fac-[ReI(CO)3L]n complexes serve as models for short-lived fac-[99mTcI(CO)3L] imaging tracers. Dangling groups on L, needed to achieve desirable biodistribution, complicate the NMR spectra, which are not readily understood. In fac-[ReI(CO)3L]+ with less complicated L, NH groups (exo-NH) projecting toward the L face sometimes showed an upfield shift attributable to steric shielding of the exo-NH group from the solvent by the chelate rings. To investigate whether exo-NH groups in six-membered rings exhibit the same effect and whether the presence of dangling groups alters the effect, we prepared new fac-[Re(CO)3L]n complexes that allow direct comparisons of exo-NH shifts for six-membered vs. five-membered chelate rings. The use of anions as probes, including the new use of the [ReBr6]2– anion as a paramagnetic outer-sphere H-bonding shift reagent, establishes that these NH protons are not well solvated. Lack of solvation, induced by chelate ring bulk, accounts for the upfield shift.
To evaluate syntheses of fac-[Re(CO)3L]+ complexes in organic solvents, we treated fac-[Re(CO)3(CH3CN)3]PF6/BF4 in acetonitrile with triamine ligands (L). When L had two primary or two tertiary terminal amine groups, the expected fac-[Re(CO)3L]+ complexes formed. Treatment of fac-[Re(CO)3(CH3CN)3]+ with various tridentate amine ligands has produced several novel compounds, which most likely arise from reaction of the coordinated nitrile with ligand terminal amines. The new compounds advance our understanding of the spectral and structural properties of Re analogues of 99mTc radiopharmaceuticals.
In fac-[Re(CO)3(5,5¢-Me2bipy)(HNC(CH3)NHR)]BF4 complexes, the monodentate amidine ligand adopts the E, E¢, and Z, but not the Z¢ configuration in solution. Both amidine CN bonds have double-bond character, leading to slow isomerization on the NMR time scale. The equilibrium favors the E¢ isomer as NHR rises above a threshold size or when stacking can occur.
The structural characterization of fac-[Re(CO)3L]+ complexes bearing novel ligands having a central sulfonamide group and two pyridine rings has revealed that the central N of the tertiary sulfonamide group binds to Re. These are among the few structurally characterized complexes with a tertiary (neutral) sulfonamide bound to a metal. We show that a sulfonamide can be used to conjugate the {Re(CO)3}+ unit to a porphyrin. The new ligands may be used eventually in 99mTc imaging.
","abstract_html":"<p class=MsoNormal style='text-align:justify;text-justify:inter-ideograph; text-indent:.5in'><span class=GramE><i style='mso-bidi-font-style:normal'>fac</i>-[</span><span class=SpellE>Re<sup>I</sup></span>(CO)<sub>3</sub>L]<sup>n</sup> complexes serve as models for short-lived <i style='mso-bidi-font-style:normal'>fac</i>-[<sup>99m</sup>Tc<sup>I</sup>(CO)<sub>3</sub>L] imaging tracers. Dangling groups on L, needed to achieve desirable <span class=SpellE>biodistribution</span>, complicate the NMR spectra, which are not readily understood. In <i style='mso-bidi-font-style:normal'>fac</i>-[<span class=SpellE>Re<sup>I</sup></span>(CO)<sub>3</sub>L]<sup>+</sup> with less complicated L, NH groups (<span class=SpellE><i style='mso-bidi-font-style: normal'>exo</i></span>-NH) projecting toward the L face sometimes showed an upfield shift attributable to <span class=SpellE>steric</span> shielding of the <span class=SpellE><i style='mso-bidi-font-style:normal'>exo</i></span>-NH group from the solvent by the <span class=SpellE>chelate</span> rings. To investigate whether <span class=SpellE><i style='mso-bidi-font-style:normal'>exo</i></span>-NH groups in six-<span class=SpellE>membered</span> rings exhibit the same effect and whether the presence of dangling groups alters the effect, we prepared new <i style='mso-bidi-font-style:normal'>fac</i>-[Re(CO)<sub>3</sub>L]<sup>n</sup> complexes that allow direct comparisons of <span class=SpellE><i style='mso-bidi-font-style:normal'>exo</i></span>-NH shifts for six-<span class=SpellE>membered</span> vs. five-<span class=SpellE>membered</span> <span class=SpellE>chelate</span> rings. The use of anions as probes, including the new use of the [ReBr<sub>6</sub>]<sup>2</sup><sup><span style='mso-bidi-font-family: Times'>–</span></sup> anion as a paramagnetic outer-sphere H-bonding shift reagent, establishes that these NH protons are not well solvated. Lack of <span class=SpellE>solvation</span>, induced by <span class=SpellE>chelate</span> ring bulk, accounts for the upfield shift.