Zig‐Zag Diphosphene Oligomers Linked by Silver(I) Cation

The coordination of silver cation to diphosphene Mes*P=PMes* ( 1 , Mes* = ^tBu₃C₆H₂) was investigated in detail. The reaction of 1 with Ag[Al(OR_F)₄] (OR_F = OC(CF₃)₃) in the ratios of 2 : 1, 3 : 2 and 1 : 2 led to the formation of the first cationic silver linked diphosphene complexes 2 — 4 . Complexes 2 and 3 contain two and three diphosphene molecules linked by the linear Ag(I) cation, respectively, and they feature unusual zig‐zag topologies. Complex 4 is a dinuclear silver complex, and each Ag(I) center features a tetrahedral geometry, coordinated by one phosphorus atom of diphosphene 1 and three chloro atoms of two CH₂Cl₂ molecules.     

Diaminodiphosphen- und aminophosphiniden-komplexe

2,2′,6,6′-Tetramethylpiperidylphosphorousdichloride, (pip)PCl₂, reacts with Na₂-M₂(CO)₁₀ (M = Cr, Mo, W) to give phosphinidene and diphosphene complexes. The diphosphene compounds [(pip)P=P(pip)]M(CO)₅ (Ia to Ic) are obtained as stable products for all three metals. The phosphinidene compounds (pip)[M(CO)₅]₂ are only obtained for M = Cr(IIa) and M = W (IIb). X-ray analyses reveal that the NR₂ substituents in I as well as in II are oriented in such a way relative to the phosphorus centered π-systems that they cannot participate in π-conjugation. This bonding situation is analyzed by EHT methods.     

Comparison of σ-/π-Hole Tetrel Bonds between TH3F/F2TO and H2CX (X=O,S, Se)

Several σ-hole and π-hole tetrel-bonded complexes with a base H₂CX (X=O, S, Se) have been studied, in which TH₃F (T=C−Pb) and F₂TO (T=C and Si) act as the σ-hole and π-hole donors, respectively. Generally, these complexes are combined with a primary tetrel bond and a weak H-bond. Only one minimum tetrel-bonded structure is found for TH₃F, whereas two minima tetrel-bonded complexes for some F₂TO. H₂CX is favorable to engage in the π-hole complex with F₂TO relative to TH₃F in most cases, and this preference further expands for the Si complex. Particularly, the double π-hole complex between F₂SiO and H₂CX (X=S and Se) has an interaction energy exceeding 500 kJ/mol, corresponding to a covalent-bonded complex with the huge orbital interaction and polarization energy. Both the σ-hole interaction and the π-hole interaction are weaker for the heavier chalcogen atom, while the π-hole interaction involving F₂TO (T=Ge, Sn, and Pb) has an opposite change. Both types of interactions are electrostatic in nature although comparable contributions from dispersion and polarization are respectively important for the weaker and stronger interactions.     

A fluoroaryl substituent with spectator function: Reactivity and structures of cyclic and acyclic HF4C6-substituted phosphanes

The reactivity of a series of phosphanes with a fluoroaryl group (HF₄C₆-) carrying a spectator function in para position has been explored with respect to the formation of low coordinated and phosphorus rich phosphanes. An asymmetric diphosphene has been indentified as an intermediate in the synthesis of a linear 1,3-dihydrophosphane, while the symmetric diphosphene undergoes 2 + 2 cycloaddition under formation of the corresponding cyclotetraphosphetane for which a crystal structure could be obtained. Attempts to synthesize HF₄C₆-substituted iminophosphanes generally failed, which is attributed to the electronic nature of the corresponding precursors as suggested by quantum chemical calculations.     

An Isolable Bis(Germylene)-Stabilized Plumbylone

We report herein the synthesis of a stable plumbylone ( 3 ) by reduction of a bromodigermylplumbylene ( 2 ) with 2.2 equiv of potassium graphite (KC₈). The molecular structure of 3 was established by a single-crystal X-ray diffraction study and features a two-coordinated Pb center with an acute Ge−Pb−Ge bond angle. Computational studies showed that this complex ( 3 ) possesses a singlet electronic ground state with a Pb⁰ center. Its high thermal stability can be most likely ascribed to the delocalization of π electrons over the Ge−Pb−Ge moiety. A preliminary reactivity study demonstrates that complex 3 can deliver Pb⁰ atoms to an organic azide producing a tetrameric imido complex [(PbNDipp)₄] (Dipp=2,6-ⁱPr-C₆H₃, 4 ) and perform a metathesis reaction with GeCl₂⋅dioxane to produce a bis(germylene)-stabilized germylone ( 5 ), highlighting the synthetic utility of 3 .     

