Template syntheses based on tris (ethane-1,2-diamine)cobalt(III) lead to cobalt(III) complexes of cage hexamines of the ' sarcophagine ' type ( sarcophagine = sar = 3,6,10,13,16,19- hexaazabicyclo [6.6.6] icosane ) rapidly and in high yield. Reduction of these species to their cobalt(II) forms enables the ligands to be removed in concentrated acids at elevated temperatures, and in hot aqueous solutions containing excess cyanide ion. The free sarcophagine and 1,8-diaminosarcophagine [(NH2)2sar or diamsar] ligands are strong bases, accepting up to four and five protons, respectively, in aqueous solution. In chloride medium, I = 1.0, at 298 K, pK1 = 11.95, pK2 = 10.33, pK3 = 7.17, pK4 ≈ 0 for sarcophagine , and pK1 = 11.44, pK2 = 9.64, pK3 = 6.49, pK4 = 5.48, pK5 ≈ 0 for diaminosarcophagine , with very similar values being found for triflate medium. Crystal structure determinations for both free bases, the chloride, sulfate, perchlorate and nitrate salts of diamsar , the complex of zinc chloride with sar, and the magnesium nitrate complex with diamsar show remarkably small variations in the cavity defined by the bicyclic ligands, though relatively subtle bond length and bond angle changes can be rationalized in terms of the effects of proton and metal ion binding. Exhaustive methylation of sarcophagine produces the highly lipophilic, hexatertiary base hexamethylsarcophagine , which, in the solid state, adopts quite different conformations and nitrogen-atom configurations to those of sar itself. All the ligands rapidly form metal ion complexes of generally exceptional kinetic and thermodynamic stability.

Die Tri‐N‐tosyl‐Derivate (VIa) und (VIb) der Titelverbindungen werden jeweils nach zwei Methoden dargestellt: Kondensation des Tri‐N‐tosyl‐diethylentriamins (I) mit den Ditosylaten (IIa) bzw. (IIb) und Kondensation des Bis‐(tosyloxyeth′yl)‐tosylamids (IV) mit den Di‐N‐tosyl‐alkylendi‐ aminen (Va) bzw. (Vb) [im Falle der Kondensation von (IV) mit (Va) entstehen neben (VIa) höhere Kondensationsprodukte in wechselnden Mengen].

[(1,1,1-Tris(4-amino-2-azabutyl)ethane)cobalt(III)](3+) ([co(sen)]3+) and [(tris(4-amino-2- azabutyl)amine)cobalt(III)](3+) ([Co(azasen)]3+) react with formaldehyde and diethyl malonate or cyanoacetic acid ethyl ester in the presence of base to form macrobicyclic cages [ox- osarcophagine (oxosar) and oxoazasarcophagine (azaoxosar)] about the metal ion. The cage structure of the complexes has been established by an X-ray crystallographic analysis of [(1-carboxy-8-methyl-2-oxo-3,6,10,13, 16,19-hexaazabicyclo[6.6.6]icosanato)cobalt(III)] diperchlorate [Co(Me,CO2H-oxosar- H)]2+ which crystallizes in the orthorhombic space group Pbcn, with cell parameters a 33.61, b 10.42, c 13.743 � , and V 4813 � 3 , and Z 8. The chiral cobalt(III) complex is characteristically inert to substitution and racemization, but the cobalt(II) complex, obtained by reduction of the appropriate cobalt(III) compound, is surprisingly stable both to loss of Co2+ ion and to racemization at 25°C (pH 7.1, t½4.5 days). The syntheses, spectroscopic and chemical properties are reported. The kinetics of the electron self exchange for the cage system [Co(Me,CO2Et-oxosar-H)]+/2+, and of H2O2 formation from [coII(Me,co2Et-oxosar - H)]+ and O2 are reported. Similar syntheses have been carried out to half-cap the [co(en)3]3+ ion (en = ethane-1,2-diamine). These and related reactions have allowed substituents such as COOR, COOH, CN, COCl, CONR2, NH2 and NO2 to be placed on the bridgehead carbon atoms, and have altered the redox potentials of the systems by at least 0.3 V. The oxosar COII ions are useful as powerful reducing agents [from c. -0.3 to -0.6 V (v. n.h.e.)], and the cages are capable of further derivatization to build larger macromolecules.

