Hydroxo-bridged platinum(II) complexes. 4. Crystal structure and vibrational spectra of di-.mu.-hydroxo-bis[diammineplatinum(II)] carbonate dihydrate, [(NH3)2Pt(OH)2Pt(NH3)2](CO3).2H2O

Lippert, Bernhard; Lock, C. J. L.; Rosenberg, Barnett; Zvagulis, M.

doi:10.1021/ic50189a001

Cited by 63 publications

(15 citation statements)

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“…(2) were synthesized according to published methods. [12,19] [{cis-Pt(NH 3 ) 2 ] 2 (m-OH)(m-tetrazolato-N1,N2)](NO 3 ) 2 (3) and [{cis-Pt(NH 3 ) 2 } 2 (m-OH)(m-tetrazolato-N2,N3)](NO 3 ) 2 (4) were prepared as follows: 1H-tetrazole (0.252 g, 3.60 mmol) was added to a solution of [cis-Pt(NH 3 ) 2 (m-OH)] 2 (NO 3 ) 2 (2.0 g, 3.25 mmol) in H 2 O (75 mL). The solution was stirred and heated at 40 8C for 24 h in the dark and was then filtered and evaporated at 40 8C.…”

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confidence: 99%

A Tetrazolato‐Bridged Dinuclear Platinum(II) Complex Exhibits Markedly High in vivo Antitumor Activity against Pancreatic Cancer

Komeda¹,

Lin²,

Chikuma³

2011

ChemMedChem

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Some platinum(II) coordination complexes are effective anticancer agents. cis-Diamminedichloridoplatinum(II) (cisplatin), a mononuclear platinum(II) complex, is one of the most commonly used anticancer drugs.[1] Although platinum-based chemotherapy can cause serious side effects, its efficacy has prompted the design and synthesis of next-generation anticancer platinum(II) drugs which are effective against cancers that are typically resistant to chemotherapy, such as lung cancer, pancreatic cancer, and platinum-refractory cancer. [2,3] Lung cancer is the leading cause of cancer deaths worldwide, and non-small-cell lung cancer (NSCLC) accounts for 80 % of lung cancers. Pancreatic cancer remains the fourth leading cause of cancer-related deaths in the United States. [4] Clinical platinum-based drugs show antitumor efficacy by forming Pt-DNA adducts. [5][6][7][8] We and others have reported that azolato-bridged dinuclear Pt II complexes such as [{cis-Pt-, interact with DNA through a mechanism different from that of cisplatin and exhibit much higher in vitro cytotoxicity than cisplatin.[9-11] The chemical structures of 1 and 2 are shown in Figure 1. To further expand drug discovery, we designed two new tetrazolatobridged complexes, [{cis-Pt(NH 3 ) 2 } 2 (m-OH)(m-tetrazolato-N1,N2)](ClO 4 ) 2 (3) and [{cis-Pt(NH 3 ) 2 } 2 (m-OH)(m-tetrazolato-N2,N3)](ClO 4 ) 2 (4), which are structural isomers (Figure 1). Herein we report their synthesis, characterization, in vitro cytotoxicity, and preliminary in vivo antitumor efficacy.Complexes 3 and 4 were synthesized by using a modified protocol for azolato-bridged complexes, as previously described (Scheme 1).[12] A slight excess of tetrazole was added to an aqueous solution of the starting material, [cis-Pt(NH 3 ) 2 (m-OH)] 2 (NO 3 ) 2 , which was then incubated at 40 8C in the dark to yield 3 and 4 at a molar ratio of 6.5:3.5 (see Supporting Information). This preparation ratio likely resulted from the higher nucleophilicity of N1 or N4 bound to one carbon and one nitrogen atom, compared with N2 or N3 bound to two nitrogen atoms. The two structural isomers were separated and purified by reversed-phase liquid chromatography and characterized by 1 H, 13 C, and 195 Pt NMR spectroscopy and ESI mass spectrometry. For 3, two 195 Pt NMR chemical shifts appeared at À2127 and À2177 ppm, reflecting two slightly different Pt[N 3 O] environments, because the tetrazolato bridge is arranged in an asymmetric fashion; there is N1,N2 coordination of Pt atoms.[12] In contrast, for 4, a single 195 Pt NMR chemical shift appears at about À2180 ppm, confirming the Pt[N 3 O] environment and the symmetric structure of the complexes on the tetrazolato bridge; there is N2,N3 coordination of Pt atoms.We tested the cytotoxicity of our azolato-bridged dinuclear Pt II complexes, along with cisplatin for comparison, on the H460 human NSCLC cell line; the IC 50 values are listed in Table 1. Complex 1 showed no activity at concentrations [a] Dr.

