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The synthesis of neutral mono- and cationic bis-aziridine complexes of ruthenium(II), rhodium(III) and iridium(III) are described. The dimeric complexes [MCl2L]2 (M = RuII, L = C6Me6; M = RhIII/IrIII, L = C5Me5) (1-3) react with a series of aziridines (Az = C2H4NH, C2H3MeNH, C2H2Me2NH, C2H3EtNH, C2H3PhNH) (a-e) in a 1:2 or 1:5 molar ratio to give the neutral mono-aziridine complexes [MCl2L(Az)] (4e-6e) or cationic bis-aziridine complexes [MClL(Az)2]Cl (7a-9d), respectively. After purification, all of the complexes were fully characterized and the IR, MS, 1H and 13C NMR spectra are reported and discussed. The single crystal structure analysis revealed a distorted octahedral structure for all complexes.

Ti(OPr i ) 4 reacts with N -phenylsalicylideneimine in anhydrous benzene in 1:2 molar ratio to afford precursor [Ti{O(C 6 H 4 )CH NPh} 2 {OPr i } 2 ] ( A ). Further reactions of A with various glycols yield heteroleptic complexes of the type [Ti{O(C 6 H 4 )CH NPh} 2 {O–G–O}] [where –G– = (CH 2 ) 2 ( 1 ), (CH 2 CHCH 3 ) ( 2 ), (CH 3 CHCHCH 3 ) ( 3 ), (CH 2 CHC 2 H 5 ) ( 4 ), C(CH 3 ) 2 C(CH 3 ) 2 ( 5 ), (CH 2 ) 3 ( 6 ), (CH 2 CH 2 CHCH 3 ) ( 7 ), (CH 3 ) 2 CCH 2 CHCH 3 ( 8 ), (CH 2 ) 5 ( 9 ) and (CH 2 ) 6 ( 10 )]. FAB mass spectroscopic studies of some of the derivatives suggest their monomeric nature. Single crystal X-ray diffraction study of A reveals cis -orientation of the isopropoxy groups [O(3)–Ti(1)–O(4) = 102.23(11)°] and distorted octahedral geometry around the titanium atom. Crystal structure of a trinuclear titanoxane [{Ti(O(C 6 H 4 )CH NPh) 2 }O] 3 , obtained from the partial hydrolysis of A , exhibit the formation of a six-membered Ti 3 O 3 ring. Complete hydrolysis and low temperature (300–500 °C) transformation of precursor A , as well as of 1 and 7 to pure TiO 2 have also been achieved using sol–gel technique. The XRD patterns indicate formation of anatase phase of TiO 2 . The XRD and SEM observations on all the three samples indicate the formation of pure grains of nanosized titania. TGA curves of A and 7 suggest occurrence of multiple large thermal events.

The reaction of 2,2′-dimethylaziridine with the carbonyl halogenido complexes [(CO)5MX] (M = Mn; X = Cl, I; M = Re: X = I) results in the formation of the 1,2-aminoaziridinoethane complexes [(CO)3XM{NH2CMe2CH2N(C2H2Me2)}]. The bis(2,2′-dimethylaziridine) complexes [(CO)3XM(NHCH2CMe2)2] may act as intermediates. The new asymmetric chelate ligand is the formal dimerization product of 2,2′-dimethylaziridine, which is formed and stabilized in the coordination sphere of both transition metals. The new complexes have been characterized using elemental analysis, mass, IR and NMR spectra as well as by X-ray structure analysis. The metal centers exhibit a distorted octahedral configuration with a facial (CO)3M-arrangement, and the 5-membered metallacycles show a twist conformation and lie in the trans-positions with respect to the CO ligands in the equatorial plane. Whereas the Mn-N bonds to the intact aziridine system are longer (213.3 and 213.8 pm) than those to the NH2 group (206.5 and 207.4 pm), the corresponding Re–N bonds show the opposite trend, whereby the Re–NH2 bonds are shorter (219.0 and 225.8 pm).

