Synthese und Molekülstruktur von Li[(Me2NCH2CH2CH2)4Yb]

Preparation and Structure of Li[(Me₂NCH₂CH₂CH₂)₄Yb] YbCl₃ reacts with dimethylaminopropyl lithium in tetrahydrofuran with formation of Li[(Me₂NCH₂CH₂CH₂)₄Yb]. The X-ray structure determination proves the formation of chelat rings by two of the ligands. The nitrogens of the other two ligands are coordinated to the lithium. The compound crystallizes in the monoclinic space group C2/c with the unit cell parameters a = 27.854(8) Å, b = 9.183(3) Å, c = 20.125(8) Å, β = 96.40° and Z = 8.     

The trans-Influence in Platinum (II) Complexes. 1H- and 13C-NMR. and X-ray structural studies of tridentate Schiff's base complexes of platinum (II)

¹H- and ¹³C-NMR. data are reported for the complexes [Pt (1) L] and [Pt (2) L]; 1 = OC₆H₄CH ? NCH₂CH₂O, 2 = OC₆H₄CH ? NC₆H₄O; L = PR₃, AsR₃, C ? N (cyclohexyl), DMSO, pyridine, secondary amine. The molecular structures of [Pt (2) (NHEt₂)] (I) and [Pt (2) (PPh₃)] (II) have been determined by X-ray analysis. Relevant bond distances for I: Pt-N (amine) = 2.076 Å, Pt-N (imine) = 2.017 Å, Pt-O = 1.992 Å and 2.002 Å; for II: Pt-P = 2.248 Å, Pt-N = 2.064 Å, Pt-O = 1.964 and 2.005 Å. Both the solid and solution state data are interpreted in terms of differences in the trans influence of the ligand L. The question of metal-ligand d-p π back bonding to the imine is discussed.     

Gemischtligandkomplexe des Technetiums. XV. Zur Reaktion von [TcNCl2(Me2PhP)3] mit Dialkyldithiocarbamaten und N,N-Dialkylthiocarbamoylbenzamidinen

Mixed-ligand Complexes of Technetium. XV. The Reaction of [TcNCl₂(Me₂PhP)₃] with Dialkyldithiocarbamates and N,N-Dialkylthio-carbamoylbenzamidines [TcN(Cl)(Me₂PhP)₂(Et₂dtc)], [TcN(Me₂PhP)(Et₂dtc)₂], and [TcN(Et₂dtc)₂] can be prepared by stepwise ligand exchange reactions starting from dichlorotris(dimethylphenylphosphine)nitridotechnetium(V), [TcNCl₂(Me₂PhP)₃], and diethyldithiocarbamate. In contrast to this, only one intermediate, [TcN(Cl)(Me₂PhP)₂(HEt₂tcb)], could be isolated during the reaction with N,N-Diethlthiocarbamoylbenzamidine, which yields the bis chelate [TcN(HEt₂tcb)₂]. [TcN(Me₂PhP)(Et₂dtc)₂] crystallizes in the monoclinic space group P2₁/c; a = 17.369(5) Å, b = 15.024(1) Å, c = 9.906(3) Å, β = 76.47(1)º, Z = 4. The phosphine is coordinated equatorially. The multiply bonded nitrogen ligand (Tc? N(1) 1.624(3) Å) strongly labilizes the trans positioned donor atom (distance Tc? S(4) 2.826(1) Å). [TcN(HEt₂tcb)₂] crystallizes in the triclinic space group P1 with a = 9.749(4) Å, b = 11.264(4) Å, c = 12.359(4) Å, α = 75.34(2)º, β = 79.69(2)º, γ = 87.55(2)º, Z = 2. The metal is five-coordinate with the nitrido donor atom occupying the apex of a square pyramid. It's basal plane is formed by the cis-coordinated chelate ligands. The technetium is situated over the basal plane by about 0.6 Å. The Tc?N distane was found to be 1.610(5) Å.     

