Pentaamines

At pH 7, [13]aneN3 or [12]-[15]aneN4 accommodate only two nitrogen-bound protons and these dipositive ammonium cations are apparently unable to provide sufficient electrostatic attraction to polycarboxylate anions for ion-pair formation. In contrast, the macrocyclic spermines, pentaamines and hexaamines accommodate more than three nitrogen-bound protons at pH 7 and for these ligands 1 1 associations... 

DR. ALBERT HAIM (State University of New York at Stony Brook) Dr. Meyer considered plots of optical transition energy versus 1/D(optical) minus 1/D(static) for various types of systems, some of which were binuclear and clearly delocalized. If instead, one considers a ruthenium(II) pentaamine bound to N-methyl-4,4,-bipyridinium, is this in any way different from the bridging situation In some instances there was a similar dependence for both the mononuclear systems and the binuclear systems. But some of these mononuclear systems did not seem to behave similarly. Is there any connection between whether that simple linear relationship works or not and whether the system is localized or delocalized ... 

The pyridinium chlorochromate (PCC) oxidations of pentaamine cobalt(III)-bound and unbound mandelic and lactic acids have been studied and found to proceed at similar rates.Free-energy relationships in the oxidation of aromatic anils by PCC have been studied. Solvent effects in the oxidation of methionine by PCC and pyridinium bromochromate (PBC) have been investigated the reaction leads to the formation of the corresponding sulfoxide and mechanisms have been proposed. The major product of the acid-catalysed oxidation of a range of diols by PBC is the hydroxyaldehyde. The reaction is first order with respect to the diol and exhibits a substantial primary kinetic isotope effect. Proposed acid-dependent and acid-independent mechanisms involve the rapid formation of a chromate ester in a pre-equilibrium step, followed by rate-determining hydride ion transfer via a cyclic intermediate. PBC oxidation of thio acids has been studied. ... 

Electrodes based on 9 but no nucleobase derivative [3.0 wt% 9 bis(2-ethylhexyl) phthalate ( dioctyl phthalate , DOP) as the membrane solvent] showed similar potentiometric responses to 5 -GMP and 5 -AMP (Figure 8a), which is not surprising because cation 9 cannot interact specifically with the base pairing site of nucleotides. The EMF slope (-29 mV decade" 0.1 M HEPES-NaOH buffer solution, pH 6.8) was much greater than in case of the electrode based on the macrocyclic pentaamine 1 (-15 mV decade" ) and corresponds to the slope as expected for a dianion according to the Nemstian equation. Extraction experiments confirmed that at this pH it is indeed the dianion that enters the organic phase. 

Cyanatotetrazolato) Pentaamine Cobalt (III) perchlorate for DDT devices. Proc. 7th Inll. Pyrotechnics Seminar, Colorado, USA, pp. 322-326. 

A major compilation of solvolytic data for octahedral complexes up to 1976 can be found in the review by Edwards et a/.126 and an extensive review by House127 covers the acido—pentaamine complexes of Co(III) and Cr(III). Both are limited to substitutionally inert complexes and this section of the chapter will also be so restricted in order to allow an independent examination of the variables, in so far as they can be conveniently separated. 

Electron transfer quenching of Ru(bpy) + was first proposed by Gafney and Adamson114) in 1972. The quenchers used were pentaamine Co(III) complexes which are known to decompose upon one electron reduction ... 

Lewis acid treatment of a 2-furanylmethanol complexed to the 7t-base pentaamine osmium(n) in the presence of carbonyl compounds provides a route to 4-substituted dihydropyran-3-ones. However, the design of a protocol for efficient removal of the osmium from the products is in its early stages <2000T2313>. 

Copper(II) polyamine complexes are substitutionally labile, in a manner similar to the corresponding nickel(II) complexes. This means that individual donor atoms may at times decoordinate and thus be available for derivatization reactions, e.g., with suitable carbonyl compounds. More complex ligands may thus be constructed, including macrocycles (35), polymacrocycles (36 38), and concave chelators (35). The copper(II) complex of 1 was synthesized as a starting material for reactions aiming at the derivatization of the pentaamine ligand (24-28). 

In the case of the purely aliphatic ligand 2,2,6,6-tetrakis(amino-methyl)-4-azaheptane (12), complex formation with copper appears to proceed in two steps, as elucidated by titration experiments with the fully protonated ligand (12 5 HC1). Three and two protons from (Hr,12) + are sequentially abstracted, and the predominant species after full deprotonation appears to be a dinuclear complex in which two copper(II) ions are coordinated, each in square planar fashion, by the l,3-diaminoprop-2-yl units of two molecules of pentaamine ligand, thus forming a macrocyclic complex of composition [Cu2(12)2]4+ (23). The UV/vis spectral data show an interesting solvent dependence, suggesting an equilibrium between [Cu2(12)2]4 + and two equivalents of mononuclear complex [Cu(12)]2+ under suitable conditions. ESR spectroscopic data are also compatible with the formulation of a dinuclear species. Further addition of base to an aqueous solution of [Cu2(12)2]4+ gives the mononuclear hydroxo complex [(12)Cu(OH)]+, as inferred from the UV/vis spectroscopic data. 

Nickel (II) Complexes of the Pentaamine Ligand 1 Obtained by Recrystallization of [(l)Ni(OH2)]Cl2 (17) in the Presence of the Reagents Listed in Some Cases, Added NH4PF6 Produces the Highly Crystalline Hexafluorophosphate Salts... 

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