Volume 56, Issue 3

Reaction of 4 N-methyl-2-[1-(pyrrol-2-yl)methylidene]hydrazinecarbothioamide (4ML 1 and 4 N-methyl-2-[1-(pyrrol-2-yl)-ethylidene]hydrazine carbothioamide (4ML 1 ) with zinc(II), cadmium(II) and mercury(II) halides afforded complexes with formulas [M(L)X 2 ] [(L; M; X) =(4ML 1 ; Cd; Cl) (4), (4ML 1 ; Hg; Cl, Br, I) (7 - 9), (4ML 2 ; Cd; Cl) (17), (4ML 2 ; Hg; Cl, Br, I) (20 - 22)] or [M(L) 2 X 2 ] [(L; M; X) = (4ML 1 ; Zn; Cl, Br, I) (1 - 3), (4ML 1 ; Cd; Br, I) (5, 6), (4ML 2 ; Zn; Cl, Br, I) (14 - 16), (4ML 2 ; Cd; Br, I) (18, 19)]. Reaction of 4ML 1 with salts of copper(II), nickel(II), palladium(II) and platinum(II) afforded complexes of formula [M(4ML 1 -H) 2 ] (10 -13). Crystals of 11, 12 and 19 were studied by X-ray diffractometry, and all new compounds were characterized by elemental analysis, mass spectrometry, and IR, electronic and 1 H and 13 C NMR spectroscopy and, when pertinent and allowed by the solubility of the compound, 113 Cd or 199 Hg NMR spectroscopy. In the complexes of Group 12 metals, both ligands are neutral and S-monodentate. In the complexes of copper or Group 10 metals, 4ML 1 is monodeprotonated and S,N-bidentate.

Zinc, 2,6-Diacetylpyridine Bis{N(4)-dimethylthiosemicarbazone}, Electrochemical Synthesis Zinc metal was oxidized in the presence of 2,6-diacetylpyridine bis{N(4)-dimethylthiosemi-carbazone} (2 ,6H 2 Ac4DM) in an acetonitrile solution, to produce a complex of the formula [Zn(2 ,6Ac4DM)] 2 -CH 3 CN. One of the zinc atoms is distorted octahedrally 6-coordinate and the coordination involves both pyridyl nitrogen atoms of the two ligands, the imine nitrogen atom and the thiolato sulfur atom of one thiosemicarbazone moiety of each ligand. The other zinc center is distorted tetrahedrally 4-coordinate with NS coordination of the two remaining thiosemicarbazone moieties. The complex crystallizes in the monoclinic space group C2/c with a = 14.952(2), b = 17.656(3), c = 15.553(4) Å, ß = 111.456(16)°, V= 3821.5(13) Å 3 and Z = 4.

The reactions of bis[triphenyltin(IV)] selenate monohydrate [(Ph 3 Sn) 2 O 4 Se · H 2 O ] with tetraphenylphosphonium halides Ph 4 PX (X = Cl, Br) led to the formation of 1:1 complexes of formula {Ph 4 P[(SeO 4 )(SnPh 3 (SnPh 3 X)] k [X = Br (I) or Cl (II)], which were characterized by infrared, Mössbauer and H, 13 C and Sn 119 Sn NMR techniques and by X-ray diffractometry. The complexes have polymeric structures in which the [SnPh 3 ] + units alternate with bridging [SeO 4 ] 2- units, each of which also bears an SnPh 3 X side chain. In both the [SnPh 3 ] + and the [SnPh 3 X] units the coordination polyhedron of the tin atom is a distorted trigonal bipyramid.