Gemischtligandkomplexe des Rheniums. IX. Reaktionen am Nitridoliganden von [ReN(Me2PhP)(Et2dtc)2]. Synthese,Charakterisierung und Kristallstrukturen von [Re(NBCl3)(Me2PhP)(Et2dtc)2], [Re(NGaCl3)(Me2PhP)(Et2dtc)2] und [Re(NS)Cl(Me2PhP)2(Et2dtc)]

Mixed-ligand Complexes of Rhenium. IX. Reactions on the Nitrido Ligand of [ReN(Me₂PhP)(Et₂dtc)₂]. Synthesis, Characterization, and Structures of [Re(NBCl₃)(Me₂PhP)(Et₂dtc)₂], [Re(NGaCl₃)(Me₂PhP)(Et₂dtc)₂], and [Re(NS)Cl(Me₂PhP)₂(Et₂dtc)] BCl₃, GaCl₃ and S₂Cl₂ react with the well-known [ReN(Me₂PhP)(Et₂dtc)₂] by attack of the nucleophilic nitrido ligand. Final products of these reactions are [Re(NBCl₃)-(Me₂PhP)(Et₂dtc)₂], [Re(NGaCl₃)(Me₂PhP)(Et₂dtc)₂], and [Re(NS)Cl(Me₂PhP)₂Et₂dtc)] which have been studied by mass spectrometry, IR spectroscopy and X-ray diffraction. [Re(NBCl₃)(Me₂PhP)(Et₂dtc)₂] crystallizes in the triclinic space group P1 , Z = 2, a = 8.151(6), b = 9.935(8), c = 18.67(1) Å; α = 94.42(4), β = 97.09(1), γ = 101.35(4)°. The coordination geometry is a distorted octahedron. The equatorial coordination sphere is occupied by one phosphorus and three sulphur atoms. The fourth sulphur atom is in trans position to the Re?N? B moiety. The almost linear Re?N? B unit has an Re?N? B angle of 170.5(3)° with a Re? N bond length of 1.704(3) Å. The analogous [Re(NGaCl₃)(Me₂PhP)(Et₂dtc)₂] crystallizes in P2₁/c with a = 8.138(3), b = 18.279(2), c = 19.880(6) Å; β = 99.81(2)°; Z = 4. Rhenium has a distorted octahedral environment. The Re? N? Ga bond is slightly bent with an angle of 154.5(4)° and a Re? N bond length of 1.695(6) Å. [Re(NS)Cl(Me₂PhP)₂(Et₂dtc)] crystallizes in the triclinic space group P1 , Z = 4, a = 9.514(2); b = 16.266(5); c = 18.388(3) Å; α = 88.75(2), β = 76.59(2), γ = 85.50(2)° with two crystallographically independent molecules in the asymmetric unit. Rhenium has a distorted octahedral environment with the chloro ligand in trans position to the almost linear thionitrosyl group. The Re?N bond lengths are 1.795(6) and 1.72(1) Å, respectively, and the N?S distances are 1.55(1) and 1.59(1) Å, respectively.     

Star poly(methyl methacrylate) with end‐functionalized arm chains by ruthenium‐catalyzed living radical polymerization

Star polymers with end‐functionalized arm chains (surface‐functionalized star polymers) were synthesized by the in situ linking reaction between ethylene glycol dimethacrylate (linking agent) and an α‐end‐functionalized linear living poly(methyl methacrylate) in RuCl₂(PPh₃)₃‐catalyzed living radical polymerization; the terminal on the surface functionalities included amides, alcohols, amines, and esters. The star polymers were obtained in high yields (75–90%) with initiating systems consisting of a functionalized 2‐chloro‐2‐phenylacetate or ‐acetamide [F? C(O)CHPhCl; F = nPrNH? , HOCH₂CH₂O? , Me₂NCH₂CH₂O? , or EtO? ; initiator] and n‐Bu₃N (additive). The yield was lower with a functionalized 2‐bromoisobutyrate [Me₂NCH₂CH₂OC(O)CMe₂Br] initiator or with Al(Oi‐Pr)₃ as an additive. Multi‐angle laser light scattering analysis showed that the star polymers had arm numbers of 10–100, radii of gyration of 6–23 nm, and weight‐average molecular weights of 1.3 × 10⁵ to 3.0 × 10⁶, which could be controlled by the molar ratio of the linking agent to the linear living polymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1972–1982, 2002     

Reaction of 3-dimethylamino-(1,1 -dimethyl) propyl magnesium chloride with tin (IV) and tin (II) chlorides. Stabilization of a SnCl+ cation in the new tin cluster [Me2NCH2CH2C(Me2)SnCl]3 · SnCl2

