Volume 44, Issue 6

All components of the two series Cs 2 [PtF„ 35 Cl 6-n ] and Cs 2 [PtF n 37 Cl 6-n ], including the pairs of geometric isomers for n = 2,3, 4, have been prepared and isolated by ion exchange chromatography on DEAE cellulose. The highly resolved low temperature (80 K) IR and Raman spectra of the pure isotopomers show distinctive isotopic shifts for different vibrational modes up to 10 cm -1 . The excellent agreement of the observed values with Teller-Redlich calculations verifies the assignment of all stretching and especially of the narrow deformation bands. For transcomplexes containing 35 Cl-Pt- 37 Cl axes, the lowered symmetry affects the restriction of the rule of mutual exclusion

The new organotris(phosphino)silanes RSi(PH 2 ) 3 (R = Me (1), Et (2), i-Pr (3), Ph (4)) have been synthesized by reaction of the appropriate chlorosilanes RSiCl 3 with LiAl(PH 2 ) 4 in the molar ratio 1:0,75. With an excess of RSiCl 3 the mixed chlorophosphinosilanes RSi(PH 2 )Cl 2 and RSi(PH 2 ) 2 Cl have also been obtained, the 31 P NMR data of which are reported. The compounds 1-4 could be isolated in pure form and have been fully characterized by elemental analyses and various spectroscopic methods

[MnCl 2 (C 12 H 22 N 6 )] (1) and [MnBr 2 (C 12 H 22 N 6 )] (2) are obtained from the reaction of MnX 2 (X = Cl, Br) with C 12 H 22 N 6 in methanolic solution. In chloroform MnI 2 , OPPh 3 , and C 12 H 22 N 6 react to give [MnI 2 (C 12 H 22 N 6 )] (3). With small variations of the reaction conditions [MnI 2 (C 12 H 22 N 6 )] · xCHCl 3 (4) may be crystallized. The reaction of [Mn(NCS) 2 (OPPh 3 ) 4 ] with C 12 H 22 N 6 in CHCl 3 solution gives [Mn(NCS) 2 (C 12 H 22 N 6 )] · xCHCl 3 (5). The structures of 1 and 2 were determined from single crystal X-ray diffraction data. The isotypic compounds crystallize in the orthorhombic space group Pbcn with Z = 4; 1: a = 1592.4(1), b = 785.0(1), c = 1270.7(1) pm; 2: a = 1590.0(1), b = 802.6(1), c = 1316.6(1) pm. C 12 H 22 N 6 acts as a tetradentate ligand. The isolated complexes exhibit a twofold symmetry. Manganese(II) is in a six-coordinate environment, which can be described better as a distorted tetrahedron with two additional Mn-N bonds rather than as a distorted octahedron. The Mn-N bond lengths are 229.9(1) and 248.7(1) pm for 1 and 228.2(3) and 248.4(3) pm for 2. The Mn-Hal bond lengths are 239.2(1) (1) and 254.2(1) pm (2)

The new compound Na[I(CN) 2 ] · 2 H 2 O can be prepared by addition of iodine to a concentrated aqueous solution of sodium cyanide. It crystallizes in the monoclinic space group P2 1 /c with a = 1044.0(2), b = 480.2(2), c = 730.2(2) pm, β = 95.94(2)° and Z = 2. The crystal structure has been refined to R f = 0.027 for 692 reflections. The structure may be described as a layer-like package of cations Na + , water molecules and trihalide-analogous anions [I(CN) 2 ] - . The anion is strictly linear at the I atom and nearly linear at the C atoms with φ(I-C-N) = 176.2° and d(I-C) = 231.1, d(C-N) = 110.6 pm. The cation is surrounded by a slightly distorted octahedron of nitrogen and oxygen atoms with d(Na · · ·N) = 263.8, d(Na · · · O) = 242.0, 242.8 pm

The 57 Fe Mößbauer spectra of mixed ligand complexes of the type trans-Fe(CO) 3 L 1 L 2 (L 1 = triphenylphosphine or triphenylphosphite and L 2 = phosphine or phosphite) show a quadrupolesplitting doublet typical of the disubstituted iron carbonyls in trigonal bipyramidal symmetry. The inverse linear dependence of the isomer shifts on the CO stretching frequencies is interpreted on the basis of the strengthening triple-bond nature of the carbonyl ligands with increasing iron-to-phosphorus π-back donation. A linear correlation, with a positive slope, between the isomer shifts and the quadrupole splittings has revealed that the phosphorus-to-iron σ-donation is offset by the iron-to-phosphorus π-back donation. A correlation between the coordination shifts and the isomer shifts demonstrates that the iron-to-phosphorus π-back donation plays an important role in the Fe-P bond. The relatively large coupling constant of 2 J(P,P) reflects a strong interaction between trans-phosphorus ligands through the P-Fe-P bond

