fac-Re(CO)3L Complexes Containing Tridentate Monoanionic Ligands (L-) with a Seldom-Studied Sulfonamido Group As One Terminal Ligating Group

Christoforou, Anna Maria; Fronczek, Frank R.; Marzilli, Patricia A.; Marzillï, Luigi G.

doi:10.1021/ic700594a

Cited by 18 publications

(37 citation statements)

References 45 publications

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“…However, Re I tricarbonyl complexes are sterically undemanding because of the small size of the CO ligands and the relatively long bonds made by Re I . Bond distances involving Re I are longer than those involving Pt II 11,25,33,34. N–M–N bite angles for chelate rings in related Pt II and Re I compounds are more acute in Re I compounds 11,35.…”

Section: Resultsmentioning

confidence: 90%

Several Novel N-Donor Tridentate Ligands Formed in Chemical Studies of Newfac-Re(CO)₃Complexes Relevant tofac-^99mTc(CO)₃Radiopharmaceuticals: Attack of a Terminal Amine on Coordinated Acetonitrile

et al. 2010

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SynopsisA novel ligand was discovered in which acetonitrile appears to have inserted between the two protons and the nitrogen of a primary amine. A proposed pathway for this process involves a putative sevenmembered chelate ring (formed by attack of a primary amine on coordinated acetonitrile) that undergoes proton transfer and rearrangement. The pathway is supported by the structure of a related compound that has a methyl group in place of one of the protons.To evaluate syntheses of fac- [Re(CO) 3 L] + complexes in organic solvents, we treated fac- [Re (CO) 3 (CH 3 CN) 3 ]PF 6 /BF 4 in acetonitrile with triamine ligands (L). When L had two primary or two tertiary terminal amine groups, the expected fac- [Re(CO) 3 L] + complexes formed. In contrast, N,N-dimethyldiethylenetriamine (N,N-Me 2 dien) formed an unusual compound, fac-[Re(CO) 3 (DAE)]BF 4 {DAE = (Z)-N′-(2-(2-(dimethylamino)ethylamino)ethyl)acetimidamide = (Me 2 NCH 2 CH 2 )NH(CH 2 CH 2 N=C(NH 2 )Me)}. DAE is formed by addition of acetonitrile to the N,N-Me 2 dien terminal primary amine, converting this sp 3 nitrogen to an sp 2 nitrogen with a double bond to the original acetonitrile sp carbon. The three N's bound to Re derive from N,N-Me 2 dien. The pathway to fac- [Re(CO) 3 (DAE)]BF 4 is suggested by a second unusual compound, fac-[Re(CO) 3 (MAE)]PF 6 {MAE = N-methyl-N-(2-(methyl-(2-(methylamino)ethyl NIH Public Access [Re(CO) 3 (MAE)]PF 6 (MAE = N-methyl-N-(2-(methyl-(2-(methylamino)ethyl)amino)ethyl) acetimidamide)A 10% excess of N,N′,N″-Me 3 dien (16 µL, 0.11 mmol) was added to a solution of [Re (CO) 3 (CH 3 CN) 3 ]PF 6 (54 mg, 0.10 mmol) in 10 mL of acetonitrile. The reaction mixture was heated at reflux for 24 h. A white powder was collected, which later gave X-ray quality crystals upon slow evaporation of a methanol solution (29 mg, 48% yield 3 ]PF 6 (54 mg, 0.10 mmol) in 8 mL of acetonitrile, and the reaction mixture was heated at reflux for 16 h, whereupon a very small amount of a fine precipitate was visible. The reaction mixture was transferred to a vial and allowed to evaporate to dryness at room temperature. The residue was dissolved in methanol, an excess of diethyl ether was added, and the mixture was left at room temperature. The white precipitate that had aggregated into clumps after 2 days was scraped from the walls of the vial, placed on a filter, and washed with diethyl ether. The NMR spectrum of this precipitate was identical to that of the crystals described above. The BF 4 − salt could also be obtained by using a similar procedure, which yielded a white precipitate having an NMR spectrum identical to that of the PF 6 − crystals; however, the precipitate could not be crystallized.[ [Re(CO) 3 (EAE)]BF 4 (EAE = N-ethyl-N-(2-(ethyl-(2-(ethylamino)ethyl)amino)ethyl) acetimidamide)A 10% excess of N,N′,N″-Et 3 dien (20 µL, 0.11 mmol) was added to a solution of [Re (CO) 3 (CH 3 CN) 3 ]BF 4 (48 mg, 0.10 mmol) in 6 mL of acetonitrile, and the reaction mixture was heated at reflux for 16 h. The volume was reduced to ~2 mL, and diet...

