Gert J. Kruger

Oxidative addition of mono and bis(carbene) complexes derived from imidazolyl and thiazolyl gold(I) compounds

Abstract A series of cationic imidazolinylidene and thiazolinylidene gold(III) complexes was synthesized by the oxidative addition of halogens to the corresponding bis (carbene) gold(I) compounds. Similar reactions with the thiazolyl-derived mono (carbene) gold(I) complex only give mono (carbene) halogold(I) compounds. Quantum mechanical calculations employing the GAUSSIAN92 series of programs at the DFT/HF (hybrid density functional theory) level were carried out for the model complexes [Au{ovbar|CNHCHCHNH} 2 Cl 2 ] + and [Au- CNHCHCHNH ) 2 ) and compared to the molecular structure of the imidazolinylidene gold(III) compound [Au{ CNMeCHCHN Me} 2 Cl 2 ][CF 3 SO 3 ] as well as an analogous gold(I) complex.

Group 6 carbene complexes derived from lithiated azoles and the crystal structure of a molybdenum thiazolinylidene complex

Fischer-type (alkoxy)azolyl carbene complexes and Ofele–Lappert-type azolylinylidene complexes were synthesised by reaction of 1-phenylpyrazol-3-yllithium, 4-methylthiazol-2-yllithium, benzothiazol-2-yllithium, 1-methylimidazol-2-yllithium with M(CO) 5 L (L=CO, THF or Cl − ; M=Cr, Mo or W) and subsequent alkylation with CF 3 SO 3 CH 3 . The alkylation of Fischer-type carbene complexes containing an azolyl as the organic substituent proceeded via ring opening of tetrahydrofuran. When the alkylation is carried out in THF, the carbocation CH 3 O(CH 2 ) 4 + acts as an electrophile. Protonation rather than alkylation of coordinated imidazolyl furnished cyclic imine complexes. Changing the donor atom of a coordinated thiazole from N to C by deprotonation and alkylation afforded a carbene complex.

Characterization of mono(carbene) and bis(carbene) complexes of gold(I) derived from lithiated pyridine

Abstract The carbene complexes [Au(¯CNHCH=¯CHCH=¯C>H)Cl] ( 2 ) and [Au(¯CN(R) ¯CH=¯CHCH=¯C>H) 2 ][X] (R = H, X = Cl ( 4 )) (R = Me, X = CF 3 SO 3 ( 5 ) are formed when the products of the reactions between [Au(THT)Cl] (THT = tetrahydrothiophene) and 2-lithiopyridine are acidified with HCl or alkylated with CF 3 SO 3 Me. Compound 4 crystallizes with two molecules of H 2 O. The complex is monomeric and interacts with the water molecules and the chloride ion through a complex network of hydrogen bonds.

Sulphur-containing metal complexes: X. Reactions of [Fe(CO)5] with ethylenetrithiocarbonate. Structure of [Fe3(Co)9{CS(CH2)2S}S] containing a μ-dithiocarbene ligand

Abstract Four different conversions were observed when a mixture of [Fe(CO)5] and ethylenetrithiocarbonate was irradiated with ultraviolet light in tetrahydrofuran: (i) the thione bond in the ligand was broken and the sulphur atom was incorporated into a cluster to produce [Fe3(CO)9(μ3-S)2], (I); (ii) cleavage of the two CS single bonds occurred and the S(CH2)2S moiety was used to stabilize the complex [Fe2(CO)6{μ-S(CH2)2S}], (II); (iii) the ligand exhibited significant charge redistribution during coordination, in the compound [Fe2(CO)6-{S CS(CH 2 ) 2 S }], (III) and finally, (iv) the thione bond was cleaved and both fragments were used by the metalcarbonyl to yield the major product, [Fe3(CO)9{μ3- CS(CH 2 ) 2 S }(μ3-S)], (IV). A single crystal X-ray study of IV revealed that a dithiocarbene ligand caps an open iron triangle by forming a methylene bridge between two iron atoms and links up with the third iron atom via a sulphur atom.

Preparation, and crystal and molecular structure of π-cyclopentadienyl-η-(tetraphenylborato)ruthenium(II)

The preparation of the title compound is reported. Crystals are monoclinic, a= 9·527(4), b= 15·381(6), c= 15·518(7)A, β= 105·09(5)°, Z= 4, space group P21/c. The structure was determined by Patterson and Fourier methods from diffractometer data and refined by least-squares methods to a final R of 0·032 for 2048 reflections. The ruthenium atom is sandwiched between the cyclopentadienyl ring and one of the phenyl rings of the tetraphenylborate anion. The rings are planar, parallel, and 3·52 A apart.