The title compounds were synthesized by reaction of the elements in sealed tantalum tubes in a water-cooled sample chamber in a high-frequency furnace. These magnesium intermetallics crystallize with the tetragonal Mo 2 FeB 2 type structure, space group P4/mbm. The lattice pa­ rameters of all compounds were refined from X-ray powder data. Single crystal X-ray data yielded a = 792.09(6), c = 396.31(8) pm, wR2 = 0.0396, 315 F 2 values for La 2 Cu 2 Mg, a = 778.30(5), c = 384.04(5) pm, wR2 = 0.0954, 214 F 2 values for Nd 2 Cu 2 Mg, and a = 762.65(5), c = 374.09(3) pm, wR2 = 0.0566, 186 F 2 values for Y 2 Cu 2 Mg with 12 variable parameters for each refinement. The RE 2 Cu 2 Mg structures can be described as an intergrowth of distorted A1B 2 and CsCl related slabs of compositions RECu 2 and REMg. Chemical bonding in La 2 Cu 2 Mg was investigated on the basis of extended Hückel calculations and compared to isotypic La 2 Cu 2 ln. This structure was also refined from single crystal X-ray data: P4/mbm, a = 780.8(2), c = 400.1(2) pm, wR2 = 0.0351, 211 F 2 values and 12 variable parameters.

Single crystals of [(TMEDA)LiCl] 2 · toluene (1) and [(MeCN) 2 LiCl] n (2) can be obtained by dissolving LiCl in TMEDA or acetonitrile and crystallization (after addition of toluene for 1) at -30 °C. 1 is a dimer in the solid state while 2 is polymeric. 1 crystallizes in the space group I 2/a, Z = 4, with lattice dimensions at -90 °C: a = 1475.3(1), b=1112.7(2), c = 1615.0(2) pm, β = 103.44(1)°; Rx = 0.0739 with a disorder of the TMEDA ligand in two twist-positions. Crystals of 2 possess the space group Pbcm, Z = 4, with lattice dimensions at -80 °C: a = 1256.8(2), b = 775.2(1), c = 758.6(1) pm;R 1 = 0.0419.

A new type of binuclear coordination compound of lutetium, {Lu 2 L 6 · μ-(γ,γ '-dipy)} (where L = dimethyl-N-trichloroacetylamidophosphate anion and γ,γ '-dipy = 4,4'-dipyridyl), has been obtained. The IR spectroscopic data reveal that the ambidentate phosphoryl ligand is coordinated to the metal center in a bidentate manner via the phosphoryl and carbonyl oxygen atoms. The crystal and molecular structure of {Ln 2 L 6 -μ-(γ ,γ '-dipy)} has been determined by means of X-ray diffraction (triclinic, space group P i with parameters: a = 9.259(2), b = 12.530(3), c = 16.548(3) Å, α = 85.44(3)°, β = 75.64(3)°, γ = 70.56(3)°, Z = 1). The structure is made up of centrosymmetric binuclear molecules, in which the neutral heterocyclic ligand is coordinated to the metal centers in a bidentate bridging manner via its nitrogen atoms. The coordination number of each Lu(III) atom is 7 [60(L - ) + N((γ ,γ '-dipy)]. Phosphoryl and carbonyl groups of the L - ligands are disposed in syn-position and are included in the six-membered chelate metallocycles. The coordination polyhedron of lutetium can be described as distorted mono-capped octahedron.

Imidovanadium(V) Trichlorides The reactions of Me 3 SiN=VCl 3 (1) with MeOH, PhOH, HCl, PyH + Cl - or LiO t Bu have been studied. The reductive decomposition of 1 by hydrogen chloride in toluene yields HN=VCl 3 as a labile intermediate which could be isolated only in a small amount. The syntheses of RN=VCl 3 (R = neopent, n Pr, cyclohex, CPh 3 , 1-Ad) and [( t BuN) 2 V 2 Cl 4 (μ-OC 13 H 9 ) 2 ] (15) are also described. All compounds obtained are characterized by 51 V NMR spectroscopy, the fluorenolato complex 15 by X-ray diffraction analysis.

