Elsevier

Inorganica Chimica Acta

Volume 343, 30 January 2003, Pages 41-50
Inorganica Chimica Acta

Synthesis and non-linear optical properties of (alkyne)dicobalt octacarbonyl complexes and their substitution derivatives

https://doi.org/10.1016/S0020-1693(02)01185-4Get rights and content

Abstract

A series of new donor–acceptor compounds of the form [(HCCCHCHC6H4X-p)Co2(CO)4(L1)(L2)])] (2, X=Br, L1=L2=CO; 3, X=NO2, L1=L2=CO; 6, X=NO2, L1=CO, L2=PPh3; 7, X=NO2, L1=L2=PPh3; 8, X=NO2, L1=AsPh3, L2=PPh3), where X is a π-acceptor group and the (alkyne)Co2(CO)4(L1)(L2) moiety is a donor, has been synthesized. The different σ-donor/π-acceptor abilities of the ligands L1 and L2 allow tuning of the electronic and optical properties of complexes 2, 3 and 68: the hyperpolarizability values increase in the order 2<3<6<7<8. Density functional calculations reveal that the absolute values of β do not agree with experimental results, but the general trends are consistent with experiments. The X-ray crystal structures of 2, 6, and 7 are reported.

A series of new donor–acceptor compounds of the form [(HCCCHCHC6H4X-p)Co2(CO)4(L1)(L2)])] (2, X=Br, L1=L2=CO; 3, X=NO2, L1=L2=CO; 6, X=NO2, L1=CO, L2=PPh3; 7, X=NO2, L1=L2=PPh3; 8, X=NO2, L1=AsPh3, L2=PPh3), where X is a π-acceptor group and the (alkyne)Co2(CO)4(L1)(L2) moiety is a donor, has been synthesized. The different σ-donor/π-acceptor abilities of the ligands L1 and L2 allow tuning of the electronic and optical properties of complexes 2, 3, and 68.

  1. Download : Download full-size image

Introduction

Molecular materials that exhibit non-linear optical properties are of great interest for potential applications in optical data processing technology. A wide variety of organic compounds have been shown to exhibit such properties and, more recently, organometallic compounds have been found to exhibit significant effects [1].

Metals can have a large diversity of coordination mode with various organic ligands and changing a ligand in the coordination sphere can affect the function of the metal fragment. For organometallic compounds, it is particularly easy to finely tune either the electronic and/or steric effect by substitution of labile ligands 1b[2], [2](a), [2](b), [2](c), [2](d). For example, Müller's and Tamm's groups reported the facile tuning of the electronic and optical properties of transition metal π-arene tricarbonyl complexes by carbonyl substitution [2](a), [2](b).

Alkynes can be complexed with transition metal metals through the σ- or π-bond. Recently, σ-acetylide and σ-enynyl metal complexes (M=Ru, Ni, Au) have attracted much attention as promising candidates for NLO materials [3], [3](a), [3](b), [3](c), [3](d), [3](e), [3](f), [3](g), [3](h), [3](i), [3](j). However, to our knowledge, little study has been conducted on π-alkyne transition metal complexes. It is a general feature of π-alkyne complexes that electrons are back-donated from a metal d-orbital into the ligand LUMO [4]. Thus, it is expected that an electron-rich π-alkyne complex having (an) electron-withdrawing group(s) on the alkyne can behave like a push–pull NLO molecule. Furthermore, increasing the electron-withdrawing ability enhances the stability of alkyne complexes.

We have prepared dicobalt carbonyl complexes of alkyne with an electron-withdrawing group and examine their non-linear optical properties. These complexes offer the possibility of a new class of NLO chromophore with tuning of their optical properties by carbonyl substitution. Herein we report the synthesis and non-linear optical study of new alkyne dicobalt complexes. Recently, the semiempirical calculations of the NLO properties of [Co2{μ–η2-(C6H5)CC(C6H4NO2)}(CO)6] have been published [5].

Section snippets

General considerations

All reactions with air- or moisture-sensitive materials were carried out under nitrogen using standard Schlenk techniques. Freshly distilled, dry, and oxygen-free solvents were used throughout. 1H and 31P NMR spectra were obtained with a Bruker 300 or 500 spectrometer. Elemental analyses were carried out at the National Center for Inter-University Research Facilities, Seoul National University. Infrared spectra were recorded on a Shimadzu IR-470 spectrometer. UV–Vis electronic absorption

Synthesis

Enyne dicobalt carbonyl complexes 2 and 3, in which electron-rich (alkyne)Co2(CO)6 fragment is conjugated with an electron withdrawing organic part, have been prepared by applying the Wittig reaction to an aldehyde complex 1, (HCCCHO)Co2(CO)6, using an appropriate ylide. Compound 1 has been prepared by a published procedure [6], [6](a), [6](b). Treatment of 1 with ylides p-XC6H4CHPPh3 (X=Br, NO2), generated in situ by the reaction of the corresponding phosphonium bromide and KtOBu in THF,

