Volume 38, Issue 8

Monoclinic AsSbO 3 was prepared by heating an equimolar mixture of AS 2 O 3 and Sb 2 O 3 to 670 K in an evacuated quartz tube. The crystal structure was determined [P2 1 /n, a = 458(1), b = 1316(2), c = 544(1) pm, β = 95.0(1)°, Z = 4, R = 0.055 for 745 reflections] and found to be isostructural with the As 2 O 3 modification claudetite I. Mean As-O and Sb-O bond lengths are 180 and 195 pm, respectively. There is no crystallographic evidence for any significant As/Sb disorder.

Crystals of hexaiodoplatinates(IV) M 2 PtIe (M = K, Rb, Cs, NH 4 , Tl) have been obtained by heating PtI 4 or H 2 FtCl 6 in highly concentrated aqueous solutions of MI in the presence of small amounts of HI and I 2 in an ampoule for 24 h at 160 °C. The structural parameters were determined from single crystal data. In water less soluble compounds with M = Rb, Cs, NH 4 show the cubic K 2 PtCl 6 structure, whereas the easily water soluble salts with M = K, Tl both crystallize in a tetragonally distorted version of this structure type.

CaHg(SCN) 4 · nH 2 O (n = 2(1), n = 3(2)) were isolated from an aqueous solution of Ca(NCS) 2 · 4H 2 O and Hg(SCN) 2 · 1 is compared with the analogous MgHg(SCN) 4 · 2H 2 O by means of powder patterns. The crystal structure of 2 has been determined. 2 is monoclinic, space group P2 1 /c with a =9.469(4), b = 22.781(5), c = 6.587(4) Å, β = 93.6(3)°, Z = 4, d c = 2.46 g · cm -3 . The structure was refined to R = 7.42 and R w = 4.96% for 1224 independent reflec­tions. The species MHg(SCN) 4 · 2H 2 O (M = Mg, Ca, Ni) contain nearly tetrahedral Hg(SCN) 4 and octahedral M(OH 2 ) 2 (NCS) 4 groups which are joined by Hg-SCN-M bridges. In contrast the structures of the other compounds MHg(SCN) 4 · nH 2 O (M = Co, n = 0; M = Ca, Sr, n = 3) are based on the diamond net. There is tetrahedral coordination of all the metal atoms, M having 4 N and Hg 4 S nearest neighbours. In the hydrates the H 2 O molecules are situated additionally at the Ca and Sr atoms [*].

The reaction of RuCl 3 · 3 H 2 O with aqueous KSCN does not yield [Ru(NCS)e] 3- as supposed previously, but a mixture of bond isomeric complexes [Ru(NCS) n (SCN) 6-n ] 3- , n= 1-4. On prolonged heating of the solid tetrabutylammonium(TBA)-salts of this mixture (TBA) 3 [Ru(NCS) 5 (SCN)] is formed, which decomposes above 130 °C. By an­nealing the more stable bis-triphenylphosphineiminium(PNP) salts up to 160 °C the complex mixture is rearranged to (PNP) 3 [Ru(NCS) 6 ] - On stirring the emulsion of the (PNP) compound in ethanol with a 100-fold excess of (TBA)Br, (TBA) 3 [Ru(NCS) 6 ] is obtained. The IR and Raman spectra are assigned according to the point symmetry Oh of the complex ion.

The new compound Na 4 SnTe 4 crystallizes in the orthorhombic system, space group P2 1 2 1 2 1 with lattice constants a = 865.8(5) pm, b = 884.0(5) pm, and c = 1526.9(8) pm. In the structure there are isolated SnTe 4 4 - -tetrahedra.

Na 8 Ge 4 Te 10 exists in two modifications I and II, of which structure I was determined previous by [3]. Modification II crystallizes in the triclinic system, space group P1̄ with the lattice constants: a = 1070.1(5) pm, b = 963.9(5) pm, c = 792.3(4) pm α = 67.9(1)°, β = 70.7(1)°, γ = 68.3(1)°. In the structure there are [Ge 4 Te 10 ] 8- anions in the form of six-membered rings [(GeTe 2 ) 4 Te 2 ] 8- .

A survey about the reaction between α-azidoacetophenones with aromatic nitroso compounds is given. The synthesis of α-imino-β-ketonitriles and some electrochemical properties of this class are described.

