Amines complexation, thermodynamics

Mn(acac)3 reacts with ethylenediamine (L2) or other primary amines (L) to yield [Mn"(acac)2L2], which can also be prepared by the reaction of the amine or diamine with [Mn(acac)2(H20)2]. Allylamine reacts with [Mn(acac)2-(H20)2] in ether to give a second complex, [Mn(acac)2(H2NCH2==CH2)]2 which is dimeric both in the solid and vapour phases. This is the First example of a dinuclear manganese(ii) acetylacetonate complex. Thermodynamic data have been reported for the manganese(ii)-acetylacetone system in propan-1-ol-water. ... 

Cycloheptanes.— The C-1—C-2 bond in -y-thujaplicin is essentially single, Co"-/3-thujaplicin-amine complexes have been described, and thermodynamic data on the U -/3-thujaplicin complex have been calculated. The biomimetic cyclization of the silyl enol ether (191) to karahanaenone (192), using methyl-aluminium bis(trifluoroacetate) is almost quantitative (192) is also synthesized by thermolysis followed by desilylation of the silyl enol ether (193) which is readily available from l-bromo-2-methyl-2-vinylcyclopropane and isobutyraldehyde. Dehalogenation of 3-bromo-l-iodo-3-methylbutan-2-one with Zn-Cu couple on alumina in the presence of isoprene yields (192) and minor amounts of the isomers (194) and (195) however, dehalogenation with Fc2(CO)9 favours (195). Acetolysis of karahanaenol tosylate yields anticipated p-menthane derivatives and no filifolene. ... 

Basolo555 noted that reactions of Rh111 amine complexes were not dramatically accelerated by hydroxide ion, but did show that substitutions in base do follow the standard kobs = k, + k2[OH" ] format, with k, representing the first-order aquation observed in acidic solution, and k2 representing the second-order base-catalyzed path. Poe has studied the kinetics of the base hydrolysis of a variety of frans-[Rh(en)2XY]"+ complexes (Table 41). Studies on the base hydrolyses of trans-[Rh(en)2(OH)X]+ (X = Cl, Br, I) showed that the coordinated hydroxide has an intrinsic kinetic tram effect comparable to that of Cl" but that its position in a thermodynamic trans effect series is much higher.635 For oms-[Rh(en)2X2]+ (X = Cl, Br), virtually complete tram -+ cis isomerization occurs upon hydrolysis in base, and ca. 50% isomerization is observed when X = I.653 No such... 

Complexes with other Bidentate 1,4-Diimines. The thermodynamic stability of the five-membered iron(II) 1,4-diimine chelate ring in low-spin complexes is illustrated by the facile autoxidation of saturated amine complexes to the corresponding colored 1,4-diimine complexes. The first example of this oxidative dehydrogenation is shown in equation (14), and the more recently studied " reaction (15) is known to involve iron(III) species and radical intermediates. Interestingly, the complex [Fe(CN)4(HN=CHCH=NH)] can be obtained by oxidizing [Fe(CN)4(en)] , whereas the tris-ligand complex of this smallest diimine ligand has yet to be prepared. 

The effect of increasing the chain length on the stability of the silver amine complex has been investigated. Thermodynamic data are collected in Table In general, there was an... 

KHMDS could also be used for the deprotonation of an N-H bond present in a ligand of an aminoiridium complex, providing an amidoiridium complex required in a study elucidating the kinetic and thermodynamic barriers to interconversions of late metal amido hydride complexes and late metal amine complexes. " The treatment of an ammonia complex (PCP)Ir(H)(Cl)(NH3) with KHMDS (2 equiv) in THF (—78 °C) afforded the targeted amido complex (PCP)Ir(H)(NH2) in a quantitative yield accompanied by HMDS and KCl (eq 76). The product was stable below —10 °C, and could be characterized by NMR techniques. 

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