Volume 52, Issue 3

The heats of solution of Yttrium, YOCL, YOBr, YOI, YCl 3 , YBr 3 , YI 3 and Y 2 O 3 were determined in 4n HX. From those the enthalpies of formation of Yttrium Trihalides YX 3 and Yttrium Oxyhalides YOX at 298 K were derived: ΔH B 0 (YCl 3,f,298 ) = -240.4 ± 0.6 kcal/mol, ΔH B 0 (YBr 3,f,298 ) = -202.1 ± 1.5 kcal/mol, ΔH B 0 (YI 3,f ,298 ) = -147.0 ± 1.7 kcal/mol, ΔH B 0 (YOCl f,298 ) = -240.2 ± 1.0 kcal/mol, ΔH B 0 (YOBr f,298 ) = -229.7 ± 2.0 kcal/mol, ΔH B 0 (YOI f ,298 ) = -208.8 ± 2.0 kcal/mol.

The heat of solution of all solid phases in the system YX 3 -NH 4 X with X = Cl, Br, I in 4n HX was investigated. The enthalpies of formation of the ammonium yttrium halides are derived from the enthalpies of formation of Y X 3 and of NH 4 X and their heats of solution in An HX: ΔH B 0 (NH 4 Y 2 Cl 7,f,298 ) = -561,5 ± 1,7 kcal/mol, ΔH B 0 ((NH 4 ) 3 YCl 6,f,298 ) = -474,5 ± 1,3 kcal/mol, ΔH B 0 ((NH 4 ) 3 YBr 6,f,298 ) = -400,8 ± 2,6 kcal/mol, ΔH B 0 ((NH 4 ) 3 YI 6,f,298 ) = -291,9 ± 3,0 kcal/mol.

The crystal structures of [(C 5 H 5 N) 2 CH 2 ][OsCl 4 (ox)] (monoclinic, space group I2/m, a = 10.260(5), b = 13.841(5), c = 12.273(5) Å, β = 92.050(5)°, Z = 4), [(C 5 H 5 N) 2 CH 2 ][OsBr 4 (ox)]·H 2 O(monoclinic, space group P2 1 /n, a = 11.666(3),b = 11.591(5), c = 14.926(2) Å, β = 102.45(2)°, Z = 4) and [P(C 6 H 5 ) 4 ] 2 [OsI 4 (ox)]·2CH 2 Cl 2 (triclinic, space group P1̄, a = 14.597(2), b = 11.9185(9), c = 22.5624(14) Å, α = 80.284(8), β = 78.903(8), γ = 69.432(8)°, Z = 2) have been determined by single crystal X-ray diffraction analysis. The IR and Raman spectra of the three complexes were measured at room temperature. Using the molecular parameters of the X-ray determinations normal coordinate analyses based on a modified valence force field have been performed and the normal modes of vibration are assigned. With a set of 25 force constants and taking into account the innerligand vibrations a good agreement between observed and calculated frequencies has been achieved. The valence force constants of the X-Os-X axis are f d (OsCl) = 1.77, f d (OsBr) = 1.48, f d (OsI) = 1.0 mdyn/Å, of the X′-Os-O • axes are f d (OsCl′) = 1.88, f d (OsBr′) = 1.6, f d (OsI′) =1.1 mdyn/Å and f d (OsO • ) ranges from 2.7 to 2.8 mdyn/Å.