The ligand properties of [18]crown-6 towards Co(II) ions were studied by 1 H and 13 C NMR spectroscopy in nitromethane and nitromethane/methanol. The complexes [Co([18]crown-6)] ++ and mer-[Co([18]crown-6)(CH 3 OH) 3 ] ++ which were detected in solu­tion show ligand fluctuations on the NMR time scale. For the mixed complex a crown ether rotation occurs. Additionally, a synchronous process between the movement of the macrocyclic ligand and the dissociation reaction of methanol from the metal ion is observed.

The geometry around the penta-coordinated silicon atoms in the two crystallographically independent molecules in tetramethylammonium-bis(tetramethylethylenedioxy)fluorosilane dichloromethane solvate is distorted from the trigonal bipyramid towards the square pyramid by 69.1 % and 52.3%, resp. [N(CH 3 ) 4 ] + [FSi(OC(CH 3 ) 2 C(CH 3 ) 2 O) 2 ]-. CH 2 Cl 2 crystal­lizes in the monoclinic space group P2 1 /n, Z = 8 with a= 20.926(6), 6= 15.117(1), c = 17.008(4) Å, β = 114.88(2)°. The structure was refined to R = 0.084 using 2203 independent reflections.

(OC-6-32)-W(CO) 3 [(CH 3 ) 2 PC 2 H 4 P(CH 3 ) 2 ] (olefin) complexes (9-14) were prepared photochemically from W(CO) 4 [(CH 3 ) 2 PC 2 H 4 P(CH 3 ) 2 ](l) via W(CO) 3 [(CH 3 ) 2 PC 2 H 4 P(CH 3 ) 2 ]- (THF) (2) and the electron poor olefins dimethyl inalonate(3), fumarate (4), inothylfumarate (5), fluorofumarato (6), chlorofumarato (7) and bromofumarate (8). The stereoche­mistry of 9-14 was elucidated by IR and NMR spectroscopy. The hindered rotations of the olefin ligands in 9-14 were studied by D-NMR spectroscopy. 11-14 form two diastereomeric isomers when the olefin rotation is freezed. The spectroscopic behaviour of the dimethyl fumarato complex 10 gives unambiguous proof for the rotation of the olefin ligand around the metal-olefin-bond. Alternative motions are ruled out.

4-Lithium-3,3,5-trimethyl-2-tert-butyl-1,2-diaza-3-sila-5-cyclopentene is oxidized in the reaction with transition metal halides and subsequently dimerizes. Oxidation potentials are given and a reaction mechanism is proposed.

Trimethylheptaphosphane(3) (1) was proved to possess the earlier reported structure of a 3,5,7-triorganotrieyclo[2.2.1.0 2,6 ] heptaphosphane [3] by complete analysis of its 31 P{ 1 H} NMR spectrum. The experimental spectrum can be simulated very satisfactorily by the superposition of the spectra of two isomers P 7 Me 3sym and P 7 Me 3 asym, differing from each other in the orientation of the methyl groups. A comparison of the chemical shifts with those of (Me 3 Si) 3 P 7 and Li 3 P 7 leads to a detailed information about the geometry of the P7-skeleton in both isomers of 1.

