Document Type

Honors Capstone Project

Date of Submission

Spring 5-1-2012

Capstone Advisor

Dr. Karin Ruhlandt-Senge

Honors Reader

Dr. Mathew Maye

Capstone Major

Chemistry

Capstone College

Arts and Science

Audio/Visual Component

no

Capstone Prize Winner

yes

Won Capstone Funding

no

Honors Categories

Sciences and Engineering

Subject Categories

Chemistry | Other Chemistry

Abstract

Salt metathesis has become a critical reaction pathway in organometallic chemistry; however, for alkaline earth metals this process is hindered by the need of highly pure and expensive metal iodides as starting materials. This contribution highlights recent attempts to identify inexpensive reagents for salt metathesis. Alkaline earth-tosylates can be prepared cost effectively using p-toluenesulfonic acid in one-pot reactions in water. The coordinated water molecules can be removed by gentle heating under vacuum. The anhydrous tosylates, however, have major solubility limitations as the result of extensive aggregation networks. The goal of this study was to increase the solubility of the tosylates by the addition of electron donating crown ethers, which may reduce aggregations. Crown ethers are known for their ability to coordinate metal ions in the cavity of the macrocycles and form sandwich or club sandwich complexes.

Four new complexes were synthesized and characterized using X-ray crystallography, {[Ca(OH2)2(18-crown-6)]3[OTs]3∙2H2O} ,{[Ca(OH2)2(18-crown-6)]2[OTs]4}, [Sr(OTs)2(18-crown-6)(OH2)], and [Ba(OTs)2(18-crown-6)(OH2)2]. The two calcium complexes exhibit unique metal center environments while the strontium and barium complexes show distinct coordination numbers and arrangements of coordinating ligands. The arrangement of tosylate anions in the structures is determined by the coordination atmosphere of water molecules to the metal centers. All four characterized compounds were found to be soluble in pyridine, which improves upon previous studies that only show tosylate complexes soluble in water.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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