This is an addendum to the Manganese Carbonyl experiment (linked below). In this part of the experiment, students carry out high level quantum mechanical calculations of reactants, intermediates, and products in order to determine which of two possible structures is correct.
In Haverford College's course Chem 111:Structure and Bonding, we have included a workshop exercise that guides students through their first experience using electronic structure calculations. We use the WebMO interface along with Gaussian03, but the exercise could be adapted for other electronic structure programs. The general structure of the exercise is as follows:
My technique for constructing MO diagrams is based on (and significantly simplified from) that of Verkade. While I find it works well in my classroom for my students, they benefit from careful step-by-step instruction of the method through several weeks of in-class exercises. This LO has links to pencasts where I go through three easy examples that demonstrate the technique, as well has how I handle lone pairs by this method. As transition metal complexes don’t have stereochemically active lone pairs, they are often easier to deal with than even something seemingly as simple as water!
I use this in-class exercise after I have taught the students how to construct LGOs using the generator orbital technique. The previous week, they do an in-class exercise on that topic, and this week, they use the LGOs from the previous week to construct MO diagrams.
This Lewis structure and VSEPR problem is based on a paper from Inorganic Chemistry in 2010 reporting the crystal structures of a series of salts of the [XeF]+ cation. The [MF6]– and [M2F11]– anions (M = As, Sb, Bi) were used as counterions, and in all cases, the [XeF]+ cation interacts with the anion via a weak bond between the Xe and a fluoride of the anion to form an ion-pair in the crystalline solid. These somewhat unusual ions provide an interesting application of the predictive powers of Lewis stru
This Lewis structure and VSEPR problem is based on a paper from Inorganic Chemistry in 2010 reporting the crystal structure of the carbonyl diazide molecule. This relatively simple molecule provides an interesting application of the predictive powers of Lewis structures and VSEPR theory to molecular structure, backed up by experimental data on bond distances and bond angles. Before tackling carbonyl diazide, the students warm up by considering the structures of hydrogen azide and the isolated azide ion. The reference to the original paper is
I am sure most people already use this but I always refer to students to the Organometallic hypertext book. It has excellent explanations of topics such as back-donation in organometallic complexes.
Early in 2009, Christopher Cummins’ group at MIT reported (in Science) the synthesis of AsP3, a compound that had never been isolated at room temperature. Later that year, a full article was published in JACS comparing the properties and reactivity of AsP3 to those of its molecular cousins, P4 and As4. The longer article is full of possibilities for discussion in inorganic chemistry courses, with topics including periodic trends, NMR, vibrational spectroscopy, electrochemistry, molecular orbital theory, and coordination chemistry.