Volume 48, Issue 1

The crystal structures of the fast ionic conductors Li 6 MgBr 8 and Li 2 MgBr 4 oC 14 and cF 56 were determined by single crystal X -ray diffraction and neutron powder studies, respectively. At ambient temperature, Li 6 MBr 8 (M = Mg, Mn) crystallize in a Suzuki-type structure (space group Fm3̄̄̄ m , Z = 4, Li 6 MgBr 8 : a = 1098.0(1) pm, 114 unique reflections, R = 0.037). Li 2 MgBr 4 oC 14 crystallizes in a SnMn 2 S 4 -type structure (space group Cmmm , Z = 2, a = 777.94(2), b = 1104.25(4), and c = 386.55(1) pm , R I , = 0.073, 318 K), the high-temperature polymorph (HTM I) in the Li 2 MnBr 4 cF 56 type (space group Fd 3 m , Z = 8, a = 1124.55(4) pm , R I , = 0.052, 673 K). These structure types are more or less ordered NaCl superstructures. The thermal ellipsoids of the lithium ions are discussed in terms of the conduction pathways and the order-disorder phase transitions observed.

In the course of investigations concerning the preparation of spinel ultrafiltration membranes we were able to determine the structure of MgAl 2 (iPrO) 8 (3) in the form of its adduct 3 · 2iPrOH . This precursor is used to produce spinel particles in the nanometer range.

Potassium amalgam , KHg 2 , is a shiny black-purple air-sensitive alloy crystallizing, like RbHg 2 and CsHg 2 , in the CeCu 2 structure type, which is an open variant of the AlB 2 type. We have investigated the phase stability of KHg2 under pressure by powder X -ray diffraction. At 25 kbar KHg 2 undergoes a reversible first order phase transition into the AlB 2 -type structure. Lattice constants and interatomic distances of the high pressure β-phase phase near the phase transition are close to the values for normal pressure NaHg 2 which also crystallizes in the AlB 2 -type structure. The extremely short K - K distances in the β-phase (d K-K = 3.23 Å) indicate that a major change in charge transfer between K atoms and Hg sublattice is associated with the first-order structural transition, driving the potassium atoms towards a positively charged K + state.

At high temperatures Sr 2 MnO 4-y crystallizes in the K 2 NiF 4 structure with anion defects. X -ray structure determination in space group I 4/m m m (No. 139) with a = 380.58(3), c = 1253.19(11) pm reveals the composition Sr 2 MnO 3.84±0.05 for a single crystal prepared under argon at 1510 °C. The oxygen deficiency is restricted to the basal oxygen atoms in the perovskite layer. The X -ray experiment shows a statistical distribution of the defects. They lead to a distorted tetragonal pyramidal coordination of the Mn 3+ ions.

Bromochloromethyleneiminium hexachloroantimonate BrClC = NH 2 + SbCl 6 - crystallizes in the space group P 2 l /c w ith a = 979.6(5), b = 1140.5(5), c = 2162.1(10) pm , β = 102.45(4)° and Z = 8. It is isostructural with Cl 2 C = NH 2 + SbCl 6 - .

Crystals of the adduct Cd(SCN ) 2 ·C 6 H 12 N 4 · 2H 2 O were obtained by diffusion of an aqueous solution of hexamethylenetetramine into an aqueous solution of cadmium thiocyanate. The crystals are triclinic, space group P 1̄, Z = 2, a = 600.4(2), b = 1005.1(3), c = 1283.9(4) pm , α= 105.79(9), β = 102.63(7), γ = 103.65(3)°. Each cadmium atom is bonded to one hexamethylenetetramine ligand, one water molecule, and, via the N atoms, to two NCS groups, which act as bridging ligands and form bonds, via the S atoms, to adjacent cadmium atoms. Thus a polymeric chain structure is formed. There is an other water molecule present per formula unit, which is not coordinated to cadmium but is located in channels between the chains. Between the oxygen atoms of this water molecule and the oxygen atom of the coordination water molecule, as well as the nitrogen atom of the hexamethylenentetramine ligand, a system of hydrogen bonds is formed. The coordination of the cadmium atoms is approximately octahedral.

