Pentaamine cobalt

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. ... 

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

Metal Salts and Metallic Salt Complexes Various metallic cations can be encountered Co, Fe, Ni, Cu, Cr, and so on [77]. For example, the decomposition of azido-pentaamine cobalt (III) yields an initiating azide radical the reductive interaction between the chromic acid and a suitable monomer such as acrylamide generates a radical on the monomer (10.37) [78]. Other systems are described in Ref. [79]. 

Replacing the perchlorate anion in pentaamine cobalt (III) perchlorate complexes seems to be a logical way of eliminating the potentially ecologically problematic anion. The effect of such replacement was studied by Ilyushin et al. using dinitroguanidine which was considered suitable due to its ability to form complexes, its enthalpy of formation, and its oxidizing ability [27]. 

Table 9.10 Properties of pentaamine cobalt(III) ctnnplex dinitroguanidines [27]...

Outer-sphere Cr " reductions of nitrite-bonded pentaamine cobalt(III) complexes are reported. In contrast to other species examined, the cyanoacetate complex shows acid dependence behavior consistent with formation of a bridged intermediate (1) in which outer-sphere electron... 

Nitrogen-bonded chromium(III) products are detected in the reductions of a number of pentaamine cobalt(III) tetrazole complexes by chromium(II). The rate laws show inverse [H dependences and rate constants consistent with an inner-sphere mechanism in all cases. Product isolation confirms remote attack by [Cr(H20)6 on the 4-cyanobenzoic acid derivative [(NH3)5CoNCC6H4C02H] and its deprotonated form (pX 2.51). The [V(H20)6] reaction is also consistent with a remote attack mechanism, while the 3-cyanobenzoic acid complex reacts by an outer-sphere pathway suggesting the possibility of a remote bridged outer-sphere... 

Figure 7. A plot of the observed rotational strength under the 1A, -a 1Tj absorption band (in cgs units) of pentaamine (S)-2-chloropropionato)cobalt(IIl) as a function of the dielectric constant of the solvent...

Mn-Mejtacn (Figure 16.11) is still used in automatic dishwashing products, where color and fiber damage is of lesser importance. Another metal complex used in machine dishwashing detergents is pentaamine acetate cobalt (III) nitrate (PAAN) [34]. This highly water-soluble, relatively inexpensive catalyst is effective at very low concentration. 

Pentaamine(5-cyano-2//-tetrazolato-A )cobalt(III) perchlorate (CP) was developed in the late 1960s as an alternative primary explosive material that has a rapid DDT while maintaining a high level of manipulation safety [4—6]. 

The structure of pentaamine (5-cyano-2//-tetrazoIato-A )cobalt(III) perchlorate is shown above. Bonding via the N2 ring nitrogen in the final product has been confirmed by single-crystal X-ray structure determination [7] and NMR analysis [8]. 

Very broad studies into cobalt pentaaminate analogs of CP have been reported from the Saint Petersburg State Technological Institute group of Ilyushin and Tselinskii. Numerous articles have been summarized into two monographs [26,27]. 

Best properties from all analogs of CP are reported for pentaamine (5-nitro-2//-tetrazolato-Af )cobalt(III) perchlorate (abbreviated by authors to NKT). It has low sensitivity to electrostatic discharge predetonation distance is 4.5 mm with charge diameter 6.5 mm and density 1.60-1.63 g cm". NKT is thermally stable—Cheating it at 200 °C in a hermetically sealed container for 6 h does not change its properties. It is not hygroscopic and, unlike CP, it is not too toxic. Careful optimization of reaction conditions gives up to 90 % yields [26]. 

The first coordination compound published was pentaamine(l,5-cyclopenta-methylene-tetrazolato-M ) cobalt(lll) perchlorate (PAC) ... 

Pentaamine(l,5-cyclopentamethylene-tetrazolato-)cobalt(III) perchlorate (PAC) is prepared by the substitution of water by corazol in a slightly acidic aqueous solution according to the following scheme ... 

For comparison, Ilyushin et al. [27] selected complex cobalt(III) pentaaminate perchlorates having temperature of decomposition in the range 265-280 °C and initiating efficiency around 0.2 g for RDX. 

The temperature of the start of fast decomposition (DTA, 5 °C min ) decreases by 80-100 °C when the perchlorate anion is exchanged for dinitroguanidine or azide. Unlike pentaamine (5-nitro-2//-tetrazolato-iV )cobalt(III) perchlorate (NKT), which decomposes in one step, complex I decomposes in four steps when heated by 5 °C min . It also loses crystal water around 110 °C. 

Riboflavin, Rb, can be reduced in two one-electron steps with potentials of 0.22 and 0.15 V in 1.0 M acid at 25 C to RBH and RBH2, dihydroriboflavin. Both processes can be detected in reduction by with rate constants of 8.0 x 10 M s and 3.6 x 10 M s at 21 C and 0.12 A/ HCIO4 which are too fast to be inner sphere in nature. No substituent effects have been detected in the oxidations of RBH by a variety of metal ion oxidants including a series of substituted cobalt(III)-pentaamine derivatives, and these reactions are also considered to be outer sphere in nature. Similar results are reported for dihydroriboflavin, and the presence of an unreactive protonated radical RbHi with a pKa 0.89 has been detected. 

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