IDEAS
Chemical
SYLVANIA GENERAL TELEPHONE & ELECTRONICS
"Ambidextrous, bisexual and polygamous"
In one chemical, two catalytic metals.
That's how one chemistry professor described molybdenum. Another stood before his class and stormed, "When the good Lord wanted to confuse the inorganic chemist, He invented molybdenum." This surge of emotion is easy to understand. Here is an element that boggles the mind by flaunting valences and oxidation numbers from plus 6 to minus 2. Sometimes when you put a molybdenum compound into solution, you end up with a complex mixture of compounds with Moly showing off any valence it prefers at the moment. Moly has coordination numbers of 4, 5, 6, 7, and 8. Alter some condition slightly and Moly juggles these numbers around. Molybdate ions happily clump together into chains and all sorts of aggregates when you're not looking. The only excuse they need to play polymer-round-the-rosy is some little change in pH or concentration. Any system centered around Mo molecules has to be complex. A simple reaction can give you a fallout of products that will make your head spin. No wonderwhen some little shift in pressure, temperature, pH, concentration or electric potential can trigger a change in what comes out and how much of it comes out. But there's much to be said for a skittish element like this. For instance, it takes a lot of temperament to be a good catalyst. We've got some great ones working in commercial reactions. As for taming molybdenum, be of good cheer. We have everything under control. We can give you clearly defined Mo compounds, so at least you'll know what you're starting with. Look at it this way: where there's complexity, there's also opportunity. Your opportunity. // fate brings you to molybdenum or that other mad transition element, tungsten, we can offer you more than solace. Write for data on our Mo and W compounds.
One of them is always tungsten. The other, some other transition metal. We've linked them together in a whole new series of metatungstates. For instance, we can give you tungsten plus a lanthanide in this general formula: Ln 2 [H 2 (W 3 O 1 0 )4]-xH 2 O or tungsten plus some other metal ion, as in: Ni3[H 2 (W 3 O 1 0 )4]-xH 2 O The solubility of our metatungstates is phenomenal. You can keep dumping these chemicals into water until the solution is so thick it's like syrup. Which means you can get a high concentration of catalytic metals into and onto your substrates. Considering the notorious reluctance of tungstates to dissolve, this is a most cheering development. Our metatungstates will also dissolve in certain polar organics such as DMF and DMSO. If you've been mixing catalysts, you know how tough it is to get a completely homogeneous distribution. In ours, both metals are combined in the same compound. You can't get any more homogeneous than that. Of course, there's no way of varying the proportions of the two metals, but in your application this may not be a drawback. It may even be an advantage. You may find, for example, that the transition metal is present in just the right proportion to act as a good promoter for the tungsten catalyst. What's not present in any quantity are the alkali metals (less than 500 ppm). Our rare earth metatungstates are especially pure. This is good news for catalyst makers. Here's a list of the metals we are now adding to tungsten by hanging them on the coattails of the metatungstate ion: Y, La, Ce, Nd, Er, Ni, Co, Zn, V, Ag. All compounds are acidic in aqua, though silver is not as soluble as the others. We can also make the rest of the lanthanide metatungstates if you want them. Send for our tech bulletins on metatungstates. If you'd care to mention your potential or actual use, we may be able to give you more specific answers. A cosmic remark.
Mo (element 42). Not so elementary.
At room temperature, tungsten has such a low vapor pressure that you can compare it to just one atom of gas floating around in the entire known universe. Kind of startling, even for the metal with the world's highest melting point: 6170° F.
Sylvania Metals & Chemicals, Chemical and Metallurgical Division, Towanda, Pa. 18848 8
C&EN
