Transition Metal Project
Overview. The Transition Metal Project is a term-long endeavor in which you will explore some of the chemistry of
one of the transition metals. On the first day of term, you will select from a beaker a slip of paper on which will be written
the name of the metal that you will investigate, and the name and formula of a particular compound of the metal to use as a
starting material for the syntheses that you will carry out during the term. The metals to be investigated and the starting
material options are shown in Table 1.
Table 1: Metals and Starting Materials
| Metal Ion | Metal Starting Material |
| Co2+ | cobalt chloride hexahydrate, CoCl2.6H2O |
| cobalt acetate
tetrahydrate, Co(C2H3O2)2.4H2O |
| cobalt carbonate, CoCO3 |
| Cu2+ | copper chloride dihydrate, CuCl2.2H2O |
| copper acetate monohydrate, Cu(C2H3O2)2.H2O |
| basic copper carbonate, Cu2(OH)2CO3 |
| copper metal |
| Fe3+,2+ | ferric nitrate nonahydrate, Fe(NO3)3.9H2O |
| ferric chloride hexahydrate, FeCl3.6H2O |
| ferrous acetate, Fe(C2H3O2) |
| tetrapyridinedichloroiron(II), Fe(C5H5N)4Cl2 |
| Mo4+,6+ | sodium molybdate, Na2MoO4 |
| Ni2+ | nickel chloride hexahydrate, NiCl2.6H2O |
| nickel acetate tetrahydrate,
Ni(C2H3O2)2.4H2O |
| basic nickel carbonate, Ni2(OH)2CO3 |
| V4+,3+ | divanadium pentoxide, V2O5 |
As the term progresses, you will proceed through the sequence of experiments detailed below. You will begin the term by
fully characterizing your starting material as to physical properties such as density, melting point, solubility in water,
infrared spectrum (if applicable), UV-visible spectrum (if applicable), and NMR spectrum (if applicable).
Once you are comfortable with your starting compound, you will embark on a series of chemical syntheses in which your goal is
to produce compounds of your metal ion with various Lewis bases (also called ligands). As an integral part of each
synthesis you should plan to characterize the ligand; design and carry out a reaction of your metal starting material, the
ligand, and any other reagents you believe necessary; isolate the product(s) of your reactions; and characterize your
products. For each synthesis you should prepare a mole table that accommodates the anticipated reaction stoichiometry.
At the halfway point of the term, you will submit a draft of a formal research report in
which you present the results of your experimental efforts to date. The format for the report should follow that recommended
for the ACS journal, Inorganic Chemistry. This format can be found in the first issue of the current volume of the journal. I
will read and critique your drafts, but will not grade them. Instead, I will make suggestions for you to implement in the
final draft of the report, due the last day of term. The final report will be graded. One point will be deducted for each
grammatical error (spelling, punctuation, sentence structure, formatting); two points will be deducted for each chemical or
conceptual error.
CH2670 will differ from previous courses in the 2nd year laboratory sequence in several respects. First, everyone will have
a different experience. Second, the course will simulate a true research experience, in which you have some general goals but
are not told in detail how to achieve them. Thus we will not do "canned" experiments. One advantage of "canned" experiments
from the student point of view is that they usually "work", meaning that they usually give the expected and anticipated
results. Unfortunately, this gives a misleading impression of how laboratory work in chemistry (or any science) proceeds. Of
course in real-world research, there is no "canned" plan of attack or procedure. The experimenter must therefore design a plan
and a procedure. Often the initial attempts at an experiment are "unsuccessful" in one respect or another, due to defects in
the plan or procedure. It is then necessary to find and fix these defects and to try again. Often this process of finding,
fixing, and trying must be repeated several times before "success" is achieved. (Here "success" means, of course, that one
gets the result that one expects or that one thinks someone else expects.) Many times, even with a well-designed and executed
plan, results are different from what was expected! This, of course, is what makes research really interesting! We usually
progress most rapidly when things turn out differently than we thought they would. So, real-life research is very much a
2-steps forward 1-step back (and sometimes 1 forward then 2 back!) endeavor. Becoming a productive scientist means learning
to deal with this reality. Thus in CH2670, each of you will have to feel your way through the chemistry of your assigned
metal, and will learn about techniques and synthetic strategies as you proceed. You will also become better at dealing with
the frustration and failure that inevitably accompany research. Third, the project is open-ended. That is, I will expect you
to put in the minimum of 9 hours in laboratory each week, and I expect you to work hard, but I have only mild requirements as
to how much you get finished. Rather, I am interested in the quality of your work. What you do should be done as
well as you can do it! I specifically am NOT interested in having you race through a series of experiments in order to finish
them all. This invariably results in shoddy work. The course schedule contains guidelines as to
how far along you should
try to be by the end of each week.
