AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

By treatment of [(Mo(6)X(8)(i))Y-6(a)](2-); X(i), Y-a = Cl, Br; with AgNO3 in ethanol/dichloromethane and addition of NaN3 the octa-mu(3)-halogeno-hexazido-octahedro-hexamolybdate(2-) anions [(Mo(6)X(8)(i))(N-3)(6)(a)](2-) are formed. X-ray structure determinations have been performed on single crystals of (n-Bu(4)N)(2)[(Mo6Cl8i)(N-3)(6)(a)] (1) (monoclinic, space group P2(1)/n, a=14.592(5) Angstrom, b=12.314(5) Angstrom, c=17.039(5) Angstrom, beta = 101.183(5)degrees, Z=2), (n-Bu(4)N)(2)[(Mo6Br8i)(N-3)(6)(a)] (2) (monoclinic, space group P2(1)/n, a=14.595(6) Angstrom, b= 12.416(5) Angstrom, c=16.960(3) Angstrom, beta=100.74(3)degrees, Z=2) and (Ph(3)P=N=PPh(3))(2)[(Mo6Br8i)(N-3)(6)(a)] (3) (triclinic, space group P (1) over bar, a=11.092(4) Angstrom, b=13.161(8) Angstrom, c=14.341(11) Angstrom, alpha=78.085(6)degrees, beta=82.821(5)degrees, gamma=84.379(4)degrees, Z=1). Whereas the cluster anions of the (n-Bu(4)N) salts reveal a regular geo-metry, the (Ph(3)P=N=PPh(3)) cation causes strong distortions of the cluster kernel with variation of the Mo-Mo and Mo-Br-i distances up to 8%. Using the molecular parameters of the X-ray determinations the low temperature (10 K) IR and Raman spectra of the (n-Bu(4)N) cluster salts are assigned by normal coordinate analyses based on a modified valence force field. The valence force constants are f(d)(Mo-Mo) = 1.53 (Cl-i), 1.46 (Br-i), f(d)(Mo-Cl-i) = 1.09, f(d)(Mo-Br-i) = 0.96, f(d)(Mo-N-1) = 2.09 (Cl-i), 2.36 (Br-i) mdyne/Angstrom, respectively.

The extremely air and moisture sensitive hexahydridodeuteridoplatinates(IV) K-2[PtHnD6-n], n = 0-6, have been prepared by high pressure reactions at 500 degrees C and 1500 bar. The solid homoleptic compounds K-2[PtH6] and K-2[PtD6] and mixtures of K-2[PtHnD6-n] prepared with varying H/D ratios have been investigated by Pt-195(H-1) MAS NMR and by IR and Raman spectroscopy. Because of the high mobility of the atoms in the solid clearly resolved NMR spectra without sidebands are obtained exhibiting relatively sharp, isotropic Pt-195 resonances (Delta nu(1/2) = 400 Hz) at -990 +/- 1 ppm for K-2[PtH6] and -1034 +/- 1 ppm for K-2[PtD6]. Starting with K-2[PtH6] the signals of the complexes with mixed ligand spheres are arranged systematically with an average high field shift of -9.5 ppm per substituted hydride ligand. By quantitative evaluation of the integrated intensities the statistical formation of the individual complexions within the mixtures is derived. The molecular vibrations in the IR and Raman spectra of the pure homoleptic compounds and the heteroleptic species in the mixtures are assigned with the aid of normal coordinate analyses. The Pt-H valence force constant is 2.13 mdyne/Angstrom.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

