Volume 46, Issue 11

In order to study the properties of sulfur coordinated metal centres, the chromium and tungsten complexes [Cr(NO)(µ-′S 4 ′)] 2 (4), (NR 4 ) 2 [W(NO) 2 (′S 2 ′) 2 ] (1) (R = Me (la), n-Bu (lb)), [W(NO) 2 (′S 4 ′)] (2), [µ-O{W(NO)(′S 4 ′)} 2 ] (3) and [W(NPR 3 )(NO)(′S 4 ′)] (5) (R = Me (5a), Et (5 b)) were synthesized (′S 2 ′2- = 1.2-benzenedithiolate(2-); ′S 4 ′2- = 1.2-bis(2-mercaptophenylthio)ethane(2-)). la and lb result from the reductive nitrosylation of Li 2 [W(′S 2 ′) 3 ] which was prepared by reduction of [W(′S 2 ′) 3 ] with n-BuLi. la was also obtained from [W(NO) 2 (Cl) 2 ] n , ′S 2 ′2- and NMe 4 + . Alkylation of la or lb by 1.2-dibromoethane yields 2, whose X-ray structure analysis shows that W is pseudooctahedrally coordinated by two trans thiolato S, two cis thioether S and two cis N atoms of linear W-NO groups. 2 was also obtained from [W(NO) 2 (CH 3 CN) 4 ](BF 4 ) 2 or [W(NO) 2 (Cl) 2 ] n and ′S 4 ′2- -. The reaction of [W(NO) 2 (Cl) 2 ] n yielded the dinuclear oxo-bridged complex 3 as a by-product in small amounts. In preparative amounts, 3 was synthesized by hydrolysis of [W(Cl)(NO)(′S 4 ′)]. In contrast to the analogous Mo complex, 2 does not react with N 2 H 4 ; with the ligands PMe 3 and PEt 3 , it gives the corresponding phosphiniminato complexes 5 and free phosphineoxides OPR 3 . In order to compare the [M(NO) 2 (′S 4 ′)] complexes (M = Cr, Mo, W), the structure of [Cr(NO) 2 (′S 4 ′)] was determined by X-ray structure analysis. The Cr complex exhibits the same molecular coordination geometry as 2. While growing crystals of [Cr(NO) 2 (′S 4 ′)], the dinuclear Cr complex 4 was also formed. Its X-ray structure analysis shows each of the Cr centres to be coordinated pseudooctahedrally by five sulfur donors and one nitrosyl N donor. 4 was also obtained by the reaction of [Cr(CO) 4 (nor)] with ′S 4 ′2- and NOBF 4 .

In order to study specific properties of transition metal sulfur complexes, reactions of [Mo(NO) 2 (′S 4 ′)] (1) with nucleophiles were investigated. With sodiumborohydride or hydrazine, 1 yields the hydroxylaminyl complex [Mo(η 2 -NH 2 O)(NO)(′S 4 ′)] (2). 2 crystallizes from DMF as 2 · DMF whose molecular structure was determined by X-ray structure analysis (P2 1 /c, Z = 4, a = 1204.4(3), b = 1579.7(4), c = 1253.0(4) pm, β = 117.44(2)°, R = 0,056, R w = 0,040). The Mo centre is coordinated by two trans thiolato S, two cis thioether S atoms, the co-ligand NO and side-on NH 2 O in a distorted pentagonal bipyramid; the DMF molecule is hydrogen bonded to the NH 2 O-ligand. NMR spectroscopy shows that in solution 2 exists in two configurational isomers differing in the orientation of the side-on NH 2 O with respect to the [Mo(NO)(′S 4 ′)] core. The mechanism of the reduction of 1 is discussed in terms of a 2e - -2H + -transfer.

Racemic [Ru(ClH)(PPh 3 )′S 4 '] · CH 2 Cl 2 (′S 4 ' 2- = 1,2-bis(2-mercaptophenylthio)ethane(2—)) reacts with monodentate sulfur ligands L to yield diastereospecifically yellow adducts [Ru(L)(PPh 3 )′S 4 ']. Asymmetric achiral thioethers (L = SPhMe, CH 3 SSCH 3 ) give only one of two potentially possible pairs of enantiomers, chiral thioethers and thiols (L = N-Acetyl-(L)-Methionin, N-Acetyl-(L)Methionin-methylester, S-Methyl-(L)Cystein, N-Acetyl-(L)Cystein) only two of four potentially possible diastereomers in the ratio 1:1. These results prove that the diastereospecifity is related to the coordinated thioether or thiol sulfur atom: It becomes stereogenic in the course of coordination and its configuration is determined by the chirality of the [Ru(PPh 3 )′S 4 '] fragment. Additional stereogenic centres in the substituents of chiral thioethers or thiols do not enhance the degree of diastereoselectivity.

