Zwitterionic bis(phenolate)amine lanthanide complexes for the ring-opening polymerisation of cyclic esters

The reaction of Sm{N(SiMe3)2}3 with the bis(phenol)amines H2O2N(R) (H2O2N(R) = RCH2CH2N(2-HO-3,5-C6H2(t)Bu2)2; R = OMe, NMe2 or Me) gave exclusively zwitterions Sm(O2N(R))(HO2N(R)). For R = OMe or NMe2 these were efficient catalysts for the ring-opening polymerisation of epsilon-caprolactone and D,L-lactide with a tendency to form cyclic esters; in contrast, no polymerisation was observed for R = Me.     

The N-donor stabilised cyclotriphosphazene hexacation [P3N3(DMAP)6]6+

The cyclotriphosphazene P(3)N(3)Cl(6) reacts with six equivalents of DMAP (4-(dimethylamino)pyridine) in superheated chloroform to form crystals of composition [P(3)N(3)(DMAP)(6)]Cl(6).19CHCl(3) comprising [P(3)N(3)(DMAP)(6)](6+) ions, which host five chloride ions in basket-type cavities on either side of the ring and at equatorial positions via tetradentate ortho-H-donor arrangements.     

Ultrafast excited-state dynamics of rhenium(I) photosensitizers [Re(Cl)(CO)3(N,N)] and [Re(imidazole)(CO)3(N,N)]+: diimine effects

Femto- to picosecond excited-state dynamics of the complexes [Re(L)(CO)(3)(N,N)](n) (N,N = bpy, phen, 4,7-dimethyl-phen (dmp); L = Cl, n = 0; L = imidazole, n = 1+) were investigated using fluorescence up-conversion, transient absorption in the 650-285 nm range (using broad-band UV probe pulses around 300 nm) and picosecond time-resolved IR (TRIR) spectroscopy in the region of CO stretching vibrations. Optically populated singlet charge-transfer (CT) state(s) undergo femtosecond intersystem crossing to at least two hot triplet states with a rate that is faster in Cl (～100 fs)(-1) than in imidazole (～150 fs)(-1) complexes but essentially independent of the N,N ligand. TRIR spectra indicate the presence of two long-lived triplet states that are populated simultaneously and equilibrate in a few picoseconds. The minor state accounts for less than 20% of the relaxed excited population. UV-vis transient spectra were assigned using open-shell time-dependent density functional theory calculations on the lowest triplet CT state. Visible excited-state absorption originates mostly from mixed L;N,N(?-) → Re(II) ligand-to-metal CT transitions. Excited bpy complexes show the characteristic sharp near-UV band (Cl, 373 nm; imH, 365 nm) due to two predominantly ππ*(bpy(?-)) transitions. For phen and dmp, the UV excited-state absorption occurs at ～305 nm, originating from a series of mixed ππ* and Re → CO;N,N(?-) MLCT transitions. UV-vis transient absorption features exhibit small intensity- and band-shape changes occurring with several lifetimes in the 1-5 ps range, while TRIR bands show small intensity changes (≤5 ps) and shifts (～1 and 6-10 ps) to higher wavenumbers. These spectral changes are attributable to convoluted electronic and vibrational relaxation steps and equilibration between the two lowest triplets. Still slower changes (≥15 ps), manifested mostly by the excited-state UV band, probably involve local-solvent restructuring. Implications of the observed excited-state behavior for the development and use of Re-based sensitizers and probes are discussed.     

Metall-Schwefelstickstoff-Verbindungen. 22. S4N3Cl als Ausgangsprodukt zur Herstellung von Komplexen mit dem S3N−-Liganden Die Komplexe [Ph6P2N][Cu3(S3N)2(CN)2]und [Ph4As][(CuS3N)2(CN)]