The reactions of the functional Grignard reagent Me₂ NCH₂CH₂C(Me₂)MgCl (4) with tin tetrachloride, dimethyltin dichloride, and tin (II) chloride are described. From the reactions the compounds bis(3-dimethylamino-1,1-dimethylpropyl) tin dichloride, [Me₂NCH₂CH₂C(Me₂)]₂SnCl₂ (5) , dimethyl(3-dimethylamino-1,1-dimethylpropyl) chlorostannane, Me₂ClSnC(Me₂)CH₂CH₂NMe₂ (6) , 1,1,2,2-tetramethyl-1,2-bis(3-dimethylamino-1,1-dimethylpropyl) distannane,[Me₂SnC(Me₂)CH₂CH₂NMe₂]₂ (7) , 3-dimethylamino-(1,1-dimethyl)propyl tin (II) chloride, Me₂NCH₂CH₂C(Me₂)SnCl (8) , hexakis(3-dimethylamino-1,1-dimethylpropyl) cyclotristannane, {[Me₂NCH₂CH₂C(Me₂)]₂Sn}₃ (9a) , and the tin cluster [Me₂NCH₂CH₂C(Me₂)SnCl]₃ · SnCl₂ (10) have been isolated and characterized by means of multinuclear NMR and Mössbauer spectroscopy, and X-ray diffraction. 10 crystallizes in the trigonal space group P3₁ with the unit cell dimensions a 11.938, c 21.873 Å, V 2699.6 ų Z = 3. The structure was refined to a final R value of 0.064. 10 represents a tetranuclear cluster the skeleton of which is composed out of 4 Sn and a bridging Cl. Formally, the central tin atom is a SnCl⁺ cation stabilized by three stannylene units in a Ψ-trigonal bipyramidal environment. The tin-tin bond lengths are 288.2, 287.3 and 315.6 pm. The intramolecular Sn? N interactions amount to 242.8, 247.4 and 221.0 pm.     

Synthesis and Characterization of Metal Complexes (M = Al,Ti, W,Zn) Containing Pyrrole‐imine Ligands

A series of metal compounds (M = Al, Ti, W, and Zn) containing pyrrole‐imine ligands have been prepared and structurally characterized. The reactions of AlMe₃ with one and three equivs of pyrrole‐imine ligand [C₄H₃NH‐(2‐CH=N? CH₂Ph)] ( 1 ) generated aluminum compounds Al[C₄H₃N‐(2‐CH=N? CH₂Ph)]Me₂ ( 2 ) and Al[C₄H₃N‐(2‐CH=NCH₂Ph)]₃ ( 3 ), respectively, in relatively high yield. Reacting two equivs of 1 with Ti(OⁱPr)₄, W(NH^tBu)₂(=N^tBu)₂, or ZnMe₂ afforded Ti[C₄H₃N‐(2‐CH=NCH₂Ph)]₂(OⁱPr)₂ ( 4 ), W[C₄H₃N‐(2‐CH=NCH₂Ph)]₂(=N^tBu)₂ ( 5 ), and Zn[C₄H₃N‐(2‐CH=NCH₂Ph)]₂ ( 6 ), respectively. All the compounds have been characterized by ¹H and ¹³C NMR spectroscopy. Compounds 3 – 6 have also been characterized by single‐crystal X‐ray structural analysis. The biting angles of pyrrole‐imine ligand with metals decrease and their related M? N_pyrrole and M? N_imine bond lengths increase in the order of 6 , 3 , 4 , and 5 .     

Darstellung und Eigenschaften von 3-(N,N-Dimethylamino)propyl-Verbindungen des Thalliums

Preparation and Properties of 3-(N,N-Dimethylamino)propyl Thallium Compounds TlCl₃ reacts with Me₂NCH₂CH₂CH₂Li in molar ratio 1:2 with formation of (Me₂NCH₂CH₂CH₂)₂TlCl ( 1 ) which can be transfered with MeLi into (Me₂NCH₂CH₂CH₂)₂TlMe ( 2 ) and with excess of Me₂NCH₂CH₂CH₂Li into (Me₂NCH₂CH₂CH₂)₃Tl ( 3 ) respectively. Comproportionation of 1 with TlCl₃ yields rather instable Me₂NCH₂CH₂CH₂TlCl₂ ( 4 ) from which Me₂NCH₂CH₂CH₂TlMe₂ ( 5 ) can be obtained by alkylation with MeLi. 1–3 and 5 were characterized by elemental analysis, mass spectra, ¹H- and ¹³C-n.m.r. spectra.     

