Volume 41, Issue 3

CsTlI4, which has been synthesized either by heating of a 1:1 mixture of CsI/TlI with iodine in a closed system or by dehydration of CsTlI 4 · 2H 2 O, crystallizes in the monoclinic space group P2 1 /c with a = 731.10(24) pm. b = 1870.42(126) pm. c = 847.70(43) pm. β = 105.14(4)°. Z = 4. In the crystal structure the Cs cations are coordinated by 11 iodine atoms which belong to seven TlI 4 anions.

Four reaction types were used with the aim of obtaining new cage compounds of composition Fe x (CO) y (PR) z - with R = Me, Ph, Tol: oxidation of the compounds Fe 2 (CO) 6 (PHR) 2, photolysis thereof, reaction between RPCF and Fe 2 (CO) 8 2- . and reaction between P-Cl containing iron complexes and Fe(CO) 4 2_ . Besides several known products, e.g. Fe 3 (CO) 9 (PR) 2 or Fe 4 (CO) 11 (PR) 2 , and derivatives of the Fe 2 (CO) 6 (PRX) 2 butterfly type complexes, the new octabisvalene shaped compounds Fe 4 (CO) 2 (PR) 4 with R = Me, Ph, Tol were obtained and confirmed by a crystal structure analysis for R = Me, Side products of the oxidative conversions were Fe 4 (CO) 12 (P 2 Me 2 )(MeP-C 2 H 4 -PMe) and Fe 4 (CO) 12 (P 2 Tol 2 )(PHTol) 2 which can be derived from the octabisvalene type. Side products of the irradiative conversions were Fe 3 (CO) 8 (PPh)(PHPh) 2 and (CO) 3 Fe(μ-PHPh) 2 Fe(CO)(C 6 H 8 ). the structure of the latter being proved crystallographically.

The Fe 2 P 2 tetrahedrane compound Fe 2 (CO) 6 (P -tBu) 2 has been obtained by oxidation of Fe 2 (CO) 6 (μ-PFtBu) 2 . Due to its short (206 pm) P-P bond it can be called a diphosphene com­plex. In contrast to this the P-P bond is its principal centre of reactivity: CO, C 2 H 4, and C 2 H 2 (with concomitant hydrogenation) are inserted. H 2 and HCl are added with P-P cleavage, and reductive cleavage occurs with LiBHEt 3 . The crystal structures of the title compound and of its CO and C 2 H 4 insertion products have been determined.

The structural types discussed may be thought of as being composed of two-dimensional layers cleaved out of the FCC lattice. Each layer has a square sublattice capped by apical atoms above and below four-fold hollows. The electronic structure of such an Al layer is constructed - it has eight low-lying bands per tour AI. and two of these bands are localized in apical Al s. pointing away from the layer. On stacking, bonds are formed between apical Al′s. leading to the pushing up of one Αl a -ΑΙ a σ* band, and a gap after 7 bands are filled. This is BaAl 4, with Al 4 2- . An alternative picture is of delocalized five-center six-electron bonding in each hollow, closely related to the electron deficient bonding in B 5 H 9 . The bonding in CeAl 2 Ga 2 and CeMg 2 Si 2 can be derived similarly, by perturbing the original BaAl 4 case. A rationale for switching from BaAl, to the CeMg 2 Si 2 structural type for electron counts exceeding ∼ 16 for four atoms is given. Finally we relate these arguments to the high cohesive energy of Al metal.

Trimesitylstibane (1) reacts with SbCl 3 or SbBr 3 to form the halostibanes Mes 2 SbCl (2), MesSbCl 3 (3), Mes 2 SbBr (4). or MesSbBr 2 (5) [Mes = 2,4,6-(CH 3 ) 3 C 6 H 2 ]. Action of MesMgCl on an excess of SbCl 3 or SbBr 3 at low temperatures gives Mes 3 SbCl 2 (6) or Mes 3 SbBr 2 (7), resp. Addi­tion of Br 2 to 1 gives 7 in 96% yield. The silylstibanes Mes 2 SbSiMe 3 (8) and McsSb(SiMc 3 ) 2 (9) are formed by dehalogenation of Me 3 SiCl and 4 or 5 by Mg filings in tetrahydrofuran. Mes 2 SbOSiMe 3 (10) is obtained by air oxidation of 8. Reduction of 4 with Mg gives Mes 2 SbSbMes 2 (19). Crystals of the composition (MesSb) 6 ·C 6 H 6 (13a) or (MesSb) 4 ·C 6 H 5 CH 3 (13b) are obtained from Mg and 5 after work-up in benzene or toluene, resp.

