Homoleptic cage

The only homoleptic cage described above is [Copfchpjig] 45, and therefore one might conclude that, in the absence of other influences, pyridonates favour structures based on tetrahedra. However, structures featuring pyridonates are found in virtually all the categories, chiefly due to the coordinative flexibility of the ligands. There is also a marked difference between the coordination chemistry of the 6-chloro- and 6-methyl-2-pyridonate ligands, due to electronic factors which influence the coordi-... 

The metalation of trialkylsilylphosphane and -arsane with the alkaline earth metal bis[bis(trimethylsilyl)amides] of calcium, strontium, and barium yields the mixed phosphanides and phosphanediides as well as arsanides and arsanediides depending on the stoichiometry and the demand of the trialkylsily] substituents according to Scheme 3.6-11. The main feature is the M2E3 bipyramid with the metal atoms in apical positions. These cages are often interconnected via common faces (61, 63, 64, 65, 67, and 69). A substitution of the phosphanide substituents by other Lewis bases such as THF or benzonitrile is not possible for these compounds and, consequently, homoleptic phosphanediides and arsanediides with inner M4E4 heterocubane moieties are so far unknown for M = Ca, Sr, and Ba. In all these cases a further metalation to obtain homoleptic phosphanediides failed. 

Fig. 12. Plot of number of amine protons versus log of the self-exchange rate constant (M s ) for cobalt hexaamine complexes at 25°C. No correction has been made for ionic strength differences. The data include some nonhomoleptic complexes. (1) [CoCNHslg], (2) [Co(en)3]3+ 2+, (3) [Co(chxn) ] + 2+ (4) [Co(tmen) ]3+ 2+, (5) [Co(dien)"]"+ 2+, (6) [Co(pet) P+ 2+, (7) [Co(linpen)P" 2 + (g) lCo(medien)(9) [Co(tacn)(dien)]3+ 2+, (10) [Co(tacn) (pet) (11) [Co(tacn) (etdien) (12) [Co(tacn) (budien) p+ 2+ 3 [Co(tacn)(medien)P, (14) [Co(diAmsar)] , (15) [Co(taptacn)P, (16) [Co(metacn) ] 2+, (17) [Co(diAmsar)P 2+, (18) [Co(sar)(19) [Co(sep)P 2, (20) [Co(dtne)] , (21) [Co(Amsartacn)], (22) [Co(Amsartacn)] , (23) [Co-(diAmchxnsar)] , (24) [Co(diAmchxnsar)] . The data for homoleptic complexes are taken from Table IV the other data are from reference U02). The line was calculated without the data for the sep and sar derivative cages and the [Coftmenls] couple.

However, such molecules can be prepared by incorporation of tin(n) atoms into the cage compounds, as shown in the bottom part of Scheme 3. The heterobimetallic phosphanide of barium and tin(n) in a ratio of 1 2 (26) gives bicyclic stroctures, whereas a ratio of 2 1 leads to a cage compound of two trigonal bipyramids with a common MP2 face, thus giving a mixed phosphanide/phosphanediide compound (27 to 29). Homoleptic... 

Osvath P, Sargeson AM (1993) Synthesis of a large cavity homoleptic thioether cage and its cobalt(III) complex. J Chem Soc Chem Commun 40-42... 

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