Quinquedentate Coordination of 10-Methyl-1,4,8,12-tetraazacyclopentadecan-10-amine (L) to Rhodium(III). Crystal Structure of cis-[Rh(L)Cl][ClO4]2.H2O And Comparative Activation Volumes for Base Hydrolysis of [M(L)Cl]2+ (M = Rh, Co, Cr)

1992 ◽  
Vol 45 (2) ◽  
pp. 351 ◽  
Author(s):  
GA Lawrance ◽  
M Martinez ◽  
BW Skelton ◽  
R Vaneldik ◽  
AH White
Keyword(s):  
Primary Amine ◽  
Metal Ion ◽  
Exchange Chromatography ◽  
Hot Water ◽  
Base Hydrolysis ◽  
Secondary Amines ◽  
Orthorhombic Space Group ◽  
Pendant Arm ◽  
Base Mechanism ◽  
Hydrolysis Of

The pendant-arm macrocycle 10-methyl-1,4,8,12-tetraazacyclopentadecan-10-amine (1) reacts slowly in hot water with rhodium(III) chloride to yield, following cation-exchange chromatography, exclusively cis -[ Rh (l) Cl ]2+. The cis -complex was crystallized readily as a perchlorate monohydrate salt, in the orthorhombic space group Pn21a, a 16.854(3), b 13.341(3), c 9.985(1) � , Z = 4, isomorphous with its cobalt(III) counterpart; a single-crystal X-ray structure determination was refined to R 0.027 for 1626 'observed' reflections. The pendant primary arnine and two adjacent secondary amines necessarily occupy an octahedral face, with the chloro ligand cis to the primary amine, and secondary amines adopt R,R,S,S stereochemistries. The Rh -N distances [2.056(6) � (pendant primary amine), average 2.08 � (secondary amines)], are at the short end of the range for Rh-N bonds. The Rh-Cl distance is 2.347(2) �. Activation volumes for chloride base hydrolysis were determined for cis -[ Rh (l) Cl ]2+as +19.5( � 1.2), for cis -[Co(l) Cl ]2+ as +27.1(�0.4), and for trans-[Cr(l) Cl ]2+ as +31.1( �0.1) cm3 mol-l, and are consistent with a conjugate base mechanism in each case; variations with metal ion are discussed.

Coordination of 5-Methyl-3,7-diazanonane-1,5,9-triamine (L) to Rhodium(III). Crystal Structure of fac-[Rh(H2L)Cl3] Cl(ClO4).3H2O

1994 ◽  
Vol 47 (5) ◽  
pp. 829 ◽  
Author(s):  
TW Hambley ◽  
TW Hambley ◽  
GA Lawrance ◽  
GA Lawrance ◽  
M Maeder ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Structure Determination ◽  
Primary Amine ◽  
Hot Water ◽  
Secondary Amines ◽  
Primary Amines ◽  
Triclinic Space Group ◽  
X Ray ◽  
Shortest Distance

The branched, potentially quinquedentate , 5-methyl-3,7-diazanonane-1,5,9-triamine (1) reacts in hot water with rhodium(III) chloride to yield fac -[ Rh (H2(1))Cl3]2+. Only upon extended reflux for several weeks is coordination as a quinquedentate achieved. The fac complex was crystallized readily as a mixed chloride perchlorate trihydrate salt, in the triclinic space group Pī , a 8.666(2), b 10.319(2), c 12.558(3) Ǻ, α 94.34(2), β 98.86(2), γ 97.75(2)°, Z = 2; a single-crystal X-ray structure determination was refined to Rw 0.037 for 3703 'observed' reflections. The central primary amine and two adjacent secondary amines occupy an octahedral face, with the chloro ligands then necessarily fac also. The Rh -N distances vary, with the shortest distance to the primary amine [2.023(2)Ǻ] rather than to the secondary amines [2.066(2), 2.077(2) Ǻ], as do the Rh-Cl distances [range 2.345(1)-2.369(1)Ǻ]. The two primary amines on the chain terminals remain uncoordinated, the central facially capping unit preferring coordination first, possibly indicating a general intermediate for coordination of polydentate l igands containing this type of unit.

Volumes of Activation for the Base Hydrolysis of [Rh(NH3)5X]2+ Complex Ions

1979 ◽  
Vol 32 (12) ◽  
pp. 2589 ◽  
Author(s):  
DA Palmer
Keyword(s):  
Partial Molar Volumes ◽  
Base Hydrolysis ◽  
Volume Data ◽  
Complex Ions ◽  
Molar Volumes ◽  
Base Mechanism ◽  
Hydrolysis Of ◽  
Conjugate Base

The pressure dependencies of the rates of base hydrolysis of [Rh(NH3)5X]2+ were measured at 313.2 K and μ1M, where X = Cl-, Br-, I- and NO3-, in the range 1-1500 bar. The respective Δν‡exp values are 19.3 � 0.9, 20.2 � 0.5, 20.4 � 0.5 and 22.3 � 0.9cm3 mol-1. The partial molar volumes of these complexes, as well as those of other relevant pentaamminerhodium(III) complexes, were also determined. The volume data are discussed in terms of the conventional dissociative conjugate base mechanism. The Δν‡exp for the aquation of [Rh(NH3)5NO3]2+ was found to be -6.9 � 0.4cm3 mol-1 at 313.2K, [H+] 0.005M and μ0.1 M. An I mechanism is favoured for this process.