</p> <p class=MsoNormal style='text-align:justify;text-justify:inter-ideograph; text-indent:.5in'>To evaluate syntheses of <i style='mso-bidi-font-style:normal'>fac</i>-[<span class=GramE>Re(</span>CO)<sub>3</sub>L]<sup>+ </sup>complexes in organic solvents, we treated <i style='mso-bidi-font-style:normal'>fac</i>-[Re(CO)<sub>3</sub>(CH<sub>3</sub>CN)<sub>3</sub>]PF<sub>6</sub>/BF<sub>4 </sub>in acetonitrile with <span class=SpellE>triamine</span> ligands (L). When L<b style='mso-bidi-font-weight:normal'> </b>had two primary or two tertiary terminal amine groups, the expected <i style='mso-bidi-font-style:normal'>fac</i>-[<span class=GramE>Re(</span>CO)<sub>3</sub>L]<sup>+ </sup>complexes formed. Treatment of <i style='mso-bidi-font-style:normal'>fac</i>-[<span class=GramE>Re(</span>CO)<sub>3</sub>(CH<sub>3</sub>CN)<sub>3</sub>]<sup>+ </sup>with various tridentate amine ligands has produced several novel compounds, which most likely arise from reaction of the coordinated <span class=SpellE>nitrile</span> with ligand terminal amines. The new compounds advance our understanding of the spectral and structural properties of Re analogues of <sup>99m</sup>Tc radiopharmaceuticals.</p> <p class=MsoNormal style='text-align:justify;text-justify:inter-ideograph; text-indent:.5in'>In <i style='mso-bidi-font-style:normal'>fac</i>-[<span class=GramE>Re(</span>CO)<sub>3</sub>(5,5<span lang=IT style='font-family:Symbol; mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"; mso-ansi-language:IT;mso-char-type:symbol;mso-symbol-font-family:Symbol'><span style='mso-char-type:symbol;mso-symbol-font-family:Symbol'>¢</span></span>-Me<sub>2</sub>bipy)(HNC(CH<sub>3</sub>)NHR)]BF<sub>4 </sub>complexes, the <span class=SpellE>monodentate</span> <span class=SpellE>amidine</span> ligand adopts the <i style='mso-bidi-font-style:normal'>E</i>, <i style='mso-bidi-font-style:normal'>E</i><i style='mso-bidi-font-style:normal'><span lang=IT style='font-family:Symbol;mso-ascii-font-family:"Times New Roman"; mso-hansi-font-family:"Times New Roman";mso-ansi-language:IT;mso-char-type: symbol;mso-symbol-font-family:Symbol'><span style='mso-char-type:symbol; mso-symbol-font-family:Symbol'>¢</span></span></i>, and <i style='mso-bidi-font-style: normal'>Z</i>,<span style='mso-spacerun:yes'> </span>but not the <i style='mso-bidi-font-style:normal'>Z</i><i style='mso-bidi-font-style:normal'><span lang=IT style='font-family:Symbol;mso-ascii-font-family:"Times New Roman"; mso-hansi-font-family:"Times New Roman";mso-ansi-language:IT;mso-char-type: symbol;mso-symbol-font-family:Symbol'><span style='mso-char-type:symbol; mso-symbol-font-family:Symbol'>¢</span></span></i> configuration in solution. Both <span class=SpellE>amidine</span> CN bonds have double-bond character, leading to slow isomerization on the NMR time scale. The equilibrium favors the <i style='mso-bidi-font-style:normal'>E</i><i style='mso-bidi-font-style:normal'><span lang=IT style='font-family:Symbol;mso-ascii-font-family:"Times New Roman"; mso-hansi-font-family:"Times New Roman";mso-ansi-language:IT;mso-char-type: symbol;mso-symbol-font-family:Symbol'><span style='mso-char-type:symbol; mso-symbol-font-family:Symbol'>¢</span></span></i> isomer as NHR rises above a threshold size or when stacking can occur. </p> <p class=MsoNormal style='text-align:justify;text-justify:inter-ideograph; text-indent:.5in'>The structural characterization of <i style='mso-bidi-font-style: normal'>fac</i>-[Re(CO)<sub>3</sub>L<b style='mso-bidi-font-weight:normal'>]</b><sup>+ </sup>complexes bearing novel ligands having a central sulfonamide group and two pyridine rings has revealed that the central N of the tertiary sulfonamide group binds to Re. These are among the few structurally characterized complexes with a tertiary (neutral) sulfonamide bound to a metal. We show that a sulfonamide can be used to conjugate the {<span class=GramE>Re(</span>CO)<sub>3</sub>}<sup>+</sup> unit to a <span class=SpellE>porphyrin</span>. The new ligands may be used eventually in <sup>99m</sup>Tc imaging.