Single-Crystal X-Ray Diffraction Study of Pressure and Temperature-Induced Spin Trapping in a Bistable Iron(II) Hofmann Framework.

High-pressure single-crystal X-ray diffraction has been used to trap both the low-spin (LS) and high-spin (HS) states of the iron(II) Hofmann spin crossover framework, [Fe (pdm)(H O)[Ag(CN) ] ⋅H O, under identical experimental conditions, allowing the structural changes arising from the spin-transition to be deconvoluted from previously reported thermal effects.

The relative stabilities of cyclic dicationic derivatives of diphosphanes with three (3P) or four (4P) linked phosphorus atoms.

Reaction of a diphosphane with a chlorophosphane in the presence of SnCl(2) or AlCl(3) leads to the formation of dicationic heterocycles with three (3P) or four (4P) linked phosphorus atoms. Some 3P derivatives with small alkyl substituents may also be prepared by direct alkylation of cyclic triphosphenium ions. Several new species were prepared in solution, some of which were isolated and characterised by single-crystal X-ray diffraction.

Two-photon spectroscopy of cyclometalated iridium complexes.

The near-infrared two-photon absorption (TPA) spectra of a series of cyclometalated iridium complexes have been measured. These complexes exhibit moderately large TPA cross-sections of approximately 20 GM at the biological relevant wavelength of 800 nm. A new complex has been designed and synthesised, and found to have an increased cross-section of 44 GM at 800 nm.

Stereochemically inactive lone pairs in phosphorus(III) compounds: the characterisation of some derivatives with the 2,5-(CF3)2C6H3 (Ar) substituent and their complexation behaviour towards Pt(II) species.

Some new phosphorus(III) derivatives Ar(2)PX (X = Br, Cl, F or H), ArPX(2) (X = Br or Cl), Ar(3)P and Ar(t)BuPCl, with the 2,5-bis(trifluoromethyl)phenyl (Ar) substituent on phosphorus, have been prepared, and characterised by (31)P and (19)F NMR solution-state spectroscopy. The complexing ability of Ar(2)PX, Ar(3)P and Ar(t)BuPCl towards the dimeric platinum(II) complexes [PtY(μ-Y)(PEt(3))](2) (Y = Cl or Br, the latter for X = Br only) has also been investigated. Single-crystal X-ray diffraction studies at low temperature have been carried out for Ar(3)P, Ar(2)PCl and the hydrolysis or oxidation products Ar(2)P(H)OH and Ar(2)P(O)OH.

Ammonia oxide makes up some 20% of an aqueous solution of hydroxylamine.

Three independent indirect estimates based on structure-reactivity correlations indicate that ca. 20% of hydroxylamine exists in aqueous solution as ammonia oxide, NH(3)(+)-O(-).

Studying the origin of the antiferromagnetic to spin-canting transition in the beta-p-NCC6F4CNSSN* molecular magnet.

The crystal structure of the spin-canted antiferromagnet beta-p-NCC(6)F(4)CNSSN* at 12 K (reported in this work) was found to adopt the same orthorhombic space group as that previously determined at 160 K. The change in the magnetic properties of these two crystal structures has been rigorously studied by applying a first-principles bottom-up procedure above and below the magnetic transition temperature (36 K). Calculations of the magnetic exchange pathways on the 160 K structure reveal only one significant exchange coupling (J(d1)=-33.

Acyl polysilanes: new acyl anion equivalents for additions to electron-deficient alkenes.

Silenes, generated through thermolysis of acylpolysilanes, add to alpha,beta-unsaturated esters to form cyclobutanes and silylsubstituted cyclopropanes in moderate yields. Upon Si-C bond oxidation the cyclopropanes are converted directly to 1,4-dicarbonyl compounds, thus demonstrating the formal acyl anion chemistry of acyl polysilanes.

Highly diastereoselective self-assembly of chiral tris(m-ureidobenzyl)amino capsules.

The self-assembly of chiral tris(m-ureidobenzyl)amines to give dimeric capsules is a highly diastereoselective process in solution, while in the solid state, the formation of the corresponding capsules is not only diastereoselective but also regioselective.

Alkyl and aryl dicationic derivatives of cyclic triphosphenium ions.

Direct alkylation of cyclic triphosphenium ions by triflates to give di-ium dications is only possible for small organic substituents on the attacking reagent. The dicationic products are not intrinsically unstable, however, and in many instances they may be synthesised by an alternative route, pioneered by Schmidpeter and co-workers. These species may be readily identified in solution by (31)P NMR spectroscopy.

Thermal, pressure and light induced spin transition in the two-dimensional coordination polymer [Fe(pmd)2[Cu(CN)2]2].

A complete structural, calorimetric, and magnetic characterisation of the 2D coordination spin crossover polymer [Fe(pmd)(2)[Cu(CN)(2)](2)] is reported. The crystal structure has been investigated below room temperature at 180 K and 90 K, and at 30 K after irradiating the sample at low temperature with green light (lambda = 532 nm). The volume cell contraction through the thermal spin transition is only 18 A(3) which is lower than the usually observed value of around 25-30 A(3) while the average Fe-N bond distances decrease by the typical value of about 0.

Au...Au interactions: Z ' > 1 behavior and structural analysis.

The tendency of molecules containing an Au...

Templated crystal nucleation: mixed crystals of very different copper(II) N,N',N''-trimethyltriazacyclononane complexes.

Templation of a daughter phase by a parent crystal results from an equilibrating mixture of two very different copper(ii) N,N',N''-trimethyltriazacyclononane complexes.