2-(2′-Pyridyl)indole acts as an N,N-bidentate ligand when deprotonated and forms (1-amido-4-imine)metallacycles with ReI, RuII, RhIII and IrIII. The crystal structures of 2-(2′-pyridyl)indole and the complexes [Re(C13H9N2)(CO)2(PPh3)2], [Ru(C13H9N2)(η6-C6Me6)Cl], [Rh(C13H9N2)(η5-C5Me5)Cl] and [Ir(C13H9N2)(η5-C5Me5)Cl] are presented and their spectra discussed. This provides a foundation for the increased use of this ligand, which is a prototype of a monoanionic, bidentate N,N-chelating ligand. The introduction of negatively charged N,N-bidentate ligands can increase the possibility of synthesising complexes tailored to catalysis and other applications. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

A series of unusual dinuclear mu2-(eta2-NO)-nitrosoaniline-bridged complexes [[(CO)3Re(mu-X)]2ONC6H4NR2] (X = Cl, Br, I; R = Me, Et) with dichroic properties have been synthesised by reaction of pentacarbonylhalogenorhenium(I) [(CO)5ReX] (X = Cl, Br, I) with the corresponding nitrosoaniline derivatives R2NC6H4NO (R = Me, Et). The deeply coloured solutions in CH2Cl2 show broad UV/Vis absorptions from 595 to 620 nm depending on the halogen bridges and N substituents. Single crystals of all six compounds exhibit a pronounced linear dichroism. The molecular structures have been determined by single-crystal X-ray analyses. All the compounds contain two face-shared octahedra, with two halogens and one NO ligand as bridges. The NO ligand coordinates in a nonsymmetrical eta2-like fashion with N or O coordination to each Re centre. Therefore, the C-nitroso group and the planar NC2 moiety of NR2 both lie almost exactly within the symmetry plane of the dinuclear complexes. These complexes belong to the novel and simple class of neutral dinuclear C-nitroso complexes that include the rare, non-assisted mu2-(eta2-NO) ligand function and have only single halogen atoms in bridging positions.

The halogeno complexes (CO)5ReX (1a–c) (X = Cl, Br, I) react with 1-nitroso-2-naphthol C10H6N(O)OH (2) in refluxing CH2Cl2 to give the substitution product cis-(CO)4Re{C10H6ON(O)} (3) via HX and CO elimination in good yield. Compound 3 is coordinated to the Re centre by the bidentate chelate ligand via the N-atom of the nitroso and O-atom of the naphtholato groups. The same reaction in refluxing toluene, however, gave no HX elimination but instead, the fac-(CO)3XRe{C10H6ON(H)} (4–6) complexes are formed, which contain the rare, N,O-chelating ligand 1,2-naphthaquinone-2-imine. The nitroso function of 2 has been reduced to the imine function by an intermolecular redox process, which was confirmed by the detection of CO2 generated during the reaction. The new compounds 3–6 have been characterised by their IR, 1H and 13C NMR, UV/Vis and mass spectra, as well as by X-ray structure analyses. The ReI centres show a distorted octahedral coordination of the CO and X (in 4–6) ligands and the almost planar aromatic (3) or quinoid (4–6) N,O chelating ligands. (© Wiley-VCH Verlag GmbH & Co. KgaA, 69451 Weinheim, Germany, 2005)

