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191 X-ray structure analysis of the [22]coproporphyrin I1 Zb space group P2,/n. a = 828.1(5), b = 2619.5(6), c = 1028.7(6) pm, fl = 100.30(2)'. Z = 2, four-circle diffractometer CAD4 (Enraf-Nonius) (Cu,,, L = 154.178 pm, graphite monochromator), 3561 measured reflections. Further details of the crystal structure investigation may be obtained from the Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftlichtechnische Information mbH. W-7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository number CSD-54603, the names of the authors, and the journal citation. (lo] H. Konig, C. Eickmeier, M. Moller, U. Rodewald, B. Franck.

Incremental addition of DMF or DMSO to a solution of 1,2-bis(chloromercurio)tetrafluorobenzene (3) in acetone results in a change of the 199Hg NMR chemical shift of 3. The titration curves thus obtained can be fitted and indicate the formation of the 1:1 host−guest complexes 3·μ 2 -DMF (4) and 3·μ 2 -DMSO (5). The stability constants of 4 and 5 have been determined and are respectively equal to 1.8 (±0.2) M-1 and 8.0 (±0.8) M-1. The X-ray crystal structures of 4 and 3·μ 2 -acetone (6) have been determined. In the structure of 4, the carbonyl oxygen atom is coordinated to three mercury atoms and has a distorted-tetrahedral geometry. In 6 however, the acetone oxygen is coordinated to only two mercury atoms and exhibits a trigonal-planar geometry. While it is difficult to detect any metrical changes undergone by the organic substrates upon chelation, the IR carbonyl stretching frequency of 4 (νCO 1635 cm-1) and 6 (νCO 1639 cm-1) indicates that the carbon oxygen bond is weakened. Accordingly, the 13C CP/MAS NMR carbonyl carbon chemical shifts of 4 (167 ppm) and 6 (215 ppm) provide evidence for a substantial polarization of the carbonyl. By comparison of the 13C CP/MAS NMR carbonyl carbon chemical shift, the Lewis acidity of 3 toward acetone can be evaluated to be just inferior to that of MgCl2. Finally, both 4 and 6 have complex and highly networked supramolecular structures which result from intermolecular Hg···Cl and Hg···F or Hg···O contacts.

Key Words: 1,3,5-Triaza-7-phospha-adamantane / Reductive cleavage of phosphonium salts t Ambidentate P,N-ligands t P,N-[3.3.l]bicyclononane systems t Phosphanes Two reaction pathways for the synthesis of 1,3,5-triaza-?-phosphoniaadamantane salts, RP[(CH2)6N3]+X-(l), were followed. Route 1 starts with commercial tetrakis(hydroxymethy1)phosphonium chloride, which is converted into P(CH,OH), by treatment with a base. Subsequent quaternization with alkyl halides RX and cyclization with formaldehyde and ammonia afford [R-TPA]+X-. This process is only applicable for R = Me (la) and Et (lb), however. Route 2 is more general and starts with primary phosphanes RPH,, which are converted into organotris(hydroxymethy1)phosphonium salts with formaldehyde and hydrochloric acid followed by ring closure with CH20/NH3 to give compounds l c -l f (R = t-Bu, c-Hex, Bz, and Ph, respectively, and X = C1, I, PFs, or BPh4). Reductive cleavage of compounds 1 by sodium in liquid ammonia proceeds with either external (P-R) or internal (P-CH2) bond rupture. P-R cleavage affords the 1,3,5-triaza-?-phosphaadamantane (TPA), while cage cleavage leads to new bowl-or helmet-shaped ligand systems with peripheral amine and phosphane functions (2). Yields of the cage-opening reaction are highest for R = Ph (2f), moderate for R = Me and Et (2a, 2b), and poor with the remaining R groups (2c-2e). A radical mechanism is proposed for this reaction, the leaving group properties of R determining the direction of the cleavage. The crystal and molecular structures of compounds 2a and 2f were determined by X-ray diffraction studies. Ex0 positions were found for the N-Me and P-R groups. The isomers with the R group in the endo position are also present in solution in small amounts, as detected by NMR spectroscopy. Isomer interconversion by P inversion is slow on the NMR time scale. Compounds 2a, 2b and 2f were oxidized with elemental sulfur and selenium to give the monosulfides and selenides, respectively (2aS, 2aSe, 2 bS, 2bSe, 2fS, 2fSe Tertiary phosphanes R3P are versatile ligands in coordination chemistry. Indroduction of functional groups in their organic substituents R can be used as a method to modify the properties of the ligands and of the complexes derived therefrom. The phosphanes can, for example, become (P,N)-ambi-or polydentate in nature, as tertiary amine functions become part of the organic framework [']. Owing to the hydrophilic nature of these amine functions, such ligands and their complexes will become soluble in water and other polar solvents.An example in case is 1,3,5-triaza-7-phospha-adamantane (TPA)L2], which is known to be a suitable "soft" P-donor for low-valent transition with a small cone angle at the phosphorus atom, but also a "hard" ligand for metals in higher oxidation stated4]. It can be integrated into hydrogen-bonding networks based on its three tertiary amine functions, and it is easily solvated. The molecule is a strong nucleophile and forms both phosphonium and ammonium cations if treated with acids or alkyl hali d e~ [~]...