Quadruple Bond Containing Molybdenum Metallopolymer
In experiment 2, you will synthesize a molybdenum quadruple bond material forming a paddle wheel complex. Variations of this paddle wheel complex can be used as a secondary building unit or monomer starting material in the synthesis of metallopolymers, metallosheets, and metal-organic frameworks. The high electron density of the product materials makes them uniquely suited for applications in conductive wires and molecular switches. You will synthesize a linear molecular wire metallopolymer from the molybdenum quadruple bond containing paddle wheel complex. Throughout this lab you will learn Schlenk line technique, glove box techniques and x-ray diffraction.
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CAUTION: Mo(CO)6 is highly toxic and may be fatal if inhaled, absorbed through the skin, or swallowed. CO is generated during the reaction. Therefore, the synthesis must be conducted in a well-ventilated hood.
Minimum characterization requirements: 1H NMR, CV, and single crystal XRD of the monomer. 1H NMR and PXRD of the polymer.
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New Methods: Schlenk line technique, glovebox technique and x-ray diffraction
References to get you started:
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Bull. Chem. Soc. Jpn. 1998, 71, 1811-1816.
Bull. Chem. Soc. Jpn. 2004, 77, 2205-2211.
Bull. Chem. Soc. Jpn. 1995, 68,2567-2572.
Inorg. Synth. 2014, 36, 78.
Appl. Organometal. Chem. 2005, 19, 76-80.
Acta Cryst. 1974, Sect. B30, 2768.
Chem. Sci. 2015, 6, 3434-3439.
Chem. Let. 1990, 1753-1756.
The following questions should be attached to the end of the report. These questions may also be asked during the prelab orals.
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Mo(CO)6 is volatile. What problems might this property present for the synthesis of the Mo2 complex from Mo(CO)6?
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What is the Lewis structure of the ligand before metallation? After metallation (you only need to show the two main resonance forms in this case)?
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What is a quadruple bond? How can it be explained using d orbital overlaps? A MO diagram and pictorial representations of the bonds using d orbitals are required for full credit. Is the Mo2 complex diamagnetic or paramagnetic? What do you expect will happen to the bond order if there is a one-electron oxidation?
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What orbitals would you expect to be used to bind the pyrazine linker? Would you expect an oxidation state change of the molybdenum metal centers before and after polymer synthesis with pyrazine?
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What are the major characteristics of a MOF? Should your metal polymer be classified as a MOF? Why or why not?