor complex [Me₃SiNPMe₃ · ICl] has been prepared from Me₃SiNPMe₃ and ICl in acetonitrile solution forming yellow-orange crystals. [Ph₃PNCl · ICl] can be prepared by the reaction of Me₃SiNPPh₃ with ICl₃ in dichloromethane solution forming pale yellow crystals. [Me₃PN(H)PMe₃][ICl₂]₂ is formed in a small amount by a slow reaction of Me₃SiNPMe₃ with ICl₃ in CCl₄ suspension in the presence of traces of moisture. All samples are characterized by IR spectroscopy and by X-ray structure analyses. [Me₃SiNPMe₃ · ICl] (1) : Space group Iba2, Z = 8, structure solution with 1 727 observed unique reflections, R = 0.051. Lattice dimensions at ?60°C: a = 1 510.7, b = 1 862.8, c = 988.9 pm. 1 has a molecular structure in which the N atom of the phosphorane imine is connected with the iodine atom of the ICl molecule in a linear arrangement N? I? Cl. Bond lengths N? I = 222.7 pm, I? Cl = 265.1 pm. [Ph₃PNCl · ICl] (2) : Space group Pna2₁, Z = 4, structure solution with 1 530 observed unique reflections, R = 0.030. Lattice dimensions at 20°C: a = 1 522.8, b = 1 408.3, c = 865.8 pm. 2 has a molecular structure in which the N atom of the N chlorophosphorane imine is connected with the iodine atom of the ICl molecule in a linear arrangement. Bond lengths N? Cl = 174.4 pm, N? I = 229.5 pm, I? Cl = 251.2 pm. [Me₃PN(H)PMe₃][ICl₂]₂ (3) : Space group P2₁/c, Z = 4, structure solution with 1 989 observed unique reflections, R = 0.029. Lattice dimensions at ?50°C: a = 1 223.1, b = 1 090.2, c = 1 482.8 pm, β = 112.21°. 3 consists of [Me₃PN(H)PMe₃]²⁺ ions and ICl₂^? anions. The PNP bond angle of the dication amounts to 134.4° with PN distances of 165.6 and 166.1 pm, approximately according to double bonds.     

Reaktionen des [η2-{P–PtBu2}Pt(PPh3)2] und [η2-{P–PtBu2}Pt(dppe)] mit Metallcarbonylen. Bildung von [η2-{(CO)5M · PPtBu2}Pt(PPh3)2] (M = Cr,W) und [η2-{(CO)5Cr · PPtBu2}Pt(dppe)]

Coordination Chemistry of P-rich Phosphanes and Silylphosphanes. XVI [1] Reactions of [g²-{P–P^tBu₂}Pt(PPh₃)₂] and [g²-{P–P^tBu₂}Pt(dppe)] with Metal Carbonyls. Formation of [g²-{(CO)₅M · PP^tBu₂}Pt(PPh₃)₂] (M = Cr, W) and [g²-{(CO)₅Cr · PP^tBu₂}Pt(dppe)] [η²-{P–P^tBu₂}Pt(PPh₃)₂] 4 reacts with M(CO)₅ · THF (M = Cr, W) by adding the M(CO)₅ group to the phosphinophosphinidene ligand yielding [η²-{(CO)₅Cr · PP^tBu₂}Pt(PPh₃)₂] 1 , or [η²-{(CO)₅W · PP^tBu₂}Pt(PPh₃)₂] 2 , respectively. Similarly, [η²-{P–P^tBu₂}Pt(dppe)] 5 yields [η²-{(CO)₅Cr · PP^tBu₂}Pt(dppe)] 3 . Compounds 1 , 2 and 3 are characterized by their ¹H- and ³¹P-NMR spectra, for 2 and 3 also crystal structure determinations were performed. 2 crystallizes in the monoclinic space group P2₁/n (no. 14) with a = 1422.7(1) pm, b = 1509.3(1) pm, c = 2262.4(2) pm, β = 103.669(9)°. 3 crystallizes in the triclinic space group P1 (no. 2) with a = 1064.55(9) pm, b = 1149.9(1) pm, c = 1693.2(1) pm, α = 88.020(8)°, β = 72.524(7)°, γ = 85.850(8)°.     