By treatment of [(Mo6Br8i)Br-6(a)](2-) with AgNO3 in acetone and addition of KCN or KNCS the hexacyano and hexaisothiocyanato derivates [(Mo6Br8i)Y-6(a)](2-), Y-a = CN, NCS are formed. X-ray structure determinations of (Ph4P)(2)[(Mo6Br8i)(CN)(6)(a)]. 4H(2)O (1) (triclinic, spacegroup P1, a = 11.63(3), b = 11.85(1), c = 14.23(5) Angstrom, alpha = 71.8(1)degrees, beta = 67.6(3)degrees, gamma = 62.8(1)degrees, Z = 1) and (n-Bu4N)(2)[(Mo6B8i)(NCS)(6)(a)]. 2Et(2)O (2) (monoclinic, spacegroup P2(1)/n, a = 11.483(3), b = 16.348(5), c = 20.059(6) Angstrom, beta = 95.44(3)degrees, Z = 2) have been performed. The via C coordinated cyano ligands of (1) reveal facial groups with (MoCN) angles of 168.0-171.5 degrees and 174.1 degrees-175.7 degrees. In (2) the via N coordinated isothiocyanato groups at the apical positions show MoNC-angles of 164.4 degrees, the equatorial angles are 172.7-173.5 degrees. Using the molecular parameters of the X-ray determinations the 10 K IR and Raman spectra of the (n-Bu4N) cluster salts are assigned by normal coordinate analyses based on a modified valence force field. The valence force constants are f(d)(MoMo) = 1.41 (CNa), 1.43 (NCSa), f(d)(MoBri) = 0.97 (CNa), 0.96 (NCSa), f(d)(MoC) = 1.62, f(d)(Mo-N) = 2.09 mdyne/Angstrom.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The tetrabutylammonium (TBA) salts of the octa-mu(3)-halogeno-hexahalogeno-octahedro-hexamolybdate (2-) anions [(Mo(6)X(8)(i))Y-6(a)](2-); X(i) = Cl, Br; Y-a = F, Cl, Br, I; have been synthesized using Mo-92, Mo-100, Cl-35, and Cl-37. Th, 10 K IR and Raman spectra reveal significant frequency shifts due to the isotopic labelling of the Mo-6 cage, the inner sphere halides X(8)(i) or the outer sphere ligands YI, respectively. The normal coordinate analysis yields (Mo-Mo) valence force constants of about 1.3 to 1.5 mdyn/A. For the mu(3)-bonded halogenes Cl-i and Br-i valence force constants of 1.1 resp. 1.0 mdyn/Angstrom are calculated. The values for (Mo-Y-a) bonds are found in the usual halide range. The observed isotopic shifts are verified very well by the calculations, allowing detailed assignment of the IR and Raman spectra of these compounds for the first time.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

By reaction of [B 6 H 6 ] 2- with dibenzoylperoxide in dichloromethane conjuncto-[B 6 H 6 - B 6 H 6 ] 2- is formed. The product could be separated from excess [B 6 H 6 ] 2- by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structure of [P(C 6 H 5 ) 4 ] 2 -conjuncto- [B 6 H 6 -B 6 H 6 ] has been determined by single crystal X-ray diffraction analysis; triclinic, space group P1̄ with a = 10.8315(10), b = 11,2422( 12), c = 20.340(2) Å, α = 91.278° (9), β = 90.178° (9), γ = 105.662°(9). The 11 B NMR spectrum reveals three signals with the intensity ratio 1:1:4, for two equivalent moieties of the conjuncto molecule ion with local C 4v symmetry. The IR and Raman spectra of the deprotonated Cs salts of the 10 B, 11 B and their respective D isotopomers of conjuncto-[B 6 H 5 -B 6 H 5 ] 4- exhibit characteristic shifts. Using averaged crystallographic data and assuming idealized D 4h symmetry, normal coordinate analyses have been performed based on a modified valence force field. With a set of eleven force constants (e.g. f d (BB) conjuncto = 2.9, f d (BB) cage = 1.6 mdyn/Å) very good agreement between observed and calculated frequencies has been achieved. From strong vibrational coupling with the B 6 clusters two vibrations result for the conjuncto B-B bond at 1142/1198 and 292/304cm -1 for 11 B/ 10 B species, respectively. They can be assigned as anti-phase and in-phase motions of the conjuncto B atoms related to the equatorial B 4 planes.

