Octreotide, a synthetic somatostatin analogue, is an octapeptide with one disulfide bridge. Crystals of octreotide are orthorhombic, space group P212121, a = 18.458 (5), b = 30.009 (7), c = 39.705 (27) A, with three molecules of octapeptide, one ordered oxalate dianion and 52 water molecules in the asymmetric unit. Complete protonation of the NH2 groups (as assumed in the refinement) would require three oxalate dianions in the asymmetric unit for charge neutrality; a chemical analysis indicated that four are present. In either case they are so disordered that they cannot be distinguished from the water molecules. The 18 951 unique reflections (Rsy m = 0.026) used for structure solution and refinement were recorded with the EMBL imaging-plate scanner using synchrotron radiation. The structure was solved by Patterson interpretation, locating the three disulfide bridges, followed by tangent phase expansion and EFourier recycling. The anisotropic refinement against all F 2 data between 1.04 and 10.0 A resolution by blocked restrained full-matrix least-squares techniques converged to a conventional R index based on F of 0.084 [I > 2a(/) and 10.0 > d > 1.04 A] and wR2, the weighted R-index on F 2, of 0.246 (for all data). One peptide molecule adopts a flat ~-sheet structure; the other two possess different irregular backbone conformations, but are similar to each other. All three molecules have a distorted type II'/3-turn around the o-Trp-Lys region, but exhibit different sidechain conformations. The crystal structure is stabilized by a network of inter-and intramolecular hydrogen bonds.

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Tricarbonylmanganese(I) complexes of the ligands tris(imidazol-4-yl)phosphane (4-tip H ), tris(1,4-diisopropylimidazol-2yl)phosphane (2-tip iPr2 ), tris(pyridin-2-yl)phosphane (tpp) and tris(N-methylimidazol-2-yl)carbinol (2-tic NMe ) were prepared. These act as N,N,N tripodal chelators. The solid-state structure of [Mn(CO) 3 (tpp)]OTf was determined by X-ray diffraction. The potential of these complexes to act as photoactivatable CO-releasing molecules (PhotoCORMs) was studied with the UV/Vis spectroscopy-based myoglobin as-

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A series of p-cymene ruthenium(II) complexes with imidazol-2-yl phosphines as PN ligands was prepared. Depending on the number of imidazolyl substituents in the ligands Ph3-nP(im)(n) 1-3: n = 1-3, im imidazol-2-yl (a), 1-methylimidazol-2-yl (b) different coordination modes were observed: kappa P, kappa N-2,N or kappa N-3,N,N. The complexes were tested for their cytotoxicity in different cancer cell lines. Most of the compounds were found to be non-toxic; The compounds (p-cymene)Ru(1a)Cl-2] (4a) shows cytotoxicity towards A2780sens and Hct116 cells in the mM range but not in H4IIE cells.

NH ... O and NH ... N hydrogen bonded networks in imidazole-based phosphane oxides: Structures of tris(2-isopropylimidazol-4(5)-yl)phosphane oxide, bis(2-isopropylimidazol-4(5)yl)phosphane oxide and diphenyl-2-isopropylimidazol-4(5)-yl phosphane oxide

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