Hydrosulfide complexes of the transition elements: diverse roles in bioinorganic, cluster, coordination, and organometallic chemistry

Molecules containing transition metal hydrosulfide linkages are diverse, spanning a variety of elements, coordination environments, and redox states, and carrying out multiple roles across several fields of chemistry.

Pyrazolylborate-zinc-hydrosulfide complexes and their reactions

Four new hydrosulfide complexes Tp*Zn-SH of substituted pyrazolylborate ligands (Tp*) were prepared by reactions of Tp*Zn-OH with H(2)S, and three of them were structurally characterized. Unlike the Tp*Zn-OH complexes they do not react with esters, phosphates, or CO(2), e.g. for thiolytic cleavage reactions. They also cannot be deprotonated, as various bases induce precipitation of ZnS and release of anionic Tp*. Acidic organic X-OH compounds (carboxylic acids, trinitrophenol, hexafluoroacetylacetone) replace the SH groups with formation of Tp*Zn-OX. Thiols undergo an entropy-driven SH substitution to yield the Tp*Zn-SR complexes. Like the Tp*Zn-SR complexes the Tp*Zn-SH complexes are quite reactive toward alkylation with methyl iodide, yielding Tp*Zn-I and CH(3)SH. The kinetic investigation of the methylation of Tp(Ph,Me)Zn-SH has shown it to be a clean second-order reaction, thereby indicating that the SH group is alkylated in the zinc-bound state.

Synthesis, characterization, and protonation of octaethylporphyrin osmium nitrosyl complexes containing axial thiolate ligands - X-ray structures of an alkyl thionitrite (RSNO) and its (OEP)Os(NO)(SR) addition product

The (OEP)Os(NO)(SR) compounds (R = Me, Et, i-Pr, t-Bu) have been prepared in 33-48% isolated yields by the formal trans-addition of the precursor alkyl thionitrites (RSNO) across the metal center in (OEP)Os(CO). The nitrosyl thiolate compounds have been characterized by IR, 1H NMR, and UV-vis spectroscopy, and by FAB mass spectrometry. Their IR spectra display bands in the 1751-1755 cm-1 (KBr) range, which is indicative of terminal N-bound NO ligands in this class of compounds. The thiolate-thiol (OEP)Os(NO)(SCH2CH2SH) complex has been prepared in 70% isolated yield from the reaction of (OEP)Os(NO)(O-i-C5H11) with ethane-1,2-dithiol. Nitrosation of the free -SH group in (OEP)Os(NO)(SCH2CH2SH) with t-BuONO, followed by reaction with (TTP)Ru(CO) gave [(OEP)Os(NO)](µ-SCH2CH2S-S,S')[Ru(NO)(TTP)] in 70% yield by 1H NMR spectroscopy. The (OEP)Os(NO)(SCR'2CH2NHC(O)Me) compounds have also been prepared either by an alkoxide-thiolate exchange reaction (for R' = H) or by RSNO addition to (OEP)Os(CO) (for R' = Me). The solid-state molecular structures of the precursor RSNO thionitrite (for R' = Me) and the metalloderivative have been determined by single-crystal X-ray crystallography. Protonation of these (OEP)Os(NO)(SCR'2CH2NHC(O)Me) complexes gave the amide-bound [(OEP)Os(NO)(O=C(Me)NHCH2CR'2SH)]BF4 derivatives. The latter cationic compounds were also obtained by the sequential reaction of (OEP)Os(CO) with nitrosonium tetrafluoroborate, followed by addition of the amide-thiol reagent. Key words: thionitrite, nitrosothiol, porphyrin, X-ray structure, nitric oxide, osmium.

Synthesis and Characterization of Thiolate-Thiol Complexes of Ruthenium Nitrosyl Porphyrins and Their Symmetrical and Unsymmetrical Dithiolate-Bridged Bimetallic Derivatives

Monometallic nitrosyl thiolate-thiol complexes of the form (por)Ru(NO)(S(CH(2))(n)()SH) (por = TPP, n = 2; TTP, n = 2-4) have been prepared in 49-61% isolated yields from the reaction of the (por)Ru(NO)(O-i-C(5)H(11)) alkoxide precursors with HS(CH(2))(n)()SH. The (OEP)Ru(NO)(SCH(2)CH(2)SH) complex was prepared in 71% isolated yield via addition of HSCH(2)CH(2)SNO to (OEP)Ru(CO). These (por)Ru(NO)(S(CH(2))(n)()SH) complexes have been fully characterized by elemental analyses, infrared and (1)H NMR spectroscopy, and by mass spectrometry. The molecular structure of (OEP)Ru(NO)(SCH(2)CH(2)SH) has been determined by single-crystal X-ray crystallography. The Ru-N-O moiety is linear with a bond angle of 170.9(9) degrees. The symmetrical bimetallic [(por)Ru(NO)](2)(&mgr;-S(CH(2))(n)()S-S,S') complexes (por(1) = por(2); i.e., TPP/TPP, TTP/TTP, OEP/OEP) have also been prepared by variations of the procedures used in the preparation of their monometallic derivatives, and they have been fully characterized by elemental analyses, infrared and (1)H NMR spectroscopy, and by mass spectrometry. The novel unsymmetric [(TPP)Ru(NO)](&mgr;-SCH(2)CH(2)S-S,S')[Ru(NO)(OEP)] complex has also been obtained, and the experimental and simulated (1)H NMR spectrum of the protons of the &mgr;-dithiolate bridge indicate that all four protons are inequivalent.