Reaction of FeCl 3 · 4 H 2 O with dttd 2- , the dianion of 2,3,8,9-dibenzo-1.4,7,10-tetru-thiadecane, leads to the solvated [Fe(dttd)], which coordinates CO, PMe 3 and N 3 H 4 yielding [Fe(CO) 2 dttd], [Fe(PMe 3 ) 2 dttd], [Fe(CO)PMe 3 (dttd)], [Fe(N 2 H 4 ) 2 dttd] and [Fe(N 2 H 4 )CO(dttd), respectively. With H 2 S and [Fe(dttd)] the Fe(III) complex (PPN) 2 [F e 2(S) 2 (dttd) 2 ] is obtained. PPh 3 cannot be coordinated to [Fe(dttd)], whereas the reaction between [Fe(PPh 3 )(CO) 3 I 2 ] and LiSC 6 H 4 SCH 3 yields [Fe(PPh 3 )CO(CH 3 SCeH 4 S) 2 ] besides the major product [Fe(CO) 2 (CH 3 SCeH 4 S) 2 ]. A PPh 3 complex can be obtained also with o-benzenedithiolate, C 6 H 4 S 2 2- : Reacting [Fe(PPh 3 )(CO) 3 I 3 ] with Li 2 S 2 C 6 H 4 yields the binuclear [Fe(PPh 3 )(CO) 2 C 6 H 4 S 2 ] 2 . Oxidation of [Fe(N 3 H 4 )CO(dttd)] by various agents leads to [Fo(CO)dttd] 2 without evidence of formation of a N 2 complex intermediate. Nucleophilic attack of [Fe(CO) 2 (CH 3 SC 6 H 4 S) 2 ] by lithium organyls as e.g. LiPh leads to the benzoylato complex [Li(THF) 3 ][Fe(CO)(PhCO)(CH 3 SC 6 H 4 S) 2 ]; the structures of the starting complex as well as of the adduct have been elucidated by X-ray structure determination. Nucleophilic attack of the corresponding [Fe(CO) 2 dttd] by LiPh occurs reversibly at the Fe center; by cleavage of a Fe-S bond [Fe(Ph)(CO) 2 dttd′] - is formed, where dttd′ is acting as a tridentate ligand. This result shows how the reactions of formally equivalent complexes like [Fe(CO) 2 (CH 3 SC 6 H 4 S) 2 ] and [Fe(CO) 2 dttd] depend strongly upon the denticity of the sulfur ligands. The dependence upon the character of the nucleophilic agent is shown by the reaction of [Fe(CO) 2 dttd] with Li[BEt 3 H]; in this case again a CO ligand is attacked reversibly yielding the formyl complex [LiBEt 3 ][Fe(HCO)CO(dttd)], the structure of which could be elucidated so far only spectroscopically as well as by elemental analysis. [Fe(Ph)(CO)gdttd′] - forms salts like e.g. (AsPh 4 )[Fe(Ph)(CO) 2 dttd]; in solution they slowly loose CO yielding e.g. binuclear (AsPh 4 ) 2 [Fe(Ph)dttd] 3 . Attempts to isolate the anion as [Li(TMED) 3 ] + salt load to the loss of CO as well as of phenyl ligands yielding the paramagnetic [Fe(TMED)dttd], which is also obtained directly from [Fe(dttd)] and TMED. The phenyl complex [Fe(Ph)dttd] 2 2- is also formed by reaction of [Fe(dttd)] with LiPh; on reaction with dimethyl-formamide it yields [Fe(DMF)dttd] 2 . A series of the above described compounds has been investigated by Mößbauer spectroscopy.

Ternary copper(II) complexes of 3′,5′-cIMP and 3′,5′-cGMP with o-phenanthroline have been isolated from aqueous solution at respective pH values of 2.8 and 5.8. Their structures have been established by single crystal X-ray diffraction. The copper atom in [Cu(3′,5′-cIMP)(phen)(H 2 O) 2 ][NO 3 ].2H 2 O (1) binds N(7) of the hypoxanthine base and displays a square pyramidal coordination. [Cu(phen) 2 (H 2 O)] 2+ and 3′,5′-cGMP form a 1 : 2 intercalation complex [Cu(phen) 2 (H 2 O)][3′,5′-cGMP]2 · 9H 2 O (2) in which direct metal- nucleotide binding is absent.

The known Z-isomers of some N-unsubstituted 5-benzylidenepyrrolin-2-ones (2, 10, 12) change the configuration upon heating with oxalylchloride. Methanolysis of the intermediate imides (6, 8, 9) yields the corresponding E-isomers.

An efficient method for the synthesis of furo[2,3-b]quinoxalines has been devised. Thus, 3-halo-2-arylfuro[2,3-b]quinoxalines, 5a-5c were synthesized by the action of cone. H 2 SO 4 on 3-(1-halo-2-oxo-2-arylethyl)-2(1H)quinoxalinones, 3b, 3c and 3f respectively. When 3-(1-halo-2-oxo-2-substitutedethyl)-2(1H)quinoxalinones 3d and 3e (substituent = t-butyl, ethoxy) were utilized in this reaction 3-halomethylene-2(1H)quinoxalinone 6a and 6b were obtained in high yield.

Following a general method N,N-dimethyl, N,N-diethyl, N-isopropyl and N-piperidinyl- amino-N-vanillylpropionamide were synthesized. Their spectroscopic ( 1 H and 13 C NMR, MS) properties are reported.