Several new binuclear nickel(II), oxovanadium(IV) and palladium(II) complexes (ML X ) of tridentate salicylaldimines (L X H 2 ) obtained from substituted salicylaldehydes and 2,4-di-tert-butyl-6-aminophenol, as well as mononuclear nickel(II) and oxovanadium(IV), MQ x nH 2 O, complexes with hydrogenated L X H 2 ligands (Q X H 2 ) have been prepared and their spectroscopic, magnetic and catalytic activity (for PdL x ) have been investigated. NiL x and VOL x complexes when dissolved in pyridine, take up three or two pyridine molecules to form six coordinated complexes, respectively. The Ni(II) and VO(IV) complexes obtained from Q X H 2 can be formu­lated as NiQ x -3H 2 O and VOQ x H 2 O. All VO(IV) complexes have been characterized by ESR parameters. It has been found that some PdLx complexes without any preliminary activation, in EtOH, THF and DMF exhibit high catalytic activity in the hydrogenation of nitrobenzene or cyclohexene at room temperature and at 30 -40 °C under 760 torr H 2 . When this reaction has been carried out in the ESR cavity at room temperature the triplet of 12 line multiplets due to the nitroxyl type coordinated radical (g = 2.013, A N = 10 G, A H = 0.8 G) was detected.

[Rb(benzo-18-crown-6)](I 5 ) H 2 O could be prepared by the reaction of benzo-18-crown-6, rubidium iodide, and iodine in ethanol / dichloromethane. It crystallizes in the monoclinic space group P2 1 /a with a = 1881.8(3), b = 1439.0(2), c = 2269.0(3) pm, ß = 111.24(1)° and Z = 8. The crystal structure was refined to R F = 0.038 for 5310 reflections. It contains two independent molecules. The two cations and the coordinating water molecules form a zigzag chain running along [100] paralleled by two structurally similar pentaiodide chains with one leg of the V-shaped pentaiodide ion forming the backbone of the chain. In both cases the other leg stands out in a novel fashion without forming a coplanar cis or trans configuration known from other pentaiodides. Anionic motifs of other crystalline pentaiodides are summarized and discussed.

The kinetics of the thermal substitution of norbornadiene (nbd) by 2,2'-bipyridine (2,2'-bipy) in (CO) 4 Mo(C 7 H 9 ) was studied by quantitative FT-IR and UV-VIS spectroscopy. The reaction rate exhibits first-order dependence on the concentration of the starting complex, and the observed rate constant depends on the concentration of both leaving nbd and entering 2,2'-bipy ligand. The mechanism was found to be consistent with the previously proposed one, where the rate determining step is the cleavage of one of the two Mo-olefin bonds. The reaction was performed at four different temperatures (35 -50 °C) and the evaluation of the kinetic data gives the activation parameters which now support states.

Ionic ozonides soluble in organic solvents have been synthesized. The crystal structures of bis(triphenylphosphine)iminium-ozonide bis(dimethylamine) (1/2) (P2 1 /c, a = 969.9(2) pm, b = 2007.1(3) pm, c = 1852.4(4) pm, Z = 4, R 1 = 14.34%, 3343 independent reflections), tetrakis[tris(dimethylamino)phosphoranylidenamino]phosphonium-ozonide (P2 1 /n, a = 1120(1) pm, b = 3192(5) pm, c = 1162(1) pm, Z = 4, R 1 = 9.18%, 1428 independent reflections) and tetrakis[tris(dimethylamino)phosphoranylidenamino]phosphonium-ozonide dimethylamine (1/1) (Pbcn, a = 1080.9(6) pm, b = 3560(5) pm, c = 1154(2) pm, Z = 4, R 1 = 12.22%, 2624 independent reflections) have been solved. While these ozonides react with ethers and nitriles, stable solutions in amines and CH 2 Cl 2 have been obtained.