Die Tetrabutylammonium (TBA)-Salze der Octa-μ3-halogeno-hexahalogeno-octahedro-hexamolybdat(2 –)-Anionen [(Mo6X8i)Y]2−; Xi = Cl, Br; Ya = F, Cl, Br, I; sind unter Verwendung von 92Mo, 100Mo, 35Cl und 37Cl dargestellt worden. Die 10 K IR- und Raman-Spektren zeigen signifikante Frequenzverschiebungen als Folge der Isotopenmarkierung des Mo6-Kafigs bzw. der inneren X8i oder der auseren Koordinationssphare Y. Die Normalkoordinatenanalyse ergibt (MoMo)-Valenzkraftkonstanten im Bereich von 1.3 bis 1.5 mdyn/A. Fur die μ3-gebundenen Halogene Cli und Bri werden Valenzkraftkonstanten von 1.1 bzw. 1.0 mdyn/A berechnet. Die Werte fur die (MoYa)-Bindungen liegen im ublichen Halogenbereich. Die beobachteten Isotopenshifts werden durch die Rechnungen sehr gut verifiziert, so das erstmals eine detaillierte Zuordnung der IR- und Raman-Spektren dieser Verbindungsreihe vorgenommen werden kann. Vibrational Spectra and Normal Coordinate Analysis of 92Mo, 100Mo, 35Cl, and 37Cl Isotopomers of the Cluster Anions [(Mo6X)Y]2−; Xi = Cl, Br; Ya = F, Cl, Br, I The tetrabutylammonium (TBA) salts of the octa-μ3-halogeno-hexahalogeno-octahedro-hexamolybdate(2 –) anions [(Mo6X)Y]2−; Xi = Cl, Br; Ya = F, Cl, Br, I; have been synthesized using 92Mo, 100Mo, 35Cl, and 37Cl. The 10 K IR and Raman spectra reveal significant frequency shifts due to the isotopic labelling of the Mo6 cage, the inner sphere halides X8i or the outer sphere ligands Y, respectively. The normal coordinate analysis yields (MoMo) valence force constants of about 1.3 to 1.5 mdyn/A. For the μ3-bonded halogenes Cli and Bri valence force constants of 1.1 resp. 1.0 mdyn/A are calculated. The values for (MoYa) bonds are found in the usual halide range. The observed isotopic shifts are verified very well by the calculations, allowing detailed assignment of the IR and Raman spectra of these compounds for the first time.

By reaction of [B6H6](2-) with dibenzoylperoxide in dichloromethane conjuncto-[B6H6-B6H6](2-) is formed. The product could be separated from excess [B6H6](2-) by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structure of [P(C6H5)(4)](2)-conjuncto-[B6H6-B6H6] has been determined by single crystal X-ray diffraction analysis; triclinic, space group <P(1)over bar> with a = 10.8315(10), b = 11.2422(12), c = 20.340(2) Angstrom, alpha = 91.278 degrees (9), beta = 90.178 degrees (9), gamma = 105.662 degrees(9). The B-11 NMR spectrum reveals three signals with the intensity ratio 1:1:4, for two equivalent moieties of the conjuncto molecule ion with local C-4v symmetry. The IR and Raman spectra of the deprotonated Cs salts of the B-10, B-11 and their respective D isotopomers of conjuncto-[B6H5-B6H5](4-) exhibit characteristic shifts. Using averaged crystallographic data and assuming idealized D-4h symmetry, normal coordinate analyses have been performed based on a modified valence force field. With a set of eleven force constants (e.g. f(d)(BB)(conjuncto) = 2.9, f(d)(BB)(cage) = 1.6 mdyn/Angstrom) very good agreement between observed and calculated frequencies has been achieved. From strong vibrational coupling with the B-6 clusters two vibrations result for the conjuncto B-B bond at 1142/1198 and 292/304cm(-1) for B-11/B-10 species, respectively. They can be assigned as anti-phase and in-phase motions of the conjuncto B atoms related to the equatorial B-4 planes.

