Reactions of Slurries

The black nickel powders prepared by lithium reduction of a metal halide are not pyrophoric when exposed to air, yet they display remarkable reactivity toward organic molecules. These powders are most conveniently used as prepared, that is, they are not separated from the lithium salts, naphthalene, nor any other products formed in the reduction. 

In some previous studies, Klabunde has shown that a variety of transition metal atoms when cocondensed with CeFsX (X = I, Br) undergo rapid oxidative addition to yield CeFsMX complexes [18,19, 23, 24, 26, 27]. Klabunde demonstrated that these complexes can be converted to a variety of new compounds depending on the metal and halogen. It was also demonstrated that CeHsPdX can be prepared but is only stable at low temperatures [23]. We felt it would be of value and interest to see if transition metal powders prepared by the simple and convenient reduction method were reactive enough to undergo oxidative addition to CeFsX and other aryl halides. 

The addition of a stabilizing ligand to a metal slurry prior to the addition of an organic halide allows preparation and isolation of organometallic compounds with groups other than CeFs. This route may allow the preparation of entirely new classes of organometallic compounds. 

Surface analysis indicates that these powders are finely divided and very complex materials. Carbon as well as hydrogen is found in these metals. The metal surfaces appear to be coated with LiOH and some carbonaneous material, leaving the question of origin of high reactivity still somewhat in doubt. 

Amines can also displace the coordinated glyme molecule from Ni(C6F5)2(C4Hio02). Thus the addition of pyridine to the orange-brown mixture of solvated Ni(QFs)2 and NU2 results in an immediate color change and the formation of Ni(C6F5)2(C5H5N)2. 

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To ensure uniform slurry distribution across the pad surface and delivery of slurry to the wafer center in order to maintain uniform polishing from wafer center to edge. This is especially important for larger size wafer (300 mm) and for polishing reactive metals such as Cu, since chemical reaction of slurry with metal layer is as critical to polishing rate as mechanical action ... 

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