Übergangsmetallphosphidokomplexe. XII. Diphosphenkomplexe (DRPE)Ni[η2-(PR′)2] und die Struktur von (DCPE)NiP(SiMe3)2

Transition Metal Phosphido Complexes. XII. Diphosphene Complexes (DRPE)Ni[η²-(PR′)₂] and the Structure of (DCPE) NiP (SiMe₃)₂ LiP(SiMe₃)₂ reacts with the complexes (DRPE)NiCl₂ 1 (DRPE = R₂PCH₂CH₂PR₂; R = Et: DEPE a ; R = Cy: DCPE b ; R = Ph: DPPE c ) to form the diphosphene complexes (DRPE)Ni[η²-(PSiMe₃)₂] 5a–c . Using low temperature nmr measurements the monosubstitution products (DRPE)Ni[P(SiMe₃)₂]Cl 2a–c and the disubstitution products (DRPE)Ni[P(SiMe₃)₂]₂ 3a, 3c can be detected as intermediates. From the reaction of 1b the paramagnetic nickel(I) complex (DCPE)NiP(SiMe₃)₂ 4b can be isolated. Reacting 1a, 1b with LiP(SiMe₃)CMe₃ the complexes (DRPE)Ni[P(SiMe₃)CMe₃]Cl 8a, 8b , which are analogous to 2 , and the nickel(0) diphosphine complex (DEPE)Ni[η¹-P(SiMe₃)CMe₃P(SiMe₃)CMe₃] 9a can be detected n.m.r. spectroscopically, but no diphosphene complexes can finally be isolated. The diphosphene complexes (DRPE)Ni[η²(PPh)₂] 10a-c are available from reactions of PhP(SiMe₃)₂with l a - c. MeP(SiMe,), reacts only with 1b to give a diphosphene complex (DCPE)Ni[η²(PMe)₂] 11 b. Reacting [P(SiMe₃)CMe₃]₂ with 1a-c the diphosphene complexes (DRPE)Ni[η²(PCMe₃)₂] 12a-c can be obtained. 4b crystallizes monoclinic in the space group P2Jc with a = 1228.6 pm, b = 2387.1 pm, c = 2621.8 pm, β = 92.16°, and Z = 8 formula units. The nickel atom is nearly planar coordinated by three phosphorus- atoms, the phosphorus atom of the terminal P(SiMe₃)₂ group is pyramidally coordinated. The Ni? P bond distances of the two four-coordinated phosphorus atoms are with 219.2 pm and 220.2 pm only slightly shorter than the corresponding distance of the P-atom of the P(SiMe₃)₂ group with 223.5 pm. N.m.r. and mass spectral data are reported.     

Syntheses and Characterization of a New One-Dimensional Polymer Containing (µ-Thiocyanate)(bpy)Lead(II) Molecule and New Mixed-Anion Lead (II) Complexes: Crystal Structures of [Pb(bpy)(SCN)2] n (byp = 2,2'-Bipyridine) and [Pb(phen)2(NO3)0.7(ClO4)0.3](ClO4) (phen = 1,10-Phenanthroline)

Complexes [Pb(bpy)(SCN)₂] _n (bpy = 2,2′-bipyridine), [Pb (phen)₂(NO₃)_0.7(ClO₄)_0.3](ClO₄), Pb(phen)₂(SCN)-(NO₃), and Pb(phen)₂(SCN)(ClO₄) (phen = 1,10-phenanthroline)], have been synthesized using a direct reaction between Pb(NO₃)₂ and ligands. The complexes have been isolated and characterized by IR-spectra and CHN-elemental analysis. The structures of [Pb(bpy)(SCN)₂] _n and [Pb(phen)₂(NO₃)_0.7(ClO₄)_0.3](ClO₄) have been confirmed by X-ray crystallography. The single crystal X-ray crystallography of a new one-dimensional complex of Pb(II) with 2,2′-bipyridine, [Pb(bpy)(SCN)₂] _n , shows the complex to be polymeric as a result of thiocyanate ligand bridging. The Pb atom being in a unsymmetrical eight-coordinate, N₄S₄, environment and the arrangement of the 2,2′-bipyridine, thiocyanate anion suggest a gap in coordination geometry around the Pb(II) ion, occupied possibly by a stereoactive lone pair of electrons on lead (II) and the coordination around atoms is hemi-directed. There is a π-π interaction between the aromatic rings of the interchains in [Pb(bpy)(SCN)₂] _n , this stacking causes the complex to be more stable. An attempt to isolate single crystals of Pb(phen)₂(NO₃)(ClO₄) from water led to the isolation of [Pb(phen)₂(NO₃)_0.7(ClO₄)_0.3](ClO₄). The single crystal X-ray study shows the complex to be monomeric. The Pb atom lies in an unsymmetrical six-coordinate, N₄O₂, environment and the arrangement of the 1,10-phenanthrolines, suggest a gap in coordination geometry around the Pb(II) ion, occupied possibly by a stereoactive lone pair of electrons on lead (II) and the coordination around atoms is hemi-directed.     