Transient Silenes as Versatile Synthons – The Reaction of Dichloromethyl‐tris(trimethylsilyl)silane with Organolithium Reagents

Treatment of dichloromethyl‐tris(trimethylsilyl)silane (Me₃Si)₃Si–CHCl₂ ( 1 ), prepared by the reaction of tris(trimethylsilyl)silane with chloroform in presence of potassium tertbutoxide, with organolithium reagents (molar ratio 1 : 3) affords the bis(trimethylsilyl)methyl‐disilanes Me₃SiSiR₂–CH(SiMe₃)₂ ( 12 a–d ) ( a : R = Me, b : R = n‐Bu, c : R = Ph, d : R = Mes). The formation of 12 a–d is discussed as proceeding through an exceptional series of isomerization and addition reactions involving intermediate silyl substituted carbenoids and transient silenes. The carbenoid (Me₃Si)₂PhSi–C(SiMe₃)LiCl ( 8 c ) is moderately stable at low temperature and was trapped with water to give (Me₃Si)₂PhSi–CH(SiMe₃)Cl ( 9 c ) and with chlorotrimethylsilane affording (Me₃Si)₂PhSi–CCl(SiMe₃)₂ ( 7 c ). For 12 d an X‐ray crystal structure analysis was performed, which characterizes the compound as a highly congested silane with bond parameters significantly deviating from standard values.     

Polyhydrogenchloride: Bildung und Kristallstruktur der tiefschmelzenden Addukte Me2S · 4HCl und Me2S · 5HCl

Poly(hydrogen chlorides): Formation and Crystal Structure of the Low-melting Adducts Me₂S · 4HCl and Me₂S · 5HCl The melting diagram of the system dimethylsulfide-hydrogen chloride has been determined using difference thermal analysis. It shows the existence of three adducts Me₂S · nHCl with n = 1, 4 and 5 as well as melting points of ?91, ?53 and ?80°C (decomposition), respectively. The two phases richest in HCl have been further characterized by crystal structure analysis. Me₂S · 4HCl is orthorhombic with space group Pnma and Z = 4 formula units per unit cell of dimensions a = 14.842, b = 9.747 and c = 6.652 Å at ?150°C. Me₂S · 5HCl is monoclinic with P2₁/n and Z = 4 as well as a = 7.292, b = 12.537, c = 12.479 Å and β = 92.73° at ?168°C. The R values obtained with 1737 and 3047 independent observed reflections are 0.039 and 0.045, respectively. Both structures are ionic, according to [Me₂SH][Cl(HCl)_n?1], and shaped by hydrogen bonding.     

Gemischtligand-Komplexe des Rheniums. IV. Die Reaktion von [ReNCl2(Me2PhP)3] mit Dithiocarbamaten. Kristallstrukturen von trans-Chloro-dimethyldithiocarbamato-bis(dimethylphenylphosphan) nitridorhenium(V), [ReN(Cl)(Me2PhP)2(Me2dtc)], und Bis(diethyldithiocarbamato)(dimethylphenylphosphan)nitridorhenium(V), [ReN(Me2PhP)(Et2dtc)2]

