Showing papers by "Louis J. Farrugia published in 1999"
TL;DR: The category Computer Program Abstracts provides a rapid means of communicating up-to-date information concerning both new programs or systems and signi®cant updates to existing ones.
Abstract: The category Computer Program Abstracts provides a rapid means of communicating up-to-date information concerning both new programs or systems and signi®cant updates to existing ones. Following normal submission, a Computer Program Abstract will be reviewed by one or two members of the IUCr Commission on Crystallographic Computing. It should not exceed 500 words in length and should follow the standard format given on page 189 of the June 1985 issue of the Journal [J. Appl. Cryst. (1985). 18, 189± 190] and on the World Wide Web at http://www.iucr. org/journals/jac/software/. Lists of software presented and/or reviewed in the Journal of Applied Crystallography are available on the World Wide Web at the above address, together with information about the availability of the software where this is known.
18,151 citations
TL;DR: The X-ray structure of Co4(CO)12 has been determined at 120 K, and redetermined at ambient temperature as discussed by the authors, where the carbonyl positions for both disordered components have been resolved, affording more accurate molecular geometrical parameters.
24 citations
TL;DR: The metal atom disorder in the crystalline clusters Fe2Ru(CO)12 (1) and FeRu2(CO)(2) has been shown to be dynamic in origin this article.
21 citations
TL;DR: In this article, a series of macrocyclic ligands based on N,N′,N″-1,4,7-triazacyclononane with pendant alkyne arms were synthesized.
17 citations
TL;DR: The first pseudooctahedral tris(binaphtholates) of first-row transition elements, Na3[Fe(S-binaphTHolate)3]·3Et2O·H2O (1), Li3 [Fe(R-biophtholate) 3]·6THF (2), and Li3[Cr(R)-binaphthyolate) 4]· 6THF(3) were reported to be isomorphous in this article.
Abstract: The first pseudooctahedral tris(binaphtholates) of first-row transition elements, Na3[Fe(S-binaphtholate)3]·3Et2O·H2O (1), Li3[Fe(R-binaphtholate)3]·6THF (2), and Li3[Cr(R-binaphtholate)3]·6THF (3), are heterobimetallic complexes incorporating alkali metal ions 1 crystallizes in the monoclinic spacegroup P21 with a = 113256(10) A, b = 20735(3) A, c = 135741(15) A, β = 91086(8)°, and Z = 2 2 and 3 are isomorphous, crystallizing in the hexagonal space group P6322 with a = 14897(15) A, b = 192849(19) A, and Z = 2 (2) and a = 14850(4) A, b = 19052(7) A, and Z = 2 (3) The CD and absorption spectra of the Fe(III) and Cr(III) compounds are discussed and compared with those reported for [Fe(enterobactin)]3- and model compounds and for [Cr(entereobactin)]3-, respectively
14 citations
TL;DR: The coordination of these tetradentate ligands is stereospecific, but the absolute configuration of the complexes formed (Delta or Lambda) is dependent on the metal ion involved.
Abstract: N,N'-Bis(2R-hydroxy-2R-phenylethyl)-N,N'-dimethyl-1R,2R-diaminocyclohexane, H(2)L1, and N,N'-bis(2S-hydroxy-2S-methylethyl)-N,N'-dimethyl-1R,2R-diaminocyclohexane, H(2)L2, have been synthesized from readily available chiral precursors. They coordinate as neutral tetradentate ligands to Ni(II) and Cu(II) ions, from which the thiocyanates [M(H(2)L)(NCS)(2)] have been isolated and the structures of the H(2)L1 complexes determined by single-crystal X-ray techniques. In the blue complex [Ni(H(2)L1)(NCS)(2)].H(2)O.2EtOH, 1, and green [Cu(H(2)L1)(NCS)(2)]. 0.5H(2)O, 2, the neutral tetradentate ligands coordinate with the cis-alpha geometry with mutually cis N-bound thiocyanate groups, though the chiral ligands adopt a different stereochemistry in the two complexes. In 2, the absolute configuration about the Cu(II) center is Delta, with the nitrogens possessing the S stereochemistry, whereas for the Ni(II) analogue, coordination gives the Lambda isomer with the R configuration at the stereogenic nitrogens. Addition of H(2)L1 or H(2)L2 to Mn(II) in basic methanol solution results in rapid aerial oxidation. Delta-cis-alpha-[Mn(L1)(OMe)(2)].MeOH, 3, was isolated as black crystals from the reaction mixture after addition of 2 mol of NaOMe. The analogous complex with (L2)(2)(-) proved extremely hygroscopic and was not obtained in pure form. Colorless crystals of Lambda-cis-alpha-[MoO(2)(L1)], 4, were precipitated from a methanolic solution of [MoO(2)(acac)(2)] and H(2)L1. The analogous reaction with H(2)L2 gave Delta-cis-alpha-[MoO(2)(L2)], 5. Structures of 3, 4, and 5 are reported. The reactions of H(2)L1 and H(2)L2 with 1 mol equiv of [Ti(OPr(i))(4)] produced the complexes Delta-cis-alpha-[Ti(L1)(OPr(i))(2)] (white solid) and Lambda-cis-alpha-[Ti(L2)(OPr(i))(2)] (colorless oil), structural assignments for which were made possible by analysis of their (1)H NOE difference spectra. Thus the coordination of these tetradentate ligands is stereospecific, but the absolute configuration of the complexes formed (Delta or Lambda) is dependent on the metal ion involved.
14 citations
TL;DR: In this paper, a short review of the relevant aspects of this work as well as the potential use of metal-based cyclophanes as binders for aromatics is presented.
Abstract: T h e creation of systems tha t are capable of per forming molecular-scale operations i s currently under extensive investigation, particularly in the emerging f ield of nanotechnology. Towards this end, we have been actively involved in the construction and study of the properties of metallo-based assemblies based on electron-deficient cyclophanes and donor-acceptor [2]catenanes. Metallic moieties, such as [Ru(bipy)?(L)] '+ and [Os(bipy),(L)]"' , where bipy = 2,2'bipyridyl and L = tetracationic cyclophane ligand, f o r m a n integral par t of the molecular structures of these assemblies and in these specific cases create photoactive complexes. T h e photoinduced electron transfer reactions which occur wi th in these molecules have been extensively studied, especially in relation to the corresponding processes found in natural photosynthetic reaction centres. Here, we present a short review o n relevant aspects of this work as well as the potential use of metal-based cyclophanes as binders for aromatics.