The reaction of S₄N₃Cl with metal salts leads to complexes containing the S₃N^?chelating ligand, a reaction which proceeds smoothly especially in an alkaline medium. Thus we were able to prepare, by the reaction of CuCN with S₄N₃Cl and [Ph₆P₂N]OH (Ph = phenyl), the salt [Ph₆P₂N][Cu₃(S₃N)₂(CN)₂], a compound in which the anions build a bidimensional network through supplementary Cu - S contact interactions. The salt is monoclinic, space group C2/c, a = 18.960, b = 14.651 and c = 15.400 Å, β = 101.03° and Z = 4. Metal Sulfur Nitrogen Compounds. 22. S₄N₃Cl as a Starting Compound for the Preparation of Complexes Containing the S₃N^? Ligand. Complexes [Ph₆P₂N] [Cu₃(S₃N)₂ (CN)₂] and [Ph₄As] [(CuS₃N)₂ (CN)] In contrast, the reaction of CuN with S₄N₃Cl and [Ph₄As]OH led to the compound [Ph₄As][(CuS₃N)₂(CN)], monoclinic, space group C2/c, a = 18.478, b = 6.405, c = 27.051 Å, β = 119.50°, Z = 4. In the centrosymmetric anion the two Cu(S₃N) groups are linked together by disordered CN^? groups. An additional linkage results from Cu - Cu contact interactions, with d = 2.84 Å.     

Die Kristallstruktur von (Ph4P)2[Be4Cl4(μ‐N3)6]

Suitable single crystals for X‐ray analysis of the recently published azido beryllate (Ph₄P)₂[Be₄Cl₄(μ‐N₃)₆] ( 1 ) [1] were obtained by a modified synthetic route, and the crystal structure of 1 was determined. The compound crystallizes isotypically with the corresponding bromo derivative [1] in the space group C2/c with 12 formula units per unit cell. Lattice dimensions at 193 K: a = 4125.5(1), b = 2001.7(1), c = 2050.4(1) pm, β = 101.05 (1)°, R₁ = 0.0359. The structure contains adamantanlike dianions [Be₄Cl₄(μ‐N₃)₆]^2? with a Be₄N₆ core forming by the bridging function of the α‐nitrogen atoms of the azido groups.     

On the Reactivity of P Trichloro N Dichlorophosphor-Yl-Mdnophosphazene Cl3P=N-P(O)Cl2

Abstract

In this poster we give the results of some reactions of P trichloro N dichlorophosphoryl monophosphazene Cl₃P=N-P(O)Cl₂ (I) with inorganic and organic nucleophilic reagents.     

Neutral tellurium rings in the coordination polymers [Ru(Te9)](InCl4)2, [Ru(Te8)]Cl2, and [Rh(Te6)]Cl3

Shiny black, air‐insensitive crystals of tellurium‐rich one‐dimensional coordination polymers were synthesized by melting a mixture of the elements with TeCl₄. The compounds [Ru(Te₉)](InCl₄)₂ and [Ru(Te₈)]Cl₂ crystallize in the monoclinic space group type C2/c, whereas [Rh(Te₆)]Cl₃ adopts the trigonal space group type R$\bar 3Shiny black, air-insensitive crystals of tellurium-rich one-dimensional coordination polymers were synthesized by melting a mixture of the elements with TeCl(4). The compounds [Ru(Te(9))](InCl(4))(2) and [Ru(Te(8))]Cl(2) crystallize in the monoclinic space group type C2/c, whereas [Rh(Te(6))]Cl(3) adopts the trigonal space group type R ?3c. In the crystal structures, linear, positively charged [M(m+) (Te(n)(±0))] (M=Ru, m=2; Rh, m=3) chains run parallel to the c axes. Each of the uncharged Te(n) molecules (n=6, 8, 9) coordinates two transition-metal atoms as a bridging bis-tridentate ligand. Because the coordinating tellurium atoms act as electron-pair donors, the 18-electron rule is fulfilled for the octahedrally coordinated transition-metal cations. Based on DFT calculations, the quantum theory of atoms in molecules (QTAIM) and the electron localizability indicator (ELI) provide insight into the principles of the polar donor bonding in these complexes. Comparison with optimized ring geometries reveals substantial tension in the coordinating tellurium molecules.     