</p>","abstract_has_math":false,"creators":["Perera, Theshini"],"institution":"Chemistry","degree_name":"Doctor of Philosophy (PhD)","degree_level":"Dissertation","degree_discipline":"Chemistry","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2010,"date_issued":"2010-01-01T08:00:00Z","date_published":"2010-01-01T08:00:00Z","updated_at":"2026-07-24T02:59:15Z","subjects":["iminoether","amidine","polyamine","rhenium tricarbonyl","sulfonamide"],"languages":[],"rights":["unrestricted","Release the entire work immediately for access worldwide."],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["etd-07082010-165000","https://repository.lsu.edu/gradschool_dissertations/1204"],"render_values":[{"text":"etd-07082010-165000","href":null,"code":true},{"text":"https://repository.lsu.edu/gradschool_dissertations/1204","href":"https://repository.lsu.edu/gradschool_dissertations/1204","code":true}]}]},"links":{"outbound_url":"https://doi.org/10.31390/gradschool_dissertations.1204","outbound_label":"DOI","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Perera, Theshini"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2010-06-18"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2022-05-12T23:11:21Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemistry"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Chemistry"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["iminoether","amidine","polyamine","rhenium tricarbonyl","sulfonamide"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["unrestricted","Release the entire work immediately for access worldwide."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["etd-07082010-165000","10.31390/gradschool_dissertations.1204","https://repository.lsu.edu/gradschool_dissertations/1204"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["fac-[ReI(CO)3L]n complexes serve as models for short-lived fac-[99mTcI(CO)3L] imaging tracers. Dangling groups on L, needed to achieve desirable biodistribution, complicate the NMR spectra, which are not readily understood. In fac-[ReI(CO)3L]+ with less complicated L, NH groups (exo-NH) projecting toward the L face sometimes showed an upfield shift attributable to steric shielding of the exo-NH group from the solvent by the chelate rings. To investigate whether exo-NH groups in six-membered rings exhibit the same effect and whether the presence of dangling groups alters the effect, we prepared new fac-[Re(CO)3L]n complexes that allow direct comparisons of exo-NH shifts for six-membered vs. five-membered chelate rings. The use of anions as probes, including the new use of the [ReBr6]2– anion as a paramagnetic outer-sphere H-bonding shift reagent, establishes that these NH protons are not well solvated. Lack of solvation, induced by chelate ring bulk, accounts for the upfield shift.
To evaluate syntheses of fac-[Re(CO)3L]+ complexes in organic solvents, we treated fac-[Re(CO)3(CH3CN)3]PF6/BF4 in acetonitrile with triamine ligands (L). When L had two primary or two tertiary terminal amine groups, the expected fac-[Re(CO)3L]+ complexes formed. Treatment of fac-[Re(CO)3(CH3CN)3]+ with various tridentate amine ligands has produced several novel compounds, which most likely arise from reaction of the coordinated nitrile with ligand terminal amines. The new compounds advance our understanding of the spectral and structural properties of Re analogues of 99mTc radiopharmaceuticals.