Isonitroso-(4-methylthiazol-2-yl)acetamide H (L 1 ), isonitroso-(4-methylthiazol-2-yl)(benzo-thiazol-2-yl)methanide H(L 2 ) and their copper(II) complexes of composition [Cu(Phen){L 1 }(ClO 4 )] (1) and [Cu(Phen){L 2 }Cl]*C 2 H 5 OH (2) have been prepared. Crystal and molecular structures of the complexes have been determined from X-ray diffractioon data (1: monoclinic, space group P2 1 /c, with a = 11.611(2), b = 10.259(2), c = 17.869(4) Å, β = 104.67(3)°, V = 2059.1(7) Å 3 , Z = 4; R1 = 0.046 for the 2522 unique reflections with I > 2σ(I). 2: triclinic, space group P1̄, with a = 8.351(1), b = 10.876(1), c = 14.891(2) Å, a = 96.170(8)°, β = 94.201(9)°, γ = 106.721(9)°, V = 1280.1(2) Å 3 , Z = 2; R1 = 0.034 for the 4038 unique reflections with I > 2σ(I)). In the structure of 1 the coordination polyhedron of Cu 2+ is a distorted square pyramid with an oxygen atom of the CIO 4 counter anion in the apex (C u -O 2.505(3) Å); in complex 2 the copper atom adopts fivefold coordination of a slightly distorted trigonal-bipyramidal geometry with a chlorine atom in the equatorial plane (Cu-Cl 2.3504(9) A). Ethanol of crystallization gives rise to a hydrogen bond at the chlorine atom. In both structures the oximic anions are coordinated to the metal center in a bidentate chelate manner via the nitrogen atom of the nitroso group and the carbonyl oxygen atom (1) or via the benzothiazole nitrogen atom (2) (Cu-O, Cu-N in the range 1.963(2) -2.031 (2) Å). The thiazole group of the ligands takes no part in the coordination. The nitroso oxygen atoms possess short intramolecular contacts with thiazole sulphur atoms, with d(S--- O) at 2.605(3) (1) and 2.676(3) A (2), which may be attributed to a strong intraligand interaction.

The peculiarities of the formation of zinc and nickel(II) complexes by interaction of metal powder or metal oxide with ammonium salts (halides, nitrate, thiocyanate) were investigated in non-aqueous solutions (methanol, acetonitrile, N,N-dimethylformamide=DMF, dimethylsulfoxide=DMSO) in presence of 1,4-diazabicyclo[2.2.2]octane. The stoichiometry of the com ­ plexes was found to depend on the initial reagent ratio Ni/ZnO:NH 4 X and Ni/ZnO:Ten. The compounds of compositions Zn(HTen)(H 2 O)(NO 3 ) 3 and Ni(HTen)(Ten)Cl 3 were character­ized by X-ray crystallography. Both complexes contain five-coordinate metal atoms. The zinc compound possesses monomeric molecular structure whilst the nickel complex is polymeric.

A heterotetranuclear Cu II Pb II complex containing 2-dimethylaminoethanol has been synthesized, using copper powder and PbBn 2 as starting materials, and characterized by X-ray crystallography. The crystal is composed of centrosymmetric molecules [CuPbBr 2 {(CH 3 ) 2 NCH 2 CH 2 O} 2 dmso] 2 . The central strictly planar fragment is a Pb 2 O 2 parallelogram completed by bridging oxygen atoms of chelating 2-dimethylaminoethoxo groups. The Pb atom forms four quite short bonds with oxygen atoms of the three 2-dimethylaminoethoxo groups and of the dmso molecule and assumes a six-coordinate structure also involving two bromine atoms. The two oxygen and two nitrogen atoms of two 2-dimethylaminoethoxo groups form the copper coordination environment, which possesses a somewhat distorted square planar geometry.

The new compounds Ca 2 ClBN 2 (1) and Sr 2 ClBN 2 (2) were prepared from the respective metal, its dihalide and h-BN in sealed tantalum ampoules at 1200 °C. The crystals obtained were transparent yellow (1) and blue (2), respectively. The crystal structures were determined from single crystal X-ray data. Ca 2 ClBN 2 and Sr 2 ClBN 2 are isotypic and crystallize in the orthorhombic space group Pnma (No. 62), Z = 4 (Ca 2 ClBN 2 : a = 1166.7(2), b = 390.26(4), c = 899.8(1) pm, R1 = 0.043, wR2 = 0.115 for 554 independent reflections; Sr 2 ClBN 2 : a = 1242.8(1), b = 416.75(4), c = 920.8(1) pm, R1 = 0.031, wR2 = 0.054 for 662 independent reflections). The structures contain two different layers of M2+, Cl - and BN 2 3- alternating along the [010] direction. The bond angles N-B-N are 177.2(4)° for (1) and 176,6(5)° for (2), the bond distances of the BN 2 3- ions are d B_ N1 ] = 134.6(5) pm for (1), 136,3(7) pm for (2) and d B_N2 = 132.4(5) pm for (1) and 131,3(7) pm for (2). The unsymmetric structure of the BN 2 3- ion, as is manifested particularly in the Sr compound (2), is caused by the coordination of N1 to four cations while N2 is coordinated only to three.

