We report IR active N2 stretching frequencies in isolated and size selected cobalt cluster nitrogen adsorbate complexes, [Con(N2)1](+) as recorded by virtue of InfraRed Photon Dissociation (IRPD) spectroscopy. The observed frequencies of the [Con(N2)1](+) complexes (n = 8-17) are significantly redshifted (2180 to 2290 cm(-1)) with respect to the IR inactive vibrations of free N2 (2359 cm(-1)). These bands are assigned to a μ1 head-on type of coordination of the N2 to the cobalt cluster surface, revealing remarkable cluster size dependent features to interpret.

We present "non-classical" dinitrogen Fe(iii) oxo acetate complexes in vacuo utilizing Infrared Photodissociation (IR-PD) at cryo temperatures. The IR-PD spectra reveal a blue shift of the N stretching vibration frequencies in the complexes. Density Functional Theory (DFT) calculations confirm the experiments and indicate strengthened N-N bonds due to pronounced σ bonding and a lack of π back donation.

A catalyst system composed of [(CMe)RuCl], potassium carbonate/guanidine carbonate, and mesitoic acid efficiently promotes the doubly regioselective C-H hydroarylation of unsymmetrical alkynes. The process involves carboxylate-directed ortho-C-H bond activation followed by regioselective addition to the alkyne C-C triple bond with concerted decarboxylation. This action of the carboxylate as a deciduous directing group ensures exclusive monovinylation with high selectivity for the (E)-1,2-diarylalkene.

We elucidate the correlation between geometric structures and magnetic couplings in trinuclear iron(iii) oxo acetate complexes [Fe3O(OAc)6(Py)n]+ (n = 0, 1, 2, 3) when isolated and trapped as gaseous ions. Structural information arises from Infra Red-Multiple Photon Dissociation (IR-MPD) and Collision Induced Dissociation (CID) experiments in conjuction with Density Functional Theory (DFT) based calculations. We simulate the antiferromagnetic couplings between the FeIII (d5) centers by employing a Broken Symmetry approach within our DFT calculations, and we extract the associated antiferromagnetic coupling constants. Coordination of one, two or three axial pyridine ligands to the [Fe3O(OAc)6]+ subunit distorts the geometry of the triangular Fe3O core. The Fe-Ocentral bond lengths are enlarged or shortened depending on number of coordinated pyridine ligands. This significantly affects the antiferromagnetic coupling constants between the FeIII centers ranging from -62 cm-1 to -28 cm-1 in [Fe3O(OAc)6(Py)n]+ (n = 0, 1, 2, 3). A detailed analysis of the associated exchange couplings indicates a switching of magnetic ground states by pyridine coordination. The total spin ST in the ground states of [Fe3O(OAc)6(Py)n]+ raises from ST = 1/2 (n = 0) to 3/2 (n = 1) and 5/2 (n = 2). Coordination of the third pyridine ligand (n = 3) re-establishes a spin ground state of ST = 1/2. We thus identify a coordination controlled switching of magnetic ground states.

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