Tetradentate macrocyclic complexes of platinum. X-ray crystal structures and redox behavior of complexes containing nitrogen or sulfur donor atoms

Waknine, David.; Heeg, Mary Jane; Endicott, John F.; Ochrymowycz, L. A.

doi:10.1021/ic00019a025

Cited by 31 publications

(19 citation statements)

References 13 publications

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“…The Pt-N dis tances are 1.948(4) and 2.069(4) Å and are similar to those in the "free" complex [Pt(cyclam)]Cl 2 •HCl•H 2 O (2.039-2.045 Å). 40 Cyclam in the structure of 4 adopts the most stable trans III configuration (S,S,R,R) characteristic of both 12 The authors attributed the stabilization to the inclusion of the complexes into CB [8].…”

Section: Resultsmentioning

confidence: 99%

Inclusion compounds of cucurbit[8]uril with noble metal polyamine complexes

et al. 2010

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Inclusion compounds of the macrocyclic cavitand cucurbit[8]uril (CB[8]) with the ruthenium(III) bis(ethylenediamine) complex {trans [Ru(en) 2 Cl 2 ]@CB[8]}Cl•27.5H 2 O (1), the gold(III) diethylenetriamine complex {[Au(dien)Cl]@CB[8]}Cl 2 •11H 2 O (2), and the gold(III) and platinum(II) cyclam complexes (H 3 O) 5 {[Au(cyclam)]@CB[8]}Cl 8 •18H 2 O (3) and {[Pt(cyclam)] 0.11 (H 2 cyclam) 0.89 @CB[8]}Cl 2 •16H 2 O (4), respectively, where cyclam is the tetra azamacrocyclic ligand, were synthesized. The inclusion compounds were synthesized both directly starting from CB[8] and the metal complexes with polyamines (en or dien) and by the two step method with the use of the cyclic polyamine ligand (cyclam) pre included into the cavity of the macrocycle. The inclusion compounds were characterized by X ray diffraction (1, 2, and 4), IR spectroscopy, electrospray ionization mass spectrometry, UV-Vis spectro scopy, and thermogravimetric analysis.Cucurbit[n]urils (C 6n H 6n N 4n O 2n , CB[n]; n = 5-10) comprise a family of macrocyclic molecules containing an open hydrophobic intramolecular cavity accessible through two hydrophilic portals formed by n carbonyl groups. 1-4 This structure determines the behavior of cucurbit[n]urils as cavitands, viz., host molecules capable of encapsulating guest molecules of suitable size into the inner cavity. A high negative electrostatic potential on the portals 3 is responsible for the formation of stable inclusion compounds of CB[n] with positively charged guests, for example, with alkylammonium cations. 2,3 The cavity sizes in cucurbit[n]urils with n > 6 are sufficient for the inclu sion of metal complexes with small organic ligands. The spectroscopic (NMR), calorimetric, and electrochemical studies showed that highly stable host-guest compounds are formed. 5-9 However, only a few inclusion com pounds of CB[n] with metal complexes were structurally characterized. 6,10-12 Complexes included into the bar rel shaped cavity of CB[n] can be fully embedded in the cavitand, as opposed to most of inclusion compounds of such receptors as calixarenes and cyclodextrins where com plexes are only partially encapsulated in the bowl shaped cavities. 13 In recent years, this class of compounds has attracted considerable interest because of the possibility of the inclusion of biologically active metal complexes into cavitands. This opens wide opportunities for the design of new generation prolonged action pharmaceuticals in which the host molecules prevents the guest molecules from rapid decomposition, decrease their toxicity, and have the transport function of the active component in the organism. 14 Recent studies 14-16 have shown that the in clusion of platinum polyamine complexes having antitu mor activity into cucurbit[n]urils leads to a substantial decrease in the toxicity of these complexes. Antitumor drugs containing inclusion compounds of CB[7] and CB [8] with platinum, palladium, and gold complexes were cov ered by patents. 17-20Previously, 21-25 we have shown that CB[8] forms inclusion compoun...

