Coordination chemistry of the rhenium-organodiazenido core with facultative tetradentate ligands possessing thiolate-amine and thiolate-thioether donor sets. Crystal and molecular structures of [Re(SCH2CH2NMeCH2CH2NMeCH 2CH2S) (N2COC6H4-p-Cl) (PPh3 ...

Article abstract of DOI:10.1021/ic00260a017

Full title: Coordination chemistry of the rhenium-organodiazenido core with facultative tetradentate ligands possessing thiolate-amine and thiolate-thioether donor sets. Crystal and molecular structures of [Re(SCH₂CH₂NMeCH₂CH₂NMeCH ₂CH₂S) (N₂COC₆H₄-p-Cl) (PPh₃)]·CH₃OH, [Re(SCH₂CH₂S(CH₂)₃SCH ₂CH₂S)(N₂COPh)(PPh₃)], and [Re(SCH₂CH₂S(CH₂)₃SCH ₂CH₂S)(N₂CO₂Me)(PPh ₃)]·CH₂Cl₂ and a comparison with the structure of the oxidation product [N,N′-dimethyl-N,N′-bis(sulfinatoethyl)ethylenediamine-S,N,N′, O′][(2-chlorophenyl)diazenido](triphenylphosphine)rhenium(I), [Re{O₂SCH₂CH₂NMeCH₂CH ₂NMeCH₂CH₂SO₂}(N₂C ₆H₄-o-Cl)(PPh₃)]. The syntheses, crystal structures, electronic spectra, and electrochemical characteristics of a series of rhenium-organodiazenido complexes with facultative tetradentate ligands are reported. Complexes of the type [Re{SCH₂CH₂X-(CH₂)_nXCH ₂CH₂S}(N₂R)(PPh₃)] (X = NCH₃, n = 2, R = -COC₆H₄Cl (1); X = S, n = 3, R = -COC₆H5 (2); X = S, n = 3, R = -CO₂Me (3)) are synthesized from the reaction of [ReCl₂(PPh₃)₂(N₂R)] complexes with the appropriate tetradentate ligand. Crystal data: for 1, monoclinic space group P2₁/n, a = 8.683 (2) A?, b = 18.278 (4) A?, c = 24.691 (4) A?, β = 97.95 (1)°, V = 3881.2 (8) A?³, Z = 4, R = 0.055 for 2469 reflections; for 2, monoclinic space group P2₁/n, a = 11.804 (3) A?, b = 12.529 (3) A?, c = 21.448 (4) A?, β = 89.39 (1) A?, V = 3171.8 (9) A?³, Z = 4, R = 0.068 for 2981 reflections; for 3, monoclinic space group P2₁/n, a = 8.570(2) A?, b = 10.720 (2) A?, c = 35.618 (6) A?, β = 90.14(11)°, V = 3272.3 (11) A?³, Z = 4, R = 0.061 for 3172 reflections. The structures display rhenium centers in distorted octahedral environments, with coordination sites occupied by two thiolate donors and two amine or sulfido donors from the tetradentate ligands, the phosphorus donor of the PPh₃ group, and the α-nitrogen of the linearly end-on coordinated organodiazenido group. The complexes are electrochemically active, exhibiting reversible 1-electron oxidations in the +0.3 to +0.5 V range. The more electron withdrawing the diazenido substituent R, the more positive the oxidation potential, suggesting that the oxidation potential is a measure of the energy of the HOMO. Although complexes of type 1-3 exhibit no tendency toward oxidation under ambient conditions, reaction of [ReCl₂(PPh₃)₂(NH₃)-(NNC ₆H₄Cl)] with N,N′-dimethyl-N,N′-bis(mercaptoethyl)ethylenediamine yields a product, 4, which oxidizes during subsequent chromatographic purification to yield the sulfinato derivative [Re(O₂SCH₂CH₂N(CH₃)CH ₂CH₂N(CH₃)-CH₂CH₂SO ₂}(N₂C₆H₄Cl)(PPh₃)] (5). Crystal data: for 5, triclinic space group P1, a = 9.060 (3) A?, b = 10.499 (3) A?, c = 19.050 (4) A?, α = 78.18 (1)°, β = 84.85 (1)°, γ = 76.34 (1)°, V = 1722.5 (10) A?³, Z = 2, R = 0.077 for 3395 reflections. The pseudooctahedral geometry about the rhenium center is generated by two amine donors, a sulfur from one sulfinato group and an oxygen from the second sulfinato group of the oxidized tetradentate ligand, the PPh₃ phosphorus donor, and the α-nitrogen of the organodiazenido ligand. The structure provides the first example of a complex exhibiting coordination through the oxygen of one sulfinate group and the sulfur of the second sulfinato moiety.