Mixed-Ligand Complexes of Rhenium IV. The Reaction of [ReNCl₂(Me₂PhP)₃] with Dithiocarbamates. X-Ray Crystal Structures of trans-Chloro-dimethyldithiocarbamato-bis(dimethylphenylphosphine) nitridorhenium(V), [ReN(Cl)(Me₂PhP)₂(Me₂dtc)], and Bis(diethyldithiocarbamato)(dimethylphenylphosphine)nitridorhenium(V), [ReN(Cl)(Me₂PhP)(Et₂dtc)₂] [ReNCl₂(Me₂PhP)₃] reacts with dialkyldithiocarbamates, R₂dtc^?, under a stepwise ligand exchange. Final products of these reactions are the well-known [ReN(R₂dtc)₂] bischelates. Intermediatelly, however, complexes of the general formulae [ReN(Cl)(Me₂PhP)₂(R₂dtc)] and [ReN(Me₂PhP)(R₂dtc)₂] can be isolated. Representatives have been structurally characterized. [ReN(Cl)(Me₂PhP)₂(Me₂dtc)] crystallizes monoclinic in the space group P2₁/c, Z = 4. The dimensions of the unit cell are a = 13.071(3); b = 11.622(1); c = 15.667(3) Å; β = 97.09(1)°. The rhenium atom has a distorted octahedral environment; the Re≡N bond length is 1.71(1) Å. The Re? Cl bond distance is markedly lengthened (2.665(2) Å) as a consequence of the strong trans labilizing influence of the coordinated nitrido ligand. [ReN(Me₂PhP)(Et₂dtc)₂] crystallizes monoclinic in the space group P2₁/c, Z = 4, a = 17.262(3); b = 14.915(2); c = 9.888(2); β = 76.35(8)°. The equatorial coordination sphere is occupied by one phosphorus atom and three sulphur atoms. One of the dithiocarbamate ligands is coordinated bidentately; the second one with two distinct Re? S bond lengths. The Re? S(4) distance is 2.7983(2) Å which can be discussed as a weak interaction with the metal.     

Synthese und Kristallstruktur des trimeren [(Me3Si)2CH]2Al?CN

Synthesis and Crystal Structure of the Trimeric [(Me₃Si)₂CH]₂Al? CN Tetrakis[bis(trimethylsilyl)methyl]dialane(4) 1 with an Al? Al bond reacts with tert-butyl isocyanide in the molar ratio of 1:2 within three days to give a mixture of several unknown products, from which the title compound 4 is isolated in a 26% yield by recrystallization from n-pentane. 4 is a trimer in the solid state via Al? C?N? Al bridges showing a nine-membered Al₃C₃N₃ heterocycle in a boat conformation. In contrary to the reaction with phenyl isocyanide the expected dark red product of the twofold insertion into the Al? Al bond under formation of a carbon-carbon single bond is detected only spectroscopically as a minor by-product.     

A Tetrameric Neodymium Silanolate: [Nd(OSiMe3)3]4

The title compound [Nd(OSiMe₃)₃]₄ ( 1 ) was prepared by reaction of [Nd{N(SiMe₃)₂}₃] with Me₃SiOH in toluene at room temperature. Compound 1 crystallized from a concentrated toluene solution in the monoclinic space group P2₁/n with the lattice constants a = 15.144(1) Å, b = 25.142(1) Å, c = 20.391(1) Å and β = 103.755(2)°. In the solid state a tetramer is observed which shows Nd‐O bond distances in the range 2.129(2)‐2.675(2) Å.     

Synthese und Kristallstruktur von iso‐Butylimidogalliummethyl, [CH3Ga–NCH2CH(CH3)2]6

Synthesis and X‐Ray Structure Determination of iso ‐Butylimido Galliummethyl, [CH₃Ga–NCH₂CH(CH₃)₂]₆ The thermal decomposition of [Me₂Ga–N(ⁱBu)SnMe₃]₂ (prepared by the reaction of [Me₂SnNⁱBu]₃ with GaMe₃ in a 1:3 molar ratio) in an evacuated, sealed tube at 160°C forms [MeGaNⁱBu]₆ in high yield and SnMe₄. Mass, ¹H and ¹³C NMR as well as some IR and Raman spectroscopic data are given and the crystal structure of this cage molecule with a hexagonal prismatic Ga₆N₆ skeleton has been determined.     

Synthesis,Spectroscopic and X-ray Structural Study of cis-diazidobis- (ethylenediamine)Cobalt(III) Thiocyanate

Reaction of cis-diazidobis(ethylenediamine)cobalt(III)nitrate with ammonium thiocyanate in a 1?:?2 molar ratio in aqueous medium gave the title cobalt(III) compound, cis-[Co(en)₂(N₃)₂]SCN, as reddish brown crystals in almost quantitative yield. The complex salt was characterized by elemental analysis, IR, electronic, ¹H and ¹³C NMR spectroscopic studies. An X-ray structure determination revealed an ionic structure with the monoclinic space group P2₁/c, having cell dimensions a = 12.1950(6), b = 9.0317(5), c = 12.6017(7)?Å; β = 113.419(1)°, V = 1273.63(12)?ų and Z = 4. The structure was refined by a full-matrix least-square procedures to R ₁ = 0.0297 and wR ₂ = 0.0697.     

