W. Swiridoff

Preparation and characterization of binuclear (1,4,7-triazacyclononane)molybdenum(III) complexes. Crystal structures of [MoIII2(.mu.-OH)2Cl2(C6H15N3)2]I2 and [MoIII2(.mu.-OH)2(.mu.-O2CCH3)(C6H15N3)2]I3.H2O

Les deux complexes du titre cristallisent dans le systeme monoclinique avec les groupes C2/c et P2 1 /a respectivement. Le premier complexe est forme de cations dinucleaires constitues de deux octaedres deformes mettant en commun une arete. Le deuxieme est forme de cations dinucleaires constitues de deux octaedres deformes pontes par un groupe acetate et un groupe hydroxo

Synthesis and crystal structure of bis(1,4,7-triazacyclononane-NN′)platinum(II) dibromide dehydrate and its facile oxidation by oxygen: characterisation of bis(1,4,7-triazacyclononane-NN′N″)platinum(IV) tetraperchtorate

1,4,7-Triazacyclononane (L) reacts with [PtCl4]2– in aqueous solution to form a variety of complexes containing the potentially tridentate amine as a uni- or bi-dentate ligand. The complex [PtII(L)2]Br2·2H2O containing two bidentate ligands was oxidised by molecular oxygen in aqueous solution to form the octahedral cation [PtIV(L)2]4+. 1H N.m.r. spectra indicated that the two cyclic amines were co-ordinated via six N-donor atoms. The X-ray crystal structure of [PtII(L)2]Br2·2H2O was determined. The complex crystallises in space group P2/n, with a= 8.990(2), b= 7.987(2), c= 14.424(4)A, β= 93.34(2)°, and Z= 2. 1 419 Independent reflections with I > 2.5σ(I) gave R= 0.0335. The geometry of the complex cation is essentially square planar with one unco-ordinated nitrogen atom per bound amine ligand.

Kinetics and mechanism of the equilibration reaction between (2,2′,2″-nitrilotriethoxy)nitrosylvanadate(1–) and cyanide. Crystal structures of sodium (2,2′,2″-nitrilotriethoxy)nitrosylvanadate(I)–sodium perchlorate tetrahydrate and of barium cyano(2,2′,2″-nitrilotriethoxy)nitrosylvanadate(I) pentahydrate

The reaction of triethanolamine, ammonium vanadate(V), and hydroxylamine in aqueous solution (pH 10) affords quantitatively a red nitrosyl complex (reductive nitrosylation), Na[V(NO){N-(C2H4O)3}]·NaClO4·4H2O, (1), which upon addition of cyanide forms a blue complex, Ba[V(NO)-(CN){N(C2H4O)3}]·5H2O, (2). The structures of these two compounds have been determined by single-crystal X-ray studies: (1), monoclinic, space group P21/a, with a= 12.234(3), b= 11.405(3), c= 12.478(4)A, β= 93.56(3)°, and Z= 4, R= 0.089 from 2 104 reflections; (2), orthorhombic, space group P21ab, with a= 10.918(1), b= 11.604(3), c= 12.327(3)A, and Z= 4, R= 0.047 for 3 285 reflections. The complex anion of (1) exhibits distorted trigonal-bipyramidal co-ordination (O3N2) about the vanadium atoms with a linear {V–N–O}4 moiety. In contrast, the anion in (2) has distorted octahedral co-ordination (O3N2C) about the vanadium, involving the quadridentate ligand, a linear V–N–O group, and a cyanide. The rather long N–O distances in complexes (1) and (2)(average 1.253 A) are in accord with low ν(N–O) stretching frequencies at 1 490 and 1 450 cm–1. The {V–NO}4 moiety of (1) is susceptible to electrophilic attack by protons, generating most probably a hydroxylamidovanadium(V) species. This process is reversible; in alkaline solutions (1) is regenerated. The kinetics of the equilibration reaction of complex (1) with cyanide have been measured by stopped-flow spectrophotometry at pH 11 [I= 2.0 mol dm–3(NaClO4)]. A rate constant, kf= 1.12 dm3 mol–1 s–1, for the forward step and one, kr= 0.61 s–1, for the reverse have been determined at 20 °C.