Multifunctional Transition Metal Ligands

2- and 1,7-isomers of the B9II10CHE ions (E= P or As) also show multifunctional character. In addition to forming 7r-complexes as described earlier, these ligands also use the available electron pair on phosphorus or arsenic to form a-bonded complexes with metals [Eq. (9)] (40). 

I am indebted to Mrs. B. G. Rogainis and Mrs. S. G. Welcker for their capable assistance with the manuscript. Some of the research was supported in part by the National Science Foundation under Grant GP-10148. 

Hawthorne, M. F., George, T. A., and Pitts, A. D., Abstr. 156th Meeting Am. Chem. 

Department of Inorganic Chemistry, The University Bristol, England 

The phenomenal growth in the chemistry of metal carbonyl compounds has been heavily concentrated upon the neutral and anionic complexes. Only very recently have the occurrence and usefulness of the cationic metal carbonyls come into real prominence. 

---

As multifunctional compounds, 5(4//)-oxazolones can act as ligands and, as such, they provide interesting organometallic transition metal complexes depending... 

The association of a metallic center (i.e., a transition metal) and TT-heficenic ligands represents a powerful tool to elaborate multifunctional systems and... 

Arsenic-containing heterocyclic derivatives are multifunctional ligands. For example, arsole can form several types of complexes (a) one involving the lone electron pair on As (156), (b) as a two-electron donor to one metal atom and, at the same time, as a one-electron donor to the other transition element (157), (c) as a four-electron ligand of the 7t-butadiene type due to the presence of two double C=C bonds (158), and (d) as a five-electron elementacyclopentadienyl ligand (159-162). Each of these types of compounds have been characterized by mass spectrometry (Tables 9 and 10). Unfortunately a detailed discussion of their mass spectral behaviour is unavailable. 

---