“Poly(1,4-diselenobenzene)”, obtained by reaction of 1,4-dibromobenzene with disodiumdiselenide is shown to contain many different polymer sequences. Bromination of the polymer yields a variety of low molecular weight species thus confirming the non-uniformity of the polymer and giving some hints about its composition. The aryl-selenium-bromine compounds 1,4-benzene-diselenenyldibromide, 4,4′-di(bromoselenenyl)-diphenylseleniumdibromide, and bromo-bis(4-bromophenyl)selenonium hexachloroantimonate were fully characterised inclu­ding X-ray structure determinations.

The heteroaryl borates Li[C 4 Me 4 NBH 3 ] (6) and Na[C 3 H 3 N 2 (BMe 3 ) 2 ]• 2 C 4 H 8 O (8) are ob­tained by treatment of Li[C 4 Me 4 N] and Na[C 3 H 3 N 2 ] with Me 2 S • BH 3 and BMe 3 , respectively. The X-ray structure of [Na(C 4 H 8 O) 6 ][C 3 H 3 N 2 (BMe 3 ) 2 ] (10) is reported.

The title compound 2c, a potentially useful synthetic intermediate in stereoselective biaryl synthesis, has been prepared from the oxolactone 1c, by treatment with Lawesson′s reagent. An X-ray structure analysis reveals its strongly helically distorted structure, the overall molecular distortion even slightly exceeding that of the corresponding oxo compound 1c.

Reactions of perfluoroalkane-1,n-bis(sulfonylfluorides) (n = 1-2) (1-2) with liquid ammonia in tetrahydrofuran (TH F) lead to the cyclic ammonium imides 3-4. These cyclic imides 3-4 can easily be transform ed to other salts using the corresponding hydroxides. X -ray structure analyses (T = 150 K) were perform ed for the potassium 4,4-difluoro-[1,3,2]dithiazetidinide-1,1,3,3-tetraoxide 5 and rubidium -4,4,5,5-tetrafluoro-[1,3,2]dithiazolidinide-1,1,3,3-tetraoxide 6. Cylic imides of the type 3, 5 have not been reported previously. Their formation and their nmr-data are discussed.

Single crystals of BaZn (VO)(PO 4 ) 2 have been prepared by solid state reactions of prereacted BaCO 3 and P 2 O 5 mixtures with ZnO, V 2 O 3 and V 2 O 5 in evacuated quartz tubes. X-ray investigations led to orthorhombic symmetry, space group D 2h 15 -Pbca, a = 8.814(1), b = 9.039(1), c = 18.538(1) A, Z = 8 . The crystal structure is characterized by layers of PO 4 tetrahedra and square VO 1+5 pyramids, connected by corrugated layers of PO 4 and ZnO 4 tetrahedra. The resulting tunnel structure is filled by Ba 2+ ions. The short distance of the V 4+ center to the apical oxygen atom of the square VO 5 pyramids is a typical feature of vanadyl groups.