Prerequisite Training. As everyone knows, we are not allowed to specify prerequisites at WPI. However, as everyone
also knows, this does not mean that there aren't any! As you come into CH2670, I will assume that you have acquired, from your
work in CH2640, 2650, and/or 2660, a reasonable fundamental knowledge about laboratory protocol and
comportment. I will also assume that you have developed some level of skill in laboratory techniques and procedures and in
maintaining a lab notebook, although I will have a few suggestions to make along these lines.
If at any time you feel uncertain of the proper way to do something, please feel free to ask!
Description of the Project. During your 63+ hours of laboratory time during D term, you should work
toward completing the following series of experiments:
- Select by lot a metal ion and a starting material.
- Characterize the starting material by physical properties and compare with literature values:
- Melting point and/or decomposition behavior.
- Density.
- Solubility in water and other good synthetic solvents (alcohols; halogenated alkanes).
- Infrared spectrum by Nujol mull (if applicable). You will run IR spectra as nujol mulls
between sodium chloride plates. Before running the IR spectrum of your first sample, please run the IR spectra of
The NaCl plates;
Nujol between NaCl plates.
Having these spectra available will enable you to determine which absorption bands are actually due to your sample!
- UV-visible spectrum in an appropriate solvent. Spectra in the region 700-300 nm can be run in
plastic cuvets. Outside of this range, quartz cuvets are necessary. Before attempting to run the UV-visible spectrum of your
first sample, please run the UV-visible spectra of
A plastic cuvet;
A quartz cuvet;
This will show you clearly the regions in which the cuvet materials absorb. In addition, you should obtain the UV-visible
spectrum of each solvent that you use as you go along. Water is a good one to start with.
- NMR spectrum (if applicable).
- Synthesize a complex of your metal ion with the monodentate ligand,
imidazole (C3H4N2)
- Predict a reaction stoichiometry and propose a synthetic procedure
(consult with instructor if necessary). Click here for a procedure for the
cobalt
complex.
- Carry out stoichiometric calculations
based on 0.5 mmole of metal.
- Characterize imidazole by melting point, IR and NMR in deuterochloroform.
- Attempt your synthetic procedure; modify it and reattempt if necessary.
- Isolate and purify your product. Judge purity by thin-layer chromatography (TLC).
- Characterize your product by melting point, IR, UV-visible spectroscopy, and magnetic susceptibility.
- Carry out a Job's Method study of the metal-ligand system to determine stoichiometry.
- Analyze your product for metal content. You can accomplish this by digesting a precisely known mass of the product with
a small volume of concentrated nitric acid to oxidize the organic portion; neutralizing the solution of aquo metal ion;
diluting the solution to a precise volume; and analyzing the resulting solution for metal content. It will be necessary for
you to locate in the literature a procedure for analysis of an aqueous solution of your metal ion.
- Synthesize a complex of your metal ion with the bidentate ligand,
acetylacetonate anion.
- Synthesize a complex of your metal ion with the tetradentate
macrocyclic ligand, Me6[14]dieneN4.
- Synthesize the hydrogen iodide adduct of the macrocyclic ligand by
the given procedure. SCALE THE PROCEDURE TO 6.6
mL OF ETHYLENEDIAMINE.
- Characterize the hydrogen iodide adduct of the macrocyclic ligand by
melting point, IR, NMR in deuterium
oxide.
- Propose a synthetic procedure for the complex of the macrocycle with
your metal. Click here for a procedure for the nickel
complex. BE AWARE THAT DEPROTONATION OF THE MACROCYCLIC LIGAND IS
NECESSARY BEFORE IT CAN INTERACT WITH A METAL ION; THEREFORE YOUR PROPOSED
PROCEDURE MUST INVOLVE A SUITABLE BASIC SPECIES.
- Carry out stoichiometric calculations based on 0.5 mmole of metal.
- Carry out your synthesis; modify and redo if necessary.
- Isolate and purify a product.
- Characterize your product by the applicable methods from among
melting point, IR, UV-vis, NMR, and magnetic susceptibility.
- Analyze your complex for metal content.
- Synthesize a complex of your metal ion with the linear tetradentate
ligand, salenH2.
