Band 51, Heft 2

The structures of seven di- or tetrasubstituted p-benzoquinone derivatives O=C(XC=CH ) 2 C=O and O=C(XC=CX) 2 C=O with substituents X = -OCH 3 , -N(CH 2 ) 5 , - N(CH 2 CH 2 ) 2 O, -Cl, -CN and - ⊕ N(HC=CH) 2 C-N(CH 3 ) 2 are presented and discussed in comparison with published ones substituted by X = -Si(CH 3 ) 3 , -C 6 H 5 , -N(CH 3 ) 2 , - ⊕ N(HC=CH) 2 CN(CH 3 ) 2 , -O ⊖ , and - NO 2 . Based on the introduction, in which halfwave-reduction potentials, geometry-optimized quantum-chemical calculations on substituent perturbation and known structural data of p-benzoquinone derivatives are used to characterize their molecular ground states. The structural changes indicate how substituent perturbations might be rationalized. Of the categories defined - imperturbed, donor, donor/acceptor and acceptor perturbed - the donorsubstituted p-benzoquinones do exhibit the largest differences, often called cyanine distorsion. In very satisfactory agreement with extensive semiempirical calculations, all effects determined experimentally are discussed in terms of varying charge distribution. With respect to the biochemical importance of p-benzoquinone derivatives, this first structural summary points out important facets.

Single crystals of strontium danburite, SrB 2 Si 2 O 8 , were found after high-pressure treatment of SrSiO 3 /SiO 2 /Al 2 O 3 mixtures at 40 kbar and 1400°C, obviously formed by an unwanted side reaction with the boron oxide-containing boron nitride capsules used. The crystals are orthorhombic, space group Pnma, with a = 8.1891 (5), b = 7.9311 (6), c = 8.9284(5) Å and Z = 4. The structure was refined to R = 0.031, R w = 0.028 for 590 independent, absorption-corrected reflections. SrB 2 Si 2 O 8 is isostructural with danburite (CaB 2 Si 2 O 8 ). The structure comprises a tetrahedral framework of ordered B 2 O 7 and Si 2 O 7 groups which contains Sr in irregular coordination.

The crystal structure of the compound (dpd) 2 Cu 2 Cl 6 at 120 K has been determined. Space group P2 1 /n , Z = 2, 3997 collected reflections, R = 6.8. Lattice dimensions (120(1)K) : a = 7.328 (8), b = 16.863 (14), c = 13.271 (10) Ä; β = 91.44(7).

Current interest in nickel complexes with sulfur donor ligands as models for the active sites of nickel-containing hydrogenases has prompted us to investigate the structural and electrochemical behaviour of nickel complexes with bifunctional thioether ligands. Crystals of [Ni(MeSCH 2 CH 2 SMe) 2 (NCS) 2 ] (1) and [Ni(EtSCH 2 CH 2 SEt) 2 (NCS) 2 ], (2) are triclinic, space group Pī, Z = 1, 1: a = 7.293(3) Å, b = 7.567(3) Å, c = 8.784(3) Å, α = 72.81(3)°, β = 78.41(3)°, γ = 85.14(3)°; 2: a = 8.611(1) Å, b = 8.101(1) Å, c = 9.163(1) ßrbÅ, α = 66.54(1)°, β = 76.19(1)°, γ = 67.88(1 )ßrb°. [Ni(MeSCH 2 CH 2 SMe) 2 Br 2 ] (3) crystallizes in the monoclinic space group P2 1 /n, a = 6.757(2) A, b = 7.881(2) Å, c = 14.674(4) Å, β = 94.05(2)°, Z = 2. In crystals of 1, 2 and 3 mononuclear neutral complex molecules are observed which have pseudo-octahedral trans-NiS 4 L 2 coordination sites. The cyclovoltammograms of 1 and 3 in MeCN (Ag/AgCl/KCl, 3 mol/l) show only irreversible oxidation waves at +837 mV for 1 and +846 mV for 3, respectively, which are characteristic features of NCS⊖ and Br⊖ ions. In addition, a reduction wave at +393 mV is observed in 3. No redox response is found in the potential region between -700 and +100 mV which is used by the NiFe hydrogenase enzymes.