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Section: Resultsmentioning

confidence: 90%

Several Novel N-Donor Tridentate Ligands Formed in Chemical Studies of Newfac-Re(CO)₃Complexes Relevant tofac-^99mTc(CO)₃Radiopharmaceuticals: Attack of a Terminal Amine on Coordinated Acetonitrile

et al. 2010

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“…In [Re(CO) 3 L] + complexes with prototypical NNN donor ligands, Re–N(sp 3 ) bond distances (generally ∼2.23–2.29 Å) 44,45 are longer than Re–N(sp 2 ) bond distances (generally 2.14–2.18 Å). 37,46,47 The Re–N(sp 2 ) bond distances involving the pyridyl groups (N1 and N3, Figure 2) of [Re(CO) 3 ( N (SO 2 Me)dpa)]PF 6 ( 1 ), [Re(CO) 3 ( N (SO 2 tmb)dpa)]PF 6 ( 2 ), [Re(CO) 3 ( N (SO 2 tol)dpa)]PF 6 ( 4 ), and [Re(CO) 3 ( N (SO 2 Me 2 Nnap)dpa)]BF 4 ( 5 ) are similar and fall within a normal range (Table 2). For the most part, the Re–N(pyridyl) bond distances are not significantly different from the values reported for [Re(CO) 3 ( N (H)dpa)]Br (2.177(5) and 2.183(5) Å) 21 and for [Re(CO) 3 ( N (CH 2 CO 2 Et)dpa)]Br (2.161(6) and 2.174(5) Å).…”

Section: Resultsmentioning

confidence: 99%

Formation of a Metal-to-Nitrogen Bond of Normal Length by a Neutral Sufonamide Group within a Tridentate Ligand. A New Approach to Radiopharmaceutical Bioconjugation

et al. 2013

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We demonstrate that a tertiary sulfonamide group, N(SO2R)R′2, can re-hybridize to form a M–N bond of normal length even when the group is in a linear tridentate ligand, such as in the new tridentate N(SO2R)dpa ligands derived from di-(2-picolyl)amine (N(H)dpa). N(SO2R)dpa ligands were used to prepare fac-[Re(CO)3(N(SO2R)dpa)](PF6 or BF4) complexes. Structural characterization of the new complexes established that the tertiary sulfonamide nitrogen atom binds to Re with concomitant sp2-to-sp3 re-hybridization, facilitating facial coordination. The new fac-[Re(CO)3(N(SO2R)dpa)]X structures provide the only examples for any metal with the sulfonamide as part of a noncyclic linear tridentate ligand and with a normal metal-to-nitrogen(tertiary sulfonamide) bond length. Rare previous examples of such normal M–N bonds have been found only in more constrained situations, such as with tripodal tetradentate ligands. Our long-term objectives for the new tridentate N(SO2R)dpa ligands are to develop the fundamental chemistry relevant to the eventual use of the fac-[MI(CO)3]+ core (M = 99mTc, 186/188Re) in imaging and therapy. The sulfonamide group uniquely contributes to two of our goals: expanding ways to conjugate the fac-[MI(CO)3]+ core to biological molecules and also developing new symmetrical tridentate ligands that can coordinate facially to this core. Tests of our conjugation method, conducted by linking the fac-[ReI(CO)3]+ core to a new tetraarylporphyrin (T(N(SO2C6H4)dpa)P) as well as to a dansyl (5-(dimethylamino)naphthalene-1-sulfonyl) group, demonstrate that large molecular fragments can be tethered via a coordinated tertiary sulfonamide linkage to this core.

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“…They have shown that organic soluble metal precursors can serve as synthons for effective radiolabeling. 9 In addition, electron-rich bidentate O-donor ligands ( β -diketones acetylacetone and curcumin) along with monodentate nitrogen ligands have been explored to generate stable fac -[M(CO) 3 (OO)(N)] + complexes. 10 However, precise knowledge of ligand design is not completely understood—more specifically, which combinations of hard bases vs soft donors would lead to enhanced in vivo stability of the [ 99m Tc(CO) 3 ] + moiety in order to engineer the design and development of organ-specific (or tumor-specific) radiopharmaceuticals.…”

Section: Introductionmentioning

confidence: 99%

Design and Synthesis of a Bombesin Peptide-Conjugated Tripodal Phosphino Dithioether Ligand Topology for the Stabilization of the fac-[M(CO)₃]⁺ Core (M = ^{99 m}Tc or Re)

Kannan¹,

Pillarsetty²,

Gali³

et al. 2011

Inorg. Chem.

