| Abstract
| - The 6-aminofulvene-2-aldiminate (AFA) ligand is found to be a very flexible ligand in late transition metal chemistry, being capable of metal coordination through the nitrogen or the C5-ring donors, or both at the same time.
- The 6-aminofulvene-2-aldiminate (AFA) ligand contains both cyclopentadienyl and diimine donors.The ligand preferentially coordinates to transition metals via the nitrogen atoms; however once these areoccupied, the cyclopentadienyl ring may be coordinated to a Cp*Ru+ unit, providing bi- and trimetallicspecies. In the tetrahedral [Zn(Ph2AFA)2] (2) the metal is located approximately in the planes of the twoligands; however in the square-planar [Pd(Ph2AFA)2] (1) there is a severe distortion of the coordinationand the metal is located almost 1.3 Å out of the planes of the two ligands. This situation arises to avoidthe steric interaction of the ligand phenyl substituents. Treatment of 2 with [Cp*Ru(NCMe)3][BF4] gives[Cp*Ru(η5-Ph2AFA)] (3), providing the first example of the cyclopentadienyl coordination of an AFAligand in which the nitrogen donors are vacant, and it is thought to form as a result of the fragmentationof an intermediate mixed Zn/Ru species. The X-ray structure of 3 provides some evidence for an interactionbetween the Ru center and one of the exocyclic carbon atoms, thus suggesting a fulvene form of theligand in this complex. Similar treatment of 1 with [Cp*Ru(NCMe)3][BF4] provides a trimetallic PdRu2species (4) in which both of the cyclopentadienyl rings in the complex 2 are coordinated to Ru. Thecomplex [(Ph2AFA)Pd(Me)PPh3] (5) is formed on treatment of [(COD)PdMe(Cl)] with NaPh2AFA inthe presence of PPh3, and preliminary investigations have shown that its activation with [Ni(COD)2] asa phosphine scavenger provides species active toward ethylene oligomerization and polymerization.
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