The synthesis and reactivity of non-coordinated and coordinated propargyl phosphanes are discussed. The isomerization of the propargyl unit in (R)P(Cl)(CH 2 C ≡ CH ) (3) (R = 2,4,6- t Bu 3 -C 6 H 2 O) in the presence of NEt 3 yields the allenyl substituted p roduct (R)P(Cl)(CH = C = CH 2 ) (4). However, in the presence of HNEt 2 the dimethylenecyclobutane 7 is formed. Different synthetic pathways for the preparation of L n MP(Ph) m (CH 2 C ≡ CH) 3-m complexes (m = 2: L n M = (η 5 -C 5 H 5 )(CO) 2 Mn: 10a; L n M = (CO) 5 Cr: 10b; m = 1: LnM = (η 5 -C 5 H 5 )(CO) 2 Mn: 13a; LnM = (η 5 -C 5 H 4 Me)(CO) 2 Mn: 13b) are described. The synthesis o f the alkynyl substituted phosphane compounds L n MP(Ph) m (C ≡ CR ) 3-m (m = 2: R = Ph, L n M = (η 5 -C 5 H 5 )(C O ) 2 Mn: 20a; L n M = (CO ) 5 Cr: 20b; R n Bu, L n M = (CO) 5 Cr: 20c; m = 1: R = Ph, L n M = (η 5 -C 5 H 5 )(CO) 2 Mn: 22) was also possible. The reaction of (η 5 -C 5 H 4 Me)(CO) 2 ,MnPPh (CH 2 C ≡CH) 2 (13 b) with Co 2 (CO) 8 affords in high yields (η 5 -C 5 H 4 Me)(CO) 2 MnPPh[(η 2 -CH 2 C ≡ CH )Co 2 (CO ) 6 ] 2 (15). All new com pounds have been characterized by analytical and spectroscopic data (IR , 1 H -, 13 C { 1 H }-, 31 P { 1 H } -NMR , MS) and (η 5 -C 5 H 5 )(CO) 2 MnP(Ph)(CH 2 C ≡ CH) 2 (13a) by X -ray analysis.

[μ-Bis(dialkylphosphino)alkane]-bis[pentacarbonylmetal(0)] complexes (CO) 5 MR 2 P(CH 2 ) n PR 2 M(CO) 5 , (M: Cr, Mo, W; n: 1, 2, 3; R: CH 3 , C 2 H 5 , C 6 H 5 ) were synthesized from the reaction of M(CO) 5 (CH 3 CN) with the appropriate ligand and characterized by means of IR and NMR ( 1 H , 13 C, 31 P) spectroscopy. Spectral data indicate that the complexes contain two identical M(CO) 5 moieties linked to each other by the R 2 P(CH 2 ) n PR 2 ligand. Each metal atom has a pseudo-octahedral arrangement of the five CO ligands and one phosphorus atom .

By ligand exchange reactions of (n-Bu 4 N )[ReOBr 4 ] with NaI dissolved in acetone pure (n-Bu 4 N )[ReOI 4 ], and with AgSCF 3 suspended in dichloromethane (n-Bu 4 N )[ReO(SCF 3 ) 4 ] have been prepared for the first time. The vibrational spectra of both complexes are assigned according to point group C 4v , supported by normal coordinate analysis based on a general valence force field. 13 C and , 19 F NMR spectra provide evidence for the equivalence o f the SCF 3 groups.

The hydrogen content in NbH 0.177 , G d H 2, and the chlorides and brom ides of the type LnXH n (Ln = Y, Gd; 0.67 ≤n≤ 1.00) is determined. The samples are burnt in an oxygen atmosphere and the H 2 O produced in the combustion process is potentiometrically titrated with an accuracy of ± 3% (Karl-Fischer method).

