clPxE'~lu~iotzstare. Tlsere are various ways to determine the oxidation state of the
metal. One approach is to assign the metal a formal oxidation state of (0), unless it is
o-bonded to ligands such as halogens, alkyl, aryl, or vinyl. In these cases, the metal
and the ligands form bonds with shared electrons, with the ligands having a formal
charge of -1. Neutral ligands such as Ph,P and CO are not counted since they provide two of their own electrons. For example, palladium in Pd(PPh,), is in the zero
oxidation state, whereas in Pd(PPh,),Cl,, the palladium is in the -t-2oxidation state. It
is assumed that the outer electrons of the metal are all d electrons. Thus, Pd(0) is a dsO
rather than 4ds5s' metal, and belongs in the transition metals Group 10, which
includes Ni(0) and Pt(0). Pd(1I) is a dsrather than a 4d65s'rnetal. Complexes derived
from these metals are widely used in synthetic transformations.
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