Slow air oxidation of PhSb(SiMe 3 ) 2 in 1,4-dioxane. benzene, or toluene gives (Me 3 Si) 2 O and crystals of (PhSb) 6 · 1,4-dioxane, (PhSb) 6 · benzene, or (PhSb) 6 · toluene, respectively. The crystal structure of the three isomorphous phases are reported. There are centrosymmetric Sb 6 chairs with equatorial phenyl groups (total symmetry of the molecules approximately D 3d , distances Sb-Sb 284 and Sb-C 216 pm. angles Sb-Sb -Sb 90°). The ring compounds are stabilized in forming stacks of (PhSb) ft molecules with short intermolecular Sb···Sb interactions (420 pm). The solvent molecules are needed for an optimum packing of these stacks. Air oxidation of PhSb(SiMe 3 ) 2 in the gas phase gives PhSb(OSiMe 3 ) 2 . (Me 3 SiO) 3 Sb and Ph 2 SbOSiMe 3 are formed, when Ph 2 SbSiMe 3 is exposed to the air in an open flask. (Me 3 SiO) 3 Sb is also obtained from (Me 3 Si) 3 Sb and O 2 . Access of air to Ph 2 SbSiMe 3 leads to 65% of Ph 2 SbOSiMe 3 .

The average unit cell of the methanol solvate [Ni(C 2 H 5 N 4 O 2 ) 2 ] × C 14 H 8 N 4 × 2CH 3 OH, M Γ = 589.22 is triclinic. Ρ1̄, a = 8.539(3). b = 8.937(3). c = 9.418(3) Å, α = 103.39(3). β = 100.12(2), γ = 105.39(2)°, V = 652.2 Å 3 Z = 1, d c = 1.50 gem -3 , final R w = 0.050 for 1580 observed independent reflections. Satellite reflections hint at a modulation of the structure in the ac plane. Mixed stacks of alternating and mainly neutral metal complex and Me 2 tcnq molecules are formed. Crystals grown with electrochemical reduction show a weak activated paramagnetism, those grown without electrochemical support are diamagnetic.

The complex salt [Ni(C 2 H 6 N 4 O 2 ) 2 ][Pt(C 2 O 4 ) 2 ] × [Νi(C 2 Η 5 Ν 4 O 2 ) 2 ] × 2 H 2 O has been crystal­lized by interdiffusion of [Ni(C 2 H 6 N 4 O 2 ) 3 ]Cl 2 and K 2 [Pt(C 2 O 4 ) 2 ]. It is triclinic. Ρ1̄. a = 3.673(1), b = 13.622(4), c = 14.371(4) Å, α = 94.01(2), β = 95.11(2), γ = 92.14(2)°. V = 713.7(4) Å 3 , Z = 1, M r = 994.96, D x = 2.31 g cm -3 , MoK α , γ = 0.710 Å. μ = 61.3 cm -1 , F(000) = 488, room temperature, wR = 0.034 for 3109 observed independent reflections. Segregated parallel stacksof [Pt(C 2 O 4 ) 2 ] 2 - anions, [Ni(C 2 H 6 N 4 O 2 ) 2 ] 2+ cations, and neutral [Ni(C 2 H s N 4 O 2 ) 2 ] complex molecules run along a, and there is a 2:1 ratio of Ni and Pt complex stacks, interlinked by a network of strong intermolecular H bridges. The difference between the double positive and the neutral Ni complexes is marginal, as the assignment of the charges is based upon a slightly asymmetric intermolecular Ο-H--O bridge. 1.06(7) and 1.44(8) Å.