Influence of substitution on the strength and nature of CH···N hydrogen bond in XCCH···NH3 complexes

The effect of substitution on the strength and nature of CH···N hydrogen bond in XCCH···NH₃ (X = F, Cl, Br, OH, H, Me) and NCH···NH₃ complexes were investigated by quantum chemical calculations. Ab initio calculations were performed using MP2 method with a wide range of basis sets. With tacking into account the BSSE and ZPVE, the values of BEs decrease. Replacement of the nonparticipatory hydrogen atom of HCCH by the electronegative atoms (F, Cl, and Br), lead to the BEs increases. The BE corresponding to the replacement of the nonparticipatory hydrogen atom of HCCH by the OH and CH₃ groups decreases. A far greater enhancement of the interaction energy arises from replacement of HCCH by the more acidic HCN. The natural bond orbital analysis and the Bader's quantum theory of atoms in molecules were also used to elucidate the interaction characteristics of these complexes. The electrostatic nature of H‐bond interactions is predicted from QTAIM analysis. In addition, the relationship between the isotropic and anisotropic chemical shifts of the bridging hydrogen and binding energy of complexes as well as electron density at N···H BCPs were investigated. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Alkylidinphosphane und -arsane. I [P ≡ C?S]−[Li(dme)3]+ – Synthese und Struktur

Alkylidynephosphanes and -arsanes. I [P ≡ C? S]^?[Li(dme)₃]⁺ – Synthesis and Structure O,O′-Diethyl thiocarbonate and bis(tetrahydrofuran)-lithium bis(trimethylsilyl)phosphanide dissolved in 1,2-dimethoxyethane, react below 0°C to give ethoxy trimethylsilane and tris(1,2-dimethoxyethane-O,O′)lithium 2λ³-phosphaethynylsulfanide – [P≡C? S]^? [Li(dme)₃]⁺ – ( 1a ). Apart from bis(trimethylsilyl)sulfane or carbon oxide sulfide, dark red concentrated solutions of λ³-phosphaalkyne 1 are also obtained from reactions of carbon disulfide with bis(tetrahydrofuran)-lithium bis(trimethylsilyl)phosphanide or with the homologous lithoxy-methylidynephosphane ( 2 ) [1]. The ir spectrum shows two absorptions at 1762 and 747 cm^?1 characteristic for the P≡C and C? S stretching vibrations. The nmr parameters {δ(³¹P) ? 121.3; δ(¹³C) 190.8 ppm; ¹J_CP 18.2 Hz} resemble much more values of diorganylamino-2λ³-phosphaalkynes than those of bis(1,2-dimethoxyethane-O,O′)lithoxy-methylidyne-phosphane ( 2a ). As found by an X-ray structure analysis (P2₁/c; a = 1192.6(16); b = 1239.1(19); c = 1414.8(26) pm; β = 105.91(13)° at ?100 ± 3°C; Z = 4 formula units; wR = 0.064) of pale yellow crystals (mp. + 16°C) isolated from the reaction with O,O′-diethyl thiocarbonate, the solid is built up of separate [P≡C? S]^? and [Li(dme)₃]⁺ ions. Typical bond lengths and angles are: P≡C 155.5(11); C? S 162.0(11); Li? O 206.4(17) to 220.3(20) pm; P≡C? S 178.9(7)°.     

Synthese,Eigenschaften und Struktur von Amin-Addukten der Lithium-tris[bis(trimethylsilyl)methyl]zinkate