The gold(I) complex Ph 3 PAuCl ( 1 ) reacts in the presence of AgO 3 SCF 3 (=AgOTf) with a series of aziridines with various NH-, NR-, CHR- and CR 2 -functionalities via halide elimination at ambient temperature, to give the cationic mixed phosphane-aziridine gold(I) complexes [Ph 3 PAuAz]OTf ( 2 – 8 ) (Az = aziridine, 2-methylaziridine, 2,2-dimethylaziridine, 2-ethylaziridine 2-phenylaziridine, N -benzylaziridine, N -hydroxyethylaziridine). The X-ray structure analyses show the gold(I) centres are linearly coordinated by the PPh 3 and Az ligands, and the intact three membered aziridine rings coordinate through the distorted tetrahedral N-atoms. Compounds 2 – 8 are stable with respect to both directed thermal or photolytic alkene elimination, or any ring N–C opening reaction which would result in the corresponding cationic nitrene complexes [Ph 3 PAuNH]OTf and [Ph 3 PAuNR]OTf, or any oxidative addition products. The phenyl substituent in the 2-position of 6 is obviously bowed with its plane towards the Au centre, indicating some Au–π-ring interaction with the distance Au–C n ≈ 4.00 A. The O atom of the hydroxy group in 8 also lies very close to the Au centre, with the distance Au–O = 3.078 A. The IR, 1 H, 13 C and 31 P NMR, and MS spectra are reported and discussed, and the molecular structures of 3 , 4 , 6 and 8 have been determined by single crystal X-ray diffraction analyses.

In einer thermisch induzierten Substitutionsreaktion mit 2,2-Dimethylaziridin lassen sich die Pentacarbonyl-Halogeno-Komplexe [XM(CO)5] (M = Mn, Re; X = Cl, Br) (1a – 2b) zu den neutralen Bis-Aziridin-Komplexen [M(X)(CO)3Az2] (Az = N(H)C2H2Me2) (3a – 4b) umsetzen. Den Rontgenstrukturanalysen zufolge sind die Metallatome oktaedrisch in facialer Anordnung konfiguriert; die intakten Dreiringe sind uber die verzerrt tetraedrisch konfigurierten N-Atome gebunden. Verbindungen 3a – 4b sind hinsichtlich einer gezielten Alken-Abspaltung unter Bildung von Nitren-Komplexen stabil; ihre IR-, 1H- und 13C{1H}-NMR- und MS-Spektren werden vorgestellt und diskutiert. The pentacarbonylhalogene complexes [XM(CO)5] (M = Mn, Re; X = Cl, Br) (1a – 2b) react with 2,2-dimethylaziridine by thermally induced substitution reaction to give the neutral bis-aziridine complexes [M(X)(CO)3Az2] (Az = N(H)C2H2Me2) (3a – 4b). As a result of the X-ray structure analyses, the metal atoms are octahedrally configurated in the facial arrangement; the intact three-membered rings coordinate through their distorted tetrahedrally configurated N atoms. All compounds 3a – 4b are stable with respect to the directed thermal alkene elimination to give the corresponding nitrene complexes (CO)4(X)M=NH; their IR, 1H and 13C{1H} NMR, and MS spectra are reported and discussed.

The dimeric μ2-amino-phenoxy complexes of rhenium [(CO)3Re(μ2-O∩NH2)]2 (1) do not react with the C-nitroso compounds R−C6H4NO [R = NMe2 (2), H (2′)] in the presence of AlCl3 by a condensation reaction to give the desired azo dye complexes [(CO)3Re(μ2-O∩N=NC6H4R)]2. Instead, they react to give the novel neutral η2-N,O-bridged C-nitroso complexes [{CO)3ReCl}2ONC6H4R] (3, 3′) by means of a substitution reaction. Both complexes yield golden gleaming crystals, and their solutions are deeply blue (3) or violet (3′) due to the broad UV/Vis absorption at λ = 617 (3) and 505 nm (3′). Single crystals of 3, 3′ show nonlinear optical properties, they are dichroic and have a red and blue (3) or violet and green (3′) side. The molecular structures of 3, 3′ have been determined by single-crystal X-ray analyses. Both compounds contain two face-joined octahedra, with two chloro and the NO ligands as bridges. The C-nitroso groups together with the NC2 moiety of NMe2 (3) lie almost exactly within the symmetry plane of the molecules. Both the N atoms of 3 have a trigonal-planar geometry. 3 and 3′ are the first single, neutral and dinuclear C-nitroso complexes with the rare non-assisted μ-(η2-N,O) bridge and only single atoms as additional bridges. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)