Manuela Winter

An effectively diamagnetic oximato-bridged asymmetric dinuclear copper(II) complex with a Cu(II)I bond

Abstract A new bis(oximato)-bridged dinuclear copper(II) complex containing an axial Cu(II)I bond with the formula [LCu(PyA) 2 Cu(I)]ClO 4 ·CH 3 CN ( 1 ) (where L = 1,4,7-tritrimethyl-1,4,7-triazacyclononane; PyA = monoanion of pyridine-2-aldoxine) has been characterized by IR, UV-Vis, variable temperature (81–283 K) magnetic susceptibility measurements. 1 crystallizes in the monoclinic system space group P2 1 n , with cell constants a= 8.304(2), b = 27.410(7), c = 13.975(5) A β = 93.48(2)° V = 3175(2) A and Z = 4 . The structure consists of oximato-bridged CuIICuII(I) monocations and non-coordinated perchlorate anions. Both copper ions have a distorted square-pyramidal geometry with a Cu ⋯ Cu separation of 3.45 A and Cu(II)I bond length of 2.74 A. The copper centres are very strongly antiferromagnetically coupled, the singlet-triplet splitting being greater than 1000 cm−1.

Synthesis, structure and magnetism of a tetranuclear Fe(III) complex containing an [Fe4(μ3-O)2]8+ core

Abstract The tetranuclear Fe(III) complex [L2Fe2(μ3-O)2(μ2-CH3COO)3(Sao)2Fe2]X (X=ClO4, (1), PF6 (2)), where L is the cyclic amine 1,4,7-trimethyl-1,4,7-triazacyclononane and Sao is the dianion of salicylaldoxime (H2Sao), has been synthesized and characterized on the basis of elemental analysis, IR, electronic, Mossbauer spectroscopy and variable-temperature (4–285 K) magnetic susceptibility measurements. The molecular structure has been established by X-ray diffraction of 2. The structure consists of an [Fe2wing(μ3-O)2Fe2body]8+-butterfly core. Each Fe(III) ion is in a distorted octahedral environment. The two Fe(Sao)+ units function as bridges between two terminal ‘wing’ iron ions through their deprotonated oximate oxygen and represent the ‘body’ iron ions in the tetranuclear core. Three acetate groups are singly bridging between the iron ions. Mossbauer spectra display two quadrupole doublets, consistent with two different high-spin ferric sites. Magnetic susceptibility measurements reveal a diamagnetic ground state with antiferromagnetic exchange interactions among the four high-spin ferric centers. The exchange coupling constant J12 (‘body-body’ interaction) could not be determined due to prevailing spin frustration, but the ‘wing-body’ antiferromagnetic interaction, J, was evaluated to be −46 cm−1 [H=−2J(S1·S3+S2·S3+S1·S4+S2·S4)−2J12S1·S2].

Isolation of a spin-frustrated imidazolate-bridged trinuclear copper(II) complex potentially relevant to the multicopper oxidases

The reaction of Cu(MeCO2)2·H2O with 1,4,7-trimethyl-1,4,7-triazacyclononane (L) and imidazole (ImH) in methanol affords, in the presence of a small amount of triethylamine and NaClO4, the blue trinuclear complex [L3Cu3(Im)3](ClO4)3 which has been characterized by X-ray crystallography, EPR and magnetic susceptibility measurements to be a spin-frustrated triangular imidazolate-bridged copper(II) complex without any µ3-X ligand.

Synthesis and structure of mixed isopropoxide–β-ketoester and β-ketoamide zirconium complexes: Potential precursors for MOCVD of ZrO2

The reaction of [Zr(OPri)4·(HOPri)] with β-ketoester and β-ketoamide resulted in complexes having potential to serve as precursors for MOCVD of ZrO2 thin films. Zirconium bis(isopropoxide) bis(tert-butylacetoacetate) (1), zirconium tris(isopropoxide)(tert-butylacetoacetate) (2), zirconium tetrakis(tert-butylacetoacetate) (3) and zirconium bis(isopropoxide)bis(N,N-diethylacetoacetamide) (4) were synthesised and characterised by elemental analysis, NMR, IR and mass spectrometry. The molecular structure of the compounds as determined by single crystal X-ray diffraction revealed that compounds 1 and 4 exist as monomers while compound 2 exhibits a nearly symmetric dimeric structure. It is shown that by introducing small changes in the established key structures of the existing precursors, it is possible to tune the thermal properties. Compounds 1, 2 and 4 melt at low temperatures and possess thermal properties that are promising for MOCVD of ZrO2 and related oxide thin films. ZrO2 films grown using compound 1 as precursor in the absence of additional oxidant were characterised by X-ray powder diffraction, scanning electron microscopy and Rutherford back-scattering analysis.

Synthesis, structure and bonding situation of [(dcpe)Pt(InCp*)2] and {(dcpe)Pt[GaC(SiMe3)3]2}—two novel examples of platinum complexes of low valent Group 13 metal species