The title compounds were prepared from prereacted samples of the elemental components by arc-melting. UCr 5 P 3 was also obtained from a tin flux. UV 5 P 3 and UCr 5 P 3 crystallize with a new structure type, which was determined from X -ray data of a twinned crystal of UCr 5 P 3 :P2 1 /m, a = 959.1(2), b = 370.95(6), c = 696.7(1) pm , β = 100.05(3)°, Z = 2, R = 0.030 for 827 structure factors and 29 variable parameters. UMn 5 P 3 is isotypic with YCo 5 P 3 . The structure was refined to a residual of R = 0.054 for 455 structure factors and 28 variables. UCr 5 P 3 has a relatively high, almost temperature independent paramagnetic susceptibility as is frequently observed for metallic uranium compounds. The crystal structures of these phosphides are discussed together with those of other phosphides and silicides of similar composition.

The course of the reactions o f fluorophosphaalkenes F 3 CP = C (F)OR [R = Me (1), Et (2)] with methanol or ethanol strongly depends on the experimental conditions. Thus at 70 °C a mixture of the 2-phosphapropionic acid ester F 3 CP (H )CO 2 R [R = Me (3), Et (4)] and trifluoromethylphosphane H 2 PCF 3 is formed [molar ratio: 3 or 4 /H 2 CF 3 ≈1/1]. If the precursors F 3 CP (H )CO 2 R [R = Me (3), Et) are used as starting materials, the reaction with ROH under the same conditions affords 3 and 4, respectively, (90 to 95% yield) with only traces of H 2 PCF 3 . In the presence o f iPr 2 NH these precursors react with R′OH to give the novel trifluoromethylphosphaalkenes F 3 CP = C (OR )OR [R /R′: Me/Me (6); E t/E t (7); Me/Et (8)]. With Et 2 NH , 3 undergoes an addition/elimination process yielding the interesting push/pull system Et 2 N(F)C = P-CO 2 Me (5). 1 and 2 react with primary amines R′NH 2 (R′= t Bu, Me) with stereoselective formation of the fairly labile phosphaalkenes F 3 CP = C(OR)NHR′ [R /R′: Me/ t Bu (9), Et/ t Bu(10), Me/Me (11)] with trans-positions for CF 3 and NHR′.The new compounds 3 -11 were characterized by spectroscopic investigations ( 1 H , 19 F, 31 P, 13 C NMR ; IR, MS) and determination of M + or typical fragment ions [M + -OR ] by high resolution mass spectrometry.

Reactions of 1,2-bis(trimethyIstannyl)benzene (4) with bis(dichIoroboryl)methane derivatives (Cl 2 B) 2 CHR 1 (R 1 = H ,Me) lead to the formation of the 4,5-benzo-1,3-dichloro-2,3-dihydro-1,3-diboroles 2a,b.Substitution of chlorine in 2a,b by a methyl group using A1Me 3 yields the 4,5-benzo-1,3-dimethyl-2,3-dihydro-1,3-diboroles 2c,d, of which 2c is thermally labile. Complexation of 2c,d with [(C 5 H 5 )Co(C 2 H 4 ) 2 ] did not give the expected sandwich complexes 6c,d, but the formation of the triple-decker 7d was observed. The paramagnetic 7d and the diamagnetic 7d + , obtained by oxidation with Ag + BF 4 - , were studied by 1 H NMR .

Hypercoordinate, tetraaurated carbon-complexes of the type [H 3 C--C (AuPR 3 ) 4 ] + BF 4 - , R = Ph (1), R = C 6 H 11 (2), (PR 3 ) 2 = 1,2-C 6 H 4 (CH 2 CH 2 PPh 2 ) 2 (3) have been prepared by the reaction of the appropriate (phosphane)gold(I) chlorides with 1,1,1-tris(dimethoxyboryl)ethane H 3 C -C [B(OMe) 2 ] 3 in the presence of CsF. The products have been characterized by standard analytical and spectroscopic methods, including single crystal X-ray analyses of 1 and 2. In each case the pentacoordinated carbon atoms have been located at the centre of a square pyramide built up by a methyl group at the apex and four gold atoms forming the base with short Au ··· Au distances of about 2.85 Å, which strongly contribute to the formation and stability of these species.

Trimethylbromosilane and 3,4-lutidine form a 1:1 compound which is stable at room temperature. Single crystals of this compound can be isolated by sublimation. It crystallizes in the orthorhombic space group P 2 1 2 1 ,2 1 , with lattice constants a = 737,08(9) pm, b = 1295,7(1) pm, c = 1318,8(3) pm. The crystal structure was refined to R w = 0,042 and proves an ionic structure.

