The relative rates of the migratory insertions of alkenes into the M-X bonds of (PMe3)(2)Rh(eta(2)-CH2=CHR)(X) (R = H, Me; X = CH3, NH2, OH) have been analyzed by DFT calculations. These insertions are computed to form metallacycles containing a metal-carbon bond and either an agostic interaction, a dative metal-nitrogen bond, or a dative metal-oxygen bond The computed barriers for migratory insert on into the metal-hydroxo and metal-amido bonds are lower than those for insertion into the metal-methyl bond Application of Bader's atoms-in-molecules analysis and natural localized molecular orbital analysis implies that the barriers for alkene insertion into M-X bonds are controlled by the degree of M-X bonding in the transition state, which correlates with the degree of M-X bonding in the initial product. The Rh-X bond orders in the transition states for migratory insertion of ethylene into the Rh-NH2 and Rh-OH bonds in (PH3)(2)Rh(eta(2)-C2H4)(NH2) and (PH3)(2)Rh(eta(2)-C2H4)(OH) are much larger than that in the transition state for insertion into the Rh-C bond of (PH3)(2)Rh(eta(2)-C2H4)(CH3) The free energy barriers for 1,2-and 2,1 insertions of propene into the rhodium complexes were also calculated, and the barrier for 1,2-insertion was found to be lower than that for 2,1-insertion. Most striking, the Delta Delta G double dagger values for 1,2- versus 2,1-insertion of propene into these rhodium complexes were calculated to increase in the order X = CH3 < NH2 < OH The increasing stability of the 1,2-insertion product with increasing polarity of the C-X bonds parallels the relative stabilities of linear versus branched alkanes, amines, and alcohols.