Hexafluorophosphate salts of bis and tetrakis(2,2′-bipyridine)lead(II) complexes

Both bis- and tetrakis-substituted 2,2′-bipyridine complexes of lead(II), [Pb(bpy)₂](PF₆)₂ and [Pb(bpy)₄](PF₆)₂ · bpy, respectively, have been characterized by X-ray crystallography as hexafluorophosphate salts when three equivalents of bipyridine is combined with Pb(NO₃)₂ in aqueous solution prior to metathesis. The tetrakis-substituted product, [Pb(bpy)₄](PF₆)₂ · bpy, shows an unusual combination of intramolecular and intermolecular π-stacking of two of the bipyridine ligands throughout the crystal. Incomplete metathesis also produces a catenated, mixed-anion complex, [Pb(bpy)₂(µ-NO₃)](PF₆), where the nitrate bridges lead(II) metal centers to form a 1-D coordination polymer. If metathesis is carried out using perchlorate, a known [Pb(bpy)₂](ClO₄)₂ analog is produced along with [bpyH](ClO₄), which has not been previously characterized by X-ray crystallography.     

Hydrothermal Synthesis and Crystal Structure of a New Oxalato‐bridged Lead(II) Polymer: {[Pb(phen)2(ox)]·5H20}n (phen = 1, 10‐phenanthroline,ox = oxalate)

A new one‐dimensionally neutral coordination polymer, namely {[Pb(phen)₂(ox)]·5H₂0}_n (phen = 1, 10‐phenanthroline, ox = oxalate) ( 1 ), has been synthesized under hydrothermal condition and characterized by X‐ray crystallography. Complex 1 crystallizes in the orthorhombic space group Pban (No. 50) with a = 19.358(2), b = 6.8135(6), c = 9.7015(8)Å, V = 1279.6(2)ų, and Z = 2. Each Pb(II) atom is eight‐coordinated in a square‐antiprismatic D_4d geometry by four nitrogen atoms from two phen groups and four oxygen atoms from two ox ligands. The polymeric chains further constructed into a three‐dimensional network via strong π—π stacking interactions and hydrogen bonds. The complex exhibits intense blue photoluminescence with an emission maximum at 403 nm at room temperature.     

Stereo- and regio-controlled functionalization of cycloheptene using organomolybdenum chemistry

Cycloheptene is readily converted to the cationic cycloheptadiene-Mo(C0)₂Cp complex, which reacts with a range of nucleophiles; hydride abstraction from the product π-allyl-Mo(C0)₂Cp complexes give substituted cycloheptadiene complexes which react with a second nucleophile stereospecifically, and decomplexation of the π-allyl complexes gives substituted cycloheptene derivatives with defined relative stereochemistry.     

An Alumanylyttrium Complex with an Absorption due to a Transition from the Al−Y Bond to an Unoccupied d-Orbital

The reaction between a dialkyl-substituted alumanyl anion and [Y(CH₂SiMe₃)₂(thf)₃][BPh₄] resulted in the formation of (dialkylalumanyl)yttrium complex 2 , which exhibits the first 2-center–2-electron (2 c-2 e) Al−Y bond. The ¹H and ¹³C NMR spectra of 2 together with an X-ray crystallographic analysis indicated a C_2v symmetrical structure. DFT calculations on 2 revealed that its LUMO consists of overlapping 3 p- and 4 d-orbitals of the Al and Y atoms, respectively, and that the HOMO–LUMO gap is narrow. The UV/Vis spectrum of 2 exhibited a visible absorption at 432 nm, which suggests that the strong σ-donating and π-accepting character of the three-coordinate dialkylalumanyl ligand generates a colored d⁰-complex that does not contain any π-electrons.     