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Section: Resultsmentioning

confidence: 99%

Inclusion compounds of cucurbit[8]uril with noble metal polyamine complexes

et al. 2010

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“…LiCl in water at 80°C. detrimental to 2 a (Table 1, Entries [11][12]. Excessive presence of Et 3 N generates sufficient OHÀ which promotes metal hydroxide precipitation.…”

Section: Synthesis Of Ons-bearing Cesmentioning

confidence: 99%

“…[7,8] Moreover, CEs with mixed oxygen, nitrogen, and sulfur (O,N,S) heteroatoms are known to possess strong affinities towards PGMs. [9][10][11][12][13][14] Oxathia (O,S), oxaaza (O,N), and oxaazathia (O,N,S) CEs which contain soft heteroatoms showed specific coordination towards soft metals such as Pd 2 + or Pt 2 + according to the hard soft-acid base (HSAB) principle. [12,15,16] But despite their structural tunability for improved selectivity, syntheses of these CEs require multiple reaction steps using toxic and hazardous solvents and afford low overall reaction yields.…”

Section: Introductionmentioning

confidence: 99%

Aqueous Synthesis of 14‐15‐Membered Crown Ethers with Mixed O, N and S Heteroatoms: Experimental and Theoretical Binding Studies with Platinum‐Group Metals

et al. 2019

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A series of 14‐15‐membered O, N, and S‐containing crown ethers (CEs) was synthesized by cyclization of bis‐epoxides with aryl‐N or S dinucleophiles using triethylamine as a catalyst and LiCl as a metal template in water. The catalyst dosage, and metal template type and dosage were critical in achieving yields of 56–93 %. Liquid‐liquid extraction (LLE) was performed to evaluate the CE complexation with Pd2+ and Pt2+. Among the CEs, a dioxa‐dithia dibenzo CE exhibited the highest Pd2+ selectivity even in the presence of other platinum‐group metals (PGMs). Complementary DFT studies reveal that this CE has the most compatible cavity dimension (ØCE=1.58 Å) with Pd2+ (ØPd2+=1.56 Å) forming a square‐planar S4 geometry. Binding‐energy calculations showed the Pd2+ complex has the least energy requirement for structural reorientation during complexation. Overall results highlight the importance of CE cavity dimension and presence of S heteroatoms for the structural design of CEs selective towards PGMs such as Pd2+.

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“…6). The syn Cs forms two inequivalent six-membered chair chelate rings on coordination [57]. This [3'34'4] conformer, like the [3'43'4]B/C, has six anti CSCC torsion angles with the remainder being gauche.…”

Section: 4711-tetrathiacyclotetradecane and Derivativesmentioning

confidence: 99%

“…9 9 S distances of 3.7-3.8 A,. The structure of SONNOY is similar, although the extent of interaction at such distances is disputed [57] '4] conformer also occurs in octahedral complexes with different axial ligands and this may be a result of the inequivalent electronic and steric properties of the axial coordination sites rather than a metal/ligand size mismatch. There is a strong electronic trans influence in (4b)TcfCl)(N) LEKYOP with the technetium atom displaced 0.24 A toward the nitrido ligand above the S mean plane on the less sterically hindered side of the macrocycle.…”

Section: 4711-tetrathiacyclotetradecane and Derivativesmentioning

confidence: 99%

Conformational analysis of 14- and 16-membered unsaturated oxa, thia, and selena macrocyclic ligands

1997

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Crystallographic results retrieved from the Cambridge Structural Database (CSD) have been used to perform systematic conformationai analyses of the free and metal-coordinated tigands 1,4,8,1 ltetraoxa/thia/selenacyclotetradecane, 1,5,9,13-tetraoxa/thia/selenacyclohexadecane, and their derivatives. Conformational classifications established using symmetry-modified Jarvis-Patrick cluster analysis have been displayed in torsional space by principal component analysis (PCA) plots. Relative molecular mechanics energies of free macrocycles in the observed conformations are compared with the cluster populations and the effect of metal coordination investigated. While the conformations of the free macrocycles in the solid state are those with low molecular mechanics energies, substantial reorganization is required to produce tetradentate chelating conformers, particularly with S donors. With the latter, several such conformers occur, while one predominates with O donors for both macrocycles, in agreement with molecular mechanics predictions. Factors influencing the conformations adopted are discussed.

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Tetradentate macrocyclic complexes of platinum. X-ray crystal structures and redox behavior of complexes containing nitrogen or sulfur donor atoms

Cited by 31 publications

References 13 publications

Inclusion compounds of cucurbit[8]uril with noble metal polyamine complexes

Inclusion compounds of cucurbit[8]uril with noble metal polyamine complexes

Aqueous Synthesis of 14‐15‐Membered Crown Ethers with Mixed O, N and S Heteroatoms: Experimental and Theoretical Binding Studies with Platinum‐Group Metals

Conformational analysis of 14- and 16-membered unsaturated oxa, thia, and selena macrocyclic ligands

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