Anhydrous Ga[GaBr 4 ] is readily dissolved in benzene. The resulting solutions show discrete 71 Ga NMR signals for Ga(I) und Ga(III) centers. Narrow line-widths of the former indicate a small electric field gradient of the Ga(I) nucleus due to almost spherical shielding by the 4 s 2 lone pair of electrons. Crystals obtained from the benzene solution on cooling have the stoichiometry [(C 6 H 6 ) 2 Ga · GaBr 4 ] 2 ·3 C 6 H 6 , and are isomorphous with the analogous chloride compound: a = 9.390(2). b = 10.847(1), c = 13.118(2) Å; α = 85.54(1). β = 102.91(1). γ = 105.62(1)°; triclinic, space group Ρ1̄, Z = 1. The centrosymmetric dimers are composed of bis(benzene)gallium(I) and tetrabromogallate(III) units bridged by six bromine atoms. Only two bromine atoms are not engaged in coordinative bonding. The two benzene rings are both η 6 -bonded to the gallium(I) center, but not equidistant. They are enclined by 57.5°. The remaining benzene molecules are crystal benzene with no specific cation or anion contacts.

The different species formed when gaseous formaldehyde is dissolved in aqueous medium are investigated by a 13 C NMR flow-through technique and the spectra of commercial aqueous form­aldehyde solutions containing methanol completely interpreted. 13 CH 2 O was used to study the crosslinking reaction with gelatin which leads to methylene and oxymethylene bridges between gelatin-amino-groups. On ageing, hardened gelatin shows an increase in the number of methylene bridges.

Reaction conditions for the synthesis of N-hydroxy-α, α′-iminodipropionic acid, the ligand of naturally occurring amavadin. and N-hydroxyiminodiacetic acid, the first member of this class of complexons, have been investigated.

The β-keto-ester 1b and 7 reacted with dimethyl acetylenedicarboxylate (DMAD) to give the cyclooctadienone derivatives (2a and 3b). the acid hydrolysis of which afforded the anhydride 4. Also 1a, b reacted with ethyl propiolate and gave substituted cyclooctadienone (6a, b). Michael reaction of 11 with DMAD gave adduct 12 which underwent cyclization via photo-cycloaddition (2+2) to give the photo-product (14).

N-Acyl-glycine derivatives are cleaved by the action of potassium superoxide in ether or pyridine solution to give the corresponding carboxamides.

The reaction of arylidenemalonodinitrilcs with a variety of acetophenone anils leading to 5′-amino-1,1′:3′,1″-terphenyl-2′,6′-dicarbonitriles has been investigated. The mechanism of the exchange reaction between arylidenemalonodinitrilcs and 1-arylethylideneaminobenzenes is proposed.

The naphthoquinone stypandrone (2b) ist synthesized via the intermediates 5a, 6a and 6b. Selective monoalkylation of its hydroquinone yields the monoether 12b, which, on phenol oxida­tion and oxidative dealkylation, leads to 13 and dianellinone (2a). The synthesis confirms the 3.3′-dimerisation of the natural product.

19-S-Vindolinine has been found to undergo an interesting isomerisation in chloroform to 19-R-vindolinine at room temperature. NOEDS measurements have been carried out on both isomers and a 13 C solid state CP-MAS spectrum recorded for 19-S-vindolininc. The structure assigned as 16-epi-19-S-vindolinine to an alkaloid isolated previously from Catharanthus roseus has been revised in the light of corrected 13 C NMR values for 19-S- and 19-R-vindolinine.

The metallacycle Br 2 VS 2 N 3 , has been obtained from the reaction of S 4 N 4 with VBr, in CH 2 Br 2 . The 51 V NMR spectrum reveals a singulet at 445.6 ppm and the field ionisation mass spectrum shows only the molecular ion at 317 m/e.

The reaction between ZrCl 4 and (Et 2 N) 3 P=CH 2 affords the zirconium-substituted vlide [(Et 2 N) 3 PCZrCl 2 ] 2 (1). The transylidation by-pro­duct [(Et 2 N) 3 PCH 3 ]Cl is trapped by excess ZrCl 4 to give the complex salt [(Et 2 N) 3 PCH 3 ] 2 ZrCl 6 (2) the structure of which was determined by single crystal X-ray diffraction.