A series of cyclopentadienyl and pentamethylcyclopentadienyl complexes of cobalt, rhodium, iridium, ruthenium and chromium with a-amino-acid esters (L) as ligands was prepared and characterized: Cp*(Cl) 2 M(L) (1, 2: M = Rh, Ir), Cp(I) 2 Co(L) (4), [Cp(Ph 3 P) 2 Ru(L)] + BF - (6), [Cp(OC)(Ph 3 P)Ru] + BF - (7) and the paramagnetic compounds Cp*(Cl) 2 Ru(L) (8) and Cp(Br) 2 Cr(L) (9). AlaOMe and HisOMe form N ,O and N,N chelate complexes [Cp*(Cl)M(alaOMe)] + BF - 4 (3: M = Rh, Ir), [Cp(I)Co(hisOMe)] + BF 4 . Cp*Co(CO)I 2 and GlyOMe gave the N,O-dipeptide ester complex Cp*(I)Co(glyglyOMe)] + BF - 4 (5). The crystal structures of Cp(I) 2 Co(glyOEt) and Cp*(Cl) 2 Ru(alaOMe) were determined by X-ray diffrac­tion. The complexes 1 and 2 undergo ester exchange reactions with CD 3 OD. [Cp*MCl 2 ] 2 (M = Rh, Ir) catalyze the exchange of the ethoxy group in Me 2 NCH 2 CO 2 Et by CD 3 OD.

While the reaction of anhydrous iron(III) chloride with the chelate ligand [(C 6 H 5 ) 2 P(O)] 2 NH (6) is an efficient way to synthesize the new tricyclic compound imido-tetraphenyl-diphosphinato-O,O′iron(III), [Fe{O-P(Ph 2 )=N-P(Ph 2 )=O} 3 ] (4), treatment of [(C 6 H 5 ) 2 P] 2 NLi (1) with anhydrous iron(III) fluoride in THF represents a simple route to obtain the phosphorus-phosphorus connected species Ph 2 P-N=PPh 2 -PPh 2 =N-PPh 2 (7). Both compounds were charac­terized by X-ray crystallography, 1 H , 31 P { 1 H}, 13 C { 1 H} NMR, IR, Raman and mass spectra.

The intramolecularly coordinating 2-(dimethylaminomethyl)phenyl-(X) and 4-terr-butyl-2,6-bis(dimethylaminomethyl)phenyl-(Y) ligands were employed in the preparation of the gallium and indium halides: X 2 InI (B), XInI 2 (1), X 2 InBr (2), XInBr 2 (3), XIn(Et)I (4), XGaI 2 (6) and YInI 2 (7). The first neutral indium hydride X 2 InH (5) was made in situ from LiInH 4 and 2. Z 2 InCl (8) (Z = 2-pyridyl-bis(trimethylsilyl)methyl), and X 3 Ga (C) were also synthesized. The compounds are characterized by N. M. R. ( 1 H, 13 C, 29 Si and for 6 71 Ga) and mass spectrometry and elemental analyses or peak matching M. S.. N. M. R.-data are discussed as well as the X-ray structure analyses provided for B, 2, 4, 5, 7 and 8.

Reactions of BaCO 3 , ZnO and Yb 2 O 3 mixtures at temperatures up to 1300 °C using plati­num crucibles led to yellow needles of Ba 17 Y b 16 Zn 8 Pt 4 O 57 . The compound crystallizes with a hitherto unknown tetragonal crystal structure, space group C 5 4h -I4/m, a = 22.731(1), c = 5.682(1) Å , Z = 2. The crystal structure is characterized by PtO 6 octahedra and tetragonal ZnO 5 pyramids. Yb 3+ shows a mono-capped trigonal prismatic coordination and Ba 2+ several different coordination environments (C .N = 9 to 10, by O 2- ). The relationship to the Ba 5 Ln 8 M 4 O 21 type is discussed.

Single crystals of NaSr 3 IrO 6 have been prepared by heating mixtures of Na 2 O 2 , SrO and iridium in closed silver tubes and were investigated by X-ray techniques, NaSr 3 IrO 6 crystal­lizes with trigonal (rhombohedral) symmetry in the space group D 6 3d -R3̄ c , a = 9.636(2), c = 11.556(3) Å , Z = 6, and is isotypic to compounds of the Sr 4 PtO 6 type. The substitution of Sr 2+ by Na + in NaSr 3 IrO 6 led to an ordered metal distribution and an increase of the oxida­tion state from Ir IV to Ir v .

Single crystals of Cd 1.35 Cu 1.65 (PO 4 ) 2 have been prepared by solid state reactions below the melting point of the starting compounds. The light green crystals crystallize with monoclinic symmetry, space group C 5 2h -P2 1 /c , a = 9.062(2), b = 11.669(2), c = 5.950(2) Å , β = 97.88(2)°, Z = 4. Cd 1.35 Cu 1.65 (PO 4 ) 2 shows relationship to the mineral graftonite. The crystal structure is characterized by nets of corner connected Cd 2 O 12 polyhedra. One point position is statistically occupied by Cd 2+ and Cu 2+ ions.