The chloro bridged complexes [(2-phenylpyridine-C,N) 2 RhCl] 2 and [(benzo[h]chinoline-C,N) 2 RhCl] 2 react with the anions of alanine, valine and phenylalanine to give the chiral octahedral N,O-chelates L 2 Rh(α-aminocarboxylate) (1 -5) as mixtures of two diastereoisomers. The complex (benzo[h]chinoline-C,N) 2 Rh[(S)-NH 2 CH(CH 3 )CO 2 -N,0] was characterized by X-ray diffraction. Its crystals contain two diastereoisomers in the unit cell.

The preparation and characterization of some π-donors with a pyrazine-edge-group as well as with tetrathiapentalene-, thiophene-, and dihydrobenzoselenophene-spacer-groups are de­ scribed. Some of these donors give conducting charge transfer complexes with TCNQ and/or cation radical salts with I 3 - , BF 4 - and PF 6 - as counter anions.

[NMe 4 ] 2 [As 4 O 2 Cl 10 ] · 2 CH 3 CN was recovered by the reaction of [NMe 4 ][N 3 ] with AsCl 3 in CH 3 CN under aerobic conditions. This compound was also obtained directly by the reaction of AsCl 3 , AS 2 O 3 and [NMe 4 ][Cl] in acetonitrile. The structure was determined by X-ray diffraction. [NMe 4 ] 2 [As 4 O 2 Cl 10 ] · 2 CH 3 CN crystallizes in theoorthorhombic space group Fmmm with a = 11.4144(8), b = 14.732(1) and c = 19.803(2) Å, with 4 formula units per unit cell. The frequencies obtained by Raman and infrared spectroscopy were assigned to the normal modes of the [As 4 O 2 Cl 10 ] 2- anion in comparison with computational results. The bonding situation in the [As 4 O 2 Cl 10 ] 2- anion was elucidated on the basis of an NBO analysis on the crystallographic data.

The reaction of C(NMe 2 ) 4 (1) with M(CO) 6 (M = Cr, W) in THF solution leads to the anionic carbamoyl complexes [C(NMe 2 ) 3 ][(CO) 5 MC(O)NMe 2 ] (2a, M = Cr; 2c M = W). In the case of M = Mo the resulting complex 2b is not obtained; instead, the salts [C(NMe 2 ) 3 ]2[Mo 2 (CO) 10 ] (3) and [C(NMe 2 ) 3 ][(CO) 4 Mo(O 2 CNMe 2 )] (4) are isolated. The crystal structures of 2a, 3, and 4 are presented. In the salt-like compounds no interatomic contacts between anion and cation exist, and the cations are disordered. The structure of 4 shows two independent molecules. The compounds were further characterized by IR and NMR spectroscopy.

16-β-O-methylneoquassin and 16-β-O-ethylneoquassin, and four known quassi­ noids have been isolated together with coniferyl aldehyde, coniferin, cantin-6-one, 4,5-di-methoxycantin-6-one and (+)-neo-olivil from the wood of Picrasma crenata. Their structures were determined on basis of spectroscopic and X-ray analysis.

It is show n by IR and NMR studies that the xanthines 1-5 prefer a side-on com plexation to the chiral dirhodium tetrakis[(R)-α-methoxy-α-(trifluoromethyl)phenylacetatel (Rh*) in solution whereas carbonyl groups are involved in the solid state. For 6, at least the carbonyl group C-6 contributes to complexation in solution as well. A lternating strands of 6 and Rh* exist in the solid state as revealed by X-ray diffraction analysis described in detail. The determination of enantiomeric excess of the chiral xanthine 6 can easily be accomplished by the “dirhodium method ” ( 1 H and 13 C NMR in the presence of Rh*).

Asymmetrie Total Synthesis Asymmetrie total synthesis of S-(+)-argentilactone (2) was accomplished, using methyl-a-D-glucopyranoside (3) as carbohydrate template. Benzylidene acetal 5 was hydrolysed with t BuOOH/AlCl 3 and further manipulated to produce the aldehyde 10. A Wittig reaction and subsequent oxidation of the anomeric position yielded the target argentilactone.