Treatment of 1,8-Dihydroxy-naphthaline with bromochloromethane/K 3 CO 3 in DMF gives Naphtho[1,8-de]-1,3-dioxine (1a) in good yield. The bromo (1b) and nitro compound (1c) can be obtained free of isomorics by electrophilic substitution of la. Bromolithium exchange of 1b leads to a lithium organic compound, which possibles the synthesis of alkyl-, olefinic-, and carboxylic derivatives of the substrate 1a. In a similar way the treatment of 2,3-dihydroxynaphthazarin with chlorobromomethane/K 2 CO 3 gives the naphtho[1,8-de;4,5-d′e′]-bis-1,3-dioxine (3a). The substrate 3a can be subjected to electrophilic aromatic substitutions.

1,1′-Thiocarbonyldiimidazole converts N-substituted glycolohydroxamic acids (1) at room temperature into 6-thioxoperhydro-1,5,2-dioxazino-3-ones (2 B), which are highly reactive heterocyclic compounds. In the presence of primary amines (3), benzyloxyamine (6a), hydroxylamine (6b) and hydrazines (8a-d) ring transformation of 2 B occurs, yielding 2-thioxooxazolidine-4-ones of type 5, 7 and 9.

Tho synthesis of a series of 12-O-amino acyl- and 12-O-peptidyl-13-acetate and -13,20- diacetate esters of the tetracyclic diterpene alcohol phorbol is described. These esters, which include amino acid moieties with both N-protected and free amino functions, were all tested for irritant activity on mouse ear. The highest activities were observed for esters with N-9-fluorenylmethyloxycarbonyl-protected leucine and 11-aminoundecanoic acid.

Three Roe-protected fragments of the human leukocyte interferon, LeIFA, have been synthesized: I, BOC LeIFA (99-105) (BOC-Val-Ile-Gln-Gly-Val-Gly-Val); II, BOC Lei FA (116-119) (BOC-Ile-Leu-Ala-Val); III, BOC LeIFA (123-126) (BOC-Phe-Gln-Arg(Tos)-Ile). The presence of the Boc-group was desired so that these peptides could serve as intermediates in fragment condensation toward larger segments of interferon. To achieve these intermediates, a study was desirable on three methods of cleavage of the benzyl ester-polymer bonds. It was found that hydrogenolysis with hydrogen and palla­dium generated in situ was distinctly superior to transfer hydrogenation with ammonium formate or cyclohexene. An effective swelling of the peptide-resin to allow penetration of palladium acetate into the matrix and mobility of the peptide chains on the resin to expose the bonzyl ester bond to hydrogenolysis appear to be essential conditions for the best cleavage.

The stereochemistry of the hydrolysis of tellurium hexafluoride has been followed up by 125 Te NMR spectroscopy for each individual step of replacement of fluorine by a hydroxy group.

The syntheses of (t-Bu) 2 PCH 2 P(t-Bu) 2 and (PhO) 2 PCH 2 P(Oph) 2 and an improvement of the synthesis of Me 2 PCH 2 PMe 2 are described. Mixed Me/CH 2 SiMe 3 and Cl/t-Bu diphosphinomethane derivatives are characterized by means of NMR spectroscopy.

PPh 3 Me[Os(NO)Cl 4 ] is prepared by the reac­tion of (NO) 2 [Os(NO)Cl 5 ] with methyltriphenylphosphonium chloride in CH 2 Cl 2 solution. The complex forms brown, air stable crystals, which are characterized by the IR spectrum as well as by an X-ray structure determination (space group P1̄, two formula units per unit cell, a = 906, b = 1172, c = 1198 pm, α = 76.4, β = 84.8, γ = 82.4°, 3254 independent reflexi­ons, R w = 8.6%). The structure consists of [P(C 6 H 5 ) 3 CH 3 ] ⊕ cations and disordered [Os-(NO)Cl 4 ] ⊖ anions; the latter have approximate C 4V symmetry with a linearly coordinated nitrosyl ligand in the axial position.

The diquaternary salt of 4,4 ′ -oxybispyridine, 1,1′-dimethyl-4,4′-oxybispyridinediium bis- (fluorosulfonate), is reduced polarographically by a one electron transfer not involving hydro­gen to an unstable radical cation at a potential (E 0 ) of -0.80 V in the pH range 5.1-10.4.