Tridentate amines of the type N-alkyl-N,N -bis(2-pyridylmethyl)amine with alkyl = methyl L1, benzyl L2 and adamantyl L3 form mononuclear Fe(III) complexes LFeCl 3 . In the presence of various carboxylates binuclear μ-oxo-bis(μ-carboxylato) Fe(III) complexes [L 2 Fe 2 O(RCO 2 ) 2 ] 2+ are formed. These compounds can be synthesized from mono-, bi-, tri- and tetranuclear iron complexes as starting materials. The crystal structures of three mononuclear and four binuclear complexes show that the tridentate ligand is always facially coordinated to Fe. While in binuclear complexes of L1 and L2 the N amin -atom is trans to the oxo-bridge, in a complex of L3 a coordination with one N pyridin atom trans to that bridge is found. In all complexes the Fe-N amine distances increase with increasing space requirement of the alkyl substituent. The effects of different ligands trans to N amine and N pyridin are discussed. 57 Fe Mößbauer spectra show that the electric field gradient at Fe vanishes in L1FeCl 3 and L2FeCl 3 despite non-cubic ligand spheres. For both mono- and binuclear complexes a correlation between isomer shift δ and Fe-N distances exists. The strong increase of Lamb-Mößbauer factors on cooling to 4,2 K and the Goldanski-Karyagin effect observed for some complexes can be explained by the displacement parameters of the Fe-atoms obtained by X -ray structure analysis.

Diphenyl(1-pyridyl)phosphine sulfide, Ph 2 pyPS, 1, gives a 1:1 complex (2) with AuCl upon treatment with (C 4 H 8 S)AuCl. According to an X -ray diffraction analysis, this compound is isomorphous with the Ph 3 PS complex. [Ph 3 PAu]BF 4 and 1 give the cationic complex [Ph 3 PAuSPpyPh 2 ]BF 4 (3 ) . With two equivalents of the same reagent the binuclear complex 4 is generated, in which the metal atoms are S- and N-bonded. The reaction of 2 equivalents of 1 with [(tetrahydrothiophene) 2 Au]ClO 4 affords the 2:1 complex 5 with the gold atom exclusively S-bonded. The analogous reaction with AgBF 4 gives the 2:1 complex 6, the structure of which has also been determined by X-ray diffraction. The silver atom is engaged in coordinative bonding with both sulfur and both nitrogen atoms in a quasi-tetrahedral environment. Addition of AgClO 4 to com pound 5, and of [(MeCN) 4 Cu]B F 4 to 6, gives mixed-metal complexes (7, 8) with head-to-head structures, the silver atoms being exclusively S-bonded.

Single crystals were prepared and X -ray structure determinations performed of the hexagonal com pounds (R3̄m, Z = 3) [N(CH 3 ) 4 ] 2 RbCr(CN) 6 (a = 895.9, c = 2176.4 pm), [N (CH 3 ) 4 ],TlCr(CN) 6 (a = 894.0, c = 2168.4 pm), [N(CH 3 ) 4 ],RbFe(CN) 6 (a = 886.7, c = 2149.9 pm ) and of monoclinic [N(CH 3 ) 4 ] 2 TlFe(CN) 6 (C2/c, Z = 4; a = 1511.4, b = 884.8, c = 1525.9 pm , β = 110.0°). The structure of the hexagonal complexes is closely related to that of cubic elpasolites, showing, however, orientational disorder of the tetramethylammonium groups. Within the monoclinic TIFe-compound this group has fixed orientation, which makes some of the Fe-CN-Tl bridges bent, contrary to the linear M-CN -A array within the hexagonal compounds. Details and relations are discussed with respect to similar hexacyano complexes.

On chloride abstraction from chloro-bis{1,2,4-tri(tert-butyl)cyclopentadienyl}bismut(III) (2 ) with aluminum trichloride the salt [{C 5 H 2 (CMe 3 ) 3 - 1,2,4} 2 Bi] + AlCl 4 - (1) has been obtained in good yield. The crystal structure of 1 shows a bismocenium cation with nearly parallel η 5 - cyclopentadienyl rings (10.2° inclination of the best planes) and only a slight bending of the Cp cent -Bi-Cp cent axis (172.9°).

