Synthesis, characterization, crystal structures, and reactions of trigonal bipyramidal tin(IV) complexes containing, a tetradentate tripodal tristhiolatophosphine ligand. Use in the one-step synthesis of an iron(IV) complex

Trigonal-Bipyramidal Tin(IV) Complexes Containing Tetradentate Tripodal Tristhiolatophosphine Ligands: Synthesis, Characterization, Crystal Structure, and Transmetalation Reactions

The reactions of the lithium salts of the proligands P(C(6)H(4)-2-SH)(3) (P((H)SH)(3)), P(C(6)H(3)-3-SiMe(3)-2-SH)(3) (P((TMS)SH)(3)), and P(C(6)H(3)-5-Me-2-SH)(3) (P((Me)SH)(3)) with RSnCl(3) (R = Ph, Me, n-Bu), in THF at 0 degrees C, produced a series of trigonal-bipyramidal complexes of the type RSn(PS(3)). The crystal structures of PhSn(P(H)S(3)), PhSn(P(TMS)S(3)), and PhSn(P(Me)S(3)) reveal considerable distortion from local C(3v) symmetry for the Sn(PS(3)) group. Unique to PhSn(P(Me)S(3)) is the presence of intramolecular hydrogen bonding between one sulfur atom and an ortho H atom of the Ph group, creating a plane that includes this S atom and the corresponding C(6)H(3) ring, a phosphorus atom, and the PhSn group. An analysis of the (1)H, (13)C, and (31)P NMR data from a combination of HMQC, HMBC, 2-D COSY, and (1)H{(31)P} NMR studies reveals that in solution the Sn(PS(3)) groups exhibit local C(3v) symmetry, even at low temperature. Byproducts frequently found in the synthesis of the proligands and tin complexes, and subsequent reactions, result from the oxidation of the trianionic tristhiolatophosphine ligand. The crystal structure of one of these, [OP((H)S(3))](2), shows that the molecule contains two ligands joined by a S-S bond. Within each original ligand the remaining two sulfur atoms form a S-S bond, and each phosphorus atom is oxidized. PhSn(P(TMS)S(3)) reacted with 2 equiv of FeCl(3) in CH(2)Cl(2) to produce the iron(IV) complex FeCl(P(TMS)S(3)). FeCl(P(TMS)S(3)) decomposed in the presence of excess FeCl(3). Similar transmetalation reactions with FeCl(2) or [Fe(2)OCl(6)](2)(-) required the addition of ferrocenium ion to complete the oxidation of iron to 4+. RuCl(P(TMS)S(3)) was prepared by the reaction between PhSn(P(TMS)S(3)) and RuCl(2)(DMSO)(4) without the addition of an external oxidizing agent.

Mononuclear Nickel(III) and Nickel(II) Thiolate Complexes with Intramolecular S−H Proton Interacting with Both Sulfur and Nickel: Relevance to the [NiFe]/[NiFeSe] Hydrogenases

Mononuclear, distorted square planar [Ni(II)(ER)(P(o-C(6)H(4)S)(2)(o-C(6)H(4)SH))](-) (ER = SePh (1), 2-S-C(4)H(3)S (2)) with a S-H proton directly interacting with both nickel and sulfur atoms were prepared by reaction of [Ni(CO)(SePh)(3)](-)/[Ni(CO)(2-S-C(4)H(3)S)(3)](-) and P(o-C(6)H(4)SH)(3), individually. The presence of combinations of intramolecular [Ni-S...H-SR]/[Ni...H-SR] interactions was verified in the solid state by the observation of an IR nu(SH) stretching band (2273 and 2283 cm(-)(1) (KBr) for complexes 1 and 2, individually) and (1)H NMR spectra (delta 8.079 (d) (CD(2)Cl(2)) and 8.39 (d) (C(4)D(8)O) ppm (-SH) for complexes 1 and 2, respectively) and subsequently confirmed by X-ray diffraction study. The exo-thiol proton (o-C(6)H(4)SH) in complexes 1 and 2 was identified as a D(2)O exchangeable proton from NMR and IR studies and was quantitatively removed by Lewis base Et(3)N to yield Ni(II) dimer [Ni(II)(P(o-C(6)H(4)S)(3))](2)(2)(-) (5). Instead of the ligand-based oxidation to form dinuclear Ni(II) complexes and dichalcogenide, oxidation of THF-CH(3)CN solution of complexes 1 and 2 by O(2) resulted in the formation of the mononuclear, distorted trigonal bipyramidal [Ni(III)(ER)(P(o-C(6)H(4)S)(3))](-) (ER = SePh (3), 2-S-C(4)H(3)S (4)) accompanied by byproduct H(2)O identified by (1)H NMR, respectively. The 4.2 K EPR spectra of complexes 3 and 4 exhibiting high rhombicities with three principal g values of 2.304, 2.091, and 2.0 are consonant with Ni(III) with the odd electron in the d(z)(2) orbital. Complex 3 undergoes a reversible Ni(III/II) process at E(1/2) = -0.67 V vs Ag/AgCl in MeCN.