Triorganotin cations stabilized by intramolecular SnN coordination; synthesis and characterization of {C,N,N′-2,6-bis[(dimethylamino)methyl]phenyl}diorganotin bromides

The synthesis of {2,6-bis[(dimethylamino)methyl]phenyl}diorganotin bromides, 2,6-(Me₂NCH₂)₂C₆H₃SnRR′⁺ Br^? is described. The compounds in which R = R′ = Me or Et and R = Me, R′ = Ph are extremely soluble in water and other polar solvents and insoluble or slightly soluble (R = R′ = Et) in apolar solvents. The diphenyl compounds shows the opposite solubility behaviour. The dimethyl compound is completely dissociated in water in to a triorganotin of 84.8 ohm^?1 cm^?1 (1/1 electrolyte). NMR spectroscopy reveals that the triorganotin cation has a TBP structure in which the N atoms occupy axial sites. Dynamic NMR spectra of the methylphenyl compound show that above ?90°C ratedetermining SnN dissociation occurs and that above 5°C second process, involving rate-determining rotation of the substituted aryl group around the (N₂)CSn bond begins.An X-ray investigation of single crystals of the dimethyl compound, which is unstable towards X-rays, establishes the ionic structure of the triorganotin halide in the solid (shortest SnBr 4.99 Å) as well as the molecular geometry of the triorganotin cation. Crystals are monoclinic, space group P2₁/n with Z = 4 in a unit cell of dimensions: a = 11.13(1), b = 16.73(2), c =10.10(1) Å, and β 114.2(1)°.     

Gemischtligandkomplexe des Technetiums. XVI. Darstellung und Struktur von (1,2-Dicyanoethen-1,2-dithiolato)bis(dimethylphenylphosphan)nitridotechnetium (V), [TcN(Me2PhP)2(mnt)]

Mixed-Ligand Complexes of Technetiums. XVI Synthesis and Structure of (1,2-Dicyanoethene-1,2-dithiolato)bis(dimethylphenylphosphine)nitridotechnetium(V), [TcN(Me₂PhP)₂(mnt)] [TcN(Me₂PhP)₂(mnt)] is formed from [TcNCl₂(Me₂PhP)₃] and one equivalent of the sodium salt of 1,2-dicyanoethene-1,2-dithiolate (Na₂mnt). The same reaction yields [TcN(mnt)₂]^2?, when a large excess of the ligand and long reaction periods are applied. The complex anion can be isolated as tetraalkylammonium or tetraphenylarsonium salts. [TcN(Me₂PhP)₂(mnt)] crystallizes in the triclinic space group P1 (a = 10.000(5), b = 14.182(6), c = 17.77(1) Å, α = 98.77(3), β = 103.77(3), γ = 104.55(3)°; Z = 4). The coordination sphere is a square pyramid with the sulfur and phosphorus atoms as basal plane. Tc is situated out of this plane by 0.56 Å towards the nitrido ligand.     

Investigations of the Nature of ZnII−SiII Bonds

A series of zinc(II) silylenes was prepared by using the silylene {PhC(NtBu)₂}(C₅Me₅)Si. Whereas reaction of the silylene with ZnX₂ (X=Cl, I) gave the halide‐bridged dimers [{PhC(NtBu)₂}(C₅Me₅)SiZnX(μ‐X)]₂, with ZnR₂ (R=Ph, Et, C₆F₅) as reagent the monomers [{PhC(NtBu)₂}(C₅Me₅)SiZnR₂] were obtained. The stability of the complexes and the Zn?Si bond lengths clearly depend on the substitution pattern of the zinc atom. Electron‐withdrawing groups stabilize these adducts, whereas electron‐donating groups destabilize them. This could be rationalized by quantum chemical calculations. Two different bonding modes in these molecules were identified, which are responsible for the differences in reactivity: 1) strong polar Zn?Si single bonds with short Zn?Si distances, Zn?Si force constants close to that of a classical single bond, and strong binding energy (ca. 2.39 Å, 1.33 mdyn Å^?1, and 200 kJ mol^?1), which suggest an ion pair consisting of a silyl cation with a Zn?Si single bond; 2) relatively weak donor–acceptor Zn?Si bonds with long Zn?Si distances, low Zn?Si force constants, and weak binding energy (ca. 2.49 Å, 0.89 mdyn Å^?1, and 115 kJ mol^?1), which can be interpreted as a silylene–zinc adduct.     