Mössbauer investigation of the photoexcited spin states and crystal structure analysis of the spin-crossover dinuclear complex [{Fe(bt)(NCS)(2)}(2)bpym] (bt=2,2'-bithiazoline, bpym=2,2'-bipyrimidine).

The crystal structure of the complex [{Fe(bt)(NCS)(2)}(2)bpym] (1) (bt=2,2'-bithiazoline, bpym=2,2'-bipyrimidine) has been solved at 293, 240, 175 and 30 K. At all four temperatures the crystal remains in the P space group with a=8.7601(17), b=9.

Synthetic and structural studies on C-ethynyl- and C-bromo-carboranes.

A high-yield preparation of the C-monoethynyl para-carborane, 1-Me(3)SiC[triple bond]C-1,12-C2B10H11, from C-monocopper para-carborane and 1-bromo-2-(trimethylsilyl)ethyne, BrC[triple bond]CSiMe(3) is reported. The low-yield preparation of 1,12-(Me3SiC[triple bond]C)2-1,12-C2B10H10 from the C,C'-dicopper para-carborane derivative with 1-bromo-2-(trimethylsilyl)ethyne, BrC[triple bond]CSiMe3, has been re-investigated and other products were identified including the C-monoethynyl-carborane 1-Me3SiC[triple bond]C-1,12-C2B10H11 and two-cage assemblies generated from cage-cage couplings. The contrast in the yields of the monoethynyl and diethynyl products is due to the highly unfavourable coupling process between 1-RC[triple bond]C-12-Cu-1,12-C2B10H10 and the bromoalkyne.

Unusual variations in the incidence of Z' > 1 in oxo-anion structures.

A series of Cambridge Structural Database studies show that ionic species generally form low Z' structures, even in those cases where charge assisted hydrogen bonding is a key feature, e.g. oxo-anion complexes.

2-(4-Chloroanilino)- and 2-(4-methoxyanilino)-1,2-diphenylethanone.

The title compounds, C20H16ClNO and C21H19NO2, adopt syn orientations of the C=O and N-H bonds but, like their analogues, form no strong intermolecular hydrogen bonds.

Modular nanometer-scale structuring of gel fibres by sequential self-organization.

Ag(I) and Cu(II) complexes of a series of simple bis(urea) ligands form soft metallogels. X-ray crystallographic results suggests that the gels' structure is based on hydrogen bonding to counter anions and thus suggests a route to tunable gel rheological properties.

Cooperative hydrogen-bonding effects in a water square: a single-crystal neutron and partial atomic charges and hardness analysis study.

Four isomorphous complexes of formula [M(L)(4)(H(2)O)(2)]SO(4).2H(2)O (M = Co, 1a; Ni, 1b; Cu, 1c; Zn, 1d) have been isolated and characterized by single-crystal X-ray diffraction and neutron diffraction using the quasi-Laue diffractometer VIVALDI at the Institut Laue-Langevin as well as by thermogravimetric analysis. The structures contain a discrete, strongly hydrogen-bonded water tetramer which causes a significant distortion of the metal coordination sphere in each case.

Solid- and solution-state studies of the novel mu-dicyanamide-bridged dinuclear spin-crossover system {[(Fe(bztpen)]2[mu-N(CN)2]}(PF6)3 x n H2O.

The mononuclear diamagnetic compound {Fe(bztpen)[N(CN)2]}(PF6)CH3OH (1) (bztpen = N-benzyl-N,N',N'-tris(2-pyridylmethyl)ethylenediamine) has been synthesized and its crystal structure studied. Complex 1 can be considered to be the formal precursor of two new dinuclear, dicyanamide-bridged iron(II) complexes with the generic formula {[(Fe(bztpen)]2[mu-N(CN)2]}(PF6)3 x n H2O (n = 1 (2) or 0 (3)), which have been characterized in the solid state and in solution. In all three complexes, the iron atoms have a distorted [FeN6] octahedral coordination defined by a bztpen ligand and a terminal (1) or a bridging dicyanamide ligand (2 and 3).

Influence of hydrogen bonding on coordination polymer assembly.

An extended dipyridyl ligand (L1) capable of hydrogen bonding with guest species via urea functionalities has been designed and synthesised. Assembly of a silver(I) coordination polymer of L1 is dependent on the nature of the hydrogen bond acceptor in a logical extension of the monopyridyl analogue.

4-[Bis(4-hydroxy-3,5-dimethylphenyl)methyl]pyridinium chloride and bromide.

The isostructural title salts, 4-[bis(4-hydroxy-3,5-dimethylphenyl)methyl]pyridinium chloride and bromide, C22H24NO2+.Cl- and C22H24NO2+.Br-, exhibit extended hydrogen-bonded ribbons in the solid state.

Selective Ir-catalysed borylation of polycyclic aromatic hydrocarbons: structures of naphthalene-2,6-bis(boronate), pyrene-2,7-bis(boronate) and perylene-2,5,8,11-tetra(boronate) esters.

The selectivity of the iridium boryl complex-catalysed reaction of pyrene and perylene with B2(pin)2 (pin = OCMe2CMe2O) has been employed in the synthesis of D(2h)-symmetry pyrene-2,7-(Bpin)2 and D(4h)-symmetry perylene-2,5,8,11-(Bpin)4 providing direct borylation of positions which are otherwise difficult to derivatise.

trans-Di-mu-bromo-bis[bromo(triethylphosphine-kappaP)platinum(II)].

The title compound, [Pt2Br4(C6H15P)2], is a centrosymmetric dinuclear platinum(II) complex consisting of two square-planar platinum centres connected by two bridging Br atoms.