Reaction of [P3N3Cl4(NH2)2] with [HN(POCl2)2]; The crystal structure of the phosphazenium salt [P3N3HCl4(NH2)2]+[N(POCl2)2]−

The reaction of diaminotetrachloro-cyclotriphosphazene with tetrachloride of μ-imino-diphosphoric acid leads to the formation of the salt-like compound [P₃N₃HCl₄(NH₂)₂]⁺[N(POCl₂)₂]⁻ which identity was unambiguously established by means of X-ray structure analysis. The structure is composed of [P₃N₃HCl₄(NH₂)₂]⁺ cations and [N(POCl₂)₂]⁻ anions joined by a system of H-bonds. As in other phosphazenium salts, the protonation of the ring N atom leads to significant changes in the endocyclic P N bond lengths.     

Thermal decomposition of [Co(NH3)6]Cl3

The thermal decomposition reactions of [Co(NH₃)₆]Cl₃ were determined in dynamic argon and air atmospheres. The investigations were carried out with simultaneous TG-DTG-DTA measurements under non-isothermal conditions, thermogravimetry under quasi-isothermal conditions, reflectance spectroscopy, absorption spectroscopy, X-ray diffraction and chemical analysis. The data show that the thermal decomposition of [Co(NH₃)₆]Cl₃ occurs in three and four stages in argon and air atmospheres, respectively. The determined sequences are in agreement with that proposed by Simons and Wendlandt [2, 5].The changes in the morphology of the studied complex crystalline powder in the course of thermal decomposition in air were followed by scanning electron microscopy.

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Zusammenfassung In bewegter Argon- und Luftatmosphäre wurden die Zersetzungsreaktionen für [Co(NH₃)₆]Cl₃ bestimmt. Zu den Untersuchungen wurden folgende Methoden zu Hilfe gezogen: simultane TG-DTG-DTA-Messungen unter nichtisothermen Bedingungen, Thermogravimetrie unter quasi-isothermen Bedingungen, Remissionsspektroskopie, Absorptionsspektroskopie, Röntgendiffraktion und chemische Analyse. Die Ergebnisse zeigen, daß sich [Co(NH₃)₆]Cl₃ in Argon in drei und in Luft in vier Schritten thermisch zersetzt. Die festgestellten Sequenzen stehen in Übereinstimmung mit den von Simon und Wendlandt [2, 5] vorgeschlagenen. Veränderungen in der Morphologie des untersuchten Komplexkristallpulvers wurden über die thermische Zersetzung in Luft mittels Scanning-Elektronen-Mikroskopie beobachtet.

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[Co(NH₃)₆]Cl₃. , , - , , , . , , , , , , .

     

Dinitrogen Activation by Fryzuk’s [Nb(P2N2)] Complex and Comparison with the Laplaza–Cummins [Mo{N(R)Ar}3] and Schrock [Mo(N3N)] Systems

The reaction profile of N₂ with Fryzuk’s [Nb(P₂N₂)] (P₂N₂=PhP(CH₂SiMe₂NSiMe₂CH₂)₂PPh) complex is explored by density functional calculations on the model [Nb(PH₃)₂(NH₂)₂] system. The effects of ligand constraints, coordination number, metal and ligand donor atom on the reaction energetics are examined and compared to the analogous reactions of N₂ with the three‐coordinate Laplaza‐Cummins [Mo{N(R)Ar}₃] and four‐coordinate Schrock [Mo(N₃N)] (N₃N=[(RNCH₂CH₂)₃N]^3?) systems. When the model system is constrained to reflect the geometry of the P₂N₂ macrocycle, the N? N bond cleavage step, via a N₂‐bridged dimer intermediate, is calculated to be endothermic by 345 kJ mol^?1. In comparison, formation of the single‐N‐bridged species is calculated to be exothermic by 119 kJ mol^?1, and consequently is the thermodynamically favoured product, in agreement with experiment. The orientation of the amide and phosphine ligands has a significant effect on the overall reaction enthalpy and also the N? N bond cleavage step. When the ligand constraints are relaxed, the overall reaction enthalpy increases by 240 kJ mol^?1, but the N₂ cleavage step remains endothermic by 35 kJ mol^?1. Changing the phosphine ligands to amine donors has a dramatic effect, increasing the overall reaction exothermicity by 190 kJ mol^?1 and that of the N? N bond cleavage step by 85 kJ mol^?1, making it a favourable process. Replacing Nb^II with Mo^III has the opposite effect, resulting in a reduction in the overall reaction exothermicity by over 160 kJ mol^?1. The reaction profile for the model [Nb(P₂N₂)] system is compared to those calculated for the model Laplaza and Cummins [Mo{N(R)Ar}₃] and Schrock [Mo(N₃N)] systems. For both [Mo(N₃N)] and [Nb(P₂N₂)], the intermediate dimer is calculated to lie lower in energy than the products, although the final N? N cleavage step is much less endothermic for [Mo(N₃N)]. In contrast, every step of the reaction is favourable and the overall exothermicity is greatest for [Mo{N(R)Ar}₃], and therefore this system is predicted to be most suitable for dinitrogen cleavage.     

