pH-Switchability and Second-Order Nonlinear Optical Properties of Monocyclopentadienylruthenium(II)/iron(II) Tetrazoles/Tetrazolates: Synthesis, Characterization, and Time-Dependent Density Functional Theory Calculations

Pedro R Florindo; Paulo J Costa; M F M Piedade; M Paula Robalo

doi:10.1021/acs.inorgchem.7b00138

pH-Switchability and Second-Order Nonlinear Optical Properties of Monocyclopentadienylruthenium(II)/iron(II) Tetrazoles/Tetrazolates: Synthesis, Characterization, and Time-Dependent Density Functional Theory Calculations

Inorg Chem. 2017 Jun 19;56(12):6849-6863. doi: 10.1021/acs.inorgchem.7b00138. Epub 2017 Jun 1.

Authors

Pedro R Florindo^{1

2}, Paulo J Costa, M F M Piedade¹, M Paula Robalo^{1

3}

Affiliations

¹ Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa , Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
² iMed.ULisboa, Faculdade de Farmácia da Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.
³ Área Departamental de Engenharia Química, ISEL - Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa , Rua Conselheiro Emídio Navarro, 1, 1959-007 Lisboa, Portugal.

PMID: 28569504
DOI: 10.1021/acs.inorgchem.7b00138

Abstract

Tetrazole/tetrazolate monocyclopentadienyliron(II) and ruthenium(II) compounds of general formulas [(η⁵-C₅H₅)M(dppe)(N₄(H)CC₆H₄NO₂)][PF₆]/[(η⁵-C₅H₅)M(dppe)(N₄CC₆H₄NO₂)] were investigated for their pH-switching second-order nonlinear optical (SONLO) properties. Compounds [(η⁵-C₅H₅)M(dppe)(N₄CC₆H₄NO₂)] (M = Fe, Ru) and compound [(η⁵-C₅H₅)Ru(dppe)(N₄(H)CC₆H₄NO₂)][PF₆] were fully characterized by (¹H-, ¹³C-, ³¹P-) NMR, cyclic voltammetry, and elemental analysis, and compounds [(η⁵-C₅H₅)Fe(dppe)(N₄CC₆H₄NO₂)] and [(η⁵-C₅H₅)Ru(dppe)(N₄(H)CC₆H₄NO₂)][PF₆] were further characterized by single-crystal X-ray diffraction; the synthesis of [(η⁵-C₅H₅)Fe(dppe)(N₄(H)CC₆H₄NO₂)][PF₆] was unsuccessful. Time-dependent density functional theory calculations were performed using PBE0 and CAM-B3LYP functionals to evaluate the first hyperpolarizability (β_tot) of the tetrazole/tetrazolate complexes and for a detailed analysis of the experimental data. Both functionals predict (i) high first hyperpolarizabilities for the tetrazolate complexes [(η⁵-C₅H₅)M(dppe)(N₄CC₆H₄NO₂)], with β_tot[Ru] ≈ 1.2β_tot[Fe], and (ii) a 3-fold reduction in β_tot[Ru] upon protonation, in complex [(η⁵-C₅H₅)Ru(dppe)(N₄(H)CC₆H₄NO₂)]⁺, forecasting [(η⁵-C₅H₅)Ru(dppe)(N₄CC₆H₄NO₂)]/[(η⁵-C₅H₅)Ru(dppe)(N₄(H)CC₆H₄NO₂)]⁺ complexes as on/off, pH-switchable SONLO forms.