The Trans Effect: A Guided-Inquiry Experiment for Upper-Division Inorganic Chemistry
Chemistry and Biochemistry
This article describes a guided-inquiry laboratory for upper-division inorganic chemistry. The experiment is designed to teach students about the trans effect through synthesis of the cis and trans geometric isomers of diamminedichloroplatinum(II). Students discover which factors lead to trans-substitution versus cis-substitution in square-planar transition-metal complexes. Student pairs are assigned a synthetic protocol, and product geometry is determined experimentally using a colorimetric thiourea test. Focus questions guide students to generate a trans-directing ligand series and to construct the trans effect concept. This experiment gives students technical experience in microscale inorganic synthesis and stereochemical analysis while teaching them about coordination chemistry and the importance of metals in medicine.