Generation, isolation, and reactivity of a kinetically stabilized diphosphene anion radical

The stable lithium diphosphene anion radical, [Li(dme)₃]⁺[TbtPPTbt]⁻ (dme: 1,2-dimethoxyethane, Tbt: 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl), was readily synthesized by the one-electron reduction of the corresponding neutral diphosphene (TbtPPTbt). The molecular structure of the diphosphene anion radical was discussed in detail on the basis of its ESR, UV-Vis and Raman spectra, and theoretical calculations. The diphosphene anion radical was found to undergo ready chalcogenation reactions using elemental sulfur and selenium to afford the corresponding thiadiphosphirane and selenadiphosphirane, respectively.     

Syntheses and characterization of Pb(trz) n X2 (X = CH3COO−, NCS−, and n = 1, 2) complexes,and crystal structure of [Pb(trz)2(MeOH)](ClO4)2·H2O

Lead(II) complexes with 2,4,6-tris(2-pyridyl)-1,3,5-triazine (trz) have been synthesized using a direct synthetic method and characterized by IR and ²⁰⁷Pb NMR spectroscopy and CHN elemental analysis. The structure of [Pb(trz)₂(MeOH)](ClO₄)₂·H₂O was confirmed by X-ray crystallography. Single-crystal X-ray data for [Pb(trz)₂(MeOH)](ClO₄)₂·H₂O show the complex to be monomeric with the Pb having an unsymmetrical seven-coordinate geometry, coordinated by six nitrogen atoms of the trz ligands and one oxygen atom of MeOH. The arrangement of the ligands in the [Pb(trz)₂(MeOH)](ClO₄)₂·H₂O complex exhibits a coordination gap around the Pb(II), occupied possibly by a stereoactive lone pair of electrons on lead(II); the coordination around the lead atoms is hemidirected.     

Dimeric water embedded within a hydrophobic cavity of tetra-(p-tert-butyl)thiacalix[4]arene

X-ray crystallographic analysis and density functional B3LYP/6-31G(d) calculation confirm that dimeric water is embedded within a hydrophobic cavity of tetra-(p-tert-butyl)thiacalix[4]arene and stabilized by hydrogen bondings of aromatic π?H₂O(1) and methyl?H₂O(2) in the dimeric water inclusion complex with binding energies of 1.4 and 0.9 kcal mol⁻¹ respectively, and by hydrogen bonding formed between H₂O(2) and four phenolic OH groups from an adjacent tetra-(p-tert-butyl)thiacalix[4]arene, with binding energy of 3.8-4.2 kcal mol⁻¹.     

Cycloadditionsreaktionen von Isocyaniden an Bis[tris(trimethylsilyl)methyl]diphosphen

Cycloaddition Reactions of Isocyanides with Bis[tris(trimethylsilyl)methyl]diphosphene The [2 + 1] cycloaddition reactions of isocyanoacetonitrile ( 1 a ), pentacarbonyl(diisocyanomethane)chromium ( 1 b ), and 2,2,2-trifluoroethylisocyanide ( 1 c ) with the diphosphene R–P=P–R (R = C[Si(CH₃)₃]) ( 2 ) yield the expected diphosphirane imines 3 a – c . All compounds are thermally very stable and show no evidence for a [2 + 1] cycloreversion reaction. The structures of 3 a : triclinic, P 1, a = 918.0(2), b = 1174.7(4), c = 1821.9(5) pm, α = 93.83(2), β = 97.22(2)°, γ = 97.08(2)°, Z = 2, R₁ = 0.069; 3 c : monoclinic, P2₁, a = 928.6(2), b = 1659.8(3), c = 1261.2(3) pm, β = 107.65(2)°, Z = 2, R₁ = 0.073, and 1,2-Bis[tris(trimethylsilyl)]methyl-N-trifluormethyl-3-diphosphiranimin: monoclinic, P2₁/n, a = 1374.6(3), b = 1685.9(1), c = 1658.6(5) pm, β = 108.99(9)°, Z = 4, R₁ = 0.092, were elucidated by X-ray crystallography. All three compounds possess a similar three membered PCP ring system with an exocyclic C–N double bond.     

New N-heterocyclic carbene mercury(II) and silver(I) complexes

The complexes [1-(9-anthracenylmethyl)-3-octylimy]₂Hg[HgCl₄] (2a) (imy = imidazol-2-ylidene) and [1-(9-anthracenylmethyl)-3-butylbimy]₂AgPF₆ (2b) (bimy = benzimidazol-2-ylidene) have been prepared and characterized. Crystal packing of complex 2a revealed that 1D polymeric chains are formed by [1-(9-anthracenylmethyl)-3-octylimy]Hg and [HgCl₄]²⁻ through weak Hg…Cl bonds. The packing diagram of 2b showed that 1D supramolecular chains are formed by both benzimidazole ring head to tail π–π stacking interactions and anthracene ring face-to-face π–π stacking interactions.     