Synthesis and characterisation of N-coordinated pentafluorophenyl gold(i) thiazole-derived complexes and an unusual self-assembly to form a tetrameric gold(i) complexElectronic supplementary information (ESI) available: Characterisation data for 1. See http://www.rsc.org/suppdata/dt/b3/b303625a/

Treatment of [Au(C6F5)(SC4H8)] (1) (SC4H8 = tetrahydrothiophene or tht) with HCNC(CH3)C(H)S, CH3SCNC(CH3)C(H)S, (I) or piperidine yields the neutral mononuclear imine complexes [Au(C6F5){NC(H)SC(H)CCH3}] (2) and [Au(C6F5){NC(SCH3)SC(H)CCH3}] (3), or the amine complex [Au(C6F5){N(H)CH2(CH2)3CH2}] (4). The reaction of 1 with SCN(H)C(CH3)C(H)S, (II) affords the thione complex [Au(C6F5){SCN(H)C(CH3)C(H)S}] (5), which, in CH2Cl2via spontaneous intermolecular deprotonation of the thione ligand, self-assembles to an unique tetramer of Au(I), [Au{SCNC(CH3)C(H)S}]4 (6) containing a folded rectangle of Au-atoms with aurophlilic interactions [av. Au⋯Au distance, 3.02(4) A and av. Au–Au–Au angle, 87(2)°]. N-coordination of the imine complexes has been confirmed by 15N NMR and the crystal structure determination of 2 which exhibits the expected linear N-coordination and intermolecular Au⋯Au [3.345(1) A] contacts. The crystal structure of 5 shows thione S-coordination of II to the central Au atom.

Sulphur-containing metal complexes: XXIII. Synthesis of new complexes containing the Fe2(CO)6S2 butterfly unit. Crystal and molecular structure of [Fe2(CO)6{μ-S2P(C6H4OMe-p)Fe(CO)4}], determined from two different crystal modifications☆

Abstract Diiron nonacarbonyl, [Fe 2 (CO) 9 ], reacts with Lawessons reagent, ( p MeOC 6 H 4 ){ovtsqb|P(=S)SP(=S)(C 6 H 4 OMe- p )S}, in tetrahydrofuran to give a number of products including [Fe 2 (CO) 6 {μ-S 2 P(C 6 H 4 OMe- p )Fe(CO) 4 }] (III). Single crystal X-ray analyses of this compound, show a dithionophosphine unit, S-P(R)-S (R = C 6 H 4 OMe- p ), to bridge the iron-iron bond of Fe 2 (CO) 6 via the two sulphur atoms and to link a Fe(CO) 4 moiety through coordination of the phosphorus atom. Reaction of Me 2 P(=S)P(=S)Me 2 with [Fe(CO) 5 ] under irradiation with ultraviolet light, affords the anti form of [Fe 2 (CO) 6 {μ-SPMe 2 } 2 ] (V) as major product. Two separate crystal structure determinations on compound III were carried out as it crystallizes under similar condition in two different crystal modifications. Two packing modes are possible because the near-mirror symmetry of the molecule allows two equivalent orientations in the crystal.

Re-determination of the crystal structure of Χ-Fe5C2 Hägg carbide

The crystal structure of χ-Fe5C2 Hägg carbide was re-determined using the simulated annealing capability of Topas Academic (Coelho, 2000). The unit cell is triclinic (space group P-1) with a = 11.5695(5) Å, b = 4.5713(2) Å, c = 5.0588(2) Å, α = 89.884(4)°, β = 97.765(3)° and γ = 89.964(5)°. The crystal structure was fitted by Rietveld refinement, resulting in Rwp = 8.19% and RBragg = 2.54%. The triclinic space group of χ-Fe5C2 Hägg carbide was determined using selected area electron diffraction (SAED). A TEM study was done to determine exposed crystallographic faces on coarse χ-Fe5C2 Hägg carbide particles. Energy calculations using Castep (Cambridge Sequential Total Energy Package, Payne, et al., 1992 and Milman et al., 2000) indicated the triclinic unit cell of χ-Fe5C2 Hägg carbide to have the same total energy as the monoclinic unit cell. Thermogravimetric analysis was used to characterize the carbon species in the sample.

Carbonyl insertion into a CS bond and complex dimerization during reaction of the dithioesters SC(Me)SEt and SC(Ph)SMe with iron carbonyl complexes

Abstract Dithioesters react with pentacarbonyliron or nonacarbonyldiiron under UV irradiation to give three classes of compounds. In the metalmetal-bonded complexes [Fe2(CO)6{;SC(R1)SR2};] (R1  Me or Ph; R2  Et or Me) which belong to the first class, the iron atoms are doubly-bridged by a CS unit and the original bicovalent sulphur atom of the intact dithioester unit. Similar metal links also exist in the complex [Fe2(CO)6{;μ-η2-S CS(CH 2 ) 2 S -S,S′};](Fe-Fe) (I), formed from a trithiocarbonate (R1R2  SCH2CH2) and [Fe(CO)5], as confirmed by single-crystal X-ray diffraction. The nature of the bonding in the second class of compounds was established by determining the crystal structure of the dimeric compound [Fe(CO)3{;SC(Ph)SMe};]2 (V) in which there is no metal-metal bond but each coordinated ligand forms a non-symmetrical dative sulphur-metal bond to the other iron atom. An X-ray crystal structure of a member of the third type of compound [Fe2(CO)6{;SC(R1)C(O)SR2};] (R1  Ph; R2 7z.dbnd; Me) (VI), shows that it is the result of carbonyl insertion into the C-SR2 bond of the ligand.

X-Ray crystal structure of asteltoxin, a novel mycotoxin from aspergillus stellatus curzi

The structure of a new mycotoxin, asteltoxin, isolated from cultures of Aspergillus stellatus is proposed, based on 13C and 1H n.m.r. spectral data and X-ray crystallography.