Structural systematics of some trinuclear alkynyl and diynyl Group 11 complexes containing dppm [dppm = CH(2)(PPh(2))(2)]

Available online 9 October 2017In this review the molecular structures of a series of trinuclear alkynyl and diynyl Group 11 cations [{M3(μ-dppm)3}(X)n](3−n)+ (M = Cu, Ag; n = 1, 2; where X is an alkynyl or diynyl group, an inorganic anion or solvent) are considered from the points of view of (i) the dimensions and geometries of the M3(P–P)3 cores, (ii) the conformations of the dppm ligands, and (iii) the attachment of the alkynyl and diynyl ligands. In the crowded [M3(μ-dppm)3]3+ core, the dppm ligands are arranged so that there is always one CH2 group up and two down, to give pseudo mirror symmetry perpendicular to the M3 plane (crystallographic in some cases). Attachment of the alkynyl or diynyl substituent(s) occurs roughly normal to the M3 plane; according to their perpendicularity, the C(1) atom may be μ2 or μ3. In most cases where only one alkynyl or diynyl ligand is present, a second ligand is also attached to the M3 core. Unusual and interesting dispositions/conformations of the dppm ligands are widespread, among the mono–diynyl complexes in particular, whereby some phosphorus donor atoms lie at unusual distances out of the M3 planes, a concomitant of strong agostic interactions between phenyl H atoms and the atoms of the open M3 face, and weak M⋯M interactions. With one X group, C–H⋯M interactions persist on the other face, with C–H⋯X interactions with the alkyne affecting the inclination of the alkyne and the conformation of the Ph rings. With two substituents (one of which may be a loosely bound anion), similar interactions may occur, accompanied by twisting of the dppm chelate ring to displace P atoms from the M3 plane. These factors possibly inhibit formation of the bis(diyndiyl) complexes, which are only obtained under more strongly basic conditions.Michael I. Bruce, Jean-François Halet, Boris Le Guennic, Brian W. Skelton, Alexandre N. Sobolev, Christopher J. Sumby, Allan H. Whit

Thermal and near-infrared light induced spin crossover in a mononuclear iron( ii ) complex with a tetrathiafulvalene-fused dipyridophenazine ligand

A mononuclear Fe(II) complex involving a tetrathiafulvalene-based ligand exhibits thermal spin-crossover (around 143 K) with pronounced hysteresis behaviour (48 K). The chromophoric and π-extended ligand allows Near-Infrared (NIR) sensitization for the light-induced excited spin-state trapping (LIESST) with T(LIESST) = 90 K

A density functional theory based analysis of photoinduced electron transfer in a triazacryptand based K+ sensor

The electronic structure and photoinduced electron transfer processes in a K+ fluorescent sensor that comprises a 4-amino-naphthalimide derived fluorophore with a triazacryptand lig- and is investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT) in order to rationalise the function of the sensor. The absorption and emission energies of the intense electronic excitation localised on the fluorophore are accurately described using a ∆SCF Kohn-Sham DFT approach, which gives excitation energies closer to experiment than TDDFT. Analysis of the molecular orbital diagram arising from DFT calculations for the isolated molecule or with implicit solvent cannot account for the function of the sensor and it is necessary to consider the relative energies of the electronic states formed from the local excitation on the fluorophore and the lowest fluorophore→chelator charge transfer state. The inclusion of solvent in these calculations is critical since the strong interaction of the charge transfer state with the solvent lowers it energy below the local fluorophore excited state making a reductive photoinduced electron transfer possible in the absence of K+, while no such process is possible when the sensor is bound to K+. The rate of electron transfer is quantified using Marcus theory, which gives a rate of electron transfer of k_ET=5.98 x 10^6 s−1

Preparation and molecular structure of Hg{CoCCoC[Ru(dppe)Cp*]}2-non-linearity in a molecular rod

The preparations of Hg{CCCC[Ru(PR3)2Cp′]}2 [(PR3)2=dppe, Cp′=Cp*, 1; PR3=PPh3, Cp′=Cp, 2] are reported and the molecular structure of 1 is described. Following the observation of an unusually large bending at the carbon atoms attached to mercury [C(3)---C(4)---Hg 166.5(3)°]. DFT calculations were employed to probe its electronic structure. The system exhibits a closed-shell electronic configuration and the bending must be ascribed to low-energy lattice forces.Michael I. Bruce, Jean-François Halet, Boris Le Guennica, Brian W. Skelton, Mark E. Smith and Allan H. Whitehttp://www.elsevier.com/wps/find/journaldescription.cws_home/504086/description#descriptio

The preparation, characterisation and electronic structures of 2,4-pentadiynylnitrile (cyanobutadiynyl) complexes

Convenient preparative routes to mononuclear ruthenium complexes containing the 2,4-pentadiynylnitrile, or cyanobutadiynyl, ligand are described. The electronic properties of the [C5N]− ligand are closely related to those of not only the cyanide ([CN]−) and 2-propynylnitrile or cyanoacetylide ([CCCN]−) ligands, but also those of the isoelectronic polyynyl ([{CC}nR]−) ligands

N 3 O 6 versus N 2 O 6 coordinated dysprosium slow magnetic relaxation in a tetrathiafulvalene-based dinuclear complex

International audienc

Luminescence and Single-Molecule-Magnet Behaviour in Lanthanide Coordination Complexes Involving Benzothiazole-Based Tetrathiafulvalene Ligands

International audienc