Synthese und Kristallstrukturen der mehrkernigen Rhenium–Nitrido‐Komplexe [Re2N2Cl4(PMe2Ph)4(MeCN)] und [Re4N3Cl9(PMe2Ph)6]

Synthesis and Structures of the Multinuclear Rhenium Nitrido Complexes [Re₂N₂Cl₄(PMe₂Ph)₄(MeCN)] and [Re₄N₃Cl₉(PMe₂Ph)₆] The binuclear rhenium complex [Re₂N₂Cl₄(PMe₂Ph)₄(MeCN)] ( 1 ) is obtained as a byproduct of the synthesis of [(Me₂PhP)₃(MeCN)ClReNZrCl₅] from [ReNCl₂(PMe₂Ph)₃] and [ZrCl₄(MeCN)₂] in toluene. It crystallizes as 1 · 2 toluene in the monoclinic space group P2₁/n with a = 1517.0(3); b = 1847.7(2); c = 1952.4(6) pm; β = 106.44(1)° and Z = 4. The two Re atoms are connected by an asymmetric nitrido bridge Re≡N–Re with distances Re–N of 169.9(5) and 208.7(5) pm. In course of the reaction of [ReNCl₂(PMe₂Ph)₃] with [ZrCl₄(THF)₂] in CH₂Cl₂ hydrochloric acid is formed by acting of the Lewis acid on the solvent. HCl protonates and eliminates phosphine ligands of the educt [ReNCl₂(PMe₂Ph)₃] to form the phosphonium salt [PMe₂PhH]₂[ZrCl₆] ( 2 ). It crystallizes in the monoclinic space group C2/c with a = 1536.9(3); b = 1148.8(1); c = 1402.2(3) pm, β = 100.70(2)° and Z = 4. The remaining fragments of the rhenium complex combine to yield the tetranuclear mixed valent complex [Re₄N₃Cl₉(PMe₂Ph)₆] ( 3 ), crystallizing as 3 · CH₂Cl₂ in the triclinic space group P 1 with a = 1312.9(19); b = 1661.4(2); 1897.1(2) pm; α = 78.62(1)°; β = 86.77(1)°; γ = 68.28(1)° and Z = 2. The four Re atoms occupy the corners of a tetrahedron. Its edges are formed by three nitrido and three chloro bridges. The asymmetric nitrido bridges Re≡N–Re are characterized by short distances in the range of 172(2) to 176(3) pm and long distances of 194(3) to 204(2) pm. The angles Re–N–Re are between 154(1) and 160(1)°.     

A new, convenient synthesis of the linear phosphazene salt [Cl3P=N=PCl3]Cl: preparation of higher linear homologues [Cl3P=N-(PCl2=N)x=PCl3]Cl (x = 1-3) and the 16-membered macrocycle [NCCl(NPCl2)3]2

An improved synthetic route to the linear phosphazene salt [Cl3P=N=PCl3]Cl is reported. This species is a useful precursor to higher linear homologues and also to heterocycles such as the 16-membered carbophosphazene macrocycle [NCCl(NPCl2)3]2.