Conclusion

In this paper we have synthesized a series of new donor–acceptor compounds of the form [(HCCCHCHC6H4X-p)Co2(CO)4(L1)(L2)] (2, X=Br, L1=L2=CO; 3, X=NO2, L1=L2=CO; 6, X=NO2, L1=CO, L2=PPh3; 7, X=NO2, L1=L2=PPh3; 8, X=NO2, L1=AsPh3, L2=PPh3). The concept of using the (alkyne)Co2(CO)4(L1)(L2) moiety as an electron donor was rewarded by high β values of complexes with good σ-donor and poor π-acceptor ligands L1 and L2. Transformation of 2 into 8 led to five times increase of β values. An

Supplementary material

Crystallographic data for the structural analysis have been deposited with the Cambridge Crystallographic Data Centre, CCDC Nos. 167569(7), 167570(2), and 167571(6) for compounds 2, 6, and 7, respectively (tables of atomic coordinates, bond lengths and angles, anisotropic displacement parameters, and observed and calculated structure factors). Copies of this information may be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (fax: +44-1223-336-033; e-mail:

Acknowledgements

Y.K.C. is grateful for the financial support from KOSEF (1999-1-122-001-5) and KOSEF through the Center for Molecular Catalysis at Seoul National University, and I.S.L. and D.M.S. acknowledge the award of fellowship by the Brain Korea 21.

References (17)

  • For a discussion on organometallic systems, see: (a) N.J. Long, Angew. Chem., Int. Ed. Engl. 34 (1995) 21;(b) I.R....
  • T.T.J Müller et al.

    Organometallics

    (1999)
    M Tamm et al.

    Organometallics

    (1996)
    I.S Lee et al.

    Organometallics

    (1999)
    H Wong et al.

    Eur. J. Inorg. Chem.

    (2000)
  • I.R Whittall et al.

    Organometallics

    (1995)
    I.R Whittall et al.

    Organometallics

    (1996)
    S Houbrechts et al.

    Organometallics

    (1996)
    I.R Whittall et al.

    Organometallics

    (1996)
    I.R Whittall et al.

    Organometallics

    (1997)
    I.-Y Wu et al.

    Organometallics

    (1997)
    A.M McDonagh et al.

    J. Am. Chem. Soc.

    (1999)
    V Cadierno et al.

    Organometallics

    (1999)
    S.K Hurst et al.

    Organometallics

    (2001)
    S.K Hurst et al.

    Aust. J. Chem.

    (2001)
  • R.H Crabtree
  • G.M.B Martin et al.

    Int. J. Quantum Chem.

    (2000)
  • (a)B.Y. Lee, Ph.D. Thesis, Seoul National University, Seoul,...H.-J Park et al.

    Organometallics

    (1995)
  • I.D Morrison et al.

    Rev. Sci. Instrum.

    (1996)
  • Jaguar 4.0, Schrodinger, Inc., Portland, OR,...
There are more references available in the full text version of this article.

Cited by (21)

  • Synthesis of mono- and bi-metallic dithiocarboxylate-alkyne complexes from sunlight driven insertion reaction and their antibacterial activity

    2014, Journal of Organometallic Chemistry
    Citation Excerpt :

    Antibacterial study of Cp based ferrocenyl and half sandwich cymantrenyl hydrazone compounds reported recently by our group also showed promising results [35]. Other half sandwich organometallic compounds showing potential antibacterial properties include [(η6-C6Me5)Cr(CO)3] incorporated platensimycin derivative and [(η6-p-cymene)RuCl(ofloxacin)] [36–38]. Significant antibacterial activity for the reported organometallic compounds could possibly be due to the presence of [(η5-C5R5)M] fragment linked to dithiocarboxylate group believed to play a vital role in increasing the cell permeability and lipophilicity of the compounds.

  • Spectral and computational studies in substituted pyrrolyl styryl ketones - Assessment of substituent effects

    2014, Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
    Citation Excerpt :

    In addition to well known empirical rules to estimate qualitatively the microscopic nonlinear response in 1–4, DFT calculation is a more accurate prediction of the NLO activity [13]. From Table 4 it is suggested that these compounds are polar having non-zero dipole moment, hyperpolarizabilities and hence found to possess a good microscopic NLO behavior [14-16]. Several donor–acceptor interactions are observed in all the compounds (1–4) and among the strongly occupied NBOs, the most important delocalization sites are in the π system and in the lone pairs (n) of the oxygen and nitrogen present on the styryl pyrrolyl ketone moiety.

  • The vibrational studies and theoretical investigation of structure, electronic and non-linear optical properties of Sudan III [1-{[4-(phenylazo) phenyl]azo}-2-naphthalenol]

    2013, Journal of Molecular Structure
    Citation Excerpt :

    This phenomenon is quite unusual, since generally, even in the absence of inversion symmetry, the infrared and Raman spectra are complimentary: in most cases, the strongest bands in the Raman are weak in the infrared and vice versa. These bands associated to specific modes that are simultaneously strongly active both IR and Raman spectra provide evidence for the charge transfer interaction between the donor and acceptor group through the π-systems [55]. Based on the previously reported vibrational spectra of azo dyes, the molecular vibrations of SIII were analyzed [5,36,56].

View all citing articles on Scopus
View full text