Organometallic Complexes in Nonlinear Optics I: Second-Order Nonlinearities

This paper describes a simple orbital picture for understanding the optical transitions and the second-order nonlinear optical response of metallocene-based chromophores of the form metallocene−(π-bridge)−acceptor, and experimental studies to test this model. From a combination of UV photoelectron spectroscopy, cyclic voltammetry, and density functional calculations, it is deduced that the three highest occupied orbitals are little perturbed from the parent metallocenes, that the HOMO-3 is a π-orbital delocalized between the metallocene cyclopentadienyl ring and the unsaturated bridge, and that the LUMO is acceptor based. The lowest energy transition in the UV/visible/near-IR spectra of these compounds is assigned to a metal-to-acceptor transition, while the higher energy transition is attributed to a transition to the acceptor-based LUMO from the delocalized HOMO-3 orbital. The variations in oscillator strength can be rationalized by considering the low-energy transition as borrowing intensity from the h...

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Studies of the Electronic Structure of Metallocene-Based Second-Order Nonlinear Optical Dyes

Publisher Summary This chapter reviews macrocyclic receptor molecules that contain an electrochemical responsive signaling function—that is, a redox-active center, in close proximity to a host-binding site. Depending on the complementary nature of the host cavity, these systems can, in principle, be designed to recognize electrochemically the binding of any charged or neutral inorganic or organic guest specie, through either space electrostatic interactions or electrostatic communication, via various bond linkages between the receptor site and the redox center. Evidently selective binding of a particular guest specie coupled with an electrochemical response is of paramount importance for future potential prototypes of new amperometric molecular sensory devices. The review of these types of systems is conveniently subdivided according to the nature of the target complexant—that is, a cation (metal, ammonium), anion (halide, nitrate, sulfate, phosphate, and so on), or neutral (organic or inorganic) guest. Stimulated by nature and, particularly, by the idea of modeling “coupled reactions,” that is, reactions that mutually influence each other that are known to play a fundamental role in the biological processes, such as ion transport and oxidative phosphorylation, current attention has focused on a new generation of abiotic host molecules that contain responsive or signaling functions appended to or as an integral part of a host macrocyclic framework.

Transition Metal and Organic Redox-Active Macrocycles Designed to Electrochemically Recognize Charged and Neutral Guest Species

http://alpha.chem.umb.edu/chemistry/ch612/documents/Barlow2.pdf

Electronic and optical properties of conjugated group 8metallocene derivatives

A new Schiff-base ligand based on the condensation of diaminomaleonitrile and 4-(diethylamino)salicylaldehyde is reported with its copper, nickel, and zinc complexes. Their second-order nonlinear optical properties are investigated by electric field induced second harmonic (EFISH) and ZINDO quantum-chemical calculations to probe the role of the metal center in the nonlinearity. All the complexes exhibit a second-order nonlinear response that is larger than that of the ligand with an hyperpolarizability (β) value of 400 (±100) 10-30 cm5 esu-1 for the zinc derivative at 1.34 μm. Theoretical calculations indicate that the two-level model is inadequate to describe the nonlinearity in such systems.

Synthesis and second-order nonlinear optical properties of new copper(II), nickel(II), and zinc(II) Schiff-base complexes. Toward a role of inorganic chromophores for second harmonic generation

The synthesis of ferrocenyl compounds with second-order optical non-linearities

Second-order non-linear optical properties of diironalkenylidyne complexes; crystal structure of {(η-C5H5)2Fe2(CO)2(μ-CO)(μ-(E)CCHCHC6H4(p)-NMe2)}+BF4−

A series of salts of stoichiometry (Cn-)(AI-), where A and C represent redox-active cluster cations and anions have been prepared. These compounds which we call "soft salts", have been studied with a long term view of obtaining examples in which the charge x is non-integral. The synthesis and bulk properties of new organometallic intercalation compounds such as (Moo,( Fe,(q-C,HS),(p-S),),, Is) are reported. Finally, the synthesis of organometallic compounds with large non-linear optical properties will be described. The compound ((cis)-( l-ferrocenyl-2-(4-nitrophenyl)ethylene) ) has been shown to have the ability for second harmonic generation (S.H.G.) which is 62 times that of urea.