Abstract In analogy to the corresponding Cp*Al- and Cp*Ga-compounds two further bis(phosphine)platinum complexes [(dcpe)Pt(InCp*)2] (1(In)) and {(dcpe)Pt[GaC(SiMe3)3]2} (2(Ga)) containing monovalent Group 13 metal species as ligands are accessible by thermal activation of [(dcpe)Pt(H)(CH2t-Bu)] (dcpe=bis(dicyclohexylphosphino)ethane) followed by the reaction with 2 equiv. of InCp* (Cp*=pentamethylcyclopentadienyl) or GaC(SiMe3)3. The crystal structure analysis reveals a distorted tetrahedral coordination of the platinum center for both compounds. The PtIn distances in 1(In) amount to 2.569(1) and 2.556(1) A. The PtGa distances in 2(Ga) are exceptionally short and amount to 2.315(1) and 2.318(1) A. Comparative theoretical investigations have been performed on this type of complexes and allow a deeper insight in the bonding situation. The NBO analysis reveals a significantly larger Pt→Ga π-back-donation for the model compound {(dhpe)Pt[GaC(SiH3)3]2} (2M(Ga)) (0.44 e; dhpe=1,2-diphosphinoethane) in comparison with the related model compound [(dhpe)Pt(GaCp)2] (1M(Ga)) (0.29 e) bearing a strong π-donating organic ligand at the Ga center. A similar trend is observed for the PtGa bond dissociation energies (De=33.0 kcal mol−1 for 2M(Ga), De=18.3 kcal mol−1 for 1M(Ga)). For the model compound [(dhpe)Pt(InCp)2] (1M(In)) a value of De=19.1 kcal mol−1 has been calculated.

P−P Bond Activation of P4 Tetrahedron by Group 13 Carbenoid and its Bis Molybdenum Pentacarbonyl Adduct

Activation of white phosphorus with Ga(DDP) (DDP = 2-diiso-propylphenylamino-4-diiso-propylphenylimino-2-pentene) afforded [(DDP)Ga(P(4))] (1) by insertion of the Ga(I) center at one of the six P-P bonded edges of the P(4) tetrahedron. Further reaction of 1 with three equivalents of Mo(CO)(6) results in the formation of [(DDP)Ga(eta(2:1:1)-P(4)){Mo(CO)(5)}(2)] x 2 toluene (2). Compounds 1 and 2 are characterized by (1)H, (13)C, and (31)P NMR spectroscopy, elemental analysis, and single crystal X-ray structural analysis. The solid-state structure of molecule 1 reveals the first example of a structurally characterized GaP(4) core stabilized by a beta-diketiminate ligand. Compound 2 represents a rare type of coordination mode of a gallium supported P(4) butterfly structure.

Low‐Valent Ge2 and Ge4 Species Trapped by N‐Heterocyclic Gallylene

Much π and no σ: quantum chemical calculations showed that the Ge atoms of the Ga(2)Ge(2) core in Ge(2)[Ga(DPP)](2) are not bonded by σ interactions, but rather by a transannular π interaction. The compound is formed by reduction of (PCy(3))⋅GeCl(2) with Ga(DDP)/KC(8) which also yielded a further product Ge(4)[Ga(DPP)](2) with a Ge(4) tetrahedron (DDP=HC(CMeNC(6)H(3)-2,6-iPr(2))(2)).

Ligand properties of Cp*Ga: new examples of Mo–Ga and W–Ga complexes

The compounds [ fac -(Cp*Ga) 3 M(CO) 3 ] ( 1a , M=Mo: 1b , M=W) were synthesized by reaction of [ fac -(RCN) 3 M(CO) 3 ] (R=Me, Et) with Cp*Ga. The treatment of 1a with one equivalent of [ fac -(MeCN) 3 Mo(CO) 3 ] gives the dimeric cluster compound [Mo 2 (CO) 6 (μ 2 -(GaCp*)) 3 ] ( 2 ). Addition of Cp*Ga to the Lewis-acidic unsaturated metal centres of [CpM(CO) 2 ] 2 (M=Mo, W) yields the dimeric complexes [(OC) 2 (Cp)M(μ 2 -(η 1 -GaCp*))] 2 ( 3a : M=Mo, 3b : M=W). The new compounds 1 – 3 were characterized fully including single crystal X-ray diffraction studies.

A novel series of heterotrinuclear complexes with a tris(dimethylglyoximato)metal(II) anion as bridging ligand. Structure of the FeIIICuIIFeIII complex with S= 9/2 ground state

A series of linear heterotrinuclear complexes with a tris(dimethylglyoximato) metal(II) as bridging ligand, [LFeIII{µ-(dmg)3MII}FeIIIL](ClO4)2(M = Zn, Cu, Ni, Co, Fe, Mn), where L represents the cyclic triamine 1,4,7-trimethyl-1,4,7-triazacyclononane, has been synthesized and characterized by X-ray crystallography and magnetic susceptibility measurements.

New heterometallic copper zinc alkoxides: synthesis, structure properties and pyrolysis to Cu/ZnO composites

The copper compound [(THF)KCu(O t Bu) 3 ] ∞ 1 was obtained by interaction of a 1:1 mixture of ZnCl 2 /CuCl 2 with KO t Bu. Bi- and trifunctional aminoalcohols were used to synthesize the intramolecularly donor stabilized Cu(II) alkoxides Cu(OCH(R)CH 2 NMe 2 ) 2 ( 3 : R=Me, 4 : =CH 2 NMe 2 ) where 4 was structurally characterized. Lewis acid–base adduct formation with (Me 3 Si) 3 CZnCl gave the heterodinuclear compounds (Me 3 Si) 3 CZnCl · Cu(OCH(R)CH 2 NMe 2 ) 2 ( 5 : R=Me, 6 : R=CH 2 NMe 2 ), which were characterized by X-ray single-crystal structure analysis. The two metal centers Cu and Zn of 5 and 6 are bridged by two oxygen atoms to form a Cu–O–Zn core. Pyrolysis of compounds 5 and 6 in dry argon or a H 2 /N 2 mixture at atmospheric pressure forms metallic copper and zinc oxide, whereas pyrolysis under O 2 /Ar forms additionally oxidized copper species. Elemental analysis of the pyrolysis products showed carbon and nitrogen contamination. Scanning electron microscopy and energy dispersive X-ray analysis were performed to get information on the morphology and the chemical composition of the pyrolysis products.