Chlorine reacts with CH 3 OSO + MF 6 - (M = As, Sb) at 298 K to form AsCl 4 + AsF 6 - and SbCl 4 + Sb 2 Cl 2 F 9 - , respectively. The analogous reactions with bromine at 233 K result in the formation of (CH 3 ) 2 Br + AsF 6 - and Sb 2 F 11 - . With iodine, the new methyliodonium salts (CH 3 I 2 ) n n+ (MF 6 - ) n (M = As, Sb) with yet unknown constitution are obtained.

New N 1 ,N 2 -di-Boc-N 4 -acyl-1,2,4-butanetriamines 5 (acyl = acetyl, trifluoroacetyl, benzoyl, carboxycyclohexyl, caproyl, carboxycyclobutyl) have been prepared by ring cleavage acylation of N w -acylated histamines with di-tert-butyl dicarbonate, and reduction with Raney nickel. Free vicinal diamines 6 were generated by acidic removal of Boc-protecting groups and transformed into dichloroplatinum(II) 7 and dichloropalladium(II) complexes 8. By basic treatment of the N 1 ,N 2 -di-Boc-N 4 -trifluoroacetyl-1,2,4-butanetriamine 5b the protecting group was removed from the terminal amine to give N 1 ,N 2 -di-Boc-1,2,4-butanetriamine 9 which forms cis-dichloroplatinum(II) and palladium(II) complexes 10, 11. The compounds have been characterized by IR, NMR ( 1 H, 13 C) spectroscopy and elemental analysis, and the structures of the trifluoroacetyl compounds confirmed by 1 H 13 C and 1 H 1 H 2D NMR spectroscopy.

The trinuclear copper(II) complex [(LCu) 2 Cu(H 2 O)](ClO 4 ) 2 ·2H 2 O (L = 4,7-bis(2-hydroxybenzyl)-1-oxa-4,7-diazacyclononane) has been synthesized and its crystal structure has been determined. From temperature dependent magnetic susceptibility measurements strong intramolecular antiferromagnetic coupling of the spins has been detected yielding an S = 1/2 ground state. The trinuclear species dimerizes in acetone solution to yield {[(CuL) 2 Cu] 2 }(ClO 4 ) 4 which has an S = O ground state.

The mixed chloro-bromo-technetates(IV), [TcCl n Br 6-n 2- , n = 1-5, have been separated for the first time by ion exchange chromatography on diethylaminoethyl-cellulose. Due to the stronger trans-effect of Br as compared to Cl, the ligand exchange reactions of [TcBr 6 2- with HCl and of [TcCl 6 ] 2- with HBr proceed stereospecifically, to form either cis/fac- or trans/merspecies for n = 2, 3, 4, respectively. To avoid photoisomerization the compounds have to be handled in the absence of light. The IR and Raman spectra of the ten chloro-bromo-techne-tates(IV), including the pure geometrical isomers, have been recorded at low temperature (80 K) and completely assigned to structures of point groups O h , D 4h , C 4v , C 3v , and C 2v , supported by normal coordinate analysis based on a general valence force field. Due to the different trans-influences Cl < Br in asymmetric Cl′—Tc— Br′ axes, the Tc— Br′ bonds are strengthened and the Tc—Cl′ bonds are weakened, as indicated by valence force constants, for Tc—Br′ on average 6% higher and for Tc—Cl′ 10% lower, as compared with the values calculated for symmetric Br—Tc—Br and CI—Tc—Cl axes, respectively.

The synthesis of 1,3,6,8-tetra-tert-butylcarbazole (2) by the reaction of carbazole with tertbutyl chloride in the presence of aluminium chloride is reported. The X-ray structures of 2 and its diethyl ether adduct are compared. The gap formed by the tert-butyl groups in 1,8-position has been calculated and compared with that of the supermesithyl substituent.

Trisalkoxyvanadyl compounds and products of their hydrolysis were characterized by 51 V NMR spectroscopy. There are characteristic connections between interactions of VO(OR) 3 compounds in solution and the hydrolysis behaviour. On hydrolysis, a fast condensation process leads to intermediate decavanadate species. In a following slow reaction depending on the composition of the solution different equilibrium species are formed.