New organometallic solids

The cis-ethylenehydride compounds [Mo(η-C6H6)(L2)(η-C2H4)H]PF6[L2= Me2PCH2CH2PMe2(dmpe) or o-C6H4(EMe2)2(E = P, pdmp, or As, pdma)] react with trimethylphosphine to give the η-ethylbenzene compounds [Mo(η-C6H5Et)(L2)(PMe3)H]PF6. Detailed studies of the mechanism of this reaction show that there is an initial reaction, at low temperatures, giving isomeric mixtures of thermally unstable η-cyclohexadienyl derivatives [Mo(η-C6H7)(dmpe)(PMe3)(η-C2H4)]+. The combined evidence from n.m.r. spectra, including kinetic studies, and from the preparation and reactions of intermediates shows that the η-ethylbenzene compound is formed by the sequence [Mo(η-C6H6)(dmpe)(η-C2H4)H]+→[Mo(η-C6H6)(dmpe)(PMe3)Et]+→[Mo(η-C6H6Et-endo)(dmpe)(PMe3)(solvent)]+→[Mo(η-C6H5Et)(dmpe)(PMe3)]+ H+→[Mo(η-C6H5Et)(dmpe)(PMe3)H]+. The following new compounds have been prepared and characterised: [Mo(η-C6H6){P(OMe)3}2(η-C3H5)] PF6, [Mo(η-C6H6)(pdmp)(η-C3H5)]PF6, [Mo(η-C6H6)(pdma)(η-C3H5)]PF6, [Mo(η-C6H6)(pdmp)(η-C2H4)], [Mo(η-C6H6)(pdma)(η-C2H4)], [Mo(η-C6H6)(pdmp)(η-C2H4)H]PF6, [Mo(η-C6H6)(pdma)(η-C3H5)]PF6, [Mo(η-C6H6)(pdmp)(η-C2H4)], [Mo(η-C6H6)(pdma)(η-C2H4)], [Mo(η-C6H6)(pdmp)(η-C2H4)H]PF6, [Mo(η-C6H6)(pdma)(η-C2H4)H]PF6, [Mo(η-C6H5Et)(pdmp)(PMe3)H]PF6, [Mo(η-C6H5Et)(pdma)(PMe3)H]PF6, [Mo(η-C6H6)(dmpe)(PMe3)D]PF6, [Mo(η-C6H6)(dmpe)(η-C2H4)], [Mo(η-C6H6Et-endo)(dmpe)2]PF6, [Mo(η-C6H6)(dmpe){P(OMe)3}H]PF6, [Mo(η-C6H6)(dmpe)(CO)H]PF6, [Mo(η-C6H6)(dmpe)(2,6-Me2C6H3 NC)]PF6, [Mo(η-C6H5Me)(dmpe)(η-C2H4)H]PF6, [Mo(C6H4Me-2-Et-1)(dmpe)(PMe3)H]PF6, [Mo(C6H4Me-3-Et-1)(dmpe)(PMe3)H]PF6, [Mo(C6H5Me-1-Et-6-endo)(dmpe)2]PF6, [Mo(C6H5Me-2-Et-6-endo)(dmpe)2]PF6, and [Mo(η-C6H6Et-endo)(pdmp)2]PF6.

Mechanism of the reaction of [Mo(η-C6H6)(Me2PCH2CH2PMe2)(η-C2H4)H]+ with PMe3 giving [Mo(η-C6H5Et)(dmpe)(PMe3)H]+: metal-to-ring migration of an ethyl group

Heather E. Bunting

Papers

The synthesis of ferrocenyl compounds with second-order optical non-linearities

Second-order non-linear optical properties of diironalkenylidyne complexes; crystal structure of {(η-C5H5)2Fe2(CO)2(μ-CO)(μ-(E)CCHCHC6H4(p)-NMe2)}+BF4−

New organometallic solids

Mechanism of the reaction of [Mo(η-C6H6)(Me2PCH2CH2PMe2)(η-C2H4)H]+ with PMe3 giving [Mo(η-C6H5Et)(dmpe)(PMe3)H]+: metal-to-ring migration of an ethyl group

New Organometallic Solids