Large-scale syntheses of ethylidynetris(methanamine)* (tame), 2,2-bis(aminomethyl)propan-1-ol* (hmmp), 4,4',4?-ethylidynetris(3-azabutan-1-amine)* (sen) and 5,5',5''-ethylidynetris(4-azapentan-1-amine)* (stn) are described. The pure hydrochloride salts of tame, hmmp, sen and stn are isolated directly from the crude amine mixtures by acidification and cation-exchange chromatography. Alternatively, selective complexation as [Co(hexamine)] Cl3 followed by Zn/HCl reduction and cation-exchange chromatography is used to isolate the hexamines sen and stn as their hexahydrochloride salts. These isolation procedures are exceptionally efficient compared with the conventional solvent extraction and (often pyrolytic) high-vacuum distillation methods.

On the basis of structural comparisons involving intermediates and side products of encapsulation reactions as well as several cage complexes, the efficiency of the base- catalysed reaction between formaldehyde, nitromethane and [Co(en)3]3+ (en = ethane-1,2-diamine) to give [Co((NO2)2sar)]3+ appears to be explicable in terms of the 'interlocking' of constituent parts without appreciable concomitant bond length or bond angle distortions. Thus, the structures of the podand ligand complexes Λ-[Co(NO2sen)]Cl3.2H2O [orthorhombic, space group P 212121, a 18.755(6), b 11.598(4), c 9.164(3) Ǻ; R 0.038 for No 1735 'observed' reflections] and Δ,Λ-[Co(Nt-Me,NO2sen)]Cl3.4H2O [monoclinic, P21/n, a 18.613(5), b 9.301(3), c 13.779(4) Ǻ, β 107.10(2)°; R 0.051 for No 26441 show very close configurational and conformational similarities to those of the cage complexes Δ,Λ-[Co(NO2azasar)]Cl3.3H2O [monoclinic, P 21/c, a 9.339(3), b 15.479(9), c 17.360(7)Ǻ, β 114.15(3)°; R 0.048 for No 2612], Δ,Λ-[Co((NO2)2sar)]Cl3.2H2O [triclinic, Pī , a 13.592(3), b 10.024(3), c 9.772(3)Ǻ, α 62.89(2),β 82.96(3), γ 85.15(2)°; R 0.045 for No 5646] and Δ,Λ-[Co((OH)2sar)]Cl3.3H2O [monoclinic, P21/c, a 15.97(1), b 8.758(4), c 16.760(4)Ǻ, β 98.72(4)°; R 0.052 for No 2400], as well as to published structures of [Co(en)3]3+, [Co(tame)2]3+ [tame = 1,1,1-tris- ( aminomethyl )ethane = ethylidynetris ( methanamine )] and other cage complexes. Some of these similarities may be associated with common hydrogen-bonding patterns in the solids resulting from anion ' chelation' by adjacent NH moieties in the metal ion coordination spheres. Necessary caution in relating structural and electronic properties is implied by the structure determination for Δ,Λ [Co(Cl,ClCH2absar)](NO3)3 [monoclinic, P 21/c, a 14.750(6), b 9.264(3), c 17.959(7) Ǻ, β 95.80(3)°; R 0.061 for No 1431], one of the products of molecular rearrangement following nitrosation of [Co((NH2)2sar)]3+. Despite marked electronic spectral and electrochemical differences with its parent complex, [Co(Cl,ClCH2absar)](NO3)3 contains cobalt(III) in a coordination environment which remains similar to those in more symmetrical cage complexes.