Solid state synthesis, structure and optical limiting properties of seleno cuboidal clusters [M3Se4X3(diphosphine)3] + (M=Mo, W; X=Cl, Br)

Marta Feliz, Rosa Llusar*, Santiago Uriel, Cristian Vicent, Mark G. Humphrey, Nigel T. Lucas, Marek Samoc, Barry Luther-Davies

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    33 Citations (Scopus)


    The trinuclear complexes [M33-Se)(μ-Se)3X3(dppe) 3]PF6 [M=Mo, X=Cl (1), Br (2); M=W, X=Br (3)] have been prepared by both solid state and solution syntheses. A structural study of 1 confirms the presence of an incomplete cuboidal Mo3Se4 core. The electrochemical, linear optical and optical limiting properties of 1-3 and the previously reported [M33-Q)(μ-Q)3X3(L 2)3]PF6 (M=Mo, Q=Se, X=Cl, L2=dmpe (4); M=Mo, Q=Se, X=Br, L2=dmpe (5); M=W, Q=Se, X=Br, L2=dmpe (6); M=Mo, Q=S, X=Cl, L2=dppe (7); M=Mo, Q=S, X=Br, L2=dppe (8); M=W, Q=S, X=Br, L2=dppe (9)) have been examined. Two different kinds of electrochemical behavior are proposed for the trinuclear [M3Q4X3(diphosphine)3] + complexes upon reduction: (i) MIV3↔MIVM2 III→MIII3 for all complexes except 5 and 6 (ii) MIV3→MIV2M III→MIVM2III→M III3 for 5 and 6. The ease of reduction within the [M3Q4Br3(dppe)3]+ series follows the trend Mo3S4 > Mo3Se4 > W3Se4≈W3S4, while the ease of reduction for the analogous dmpe derivatives follows the trend Mo3S4≈Mo3Se4 > W3Se4≈W3S4. A quasi-reversible oxidation process at half-wave potential close to approximately 1.2 V vs. Ag|AgCl has been identified for the first time in [W3Q4] cluster compounds. Linear optical absorption spectra are broadly similar, with intense bands at high energy and weaker bands at lower energy. The longest wavelength absorption maximum is red-shifted in this series of complexes upon replacing chloride by bromide, sulfur by selenium, and tungsten by molybdenum. Complexes 4-6 have weak absorption from 500 to 800 nm. Optical limiting in 1-9 has been assessed by open-aperture Z-scan at 523 nm using 40 ns pulses, all nine clusters exhibiting optical limiting (values of the excited state cross-sections σeff are larger than those of the ground-state cross-sections σ0) at fluences approximately 100 mJcm-2.

    Original languageEnglish
    Pages (from-to)69-77
    Number of pages9
    JournalInorganica Chimica Acta
    Publication statusPublished - 5 Jun 2003


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