Single crystals of the low (t-) and high (h-) temperature form of ZnOZn 3 (AsO 4 ) 2 have been prepared by flux and by CO 2 -LASER techniques respectively. Both compounds crystal­lizes monoclinic, space group C 5 2h -P2 1 /n with the lattice parameters t-ZnOZn 3 (AsO 4 ) 2 : a = 9.807(3), b = 8.180(2), c = 9.967(2) Å , β = 116.53(2)°, Z = 4 and h -ZnOZn 3 (AsO 4 ) 2 : a = 9.743(3), b = 8.163(8), c = 17.933(2) Å , β = 91.55(2)°, Z = 8. Similarities and differences of the crystal structures will be discussed.

Single crystals of (I) CuDyMo 2 O 8 and (II) CuYbMo 2 O 8 have been prepared by crystalli­sation from melts. Both com pounds crystallize with orthorhombic symmetry, space group D 15 2h -Pbca with (I): a = 10.195(1), b = 9.721(2), c = 14.563(3); (II): a = 10.094(6), b = 9.628(9), c = 14.467(8) Å, Z = 8. The crystal structure is characterized by a triangular CuO 3 -polygon, a square antiprismatic coordination around the Rare Earth ions and the typical Mo O 4 tetra­ hedra.

In the presence of oxygen aqueous solutions of the binuclear complex [cobalamin-μ-NC-Fe(CN) 5 ] 3- undergo a redox photolysis (ø ~ 2 x 10 -3 at λirr = 405 nm) which yields aquocoba-lamin and [Fe(CN) 6 ] 3- It is suggested that this photoreaction is induced by direct metal-to-metal charge transfer (MMCT) excitation. On the contrary, [cobalamin-μ-NC-Ru(CN) 5 ] 3- is photo-inert because a reactive MMCT state is not accessible.

The 14 carbides Ln 3.67 MnC 6 (Ln = La-Nd) and Ln 3.67 TC 6 (Ln = La-Nd, Sm; T = Fe, Ru) were prepared from the elemental components by arc-melting and subsequent annealing. Eu 3.16 NiC 6 was obtained from a lithium flux. The crystal structures of these nearly isotypic, hexagonal compounds (P6 3 /m, Z = 2) were determined from single-crystal X-ray data; La 3.67- FeC 6 : a = 878.7(2), c = 535.1(1) pm, R = 0.052 for 548 structure factors and 25 variable parameters; Eu 3.16 NiC 6 : a -860.0(1), c = 548.2(2) pm, R = 0.015 for 606 structure factors and 25 variables. The structures differ from the previously reported Gd 3 Mn 2 C 6 structure by the occupancy of one manganese position by rare earth atoms. Since the lanthanum atoms are larger than the manganese atoms, only two thirds of these manganese positions can be occupied by the lanthanum atoms in La 3.67 FeC 6 . Eu 3.16 NiC 6 has similar atomic positions. The C-C bond distances in the C 2 pairs are 130(2) and 126.5(5) pm in the La and Eu compounds, respectively. Magnetic susceptibility measurements with a SQUID magnetometer indicate La 3.67 FeC 6 to be Pauli paramagnetic. A test for superconductivity was negative down to 3 K.

The new compounds ThCu 1-x PO and ThCuAsO with ZrCuSiAs-type structure were pre­pared in well crystallized form by chemical vapor transport reactions. Th 2 Ni 3-x P 3 O with a new structure type was obtained by reaction of ThO 2 with the other elemental components in an alumina crucible at high temperatures. The crystal structures of the three compounds were determined from single-crystal X-ray data. ThCu 1-x PO: P4/nmm, a = 389.43(4), c -828.3(1) pm, R = 0.024 for 13 variable parameters and 338 structure factors; ThCuAsO: P4/ nmm, a = 396.14(5), c = 844.0(1) pm, R = 0.028 (13 variables and 379 F values); Th 2 Ni 3-x P 3 O : P4/nmm, a = 394.62(4), c = 1723.2(3) pm, R = 0.018 (27 variables and 374 F values). The refinement of the occupancy parameters revealed significant deviations from the ideal values for the transition metal sites for two compounds resulting in the exact compositions ThCu 0.938(4) PO and Th 2 Ni 2.45(1) P 3 O . Magnetic susceptibility measurements indicate Pauli paramagnetism for ThCu 1-x PO . The crystal structures of these compounds are closely related. They belong to a large family of tetragonal structures of which the ThCr 2 Si 2 -and the PbFCl-type structures are well known examples.

