Vol. 27 No. 1
January-February 2005

Coordination and Organometallic Chemistry of Germanium, Tin, and Lead

by Keith Pannell

A region near Santa Fe where meeting participants took an excursion.

The 11th International Conference on the Coordination Chemistry and Organometallic Chemistry of Germanium, Tin, and Lead, ICCOC-GTL-11, was held in Santa Fe, New Mexico, USA, 27 June–2 July 2004. Held for the first time in the USA, the conference was attended by representatives from 20 countries. The program featured 55 oral presentations—arranged by tradition in single session—and 50 poster presentations, which were displayed for the duration of the meeting.

The opening speaker, Phil Power (University of California, Davis, CA, USA), set the high standard for the meeting with a description of the alkyne analogs of the heavier group 14 elements, including a proposed new description of the bonding in these delightful compounds involving diradicaloids. To close the meeting, Klaus Jurkschat (University of Dortmund, Germany) introduced, inter alia, exciting new Sn(I) species coordinated to transition metals. Other outstanding lectures involved mechanistic studies on digermenes (Kim Baines, University of Western Ontario, Canada), the utility of organotins (OTs) for organic synthesis (Francisco Pulido, Universisad de Valladolid, Spain), and a rousing introduction of new oligomers of Zintl-type Ge₉ clusters (Slavi Sevov, Notre Dame, USA).

Germylenes, stannylenes, and plumbylenes continue to surprise and stimulate the chemistry community. Just as Willie Leigh (MacMaster University, Ontario, Canada) had rationalized, and regularized, the previous diverse characterizations of species such as Me₂Ge, Christian Drost (Universität Leipzig, Germany) reported a stimulating group of beautiful new materials (Ge—Sn—Pb) that exhibit progressive properties that require new ways of thinking in this established area.

Advances in molecular analysis are always eagerly awaited. Rudi Willem (Free University of Brussels, Belgium) presented insight into the utility of solid-state NMR for analysis of insoluble OT-containing polymers involving a new magic-angle spinning (MAS) technique. This involves addition of small amounts of solvent that locally lubricates the OT functionality with remarkable results in terms of resolution and quantification. For true solid-state analysis, X-ray crystallography, the non-sporting technique, still rules the roost. Edward Tiekink (Singapore) outlined an approach for improving the prediction of the myriad crystal packing forms that abound in the structures of OTs. The contributions of Raymundo Cea-Olivares (Universidad Autonoma de Mexico), Ravi Shankar (IIT Delhi, India), Junzo Otera (Okayama, Japan), Dominic Wright (Cambridge, UK), and Vitapali Chandrasekhar (IIT Kanpur, India) further demonstrated that some rationality in this area can be forthcoming.

The materials chemistry of the elements was writ large at the meeting. Mark Allendorf (Sandia National Laboratory, New Mexico, USA) presented the first thermodynamic approach to understanding the very empirical formation of tin oxide glass coatings using OT precursors. Des Cunningham (Galway, Ireland) introduced a simple but effective methodology for producing soluble SnO₂ for direct application, without the need for the organic radical functionalities. Thierry Toupance and Bernard Jousseaume (Université Bordeaux, France) both demonstrated the delightful utility of alkynyltins for creative materials chemistry.

Important contributions to the meeting concerned the biological impact of tin and lead compounds. Whereas organoleads have been all but abandoned for commercial usage, little is truly known concerning the reasons for their health risks. Hilary Godwin (Northwestern, Evanston, IL, USA) detailed the capacity of lead to replace Zn in proteins resulting in improper folding and inappropriate binding to DNA. In a similar vein, Margaret Whalen (Tennessee State, TN, USA) outlined in compelling detail the surprising prevalence of tributyltin in human blood samples and its ability to effectively retard the functioning of human natural killer cells. On the other hand Marcel Gielen (Brussels, Belgium) demonstrated that other OTs could be among the most effective anti-tumor compounds. Such are the diverse and perplexing properties of OTs! Jim Becvar (University of Texas at El Paso, TX, USA) presented a teasing glimpse of the possible role of luminescent bacteria for the environmental analysis of complex OT mixtures. John Batt (Atofina, Inc.) presented the industry approach and methodology for understanding the environmental impact of the large current production of OTs.

With the established icons in the field, Lappert, Veith, Roesky, Barrau, Cowley, Tokitoh, West, and Wo Wo du Mont (the only person to participate in all the GTL gatherings), and newcomers Chauhan, Konstantinos, and Layfield et al., all contributing significant new findings, the meeting was an intellectual success. In addition, the ability of graduate students/postdoctoral fellows to present posters plus a 5–10 minute oral overview was well received. The next gathering—to be chaired by Des Cunningham and to be held 2–6 July 2007 in Galway, Ireland—will include a similar opportunity and will follow the same pattern of a single oral session with posters.

The proceedings of the meeting are to be published in Applied Organometallic Chemistry.

Keith Pannell <[email protected]> is a professor of chemistry at the University of Texas at El Paso and was chairman of ICCOC-GTL-11.