Synthesis, Properties, and Structure of the Amine Adducts of Lithium Tris[bis(trimethylsilyl)methyl]zincates . Bis[bis(trimethylsilyl)methyl]zinc and the aliphatic amine 1,3,5-trimethyl-1,3,5-triazinane (tmta) yield in n-pentane the 1:1 adduct, the tmta molecule bonds as an unidentate ligand to the zinc atom. Bis[bis(trimethylsilyl)methyl]zinc · tmta crystallizes in the triclinic space group P1 with {a = 897.7(3); b = 1 114.4(4); c = 1 627.6(6) pm; α = 90.52(1); β = 103.26(1); γ = 102.09(1)°; Z = 2}. The central C₂ZnN moiety displays a nearly T-shaped configuration with a CZnC angle of 157° and Zn? C bond lengths of 199 pm. The Zn? N distances of 239 pm are remarkably long and resemble the loose coordination of this amine; a nearly complete dissociation of this complex is also observed in benzene. The addition of aliphatic amines such as tmta or tmeda to an equimolar etheral solution of lithium bis(trimethylsilyl)methanide and bis[bis(trimethylsilyl)methyl]zinc leads to the formation of the amine adducts of lithium tris[bis(trimethylsilyl)methyl]zincate. Lithium tris[bis(trimethylsilyl)methyl]zincate · tmeda · 2 Et₂O crystallizes in the orthorhombic space group Pbca with {a = 1 920.2(4); b = 2 243.7(5); c = 2 390.9(5) pm; Z = 8}. In the solid state solvent separated ions are observed; the lithium cation is distorted tetrahedrally surrounded by the two nitrogen atoms of the tmeda ligand and the oxygen atoms of both the diethylether molecules. The zinc atom is trigonal planar coordinated; the long Zn? C bonds with a value of 209 pm can be attributed to the steric and electrostatic repulsion of the three carbanionic bis(trimethylsilyl)methyl substituents.     

Acyl- und Alkylidenphosphane. XXVIII. Synthese und Struktur von 1,3-Dibenzyl- und 1,3-Diethyl-2,4-bis(phenylimino)-1,3-diphosphetan

Acyl- and Alkylidenephosphines. XXVIII. Synthesis and Structure of 1,3-Dibenzyl- and 1,3-Diethyl-2,4-bis(phenylimino)-1,3-diphosphetane Catalyzed by small amounts of solid sodium hydroxide, the adducts 1a and 1b formed from benzyl- or ethylbis(trimethylsilyl)phosphine and phenylisocyanate, react at +20°C slowly to give hexamethldisiloxane and oligomeric [(phenylimino)methylidene]phosphines. In different solvents the benzyl compound was found to exist only as a mixture of [N,N′-(E)/(Z)]-isomeric 2,4-bis-(phenylimino)-1,3-diphosphetanes 2a with their alkyl groups at the phosphorus atoms in trans position, whereas in case of the ethyl derivative 2b a second pair of [N,N′-(E)/(Z)]-isomeric dimers with their substituents in cis position and two trimeric forms ( 3b and 4b ) could be detected in cyclopentane. [N,N′-(E)]-1r,3t-dibenzyl- ( 2a ) and [N,N′-(E)]-1r,3t-diethyl-2,4-bis(phenylimino)-1,3-diphosphetane 2b isolated from 1,2-dimethoxyethane or cyclopentane, crystallize in the monoclinic space group P2₁/c or P2₁/n, resp., with following dimensions of the unit cell determined at temperatures of measurement of +20 ± 3°C/?130 ± 3°C: a = 2145.4(1)/569.3(1); b = 568.1(2)/719.1(2); c = 1960.2(2)/2042.6(4) pm; β 99.43(1)°/95.03(2)°; Z = (2+2) and 2, resp. X-ray structure determinations (R_w = 0.034/0.041) show both molecules to be centrosymmetric. Characteristic rounded bond lengths (pm) and angles (°) are: endocyclic P? C 185/184; C? P? C 82/81; P? C? P 98/99; exocyclic P? C 186/184; C?N l27/127; C?N? C 121/11.     

Trimethylsilylverbindungen der Vb-Elemente. V. Molekül- und Kristallstruktur des Lithium-bis(trimethylsilyl)-arsenids · DME

Trimethylsilyl Derivatives of Vb-Elements. V. Molecular and Crystal Structure of Lithium Bis(trimethylsilyl)arsenide · DME Lithium bis(trimethylsilyl)arsenide · DME 1 obtained from tris(trimethylsilyl)-arsine and n-butyl or methyl lithium in 1,2-dimethoxyethane crystallizes monoclinic with {a = 1813(3); b = 1327(3); c = 968(1) pm; β = 119.3(1)°; Z = 4} at +20°C. Experimental conditions unfavourable for an X-ray structure determination caused high standard deviations of all structural parameters. The refinements of these values calculated with respect to the centrosymmetric space group C2/m converged at a relatively high R-value of 0.090. In contrast to the homologous antimonide lithium bis(trimethylsilyl)arsenide · DME 1 is found to be dimeric in solution as well as in the solid state. The four-membered ring built up by bis(trimethylsilyl)arsino groups and DME-coordinated lithium atoms in alternating sequence is planar; the carbon atoms statistically occupy positions on both sides of a mirror plane. Characteristic bond lengths and angles are: As? Si 230.7(7); As? Li 259(2); Li? O 205(4) and 215(4) pm; Si? As? Si 103.2(4)°; Li? As? Li 81(1)°; As? Li? As 99(1)° and Li? As? Si 115(1)°.     