Photolysis of a mixture of Ph 3 PAuN 3 with Fe(CO) 5 , Fe 2 (CO) 9 or Fe 3 (CO) 12 in THF yields [(Ph 3 PAu) 5 Fe(CO) 3 ] + (1) which crystallizes with PF 6 ~ as counterion as air stable, yellow platelets in the space group P2 1 /c: a = 2230.0(7), b = 1655.0(6), c = 2462.7(8) pm, β = 94.04(5)°, Ζ = 4. The cationic Au 5 Fe cluster forms a bicapped FeAu 3 tetrahedron with almost equal Fe-Au distances of 259.0 to 265.1 pm to all five Au atoms. Due to the local symmetry C 3 of the Fe(CO) 3 group two v(CO) at 1880 and 1930 cm -1 are observed. Co-photolysis of Ru 3 (CO) 12 and Ph 3 PAuN 3 does not result in a cleavage of the Ru 3 cluster. Bridging μ-AuPPh 3 and μ-NCO groups substitute two CO ligands to form Ru 3 (CO) 10 (μ-AuPPh 3 )(μ-NCO) (2)

The trimethylstannylhydrazines (Me 3 Sn) 2 N-NMe 2 (1), Me 3 Sn(Me)N-N(Me)SnMe 3 (2), (Me 3 Sn) 2 N-N(Me)SnMe 3 (3), and (M e 3 Sn) 2 N-N(Ph)SnMe 3 (4) have been studied by δ 15 N NMR at natural abundance. A correlation between δ 15 N of hydrazines and δ I5 N of corresponding am ines (replacement of one N-atom by the CH-unit) is proposed in order to estimate δ I5 N values and to support the non-trivial assignment of 15 N resonances of hydrazines. Geminal coupling constants 2 J( 119 SnN 15 N) have been observed for the first time. Their relative magnitude is related to the probability of the N-Sn bond being in cis-position with respect to the orientation of the lone electron pair at the 15 N nucleus in the 119 Sn-N- 15 N fragment. Treatment of 4 with phenylacetylene causes non-selective cleavage of the Sn-N bonds, leading to the trim ethylstannylhydrazines 5 and 6 which have been characterized by 119 Sn and 15 N NMR spectroscopy in solution

The conformations of and charge distributions in indolyl(alkoxy)carbenium tetrafluoroborates 2, a new class of highly stabilized carbenium ions, were investigated by 1 H and 13 C NMR spectroscopy and the crystal structure of indol-3-yl(methoxy)phenylcarbenium tetrafluoroborate (2e) was determined by X-ray diffraction methods. The phenyl-substituted cation of 2e exhibits axial chirality in the crystalline state

A good entry to cyclopentadienyl substituted isonitrile complexes of W(IV) is provided by CpW(CO)(t-BuNC)(I) 3 (4), prepared by oxidative decarbonylation of cis- or trans-CpW(CO) 2 (t-BuNC)I (2,3) with elemental iodine. The isomers 2 and 3, separable by column chromatography on silica at low temperature, are easily obtained from CpW(CO) 3 I (1) and t-BuNC using Me 3 NO as a decarbonylating agent. Compound 4 reacts with t-BuNC to yield a mixture of the cationic complexes [CpW(CO)(t-BuNC) 2 (I) 2 ]I (5) and [CpW(t-BuNC) 3 (I) 2 ]I (6). The neutral cyano complex CpW(CN)(t-BuNC) 2 (I) 2 (7), resulting from the dealkylation of one tert-butylisonitrile ligand, is also obtained. The insoluble main product 5 is easily separated from 6 and 7, and is converted with AgBF 4 to the corresponding BF 4 -salt [CpW(CO)(t-BuNC) 2 (I) 2 ]BF 4 (8). The soluble byproducts 6 and 7 have been purified by column chromatography on silica. The composition and structure of the new complexes 4-8 have been derived from elemental analyses and spectroscopic investigations. The ionic nature of 6 and 8 has been confirmed by comparison of their conductivity data in 1,2 dichloroethane with that of NR 4 + X - salts (R = alkyl; X = Br, I)