The crystal structure of [WI 2 (CO) 3 (NCPh) 2 ] (1) has been determined by X-ray methods. The crystals are orthorhombic, space group Pnam, a = 7.815(3), b = 13.839(5), c = 18.475(3) Å, Z = 8, R = 0.0346 for 1497 observed data. The complex [WI 2 (CO) 3 (NCPh) 2 ] has a seven-coordinate geometry, which may be described as a distorted capped octahedron, with the two iodo-ligands mutually trans, while each nitrile is trans to a carbonyl group. The capped octahedral geometry consists of a capping carbonyl (C(10)} on the face defined by I(1), C(20) and C(20)#. However, the geom etry may also be described as a capped trigonal prism, which has one triangular face occupied by three carbonyl groups and the second triangular face occupied by N(1) , N (1)# and I(1) atoms, respectively. The iodide I(2) occupies the capping position on the rectangular face defined by the atoms C(20), C(20)#, N (1), and N (1)# . The low temperature 13 C NMR spectrum (203 K, CD 2 Cl 2 ) of 1 shows a single carbonyl resonance at 219.27 ppm which indicates that the complex is undergoing a rapid fluxional process in solution at 203 K.

Bis(ylidyl)phosphanes can be prepared from ylides and dichlorophosphanes or from bis-(ylidyl)phosphenium chlorides and organolithium compounds. By substituting in bis(ylidyl)-phosphenium chlorides the chloride ion for more basic anions, a large variety of bis(ylidyl)-phosphanes is accessible. They can be protonated at the ylidic carbon atoms, but alkylated and oxidized at the central phosphorus atom. As shown by 31 P NM R in solution and by X-ray investigation of the crystal, the lone pair at the tervalent phosphorus is generally oriented synperiplanar to both phosphonio groups.

The synthesis of salts of the type R n SH 3-n + MF 6 - (R = C 2 H 5 , i-C 3 H 7 ; n = 1, 2; M = As, Sb) by protonation of the corresponding thiols and sulfides in the superacid systems HF/MF 5 is reported. The salts have been characterized by vibrational and NMR spectroscopic methods. Isopropylsulfonium hexafluoroantimonate is the first known example of a sulfonium salt, for which a SH bond distance has been determined by a crystal structure analysis, i-C 3 H 7 SH 2 + SbF 6 - crystallizes in the monoclinic space group P2 1 /m with a = 568.0(4), b = 801.1(6), c = 1019.7(8) pm, β = 82.63(6) °, with two formula units per unit cell.

Polysiloxanes as side chain polymers containing the 2.2′-bithiophene unit, hexyl and octyl terminal groups and spacer units with 3, 5. 6 and 10 methylene groups were prepared and characterized. These polymers have monotropic liquid crystalline phases with transition tem ­ peratures below 0 °C (e. g. for polymer 6p: isotropic → liquid crystalline transition: -20 °C; liquid crystalline → solid transition: -43 °C). Polymers with a trimethylene spacer group must contain an octyl terminal group for forming liquid crystalline phase; a hexyl group does not form such a phase.

The carbene adduct 5 is formed from the 2-tel-luroimidazoline 4 and iodine. The X-ray structure analysis reveals a dimeric structure in the solid state.

[Mn(CH 3 CN) 6 ][MnI 4 ] crystallizes from acetonitrile solutions of Mnl 2 as yellow single crystals which were characterized by their IR spectrum and by a crystal-structure analysis. Space group P2 1 /n, Z = 4, structure solution with 3742 observed unique reflections with F o >5σ(F o ), R = 0.050. Lattice dim ensions at 20°C: a = 1258.0(5), b = 1244.7(2), c = 1753.3(6) pm, β = 92.22(3)°. The compound forms octahedral cations [Mn(CH 3 CN) 6 ] 2+ with site symmetry C i with average Mn-N bond lengths of 222.3 pm and te­trahedral anions [Mnl 4 ] 2- without symmetry with average bond lengths MnI of 271.3 pm.

The structure of Ru(cpO)(cp)Cl complex (3), which was precipitated from aqueous solutions of Ru(cp) 2 Cl + PF 6 - (1), was determined by X-ray crystallographic analysis. The Ru-halogen bond distance was shorter and the dihedral angle be­ tween the rings was larger than the values re­ ported for the corresponding Br analogue, Ru(cpO)(cp)Br (4). The complex 3 (IC 50 109 μM) was more cytotoxic than 1 (IC 50 163 μM) against mouse sarcoma S180 cells, but less toxic than 4 (IC 50 72 μM).