Products of the thermolysis of NH 4 Al-alum were prepared under dried air and characterized by X-ray powder diffraction, thermogravimetry, and for the first time by solid-state 27 Al-MAS-NMR spectroscopy. It was found, that high resolution NMR spectroscopy is applicable to follow up the thermal decomposition and to indicate even minor structural changes. 27 Al-MAS-NMR spectra show peaks with characteristic chemical shifts for octahedral Al-units up to a high stage of thermolysis. During the decomposition of Al 2 (SO 4 ) 3 to γ-Al 2 O 3 we again observed three-peak spectra with the specific signal at ≈ 35 ppm for penta-coordinated Al ions as recently proved for the thermolysis of AlCl 3 · 6 H 2 O.

New ether-phosphines of the type Ph 2 P~D (2d, 2g-1, 2n-p) with different electronic and steric properties which are provided with open-chained or cyclic ether moieties are obtained by reaction of LiPPh 2 with the corresponding chloromethyl substituted ethers ClCH 2 ~D (1d, 1g-1, 1n-p) in THF. The ligands 2d, 2g-1, and 2n-p are characterized by selected IR and NMR data which function as probes for complexation to transition metals.

Diamagnetic clusters [Mo 3 X-μ-(S 2 ) 3 -μ 3 (S)(R 2 PS 2 ) 3 ] 2-4 (2: X = Cl; 3: X = Br; 4: X = I; 2-4: a: R = Et; b: R = Pr; c: R = Bu) are conveniently obtained by reaction of [Mo 3 S 7 (R 2 PS 2 ) 3 ] + (R 2 PS 2 ) - 1 either with alkyl halides RX or with tetraalkylammonium halides R 4 NX. Between halogen X and one of the S atoms of each disulfido bridge there exist bonds which seem to be mainly of covalent character. Thus X is incorporated into the cluster core leading to a cubane type structure. [Mo 3 ClS 7 (Et 2 PS 2 )3] forms orthorhombic crystals with space group Pnma, Z = 4, a = 1931.9(7), b = 1551.2(6), c = 1286.5(4) pm. Isostructural substructures of 3b, 4a and 4b (space group P2 1 ) were also studied. All these cluster molecules reveal similar core geometries with distances S—Cl 239.4(4), S—Br 305(1) and S—I 322.5(3) pm much less than the sum of the van der Waals radii. The results of structural and spectroscopic investigations are discussed.

Synthetic procedures are described that allow access to anilinium salts containing the complex anions [Hg 2 Cl 6 2- , [Hg 2 Cl 4 X 2 ] 2- (X = Br, I), [CdHgI 6 ] 2- , [CdHgI 4 Br 2 ] 2- and [CdHgBr 4 I 2 ] 2- -. Isolated dimeric structures are proposed for the new complexes in the solid state, using X-ray powder patterns, Far-IR and Raman spectra. The spectral detail is greatly enhanced in measurements at low temperature (∼100 K).

The title compound 1 has been prepared by the reaction of i-PrInCl 2 with LiCH(SiMe 3 ) 2 in diethylether at -30 °C. The colorless substance 1 was characterized by NMR, IR, and RE spectroscopy, as well as by mass spectrometry. 1 is dimer in solution and the solid state and crystallizes in the space group P2 1 /c with the cell parameters a = 1206.4(3) pm, b = 905.7(2) pm, c = 1591.2(5) pm, and β = 101.18(2)°. The unit cell contains two centrosymmetrical dimeric molecules.

The chemical stability of 1,1′-dialkyl-4,4′-bipyridinium compounds (viologens) as electron relay agents in hydrogen producing water photolytic systems is of great importance for practical applications. Three new 1,1′-dialkyl-4,4′-bipyridinium compounds (1 = 1,1′-dimethyl-2-phenyl-6-(p-tolyl)-4,4′-bipyridiniumdiperchlorate, 2 = 1,1′-dimethyl-2-phenyl-4,4′-bipyridiniumdiperchlorate, 3 = 6-phenyl-1,1′,2-trimethyl-4,4′-bipyridiniumdiperchlorate) have been investigated with respect to their stability and turnover numbers in a classical water photolytic system. H 2 was detected during irradiation of solutions using Ru(bipy) 3 Cl 2 as sensitizer, 1-3 as electron relay, EDTA as sacrificial electron donor, and a colloidal catalyst (platinum or palladium) with light λ > 400 nm. Quantum yields (platinum catalyst, light: 400-500 nm) were 18% 1 and 3, 16% 2, compared with methylviologen: 16%. The loss of 1,1′-dialkyl-4,4′-bipyridinium compounds due to hydrogenation was monitored by HPLC. Turnover Numbers (only hydrogen in gas phase was taken into account) were found to be 82 1, 64 2, 57 3 as compared with 39 for methylviologen. Using palladium or palladium supported on BaSO 4 instead of platinum as catalysts did not increase the turnover numbers.