Crystal structure of (N,N,N′,N′-tetramethyl-1,2-diaminoethane)(1,1,1-trifluoro-6-methyl-2,4-heptanedionato)copper(II) perchlorate

The solvatochromic compound [Cu(tfmh)Me₄en]ClO₄ (tfmh^? denotes the anion of 1,1,1-trifluoro-6-methyl-2,4-heptanedione) was prepared and its structure has been determined from three-dimensional X-ray diffraction data. The structure consists of discrete [Cu(tfmh)Me₄en]⁺ monomeric units and perchlorate ions. The copper(II) ion is surrounded by the two nitrogen atoms of the diamine molecule and the two oxygen atoms of the β-dionato anion. The N,N,N′,N′-tetramethyl-1,2-diaminoethane, Me₄en, coordinates as bidentate ligand through the nitrogen atoms and adopts the gauche conformation and λ configuration. The CuN₂O₂ chromophore is virtually planar. The compound crystallizes in the monoclinic system (space group P2₁/c) with a = 11.9520(2), b = 14.6600(2), c = 17.2240(4) Å, β = 135.72(2)°, Z = 4 and V = 2107.01(7) ų.     

Homo‐ and Heteropentanuclear Coordination Compounds with Td Symmetry – the Solid State Structures of [MZn4(L)4(L′)6] (M = CoII or Zn; L = chloride or acac; L′ = 1,2,3‐benzotriazolate)

The syntheses of homo‐ and heteropentanuclear coordination compounds with the molecular formulae [MZn₄(L)₄(L′)₆] (M = Co^II or Zn; L = chloride or acac; L′ = 1,2,3‐benzotriazolate) are reported. These compounds display a highly symmetric coordination unit consisting of a central metal ion (M = Co^II or Zn) which is octahedrally coordinated by 6 tridentate benzotriazolate‐type ligands via their N(2) donor atom. The benzotriazolate ligands span the edges of an imaginary tetrahedron thus providing four coordination sites at the corners of the tetrahedron, which are then filled by four zinc ions. The coordination shell of the latter are completed by bidentate acetylacetonate (acac) ligands or by chloride anions, respectively. The solid state structures of two homopentanuclear metal complexes, namely [Zn₅(acac)₄(bta)₆]·4C₆H₁₂ ( 1 ) (acacH = acetylacetone; btaH = 1,2,3‐benzotriazole), and [Zn₅Cl₄(Me₂bta)₆]·2DMF ( 2 ) (Me₂btaH = 5,6‐dimethyl‐1,2,3‐benzotriazole) were determined by single crystal X‐ray structure analysis. The heteropentanuclear metal complex [Co^IIZn₄Cl₄(Me₂bta)₆]·2DMF ( 3 ) is isostructural with compound 2 . Compound 1 was synthesized from stoichiometric amounts of Zn(acac)₂ and btaH employing dichloromethane as solvent. The synthesis of compound 2 requires addition of an auxiliary base to the DMF solution of anhydrous ZnCl₂ and Me₂btaH. For compound 3 a stoichiometric ratio of Co(NO₃)₂·6H₂O, anhydrous ZnCl₂ and Me₂btaH was employed during synthesis. Phase purity of all compounds was proved by X‐ray powder diffraction (XRPD) analysis, IR spectroscopy, and elemental analysis. Crystal data: for 1 (C₈₀H₁₀₀N₁₈O₈Zn₅): monoclinic, space group P2₁/c with a = 23.781(5) Å, b = 16.000(3) Å, c = 25.170(5) Å, β = 115.29(3)°, V = 8659(3) ų, Z = 4, ρ = 1.357 g cm^?3. For 2 (C₅₄H₆₂Cl₄N₂₀O₂Zn₅): cubic, space group with a = 23.367(3) Å, V = 12759(3) ų, Z = 8, ρ = 1.553 g cm^?3. For 3 (C₅₄H₆₂Cl₄CoN₂₀O₂Zn₄): cubic, space group with a = 23.443(3) Å, V = 12884(3) ų, Z = 8, ρ = 1.532 g cm^?3.