Kinetics of the oxidative addition of iodine to β-diketonatobis(triphenylphosphite)rhodium(I) complexes

Ligand Effects on the Oxidative Addition of Halogens to (dpp-nacnacR)Rh(phdi)

“…Pentane (10 mL) was added to precipitate the product which was filtered, washed with an additional 5 × 2 mL of pentane, and dried in vacuo to provide 4a in 97% yield (97.6 mg). 1 H NMR (600 MHz, 223K) δ/ppm: 8.86 (s, 2H, N−H), 8.11 (d, 3 J HH = 8.4 Hz, 2H, aryl−H), 7.63 (t, 3 J HH = 7.6 Hz, 2H, aryl−H), 7.58−7.53 (m, 4H, aryl−H), 7.41 (t, 3 J HH = 6.9 Hz, 2H, aryl−H), 7.23 (d, 3 J HH = 6.6 Hz, 2H, aryl−H), 7.00 (br, 2H, aryl−H), 5.71 (s, 1H, (22,400), 358 (27,700), 461 (11,900), 530 (8,300), 600 (7,090), 684 (7,830), 789 (9,920)…”

“…The most common coordination platform for oxidative addition studies is the square-planar, 16-electron, d 8 metal complex. , The addition of halogen substrates to these complexes is generally thought to proceed through the formation of an η 1 -X 2 adduct formed by donation of an electron pair from the metal into the σ* orbital of X 2 , leading to heterolytic cleavage of the X–X bond, as shown in Scheme . − A few complexes of platinum have been characterized that serve as models for the putative five-coordinate, η 1 -adduct intermediate. A series of platinum(II) complexes of the 2,6-bis[(dimethylamino)methyl]phenyl ligand have been synthesized with an η 1 -I 2 ligand, − as well as [Pt(dmpe) 2 I(I 2 )]I 3 (dmpe = 1,2-bis(dimethylphosphino)ethane) .…”

“…A series of platinum(II) complexes of the 2,6-bis[(dimethylamino)methyl]phenyl ligand have been synthesized with an η 1 -I 2 ligand, − as well as [Pt(dmpe) 2 I(I 2 )]I 3 (dmpe = 1,2-bis(dimethylphosphino)ethane) . Heterolytic cleavage of the X–X bond in one of these “intermediates” would generate a charge-separated complex, , which generally leads to the trans addition product, ,,, though cis products have also been observed . Isomerization often complicates mechanistic understanding in these reactions, with mechanisms proposed in which the cis isomer forms first, followed by isomerization to the trans isomer, and vice versa. , No models for analogous η 1 -adducts exist for other catalytically significant metals such as rhodium, though I 2 has been shown to form a bridge between bimetallic rhodium(II) complexes .…”

“…Heterolytic cleavage of the X–X bond in one of these “intermediates” would generate a charge-separated complex, , which generally leads to the trans addition product, ,,, though cis products have also been observed . Isomerization often complicates mechanistic understanding in these reactions, with mechanisms proposed in which the cis isomer forms first, followed by isomerization to the trans isomer, and vice versa. , No models for analogous η 1 -adducts exist for other catalytically significant metals such as rhodium, though I 2 has been shown to form a bridge between bimetallic rhodium(II) complexes . The mechanism of X 2 addition to square planar Rh(I) complexes has also been shown to depend on the relative concentrations of the reactants …”