The structures of 1phenylsulphonylpyrrole, 1phenylsulphonylindole, 4,5,6,7tetra hydro-1pheny Isulphonylindole, and 1,2,3,4-tetrahydro-9-phenylsulphonylcarbazole have been determined by X-ray crystallography. The heterocyclic nitrogen is planar in some and pyramidal in others. A preferred geometry for the PhS0,N unit emerged from the structures; it is compared with available data for sulphonamides.

Fly agaric accumulate vanadium in the form of amavadin, whose structure has been elucidated (see picture for the crystal structure). Amavadin contains one VIV center coordinated to two (S,S)‐hidpa3− ligands (H3hidpa=2,2′‐(hydroxyimino)dipropionic acid) through one η2‐NO− group and two unidentate carboxylato groups from each ligand. The arrangement of the two η2‐NO− groups leads to a chiral vanadium center, which has been characterized in both the Λ and Δ forms. The carboxylato groups of the amavadin anions bind cations, for example, Ca2+ ions, and/or become involved in hydrogen bonding.

A synthetic strategy is reported for a general route to asymmetric dithiolenes. This has been used for the generation of [MoO(dithiolenepyridin-2-yl, pyridin-3-yl, pyridin-4-yl, quinoxalin-2-yl or 2-(dimethylaminomethyleneamino)-3-methyl-4-oxopteridin-6-yl], which have been characterised by analysis, spectroscopy and electrochemistry. The prototypical compound [PPh 4 ] 2 [MoO(sdt) 2 ]ؒEtOH, where sdt = α,β-styrenedithiolate (R = phenyl), crystallises in the space group P2 1 /c with a = 13.217(4), b = 31.820(8), c = 14.534(7) Å, β = 113.8(2)Њ and Z = 4. The MoOS 4 moiety is square-based pyramidal with the O atom at the apex [Mo᎐ ᎐ O, 1.700(5) Å] and contains a cis geometry of the phenyl groups. The physical properties of all the compounds are consistent with a retention of the MoOS 4 centre and the variation in the dithiolene 1 H NMR resonances, infrared ν(Mo᎐ ᎐ O) and ν(C᎐ ᎐ C) stretching frequencies and the E ₂  ₁ values for the Mo V -Mo IV couple are rationalised by a consideration of the nature of the R substituent. The complexes with the pterin [2-amino-4(1H)-pteridinone] substituent have a particular relevance to the Mo centre in oxomolybdoenzymes, and are the closest structural models to date for these enzymes containing two molybdopterin ligands per metal. † Based on the presentation given at Dalton Discussion No. 2, 2nd-5th

807leaves little doubt that the acylated phenylisoserine side chain of these taxoids is synthesized via path a of Scheme I. Unexpectedly, in both experiments 1, but not 2, also showed a pronounced M + 10 peak, as well as a P + 10 satellite for the m / z 286 fragment representing the side chain. Hence, the aromatic ring of 4a and Sa must have also becn incorporated into the benzoyl group of the 1 side chain. Together with the non-incorporation of 7a this suggests the operation of a new pathway, other than the estab-lishedI3 path b/c of Scheme I, for the genesis of the benzoate moieties in this plant which proceeds from 3 via 4 (path a/d) or 4 and S (path a/e).In summary, the side chain of 1 and 2 is formed from phenylalanine via @-phenylalanine, presumably generated by an aminomutase reaction,14 followed by hydroxylation of C-2 and acylation of the nitrogen. The benzoyl moiety is also formed via @-phenylalanine and possibly phenylisoserine rather than via cinnamic acid. A&"t .We are indebted to Prof.

Electronic and steric effects in manganese Schiff-base complexes as models for the water oxidation complex in photosystem II. The isolation of manganese-@) and -(m) complexes of 3-and 3,5-substituted N,iV-bis(salicylidene)ethane-l,2=diamine (Hsalen) ligands 7