Cycloarsanes (AsCF3)n (n = 4, 5) – Precursors for the Highly Reactive Diarsene F3CAs=AsCF3

Tetrakis(trifluoromethyl) cyclotetraarsane (F₃CAs)₄ ( 2 ) was used to repeat the UV initiated [4+2]‐cycloaddition reaction of the diarsene F₃CAs=AsCF₃ ( 1 ) with cyclohexa‐1,3‐diene (CHD) and to isolate single crystals of the cycloadduct 4 for a X‐ray diffraction analysis. 4 crystallizes in the space group and contains the diarsene group in its E‐configuration. 2 was also applied for [2+2]‐cycloaddition reactions of 1 with tBuC≡P and MeC≡CNⁱPr₂, but in contrast to positive results with (F₃CP)₄ the products were too labile for isolation. However, 2 was successfully used at room temperature as precursor for coordinating 1 as π‐donor ligand to the Pd(PPh₃)₂ complex fragment yielding η²‐bis(trifluoromethyl)diarsene‐bis(triphenylphosphane)‐palladium(0) 5 , which was characterized by X‐ray diffraction of single crystals and by spectroscopic investigations (NMR, IR, MS). Attempts to prove the existence of the diarsene 1 , generated by different methods, by spectroscopic studies very probably failed due to its extreme reactivity, not allowing the necessary concentrations for detection. Quantum chemical calculations of the stability of 1 with respect to dimerization, the stability of the [2+2]‐cycloadduct with 1‐di(isopropyl)aminopropyne and the energy difference between 4 and the 2,3‐dimethyl‐1,3‐butadiene cycloadduct of 1 were performed to understand the considerable differences between 1 and the related diphosphene F₃CP=PCF₃.     

Darstellung und reaktionen von diphosphen-komplexen RPPR[M(CO)5]3 (M = Cr,Mo, W)

Decacarbonyldimetallates Na₂M₂(CO)₁₀ (M = Cr, Mo, W) react with dihalophosphanes, (R)P(Cl)₂, to yield trinuclear diphosphene complexes of the form RPPR[M(CO)₅]₃. The by-products of these reactions are diphosphane- and phosphido-bridged complexes.The trinuclear diphosphene compounds add HX (X = CH₃COO, CH₃O) or dienes to the PP double bond; in the course of these additions one M(CO)₅ group is cleaved and binuclear derivatives of diphosphanes are obtained.     

Metal—ligand and π singlet—triplet transitions in phthalocyanine films studied by inelastic electron tunneling spectroscopy

Inelastic electron tunneling spectroscopy (IETS) on AlAl₂O₃/PcPb tunneling junctions at 4.2 K has been used to study electronic transitions involving π, π^≠ and metal-ligand orbitals of phthalocyanine (Pc) films (H₂Pc, FePc, CoPc, NiPc, CuPc, ZnPc). The results are compared with calculations for Pc molecules.     

Thermal transformation of 1D-Pb(en)2Cl2 to 3D-PbCl2via 2D-Pb(en)Cl2 and their substantial modification of the coordination environment on Pb(II)

The solvothermal synthesis and crystal structures of two new lead(II) compounds, bis(ethylenediamine)lead(II) chloride, Pb(en)₂Cl₂1 and mono(ethylenediamine)lead(II) chloride, Pb(en)Cl₂2, are reported. A detailed comparison of the two structures is given. In 1, the Pb(II) center is coordinated by two chlorine atoms and four nitrogen atoms from three en ligands, which act as either chelating or bridging ligands, allowing links to other Pb(II) centers. This creates an infinite linear chain of Pb(en)₂Cl₂. In 2, the Pb(II) center is chelated by one en ligand and is coordinated by six chlorine atoms, including two unusually weak Pb–Cl bonds (>3.5 Å) connected through μ₂- and μ₄-Cl to build a neutral layer of Pb(en)Cl₂ units. Complex 1 contains a hemidirected Pb(II), while complex 2 has a (pseudo-)hemidirected Pb(II). TGA and high-temperature controlled powder-XRD studies show that compound 1 decomposes to compound 2 near 150 °C, and finally to PbCl₂ above 320 °C.