- Synthesize the ligand starting material, salenH2. The
procedure may be found by clicking on the hypertext link just below,
paging to the references at the end of the document that comes up, then
locating reference 1 in the library. Carry out the procedure on the scale
presented in this reference.
- Characterize the ligand by applicable methods.
- Propose a synthetic procedure for the complex of your metal with
salen. Click here for a procedure for the cobalt
complex.
- Carry out stoichiometric calculations based on 0.5 mmole of metal.
- Carry out your synthesis; modify and redo if necessary.
- Isolate and purify a product.
- Characterize your product by the applicable methods from among
melting point, IR, UV-vis, NMR, magnetic susceptibility.
- Synthesize a complex of your metal with the bidentate sulfur-donor ligand, N,N-diethyldithiocarbamate (DTC).
- Characterize the ligand starting material by applicable methods.
- Propose a synthetic procedure for the complex of your metal with DTC. Click here for a procedure for the molybdenum complex.
- Carry out stoichiometric calculations based on 0.5 mmole of metal.
- Carry out your synthesis; modify and redo if necessary.
- Isolate and purify a product.
- Characterize your product by the applicable methods from among melting point, IR, UV-vis, NMR, magnetic susceptibility.
- Analyze your product for metal content.
Course Objectives. As you do these experiments you should work toward the following objectives:
- Improve and extend your laboratory skills in handling solids, handling liquids, carrying out stoichiometric calculations,
and performing standard laboratory procedures like weighing, qualitative and quantitative liquid transfer, reflux, gravity and
suction filtration, recrystallization, volume reduction, and the determination of melting point/decomposition temperature.
- Acquire skills in sample preparation for and acquisition of IR spectra, UV-visible spectra, and NMR spectra.
- Acquire and/or improve skills with thin-layer chromatography (TLC).
- Acquire and/or improve skills in planning for an effective laboratory session.
- Improve and extend your laboratory record-keeping skills.
- Acquire and improve skills in the strategy of chemical synthesis for relatively simple chemical systems.
- Acquire skills in interpretation of characterizational data
- Acquire and/or improve formal writing skills.
- Enhance your ability to work independently in the laboratory.
- Enhance your confidence in your ability to work in the laboratory.
- Improve your speed and efficiency in the laboratory.
- Improve your ability to be self-critical (that is, to notice inconsistencies or abnormalities in your experimental
findings and to take steps to check their reliability).
Because the enrollment in CH2670 is usually small, you have an opportunity to learn a considerable amount about laboratory
work from your course instructors. Take advantage of these opportunities and thereby prepare yourself for the MQP
experience.
Required Equipment and Materials
- transition metal starting materials:
- Ligand starting materials
- acetylacetone
- reagents for synthesis of Me6[14]dieneN4:
- reagent grade acetone
- ethylenediamine
- 57% hydriodic acid
- reagents for synthesis of salenH2:
- salicylaldehyde
- ethylenediamine
- sodium N,N-diethyldithiocarbamate
- Solvent reservoirs:
- acetone
- acetonitrile
- carbon tetrachloride
- chloroform
- cyclohexane
- dichloromethane
- diethylether
- ethanol
- hexane
- methanol
- petroleum ether
- toluene
- xylene
- Assorted glassware:
- beakers up to 400 mL
- Erlenmeyer flasks up to 125 mL
- Pasteur pipets, 5.25 and 9 inch, with bulbs
- graduated pipets, 1- and 2-mL
- volumetric flasks, 5- and 10-mL
- round bottom flasks up to 100 mL
- water condenser
- stirring rods
- sidearm flasks and/or test tubes
- 1-dram sample vials
- melting point capillaries
- Assorted hardware
- spatulas
- Buchner funnels
- filter paper
- Bench towels
- screw clamps
- Brinkmann pipet helper
- rubber stoppers
- filter rings
- filter paper
- hot-plate stirrer
- 1-inch stir bars
- steam baths
- rotary evaporator
- powermite/thermowell
- suction filtration setup (aspirator trap + splashgon)
- Equipment for TLC:
- silica gel plates
- capillaries
- developing tanks
- iodination chamber
- UV light
- Assorted instruments and sample preparation equipment:
- balances
- Mel-Temp apparatus
- UV-visible spectrometer
- 1-cm path length quartz cuvets
- IR spectrometer
- NaCl plates
- NaCl plate holders
- Nujol
- agate mortar and pestle
- NMR spectrometer