Different hydrates of Gd 2 (SO 3 ) 3 are obtained depending on preparation conditions. For preparation of Gd 2 (SO 3 ) 3 , gaseous SO 2 is passed through a suspension of Gd 2 O 3 in H 2 O at room temperature until a clear solution is formed. Upon immediate heating to about 100 °C a mixture of Gd 2 (SO 3 ) 3 · 2H 2 O and Gd 2 (SO 3 ) 3 · 3H 2 O is formed. If the boiling procedure is performed after 6 days, a pure product consisting of the trihydrate is obtained. The different phases are identified by REM, DTA -TG -investigation and X-ray powder analysis. The X-ray powder pattern of Gd 2 (SO 3 ) 3 · 2H 2 O is consistent with patterns of isotype Ln 2 (SO 3 ) 3 · H 2 O were Ln = Pr, Nd, Sm and Eu.

The reaction of 8 -trimethylsiloxyquinoline, 2 with PCl 3 , PhPCl 2 , and PhPF 2 has furnished the corresponding 8 -quinolyl halophosphite derivatives, 3-5 . The synthesis of two metal complexes, 8 and 9, of 4 with Au(I) and Pt(II) is described. The new compounds were characterized by elemental analysis and by 1 H and 31 P NMR spectroscopy. A single crystal X-ray diffraction study of 4 has been conducted; a short intramolecular P ··· N contact (230.9 pm) and a long P-Cl bond (218.7 pm) were observed.

The reaction of dicyclohexylamine and sulphur (molar ratio 2:7) with H 2 S in a mixture of dimethylformamide and formamide yields red crystals of bis(dicyclohexylammonium)heptasulfide. The compound crystallizes in the centrosymmetric space group P2 1 ,/c, the lattice constants are a = 9.787(2) Å, b = 18.972(4) Å, c = 17.118(3) Å, β = 96,12(2)°. The S 7 2- chain has not the common helical all-trans-conformation, but a mixed conformation trans-cis-trans (sequence of the signs of torsion angles ++ - - and - - ++).

Potassium 5-phenyl- and 5-methyltetrazolate react with chlorophosphines to give selectively the corresponding 2-phosphinotetrazoles 1. Oxidation by sulfur and selenium leads to 2-thioand 2-selenophosphinoyltetrazoles (6 , 7) which on heating loose nitrogen and yield the dimers 8 , 9 of thia- and selenadiazaphospholes. N-Phosphinoylnitrilimines are assumed to be formed as intermediates. The small 1 J SeP coupling constants indicate that the selenium atoms occupy axial positions in the tbp coordination of phosphorus in 9.

Mößbauer emission spectroscopic and susceptibility measurements of several Co(II)-nucleotide complexes have been carried out. The electronic structure derived from these data for the Co(II) central cation has been related to the distortion and the symmetry of its environment. The susceptibility data are indicative of short antiferromagnetic ordering in the majority of the samples. For the hydrated Co-5′UMP (5′-uridine monophosphate) and Co-5′CMP (5′-cytidine-monophosphate) complexes, magnetic models involving Co(II) dimers and linear chains, respectively, are proposed to explain the susceptibility data observed below 50 K.

3-Carboxymethyl-2,2-bis(trifluoromethyl)-oxazolidin-5-one 2, obtained on reaction of iminodiacetic acid 1 and hexafluoroacetone, represents a preparatively useful intermediate for the synthesis of unsymmetrically substituted derivatives of the dicarboxylic acid 1. The N-substituted glycine derivatives obtained are interesting candidates for peptide modification.

Ferrocene reacts with an excess of boron triiodide or boron tribromide in hexane solution to give mixtures of 1,3,1′-tris- and 1,3,1′,3′-tetrakis- (dihalogenoboryl)ferrocene. The borylation proceeds stepwise, the intermediates being essentially the known dihalogenoborylferrocene and 1,1′-bis- (dihalogenoboryl)ferrocene compounds, although small am ounts of 1,3-bis(dihalogenoboryl)- ferrocene can also be identified. 1 H, 11 B and 13 C NMR data are given.