Gábor Balázs

P4 activation by main group elements and compounds.

An overview about the activation of white phosphorus, P4 with main group elements and compounds is given.

Triamidoamine–Uranium(IV)‐Stabilized Terminal Parent Phosphide and Phosphinidene Complexes

Reaction of [U(Tren(TIPS) )(THF)][BPh4 ] (1; Tren(TIPS) =N{CH2 CH2 NSi(iPr)3 }3 ) with NaPH2 afforded the novel f-block terminal parent phosphide complex [U(Tren(TIPS) )(PH2 )] (2; U-P=2.883(2) Å). Treatment of 2 with one equivalent of KCH2 C6 H5 and two equivalents of benzo-15-crown-5 ether (B15C5) afforded the unprecedented metal-stabilized terminal parent phosphinidene complex [U(Tren(TIPS) )(PH)][K(B15C5)2 ] (4; UP=2.613(2) Å). DFT calculations reveal a polarized-covalent UP bond with a Mayer bond order of 1.92.

Triamidoamine uranium(IV)–arsenic complexes containing one-, two- and threefold U–As bonding interactions

To further our fundamental understanding of the nature and extent of covalency in uranium–ligand bonding, and the benefits that this may have for the design of new ligands for nuclear waste separation, there is burgeoning interest in the nature of uranium complexes with soft- and multiple-bond-donor ligands. Despite this, there have so far been no examples of structurally authenticated molecular uranium–arsenic bonds under ambient conditions. Here, we report molecular uranium(IV)–arsenic complexes featuring formal single, double and triple U–As bonding interactions. Compound formulations are supported by a range of characterization techniques, and theoretical calculations suggest the presence of polarized covalent one-, two- and threefold bonding interactions between uranium and arsenic in parent arsenide [U–AsH2], terminal arsinidene [U=AsH] and arsenido [U≡AsK2] complexes, respectively. These studies inform our understanding of the bonding of actinides with soft donor ligands and may be of use in future ligand design in this area. The nature of actinide–ligand bonding is attracting attention, in particular in the context of nuclear waste separations. Structurally authenticated one-, two- and threefold uranium–arsenic bonding interactions are now reported. Computational analysis suggests the presence of polarized σ2, σ2π2, and σ2π4 in the arsenide, terminal arsinidene, and arsenido complexes, respectively.

Size-Determining Dependencies in Supramolecular Organometallic Host–Guest Chemistry

Treatment of the pentaphosphaferrocene [Cp*Fe(η(5)-P(5))] with Cu(I) halides in the presence of different templates leads to novel fullerene-like spherical molecules that serve as hosts for the templates. If ferrocene is used as the template the 80-vertex ball [Cp(2)Fe]@[{Cp*Fe(η(5)-P(5))}(12){CuCl}(20)] (4), with an overall icosahedral C(80) topological symmetry, is obtained. This result shows the ability of ferrocene to compete successfully with the internal template of the reaction system [Cp*Fe(η(5)-P(5))], although the 90-vertex ball [{Cp*Fe(η(5):η(1):η(1):η(1):η(1):η(1)-P(5))}(12)(CuCl)(10)(Cu(2)Cl(3))(5){Cu(CH(3)CN)(2)}(5)] (2 a) containing pentaphosphaferrocene as a guest is also formed as a byproduct. With use of the triple-decker sandwich complex [(CpCr)(2)(μ,η(5)-As(5))] as a template the reaction between [Cp*Fe(η(5)-P(5))] and CuBr leads to the 90-vertex ball [(CpCr)(2)(μ,η(5)-As(5))]@[{Cp*Fe(η(5)-P(5))}(12){CuBr}(10){Cu(2)Br(3)}(5){Cu(CH(3) CN)(2)}(5)] (6), in which the complete molecule acts as a template. However, if the corresponding reaction is instead carried out with CuCl, cleavage of the triple-decker complex is found and the 80-vertex ball [CpCr(η(5)-As(5))]@[{Cp*Fe(η(5)-P(5))}(12){CuCl}(20)] (5) is obtained. This accommodates as its guest [CpCr(η(5)-As(5))], which has only 16 valence electrons in a triplet ground state and is not known as a free molecule. The triple-decker sandwich complex [(CpCr)(2)(μ,η(5)-As(5))] requires 53.1 kcal mol(-1) to undergo cleavage (as calculated by DFT methods) and therefore this reaction is clearly endothermic. All new products have been characterized by single-crystal X-ray crystallography. A favoured orientation of the guest molecules inside the host cages has been identified, which shows π⋅⋅⋅π stacking of the five-membered rings (Cp and cyclo-As(5)) of the guests and the cyclo-P(5) rings of the nanoballs of the hosts.