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A new tumor-seeking tridentate topology consisting of a phosphino dithioether ((HOCH2)2PCH2CH2S(CH2)nCH2SR; PS2) ligand framework for the production of kinetically inert and in vivo stable facial [99mTc(CO)3(PS2)]+ or [Re(CO)3(PS2)]+ is described. The X-ray crystal structure of fac-Re(CO)3(PS2)PF6 is reported. The bioconjugation strategies for incorporating bombesin (BBN) peptides on to the PS2 tripodal framework and, thereby, de novo designing of GRP receptor-seeking Tc(PS2–BBN)(CO)3 are developed.

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fac-Re(CO)₃L Complexes Containing Tridentate Monoanionic Ligands (L^-) with a Seldom-Studied Sulfonamido Group As One Terminal Ligating Group

Cited by 18 publications

References 45 publications

Several Novel N-Donor Tridentate Ligands Formed in Chemical Studies of Newfac-Re(CO)₃Complexes Relevant tofac-^99mTc(CO)₃Radiopharmaceuticals: Attack of a Terminal Amine on Coordinated Acetonitrile

Several Novel N-Donor Tridentate Ligands Formed in Chemical Studies of Newfac-Re(CO)₃Complexes Relevant tofac-^99mTc(CO)₃Radiopharmaceuticals: Attack of a Terminal Amine on Coordinated Acetonitrile

Formation of a Metal-to-Nitrogen Bond of Normal Length by a Neutral Sufonamide Group within a Tridentate Ligand. A New Approach to Radiopharmaceutical Bioconjugation

Design and Synthesis of a Bombesin Peptide-Conjugated Tripodal Phosphino Dithioether Ligand Topology for the Stabilization of the fac-[M(CO)₃]⁺ Core (M = ^{99 m}Tc or Re)

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fac-Re(CO)3L Complexes Containing Tridentate Monoanionic Ligands (L-) with a Seldom-Studied Sulfonamido Group As One Terminal Ligating Group

Cited by 18 publications

References 45 publications

Several Novel N-Donor Tridentate Ligands Formed in Chemical Studies of Newfac-Re(CO)3Complexes Relevant tofac-99mTc(CO)3Radiopharmaceuticals: Attack of a Terminal Amine on Coordinated Acetonitrile

Several Novel N-Donor Tridentate Ligands Formed in Chemical Studies of Newfac-Re(CO)3Complexes Relevant tofac-99mTc(CO)3Radiopharmaceuticals: Attack of a Terminal Amine on Coordinated Acetonitrile

Formation of a Metal-to-Nitrogen Bond of Normal Length by a Neutral Sufonamide Group within a Tridentate Ligand. A New Approach to Radiopharmaceutical Bioconjugation

Design and Synthesis of a Bombesin Peptide-Conjugated Tripodal Phosphino Dithioether Ligand Topology for the Stabilization of the fac-[M(CO)3]+ Core (M = 99 mTc or Re)

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fac-Re(CO)₃L Complexes Containing Tridentate Monoanionic Ligands (L^-) with a Seldom-Studied Sulfonamido Group As One Terminal Ligating Group

Several Novel N-Donor Tridentate Ligands Formed in Chemical Studies of Newfac-Re(CO)₃Complexes Relevant tofac-^99mTc(CO)₃Radiopharmaceuticals: Attack of a Terminal Amine on Coordinated Acetonitrile

Several Novel N-Donor Tridentate Ligands Formed in Chemical Studies of Newfac-Re(CO)₃Complexes Relevant tofac-^99mTc(CO)₃Radiopharmaceuticals: Attack of a Terminal Amine on Coordinated Acetonitrile

Design and Synthesis of a Bombesin Peptide-Conjugated Tripodal Phosphino Dithioether Ligand Topology for the Stabilization of the fac-[M(CO)₃]⁺ Core (M = ^{99 m}Tc or Re)