In fac-[Re(CO)3(5,5¢-Me2bipy)(HNC(CH3)NHR)]BF4 complexes, the monodentate amidine ligand adopts the E, E¢, and Z, but not the Z¢ configuration in solution. Both amidine CN bonds have double-bond character, leading to slow isomerization on the NMR time scale. The equilibrium favors the E¢ isomer as NHR rises above a threshold size or when stacking can occur.
The structural characterization of fac-[Re(CO)3L]+ complexes bearing novel ligands having a central sulfonamide group and two pyridine rings has revealed that the central N of the tertiary sulfonamide group binds to Re. These are among the few structurally characterized complexes with a tertiary (neutral) sulfonamide bound to a metal. We show that a sulfonamide can be used to conjugate the {Re(CO)3}+ unit to a porphyrin. The new ligands may be used eventually in 99mTc imaging.
"]},{"key":"dc:title","label":"Title","values":["Chemistry of rhenium(I) tricarbonyl complexes of biomedical relevance"]}]}],"canonical_facts":{"dc:creator":["Perera, Theshini"],"dc:date":["2010-06-18"],"dc:date.available":["2022-05-12T23:11:21Z"],"dc:description.abstract":["fac-[ReI(CO)3L]n complexes serve as models for short-lived fac-[99mTcI(CO)3L] imaging tracers. Dangling groups on L, needed to achieve desirable biodistribution, complicate the NMR spectra, which are not readily understood. In fac-[ReI(CO)3L]+ with less complicated L, NH groups (exo-NH) projecting toward the L face sometimes showed an upfield shift attributable to steric shielding of the exo-NH group from the solvent by the chelate rings. To investigate whether exo-NH groups in six-membered rings exhibit the same effect and whether the presence of dangling groups alters the effect, we prepared new fac-[Re(CO)3L]n complexes that allow direct comparisons of exo-NH shifts for six-membered vs. five-membered chelate rings. The use of anions as probes, including the new use of the [ReBr6]2– anion as a paramagnetic outer-sphere H-bonding shift reagent, establishes that these NH protons are not well solvated. Lack of solvation, induced by chelate ring bulk, accounts for the upfield shift.
To evaluate syntheses of fac-[Re(CO)3L]+ complexes in organic solvents, we treated fac-[Re(CO)3(CH3CN)3]PF6/BF4 in acetonitrile with triamine ligands (L). When L had two primary or two tertiary terminal amine groups, the expected fac-[Re(CO)3L]+ complexes formed. Treatment of fac-[Re(CO)3(CH3CN)3]+ with various tridentate amine ligands has produced several novel compounds, which most likely arise from reaction of the coordinated nitrile with ligand terminal amines. The new compounds advance our understanding of the spectral and structural properties of Re analogues of 99mTc radiopharmaceuticals.
In fac-[Re(CO)3(5,5¢-Me2bipy)(HNC(CH3)NHR)]BF4 complexes, the monodentate amidine ligand adopts the E, E¢, and Z, but not the Z¢ configuration in solution. Both amidine CN bonds have double-bond character, leading to slow isomerization on the NMR time scale. The equilibrium favors the E¢ isomer as NHR rises above a threshold size or when stacking can occur.
The structural characterization of fac-[Re(CO)3L]+ complexes bearing novel ligands having a central sulfonamide group and two pyridine rings has revealed that the central N of the tertiary sulfonamide group binds to Re. These are among the few structurally characterized complexes with a tertiary (neutral) sulfonamide bound to a metal. We show that a sulfonamide can be used to conjugate the {Re(CO)3}+ unit to a porphyrin. The new ligands may be used eventually in 99mTc imaging.
"],"dc:identifier":["etd-07082010-165000","10.31390/gradschool_dissertations.1204","https://repository.lsu.edu/gradschool_dissertations/1204"],"dc:rights":["unrestricted","Release the entire work immediately for access worldwide."],"dc:subject":["iminoether","amidine","polyamine","rhenium tricarbonyl","sulfonamide"],"dc:title":["Chemistry of rhenium(I) tricarbonyl complexes of biomedical relevance"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"],"thesis:institution_name":["Chemistry"]},"updated_at":"2026-07-24T02:59:15Z"}