The potential of a cyclo-As5 ligand complex in coordination chemistry

The reaction of [Cp*Fe(η5-As5)] (1) with CuI halides leads to the formation of the 1D-polymeric compounds [{Cu(μ-X)}3(CH3CN){Cp*Fe(η5:η2:η2:η2-As5)}]n (X = Cl (2), Br (3)), [{Cu(μ3-I)}2{Cp*Fe(η5:η2:η2-As5)}]n (4) and [{Cu(μ-I)}3{CuI}{Cp*Fe(η5:η2:η2:η1:η1-As5)}{Cp*Fe(η5:η5:η2-As5)}]n (5). The polymers are built up by the π-coordination of the cyclo-As5 ring to (CuX)n moieties forming discrete units, which are additionally linked by weak intermolecular As⋯Cu σ-interactions. Only polymer 4 is an exception revealing a (CuI)n ladder which is alternately coordinated by molecules of 1. In a side arm of polymer 5 a novel η5-coordination of a Cu atom below the cyclo-As5 ring is found, showing an unprecedented heteroleptic triple-decker sandwich complex with a polyarsenic middle-deck. All products are characterised by single crystal X-ray structure analysis. To define the differences in the coordination behaviour of 1 and its phosphorus analogue [Cp*Fe(η5-P5)] (1a), DFT calculations are described.

Mn2 bis(pentalene): a mixed-spin bimetallic with two extremes of bonding within the same molecule.

Structural, magnetic and theoretical studies show that the bimetallic pentalene complex, Mn(2)(C(8)H(4)(1,4-Si(i)Pr(3)))(2), contains both high and low spin Mn(ii) in two very different sites.

Preparation and single-crystal characterization of manganese(II) complexes of dichalcogenoimidodiphosphinato ligands. Monomeric versus dimeric Mn[(OPPh2)(XPPh2)N]2 (X=S, O)

Abstract Manganese(II) compounds of the type Mn[(XPR2)(YPR′2)N]2 (X, Y=O, S; R, R′=Me, Ph), were prepared by metathesis reactions between MnCl2·4H2O and the alkaline salt of the corresponding ligand. IR data are consistent with the coordination of the phosphorus ligand in a deprotonated form. The ESR spectra exhibit resolved hyperfine structure only for the Mn[(OPMe2)(SPPh2)N]2 derivative. The crystal and molecular structures of Mn[(OPPh2)(YPPh2)N]2 (Y=O, S) were determined by X-ray diffractometry. The crystal of the tetraphenylthioimidodiphosphinato derivative contains monomeric, spiro-bicyclic Mn[(OPPh2)(SPPh2)N]2 units, with a distorted tetrahedral MnO2S2 core, as a result of monometallic biconnective phosphorus ligands. By contrast, in the crystal of the tetraphenylimidodiphosphinato analogue distinct [Mn{(OPPh2)2N}2]2 dimers are present, in which the MnO5 core has a trigonal bipyramidal geometry. The coordination pattern of the four imidodiphosphinato ligands differs. Two of them act as monometallic biconnective (chelating) units, leading to six-membered MnO2P2N rings. The other two ligands act as bimetallic triconnective units, which results in a fused tricyclic Mn2O4P4N2 system. The central four-membered Mn2O2 ring is slightly bent [Mn(1)O(5)O(8)/Mn(2)O(5)O(8) dihedral angle 23.9°]. The overall conformation of the [Mn{(OPPh2)2N}2]2 dimer might be described as cis, i.e. with six-membered MnO2P2N rings formed by ligands of the same type placed on the same side of the four-membered Mn2O2 ring.

Cationic Chains of Phosphanyl‐ and Arsanylboranes

Whilst catena-phosphorus cations have been intensively studied in the last years, mixed Group 13/15 element cationic chains have not yet been reported. Reaction of the pnictogenboranes H2EBH2⋅NMe3 (E=P, As) with monohalideboranes lead to the cationic chain compounds [Me3N⋅BH2EH2BH2⋅NMe3][X] (E=P, As; X=AlCl4 , I) and [Me3N⋅BH2PH2BH2PH2BH2⋅NMe3][X] (X=I, VCl4(thf)2), respectively. All of the compounds have been characterized by X-ray structure analysis, NMR spectroscopy, IR spectroscopy, and mass spectrometry. DFT calculations elucidate the reaction pathway, the high thermodynamic stability, the charge distribution within the chain and confirm the observed solid-state structures.

Discrete and extended supersandwich structures based on weak interactions between phosphorus and mercury.

Supersized mercury: Adducts with polymeric (left) or discrete supersandwich structures (right) form from mixtures of the trinuclear mercury complex [(o-C(6)F(4)Hg)(3)] (A) with the triple-decker complex [(CpMo)(2)(μ-η(6):η(6)-P(6))] (B) in the solid state. This arrangement arises from P···Hg interactions between opposing atoms of the P(6) units and the Hg(3) units (see picture; P-purple, Hg-orange, F-green, Mo-red, C-gray).

Influence of the nacnac Ligand in Iron(I)‐Mediated P4 Transformations

Abstract A study of P4 transformations at low‐valent iron is presented using β‐diketiminato (L) FeI complexes [LFe(tol)] (tol=toluene; L=L1 (1 a), L2 (1 b), L3 (1 c)) with different combinations of aromatic and backbone substituents at the ligand. The products [(LFe)4(μ4‐η2:η2:η2:η2‐P8)] (L=L1 (2 a), L2 (2 b)) containing a P8 core were obtained by the reaction of 1 a,b with P4 in toluene at room temperature. Using a slightly more sterically encumbered ligand in 1 c results in the formation of [(L3Fe)2(μ‐η4:η4‐P4)] (2 c), possessing a cyclo‐P4 moiety. Compounds 2 a–c were comprehensively characterized and their electronic structures investigated by SQUID magnetization and 57Fe Mössbauer spectroscopy as well as by DFT methods.