A DFT study of Lp···π/halogen bond competition in complexes of perhalogenated alkenes with oxygen/nitrogen containing simple molecules

The possible noncovalent lone pair‐π/halogen bond (lp···π/HaB) complexes of perhalogenated unsaturated C₂Cl_nF_4?n (n = 0–4) molecules with four simple molecules containing oxygen or nitrogen as electron donor, formaldehyde (H₂CO), dimethyl ether (DME), NH₃, and trimethylamine (TMA), have been systematically examined at the M062X/aug‐cc‐pVTZ level. Natural bond orbital (NBO) analysis at the same level is used for understanding the electron density distributions of these complexes. The progressive introduction of Cl atom on C₂Cl_nF_4?n influences more on the lp···π complexes over the corresponding HaB ones. Within the scope of this study, gem‐C₂Cl₂F₂ is the best partner molecule for lp···π interaction with the simple molecules, coupled with the greatest interaction energy (IE) and second‐order orbital interaction [E(2) value], whereas C₂F₄ is the poorest one. The C₂Cl₃F·H₂CO and C₂Cl₄·H₂CO complexes exhibit reverse lp···π bonding, while the Z/E‐C₂Cl₂F₂·NH₃, C₂Cl₃F·NH₃ and C₂Cl₄·NH₃ complexes perform half‐lp···π bonding according to the NBO analysis. The lp···π interaction involving the oxygen/nitrogen and the π‐hole of C₂Cl_nF_4?n overwhelms the HaB involving the oxygen/nitrogen and the σ‐hole of the Cl atom. The electron‐donating methyl groups contribute significantly to the two competitive interactions, therefore, DME and TMA engage stronger in the partner molecules than H₂CO and NH₃. Our theoretical study would be useful for future experimental investigation on noncovalent complexes. © 2016 Wiley Periodicals, Inc.     

Metallderivate von Molekülverbindungen. VI. Lithium- und (Tetrahydrofuran)lithium-cyantrimethylsilylamid — Synthese und Struktur

Metal Derivatives of Molecular Compounds. VI. Lithium and (Tetrahydrofuran)lithium Cyanotrimethylsilylamide — Syntheses and Structures At different temperatures N,N′-bis(trimethylsilyl)carbodiimide ( 1 ) and lithium methanide react either under addition or substitution. When compound 1 , however, is treated at ?40°C with an equimolar amount of (1,2-dimethoxyethane-O,O′)lithium phosphanide ( 2 ) in 1,2-dimethoxyethane, only exchange of one trimethylsilyl group versus lithium is observed and in addition to phosphane and tris(trimethylsilyl)phosphane a very pure lithium derivative insoluble in n-pentane can be isolated. The vibrational spectra prove the compound to be lithium cyanotrimethylsilylamide ( 3 ). Recrystallization from tetrahydrofuran (+40/+20°C) yields (tetrahydrofuran)lithium cyanotrimethylsilylamide ( 3 ′). As shown by an X-ray structure analysis {C2/c; a = 2 261.1(5); b = 1 106.4(2); c = 1 045.9(2) pm; β = 113.63(1)°; Z = 8 formula units}, compound 3 ′ is polymeric in the solid state. Coordinative Li? N2′ bonds allow a head-to-tail addition of two monomeric units each to give an eight-membered heterocycle with two linear N1? C2≡N2 fragments (N1? C2 126.1; C2≡N2 117.5; N1? Si 171.4; Li? N1 203.2; Li? N2′ 206.1 pm; C2? N1? Li 109.0; N1? Li? N2′ 115.9; N2≡C2? N1 177.2°). Forming planar four-membered Li? N2? Li? N2 rings (Li? N2″″ 198.3 pm; Li′? N2? Li″ 80.3; N2′? Li? N2″″ 99.5°) these heterocycles polymerize to slightly folded tapes.