Molecular oxygen adducts of transition metal complexes

Abstract

The natural oxygen carriers of biological systems are transition metal complexes which are able to bind reversibly to molecular oxygen. While most of these natural complexes (such as the ferrous protoporphyrin group in hemoglobin) (1) tend to be quite intricate, there are a number of synthetic systems whose relative simplicity has led to intensive investigation of their chemical properties. The importance of these model systems and their novel chemistry should be of general interest. This review is not intended to be a thorough and complete one on oxygen adducts. It is designed to provide a general, and in some representative cases, an in-depth study of molecular oxygen adducts of transition metal complexes. Synthesis of the oxygen carrier, chlorocarbonylfns(triphenylphosphine)iridium(I), [IrCl(CO)(Ph3P)2], by Vaska (2) in 1963 has led to intensive investigation of numerous iridium and

Binding of dioxygen to metal complexes. The oxygen adduct of Co(acacen)

“…Calculations have been carried out with a Gaussian basis set (10,6,4/7,3/3) contracted to [4,3,2/2,1/1] (minimal set except for the 3d functions of Co which are split). The (10,6,4) basis for the Co atom is built from a (9,5,3) basis optimized for Co2+ 78 incremented with one s function of exponent 0.20, one p function of exponent 0.25, and one d function of exponent 0.20 (these exponents are chosen so as to give a maximum of radial density about at midlength of the Co-ligand bonds).79 The (7,3) basis set for first-row atoms is the one of ref 80 and the (3) basis set for H atoms is taken from ref 81. The openshell treatment was based on the restricted Hartree-Fock formalism with two hamiltonians82 using the system of programs ASTERIX.…”

Triboluminescence, single-crystal polarized absorption and photoluminescence, and high-pressure studies of linear-chain manganese(II) compounds

“…According to the recently developed theory of triboluminescence excitation, TL can occur when a crack moves through a crystal having a polar space group. 23 The dynamics of TL have been quantitatively related to the dynamics of crystal fracture. 23 In addition, a large body of evidence has been accumulated which shows a very strong correlation between triboluminescence activity and polar space groups and the corresponding absence of TL activity in crystals having nonpolar space groups.24,25 The proposed excitation mechanism involves charge production on the newly created surfaces of the moving crack followed by electron-impact excitation, charge-hole recombination excitation, or some other form of molecular excitation by the charges produced during fracture.…”

“…It is not related to the electrostatic interaction since both mono-and divalent AMP anions are bound as are positively charged alkaloid cations. 23 In summary we feel that Pfeiffer activity in these systems is due to the formation of a complex containing predominantly 6A transition from the four-coordinate manganese ion. A comparison of the emission intensities shows that the triboluminescence is equivalent to the high-pressure photoluminescence with P < 2 ± 1 kbar.…”

Oxygen uptake by a cobalt(II) complex. An undergraduate experiment

“…Oxygen Uptake by a Cobalt(ll) Complex An undergraduate experiment Natural oxygen-carrier and storage proteins contain a transition metal to which the oxygen reversibly coordinatese.g., iron (myoglobin, hemoglobin), copper (hemocyanin), vanadium (hemovanadin). Various simpler coordination compounds will also reversibly coordinate oxygen, and have been extensively studied as "model compounds" (1,2). Co-balt(ll) complexes are among the most studied.…”

“…Co-balt(ll) complexes are among the most studied. Two types of bonding of dioxygen to cobalt(II) have been distinguished CoL" + O2 n L"Co(02) (1) 2CoL" + 02 pj L"Co-02-CoL" (2) That is, the Co:02 ratio may be 1:1 or 2:1, depending on the nature of the ligands, temperature, solvent, etc. (2)(3)(4)(5)(6)(7).…”