The Kamlet and Taft basicity parameters β KT , for twelve mixtures of organic solvents with water are reported. Also the data for water-butanols (n-BuOH. i-BuOH. and s-BuOH) and alcohols (MeOH, EtOH. n-PrOH. and i-PrOH)-n-hexane mixtures are given. It was found that in the case of mixtures of 1.4-dioxane. acetone, tetrahydrofuran. dimethylsulfoxide. and acetonitrile with water, the basicity parameters of the mixture are higher than that of pure solvents in a region of smaller concentrations of water. These results, together with earlier reported results for THF and Et 2 O mixtures with MeOH are discussed in terms of breaking off the structure of the more structurized solvent (water and MeOH). All these mixtures, except the W-THF mixture, show the excess thermodynamic func­tions (ΔH E and ΔS h ) analogous to MeOH-CCl 4 mixtures, where depolymerization of MeOH clusters was postulated. Relativity of different basicity scales in respect to the acidic probe molecule is also shortly discussed

The preparations of the salts PH 3 F + SbF 6 - and PHF 3 + Sb 2 F 11 - are reported. All fluorophosphonium cations PH 4-n F n + are characterized by multinuclear ( 1 H, 19 F, 31 P) NMR spectroscopy. For n > 1 these salts are easily accessible by fluoride abstraction from fluorohydridophosphates(V). PH 3 F + SbF 6 - , however, is obtained in the reaction of PH 3 F 2 with SbF 5

Several new polyfunctionally substituted polyazanaphthalene derivatives could be synthesized via condensing readily obtainable polyfunctional nitriles with substituted alkyl heteroaromatic derivatives and reacting the latter derivatives with electrophilic reagents

Reaction of N,N′-dimethyl-N,N′-bis(trimethylsilyl)urea (1) with dichlorophosphines. RPCl 2 (R = Et: 14; R = Pr: 15) has furnished the P-chloro-substituted acyclic diphosphorus compounds, 16 and 17. In the analogous reaction of 1 with Ph 2 PCl the corresponding bis(diphenylphosphino)-substituted derivative, 21 was formed. Dehalogenation of 11, 16 and 17 with oxalic acid bis(trimethylsilyl) ester, 22 has produced the mixed-valent cyclic λ 3 P,λ 4 P-diphosphorus compounds, 23-25 in almost quantitative yield. Oxidation of the λ 3 P atom in 23-25 with tetrachloroorthobenzoquinone, 26 has given rise to partial cleavage of the P-P bond, and only moderate yields of the products, 29, 31 and 32, have been obtained. The characterization of the various compounds obtained rests, especially, on their 1 H and 31 P NMR spectra, and on a study of their mass spectral fragmentation pattern

Raney nickel, a highly reactive and air-sensitive solid, if prepared and investigated under oxygen-free conditions, exhibits interesting catalytic properties. Using photoelectron spectroscopy for real-time gas analysis in a flow reactor, the following results are obtained with alkyl and acylhalides: Dehydrohalogenation temperatures are lowered relative to thermal HHal elimination up to 350 K. Monochloro and bromo propanes and butenes yield propene and butadiene, respectively. 1,1-Dichloro ethane or 1,1-dibromo propane only split off one HHal and form chloroethene or 1-bromopropene-2. HCl elimination from 2-methyl propionic acid chloride, expectedly, produces dimethyl ketene. Most interesting, however, is the ring opening of monobromo cyclobutane to 1-bromo-butene-3, observed already at room temperature, which strongly suggests the intermediate formation of a chemisorbed surface carbene at Raney nickel. The formation of hexadiene-1,5 as a by-product in the HCl elimination of 1-chloropropane, i. e. a surface carbene dimer, indicates their presence also in other dehydrohalogenations heterogeneously catalyzed by Raney nickel. Raney nickel, a highly reactive and air-sensitive solid, if prepared and investigated under oxygen-free conditions, exhibits interesting catalytic properties. Using photoelectron spectroscopy for real-time gas analysis in a flow reactor, the following results are obtained with alkyl and acylhalides: Dehydrohalogenation temperatures are lowered relative to thermal HHal elimination up to 350 K. Monochloro and bromo propanes and butenes yield propene and butadiene, respectively. 1,1-Dichloro ethane or 1,1-dibromo propane only split off one HHal and form chloroethene or l-brom opropene-2. HCl elim ination from 2-methyl propionic acid chloride, expectedly, produces dimethyl ketene. Most interesting, how ever, is the ring opening of monobromo cyclobutane to 1-brom o-butene-3, observed already at room temperature, which strongly suggests the intermediate formation of a chem isorbed surface carbene at Raney nickel. The formation of hexadiene-1,5 as a by-product in the HCl elim ination of 1-chloropropane, i.e. a surface carbene dimer, indicates their presence also in other dehydrohalogenations heterogeneously catalyzed by Raney nickel