The fluorinating properties of CF 3 OCl have been demonstrated by the reactions with different iodate salts like (CH 3 ) 4 N + I - , (CH 3 ) 4 N + ICl 2 - and (CH 3 ) 4 N + ICl 4 - . At -70°C all reactions give hexafluoroiodate(V ) salts IF 6 - . In contrast, the reaction of CF 3 OCl with (CH 3 ) 4 N + Cl + yields (CH 3 ) 4 N + OCF 3 - . The products have been characterized by vibrational and NMR spectra.

The reaction of manganese with antimony and sulfur in an aqueous ethylenediamine (en) solution under hydrothermal conditions gives Mn(en) 3 Sb 4 S 7 . The structure of the title compound consists of Mn(en) 3 2+ cations and infinite one-dimensional (Sb 4 S 7 2- )„ anions forming slabs via long secondary interchain Sb···S bonds. A comparison between phases with polymeric (Sb 4 S 7 2- )„ anions shows in general a trend towards a lower dimensionality of the thioantimonate assembly with increasing cation size. In the title compound the lowest number of interchain Sb···S interactions is observed among other phases with chainlike Sb 4 S 7 2- anions.

A new diterpenoid named as bondenolide (1) was isolated from the ethyl acetate soluble part of the methanolic extract of Caesalpinia bonduc (seeds). In addition to 1, four known triterpenoids: α-amyrin [12-ursen-3β-ol], β-amyrin [12-oleanen-3β-ol], lup-20(29)-en-3β-ol, lup-20(29)-en-3β-yl acetate and two known sterols: β-sitosterol [24(R)-stigmast-5-en-3β-ol] and β-sitosteryl galactoside [3-O-β-D -galactopyranosyl-stigmasta-5-enen] were also isolated from the same source.

A fluorinated substrate 6 was prepared and then the enantiomers (6a and 7a) were separated by an enzyme in presence of an acetylating agent. The optical purity of 6a and 7a were determined by derivatising them into their MTPA -esters and then by taking their 19 F NMR spectra. It was observed that, PL 266 (enzyme), benzene (solvent), 24 h (time), 40 °C (temp.) and vinyl acetate (acetylating agent) were the ideal conditions for racemic resolution. The optical purity was further improved by changing the solvent (hexane), amount of enzyme (PL 266; 3000 units), reaction time (12 h) and amount of acetylating agent (vinyl acetate; two molar). The optically pure species was used for the preparation of E and Z alkenes.

A series of N-(2-chloro-7-cyclopropyl-4,7-dihydro-4-oxothieno[2,3-b]pyridine-5-carbonyl)-L-α-amino esters (5 ) have been prepared via the respective thieno[2,3-b]pyridinyl-5-carbonyl chloride (4). The CD spectra of the L-aliphatic (5a -d ) and L-aromatic (5e-g) a-amino acid derivatives display, in organic solvents, sign inversion of the measured Cotton effect (CE) bands. This chiroptical behaviour is probably associated with differences in conformational isomerism of either set. MS and NMR spectral data of the title compounds are presented.

2,5-Diallylpyrrole 1 reacts with an excess of n BuLi in hexane/diethylether to give the N,C,Ctrilithio reagent 2. 7 Li NMR spectra of 2 in THF/ HMPTA at low temperature indicate the presence of an ionic species. Reactions of 2 in THF with electrophiles such as H 2 O, D 2 O, MeI, Me 3 SiCl and Me 3 SnCl lead selectively to the cisisomers 3a - 6a, whereas the analogous reactions in hexane or diethylether afford mixtures containing both cis- and rram-isomers (e.g. 3b).

N-Lithio-N-trimethylsilyl-9-amino-9-borabicyclo[3.3.1]nonane (2) was prepared from the reaction of N-trimethylsilyl-9-amino-9-borabicyclo-[3.3.1]nonane (1) with rert-butyl lithium; 2 crystallizes as a trim er with a planar N 3 Li 3 ring. The nitrogen atoms are tetrahedrally coordinated, but should be treated as sp 2 hybridised, because the BN double bond, typical of aminoboranes, is retained.