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The synthesis and characterization of mononuclear tetrakis-aziridine nickel() and copper() complexes as well as of a dinuclear bis-aziridine copper() complex are described. The reactions of anhydrous MCl 2 (M ϭ Ni II , Cu II ) with aziridine (ϭ az ϭ C 2 H 4 NH, C 2 H 3 MeNH, CH 2 CMe 2 NH) in CH 2 Cl 2 at room temperature in a 1:5 and 1:2 molar ratio, respectively, afforded the tetrakis-aziridine complexes [M(az) 4 Cl 2 ] (M ϭ Ni, Cu) or the dimeric bis-aziridine complex [Cu(az) 2 Cl 2 ] 2 . After purification, all of the complexes were fully characterized. The single crystal structure 1171 analysis revealed two different coordination modes. Whereas both nickel() complexes can be classified as showing an elongated octahedral structure, copper() complexes show either an elongated octahedral or a square pyramidal arrangement forming dimers with chlorido bridges in axial positions. Furthermore, the results of magnetic measurements of the nickel() and copper() compounds are presented.

The synthesis of neutral mono-and cationic bis-aziridine complexes of ruthenium(II), rhodium(III) and iridium(III) are described. The dimeric complexes [MCl 2 L] 2 (M ϭ Ru II , L ϭ C 6 Me 6 ; M ϭ Rh III /Ir III , L ϭ C 5 Me 5 ) (1-3) react with a series of aziridines (Az ϭ C 2 H 4 NH, C 2 H 3 MeNH, C 2 H 2 Me 2 NH, C 2 H 3 EtNH, C 2 H 3 PhNH) (a-e) in a 1:2 or 1:5 molar ratio to give the neutral mono-aziridine complexes [MCl 2 L(Az)] (4e-6e) or cationic bis-aziridine complexes [MClL(Az) 2 ]Cl (7a-9d), respectively. After purifi-1985 cation, all of the complexes were fully characterized and the IR, MS, 1 H and 13 C NMR spectra are reported and discussed. The single crystal structure analysis revealed a distorted octahedral structure for all complexes. Scheme 1 Synthesis of the neutral mono-aziridine complexes 4e-6e by the reaction of [MCl 2 L] 2 (1-3) with 2 equivalents of the aziridines a-e. Scheme 2 Synthesis of the cationic bis-aziridine complexes 7a-9d by the reaction of [MCl 2 L] 2 (1-3) with 5 equivalents of the aziridines a-e.were prepared from β-amino-alcohols according to standard literature methods [40,41].Scheme 1 shows the reactions of the dimeric complexes [MCl 2 L] 2 (1-3) with stoichiometric amounts (1:2) of the aziridines (a-e) in dichloromethane to give the corresponding neutral mono-aziridine complexes [MCl 2 L(Az)] (4e, 5b, 6a, b, c, e).The cationic bis-aziridine complexes [MClL(Az) 2 ]Cl (7a, c, d, e, 8a, c, e, 9a, c, d) were prepared by adding an excess (1:5) of the aziridines (a-e) to a solution of [MCl 2 L] 2 (1-3) in dichloromethane (Scheme 2).All products 4e-9d were obtained in good yields (77Ϫ99 %) and are soluble in polar solvents such as acetone or dichloromethane, but insoluble in non-polar solvents such as n-pentane. Crystal Structure AnalysisThe molecular structures of compounds 4e-9d were determined using single crystal X-ray diffraction. Single crystals were obtained by the isothermic diffusion of n-pentane into acetone solutions of 9a and 9c, and by slow evaporation of dichloromethane solutions of 4e-8e and 9d. Details of the relevant data collection and refinement are summarized in Tables 1-3. For each type of compound one molecular structure (4e, 5b, 6a, 7c, 8a, 9d) is shown in Figures

Addition of 5,5‐diethylbarbituric acid (H2debarb, 1) to [CpCr(NO)2Cl], [Re(CO)5Br] or [(PPh3)Re(CO)4Br] in the presence of triethylamine and AgO3SCF3 (= AgOTf) resulted in the mono‐barbiturato complexes [CpCr(NO)2(Hdebarb)] (2), [PPh3Re(CO)4(Hdebarb)] (3) and [Re(CO)5(Hdebarb)] (4), respectively. Bis‐barbiturato complex [{(CO)5Re}2(debarb)] (5) with a doubly deprotonated barbiturate dianion formed when a molar ratio of metal complex to ligand of 2:1 was used. In the case of the rhenium complexes, AgO3SCF3 must be used additionally to cleave off bromide. All of the complexes were fully characterised by means of IR, mass and 1H, 13C and 31P NMR spectra and elemental analysis. In addition, their solid‐state structures were determined by single‐crystal X‐ray diffraction studies. The complexes exhibit distorted pseudo‐tetrahedral (2) or pseudo‐octahedral (3–5) configuration around the metal atom. In all complexes the ring system of the Hdebarb ligand is essentially planar.

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