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Created by Lori A. Watson, Earlham College ([email protected]) and posted on VIPEr on March 9, 2009.
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Group 10 and 11 Metal Boratranes (Ni, Pd, Pt, CuCl, AgCl, AuCl, and Au+) Derived from a
Triphosphine-Borane
Marie Sircoglou, Se#bastien Bontemps, Ghenwa Bouhadir, Nathalie
Saffon, Karinne Miqueu, Weixing Gu, Maxime Mercy, Chun-Hsing Chen,
Bruce M. Foxman, Laurent Maron, Oleg V. Ozerov, and Didier Bourissou
J. Am. Chem. Soc., 2008, 130 (49), 16729-16738
1. What are the authors trying to accomplish here? In your answer, include:
a) What is a  acceptor, and how do boron ligands on transition metals act as 
acceptors?
b) Why do most boron ligands have donor “arms” which also coordinate to the
metal?
c) What is a “boratrane”? Why did they study metal boratranes derived from
TPB? What were their main conclusions?
d) Why is this paper exciting? What new type of bonding is explored? What
implication does this have for future research?
2. How do the authors establish that there is a meal to boron interaction in each of the
metal complexes? Include both crystallographic and NMR evidence. You may also
wish to refer to their computational studies. In the group 11 boratranes, what happens
to the metal boron interactions when the trans chloride is removed? Why does this
happen? What evidence is there for continued metal to boron interaction?
3. Discuss the computational analysis of the HOMO and LUMO of the group 10
boratranes in Figure 9. What does each correspond with? How and why are the
HOMOs and LUMOs different for the group 11 complexes in Figure 11?
4. How would you rationalize the trends in MB interactions between and within group
10 and 11 boratranes metal complexes by appealing to Effective Nuclear Charge
arguments? Are the experimental results consistent with what you expect by looking
at Zeff for different metals and different oxidation states?
5. What is the electron count of each complex (2-8)? Would reactions with these
metalloboratranes likely be associative or dissociative in nature? Why? Many
molecules with a C3 axis which are even slightly pyramidal will invert. Can the
borotrane ligand invert here? Why or why not? Would such a process need to be
dissociative or nondissociative?