The bicyclo[2.2.2]octane-2-spirocycylohexane structure o f dimers arising from 3-methylcyclohex-2-enones by sodamide-catalyzed self-condensation is established by a study of the 3′,6-dione and 3′-hydroxy-6-ketone by the 13 C NMR two-dimensional spectral (INADEQUATE) technique. The 3′,6-dione, the ultimate source of all other compounds of this series, is obtained by an improved procedure. Only one of its keto-groups reacts with ketonic reagents, resulting exclusively in 3′-monosubstituted derivatives

The reduction of spirodiisophora-3′,6-dione under various conditions occurs exclusively at its 3′-keto-function in the cyclohexane ring. The action of lithium aluminium hydride yields the 3′-eq-hydroxyketone, while catalytic hydrogenation, hydroboration and the action of metal borohydride produces the 3′-ax-epimer. The conformers give rise to pairs of distinct epimeric functional derivatives. Anhydrous hydrazine removes the 3′-oxygen function of the 3′,6-dione entirely, with formation of spirodiisophor-6-one. Catalytic hydrogenation of the 3′-oximino-6-ketone yields the corresponding 3′-amine. The 13 C NMR spectra of the individual products are assigned and correlated with their structures.

Me 2 Sn(O 2 PMe 2 )2 has been prepared from the reaction of Me 2 PO 2 H and Me 2 SnS in benzene, and Al(Ο 2 ΡΜe 2 ) 3 and Cl 2 Sn(O 2 PMe 2 ) 2 have obtained from the reaction of Me 2 PO 2 H with AlCl 3 and SnCl 4 , respectively in CH 2 Cl 2 . The vibrational spectra of the compounds were found to be consistent with polymeric structures with hexacoordinated metal atoms.

The reaction of cyclodimeric group 4b metallocene sulfides [(RCp) 2 MS] 2 (M = Zr, R = H, Me, tBu: 2a-c; M = Hf, R = H, Me: 2d,e) with trialkylaluminum compounds gives dimeric sulfur-bridged metallocene/aluminum complexes [(RCp) 2 M(R′)SAlR′ 2 ] 2 (M = Zr, R = H, Me, tBu, R′ = Me: 3a-c; M = Hf, R = H, Me, R′ = Me: 3d,e, R′ = Et: 3f,g). At low temperature the primarily formed adduct [(MeCp) 2 ZrS] 2 · AlMe 3 6 was isolated and its temperature-de-pendent dynamic NMR spectra monitored. The metallocene sulfide/trialkylaluminum addition products exhibit a reaction pattern which indicates the occurrence of reversible alkyl migration between the main group and transition metal center. This may be of relevance for developing novel types of olefin oligomerization catalysts.

Some (cyanomethyl)alkylphenyl phosphines R(C 6 H 5 )PCH 2 CN (R = CH 3 , C 2 H 5 , C 3 H 7 , C 4 H 9 , i-C 4 H 9 , C 5 H 11 ,) were prepared by the reaction of the corresponding (trimethylsilyl)alkylphenyl phosphines with chloroacetonitrile and characterized by elemental analyses and spectroscopic data (IR; 1 H, 31 P and 13 C NMR).

The (ether-phosphine)cobalt(II) complexes I 2 Co[D~P(Ph)CH 2 CH 2 P(Ph)~D] (3a) [D = CH 2 C 4 H 7 O 2 (a)] and I 2 Co(Ph 2 P~D) 2 (6b,c) [D = CH 2 C 5 H 9 O (b), CH 2 C 3 H 5 O 2 (c)] are obtained by reaction of CoI 2 with the ligands D~P(Ph)CH 2 CH 2 P(Ph)~D (1a) and Ph 2 P~D (2b,c). Reduction of 3a and 6b, c with K[HB(sec-C 4 H 9 ) 3 ] results in the formation of the cobalt(I) complexes ICo[D⁀P(Ph)CH 2 CH 2 P(Ph)~D] (4a) and ICo(D⁀PPh 2 )(D~PPh 2 ) (7b,c) (D~P: η 1 -P coordinated; D⁀P: η 2 -O,P coordinated). 4a and 7b, c are precatalysts in the carbonylation and hydrocarbonylation of methanol to methyl acetate and acetaldehyde, respectively. The weak Co-O bond is cleaved by reaction of 4a and 7b, c with CO to give the dicarbonyl cobalt complexes 5a and 8b,c.