Octahedral cobalt(III) complexes of the chloropentammine type. XVIII. Hydrolysis of some Chloroanilinebis(ethylenediamine)cobalt(III) complexes, and a rationalization for the conjugate-base and ion-pair mechanisms

1969 ◽  
Vol 22 (9) ◽  
pp. 1851 ◽  
Author(s):  
SC Chan ◽  
OW Lau
Keyword(s):  
Chloride Ion ◽  
Ion Pair ◽  
Base Hydrolysis ◽  
Methyl Substituent ◽  
Substituted Anilines ◽  
First Order ◽  
Base Mechanism ◽  
Higher Temperature ◽  
Hydrolysis Of ◽  
Conjugate Base

The kinetics for the appearance of chloride ion from aqueous solutions of the cis-chloroanilinebis(ethylenediamine)cobalt(III) cation are determined over the pH ranges of 2-3 at 40.0� and of 8-9 at 0�. By using self-buffered mixtures, the rate constants for the reaction are also measured at 40.0� as a function of the concentration of complex or of free aniline. The results are discussed in terms of the conjugate- base mechanism. A rationalization of this mechanism and the ion-pair mechanism is proposed to incorporate the base hydrolysis of other previously investigated systems where the complexes are decidedly much less acidic. At a higher temperature (65.0�), both chloride ion and aniline are liberated at similar rates, and the process is treated as parallel first-order reactions. By using complexes with meta- and para-substituted anilines, the effect of the methyl substituent on reactivity is studied.

Syntheses and Comparative Base Hydrolysis Reactions of Chlorocobalt(III) Complexes of Pendant-Arm Macrocyclic Polyamines and Polyamino Acids

1997 ◽  
Vol 50 (9) ◽  
pp. 883 ◽  
Author(s):  
Yakup Baran ◽  
Trevor W. Hambley ◽  
Geoffrey A. Lawrance ◽  
Eric N. Wilkes
Keyword(s):  
Water Molecule ◽  
Activation Enthalpy ◽  
Base Hydrolysis ◽  
Secondary Amines ◽  
Methyl Groups ◽  
Monoclinic Space Group ◽  
Carboxylate Group ◽  
Hydrolysis Kinetics ◽  
Pendant Arm ◽  
Macrocyclic Polyamines

Chlorocobalt(III) complexes of the pendant-arm macrocycles 1,4,8,12-tetraazacyclopentadecane-10-carboxylate (2) and 1,5,9,13-tetraazabicyclo[11.2.2]heptadecane-7-carboxylate (4) have been prepared to complement the known complexes of 10-methyl-1,4,8,12-tetraazacyclopentadecan-10-amine (1) and 7-methyl-1,5,9,13-tetraazabicyclo[11.2.2]heptadecan-7-amine (3). The pairs (1),(3) and (2),(4) differ in replacement of pendant amine and methyl groups in the former pair by a pendant carboxylate group and hydrogen in the latter pair. The macromonocyclic ligands (1) and (2) form cis-chlorocobalt(III) complexes whereas the macrobicyclic ligands (3) and (4) (which contain an additional –CH2–CH2– ‘strap’ linking two amines) form trans-chlorocobalt(III) complexes, defined in terms of location of the pendant donor and the chloride donor. Chloride base hydrolysis kinetics varies with ligand {cis-[Co(1)Cl]2+, kOH 6700 dm3 mol-1 s-1 ; cis-[Co(2)Cl] +, kOH 1800 dm3 mol-1 s-1;trans-[Co(3)Cl]2+, kOH 3450 dm3 mol-1 s-1; trans-[Co(4)Cl]+, kOH 2250 dm3 mol-1 s-1 at 25°C}. Variations in rate constant are tied mainly to variations in activation enthalpy. Chloride hydrolyses occur with retention of configuration, but slow following isomerization can lead to products such as trans-[Co(2)(OH2)] (ClO4)2.2H2O, which crystallizes in the monoclinic space group P21/c, a 9·581(2), b 16·214(2), c 14·350(2) Å and β 94·66(1)°. The pendant carboxylate group and two adjacent secondary amines necessarily occupy an octahedral face, with the water molecule bound trans to the pendant carboxylate. The four Co–N distances range from 1·981(2) to 2·22(3) Å, and along with carboxylate Co–O (1·882(3) Å) and water Co-O (1·934(2) Å) distances are similar to usual distances in cobalt(III) complexes.

HYDROLYSIS OF CALF THYMUS DEOXYRIBONUCLEATE BY PANCREATIC DEOXYRIBONUCLEASE: I. A STUDY OF THE OLIGONUCLEOTIDES LIBERATED IN THE PRESENCE OF MAGNESIUM OR MANGANESE IONS

1963 ◽  
Vol 41 (1) ◽  
pp. 469-480 ◽  
Author(s):  
R. O. Hurst ◽  
G. C. Becking
Keyword(s):  
Metal Ion ◽  
Deoxyribonucleic Acid ◽  
Exchange Chromatography ◽  
Magnesium Ions ◽  
Manganese Ions ◽  
Terminal Position ◽  
Deoxyribonuclease I ◽  
Calf Thymus ◽  
Hydrolysis Of

The oligonucleotides obtained from deoxyribonucleic acid by the action of pancreatic deoxyribonuclease in the presence of magnesium ions or manganous ions have been analyzed by ion exchange chromatography and by determination of the relative amounts of purine and pyrimidine deoxynucleotides occupying the 5′-terminal position. Evidence of a difference in the specificity of action of the enzyme that is dependent upon the nature of the metal ion activator employed has been adduced.

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