Advertisement

If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.

ENJOY UNLIMITED ACCES TO C&EN

Physical Chemistry

Lucky Number Seven For Metal Carbonyls

Georgia researchers report the first convincing experimental observation of overcrowded Nb(CO)7+ and Ta(CO)7+

by Stephen K. Ritter
July 6, 2009 | A version of this story appeared in Volume 87, Issue 27

[+]Enlarge
Credit: J. Am. Chem. Soc.
Credit: J. Am. Chem. Soc.

University of Georgia researchers have reported the first convincing experimental observation of transition-metal heptacarbonyls, M(CO)7 +, along with an interesting periodic trend for the highly coordinated metal species (J. Am. Chem. Soc., DOI: 10.1021/ja903983u). Transition metals can theoretically handle up to nine ligands by using all of the five d, three p, and one s orbitals in a valence shell. But overcrowding, available electrons, and other factors preclude most metals from taking on more than six ligands at a time. The group 5 metals vanadium, niobium, and tantalum are an exception: They should be able to form stable M(CO)7 + if they utilize all their bonding capabilities, but chemists have never directly observed the heptacarbonyls until now. Georgia’s Michael A. Duncan and coworkers used laser vaporization to produce a range of multicarbonyl compounds and analyzed them by infrared spectroscopy. The researchers deduced that vanadium is limited to forming V(CO)6 +, whereas niobium forms Nb(CO)6 + and Nb(CO)7 +, and tantalum forms only Ta(CO)7 +, a trend that they say points out steric and bond-energy limitations of the metals.

Article:

This article has been sent to the following recipient:

0 /1 FREE ARTICLES LEFT THIS MONTH Remaining
Chemistry matters. Join us to get the news you need.