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A Tetrazolato‐Bridged Dinuclear Platinum(II) Complex Exhibits Markedly High in vivo Antitumor Activity against Pancreatic Cancer

Komeda¹,

Lin²,

Chikuma³

2011

ChemMedChem

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“…In 1998, two of us published a paper entitled "To Bend or Not To Bend: Dilemma of the Edge-Sharing Binuclear Square Planar Complexes of d 8 Transition Metal Ions". [1] This publication provided a structural and theoretical analysis of complexes of the type [L 4 M 2 (µ-X) 2 ] which are ubiquitous in the chemistry of catalytically important metals such as Ni, Pd, Pt, Rh, and Ir.…”

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confidence: 99%

“…[5] The Pt 2 (µ-S) 2 moiety in complexes of the type [L 4 Pt 2 (µ-S) 2 ] is commonly bent, [1] though for L = 2-(diphenylphosphanyl)pyridine, a planar structure was reported. [6] Depending on the nature of the counterion X in [Pt 2 (NH 3 ) 4 (µ-OH) 2 ]X 2 , both the planar (X = NO 3 [7] or 1/2CO 3 , dihydrate [8] ) and bent (X = ClO 4 [9] ) forms of the cation can exist in the crystalline state. The 3340 studies point to weak C-H···F intramolecular bonding as an additional factor affecting the choice between the planar and bent geometries.…”

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“To Bend or not To Bend?” Both! The Planar and Bent Structures of[(Ph₃P)₄Rh₂(μ‐F)₂]

et al. 2006

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The first experimental evidence is presented for planar–bent isomerism of complexes of the type [L4M2(μ‐X)2]. Both the planar and bent forms have been detected for the same composition, [(Ph3P)4Rh2(μ‐F)2], with full exclusion of any variation in such factors as the nature of the metal, ligand, counterion, and solvent of co‐crystallization. Computationalstudies point to weak C–H···F intramolecular bonding as an additional factor affecting the choice between the planar and bent geometries. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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“…At physiological pH, the hydrolyzed products isolated so far, for which X-ray structural data are available, were shown to contain oligomeric species. The crystal structures of hydroxo-bridged dimers (Faggiani, Lippert, Lock & Rosenberg, 1977a;Stanko, Hollis, Schreifels & Hoeschele, 1977;Lippert, Lock, Rosenberg & Zvagulis, 1978) and trimers (Faggiani, Lippert, Lock & Rosenberg, 1977b, 1978 have been reported. These oligomers are toxic (Rosenberg, 1978) and might be partly responsible for the…”

Section: Cyclo-tri-p-hydroxo-(trinitroargentio)tris-mentioning

confidence: 99%

Structure of a cyclic hydroxo-bridged PtII trimer with platinum–silver bonds

Rochon¹,

Melanson²

1988

Acta Crystallogr C

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Hydroxo-bridged platinum(II) complexes. 4. Crystal structure and vibrational spectra of di-.mu.-hydroxo-bis[diammineplatinum(II)] carbonate dihydrate, [(NH3)2Pt(OH)2Pt(NH3)2](CO3).2H2O

Cited by 63 publications

References 14 publications

A Tetrazolato‐Bridged Dinuclear Platinum(II) Complex Exhibits Markedly High in vivo Antitumor Activity against Pancreatic Cancer

A Tetrazolato‐Bridged Dinuclear Platinum(II) Complex Exhibits Markedly High in vivo Antitumor Activity against Pancreatic Cancer

“To Bend or not To Bend?” Both! The Planar and Bent Structures of[(Ph₃P)₄Rh₂(μ‐F)₂]

Structure of a cyclic hydroxo-bridged PtII trimer with platinum–silver bonds

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Hydroxo-bridged platinum(II) complexes. 4. Crystal structure and vibrational spectra of di-.mu.-hydroxo-bis[diammineplatinum(II)] carbonate dihydrate, [(NH3)2Pt(OH)2Pt(NH3)2](CO3).2H2O

Cited by 63 publications

References 14 publications

A Tetrazolato‐Bridged Dinuclear Platinum(II) Complex Exhibits Markedly High in vivo Antitumor Activity against Pancreatic Cancer

A Tetrazolato‐Bridged Dinuclear Platinum(II) Complex Exhibits Markedly High in vivo Antitumor Activity against Pancreatic Cancer

“To Bend or not To Bend?” Both! The Planar and Bent Structures of[(Ph3P)4Rh2(μ‐F)2]

Structure of a cyclic hydroxo-bridged PtII trimer with platinum–silver bonds

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“To Bend or not To Bend?” Both! The Planar and Bent Structures of[(Ph₃P)₄Rh₂(μ‐F)₂]