The tetrabutylammonium (TBA), tetraphenylphosphonium (TPP) and tetraphenylarsonium (TPAs) salts of the octa-mu3-bromo-hexahalogeno-octahedro-hexamolybdate(2 -) anions [(Mo6Br8i)X6a]2- (X(a) - F, Cl, Br, 1) are synthesized from solutions of the free acids H2[(MO6Br8i)X6a] . 8 H2O with X(a) Cl, Br, I. The crystal structures show systematic stretchings in the Mo-Mo bond length and a slight compression of the Br8i cube in the F(a) to I(a) series. The cations do not change much. The i. r. and Raman spectra show at 10 K almost constant frequencies of the (Mo6Br8i) cluster vibrations, whereas all modes with X(a) ligand contribution are characteristically shifted. The most important bands are assigned by polarization measurements and the force constants are derived from normal coordinate analysis. The Mo-95 nmr signals are shifted to lower field with increasing electronegativity of the X(a) ligands. The fluorine compound shows a sharp F-19 nmr singlet at -184.5 ppm.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Quick, facile, and high-yield syntheses of di- and trinegative octachloro- and octabromoditechnetates by reduction of tetrahalogenooxotechnetates(V) or hexahalogenotechnetates(IV) with tetrahydridoborate in organic solvents are described. The compounds are easily convertible by ligand exchange reactions. Under exclusion of air the octahaloditechnetates(lII, III) are stable in organic solvents and unstable in conc. hydrohalic acids, in contrast to the octahaloditechnetates(II, III) being stable in conc. hydrohalic acids and unstable in organic solvents. Based on a general valence force field, normal coordinate analyses on the metal-metal multiple bond systems [Re2X8]2− (X = F, Cl, Br, I), [Tc2X8]2−,3− (X = Cl, Br)(D4h), including35Cl and37Cl labeled species, and [Os2X8]2− (X = Cl, Br, I)(D4d) have been performed. With sets of seven or ten force constants very good agreement between observed and calculated frequencies has been achieved. The metal-metal valence force constants range from 2.7 to 4.9 mdyne/Å, the strength of the bonds depending on the bond order and the masses of the ligands. The bromo compounds in particular exhibit a strong vibrational coupling of the metal-metal stretching mode with the symmetric breathing vibration of the ligand sphere.

Die Tetrabutylammonium(TBA)‐, Tetraphenylphosphonium(TPP)‐ und Tetraphenylarsonium(TPAs)‐Salze der Octa‐μ 3 ‐bromo‐hexahalogeno‐octahedro‐hexamolybdat‐(2−)‐Anionen [(Mo 6 Br )X ] 2− mit X a = F, Cl, Br, I sind aus den Lösungen der freien Säuren H 2 [(Mo 6 Br )X ] · 8 H 2 O mit X a = Cl, Br, I dargestellt worden. Die Kristallstrukturen zeigen eine systematische Verlängerung der (MoMo)‐Bindungsabstände und eine geringfügige Kontraktion der Br i 8 ‐Würfel beim Übergang F a → I a . Der Kationeneinfluß ist gering. Die IR‐ und Raman‐Spektren ergeben bei 10 K für das Clustergerüst (Mo 6 Br i 8 ) nahezu lagekonstante Schwingungen, während alle Moden, an denen die X a ‐Liganden beteiligt sind, charakteristische Verschiebungen aufweisen. Die wichtigsten Banden werden durch Polarisationsmessungen zugeordnet und die Bindungskraftkonstanten durch Normalkoordinatenanalysen ermittelt. Die 95 MoNMR‐Signale werden mit zunehmender Elektronegativität der X a ‐Liganden zu tiefem Feld verschoben. Die Fluorverbindung liefert im 19 FNMR ein scharfes Singulett bei −184,5 ppm.

AbstractDie Tetrabutylammonium(TBA)‐, Tetraphenylphosphonium(TPP)‐ und Tetraphenylarsonium(TPAs)‐Salze der Octa‐μ3‐bromo‐hexahalogeno‐octahedro‐hexamolybdat‐(2−)‐Anionen [(Mo6Br)X]2− mit Xa = F, Cl, Br, I sind aus den Lösungen der freien Säuren H2[(Mo6Br)X] · 8 H2O mit Xa = Cl, Br, I dargestellt worden. Die Kristallstrukturen zeigen eine systematische Verlängerung der (MoMo)‐Bindungsabstände und eine geringfügige Kontraktion der Bri8‐Würfel beim Übergang Fa → Ia. Der Kationeneinfluß ist gering.Die IR‐ und Raman‐Spektren ergeben bei 10 K für das Clustergerüst (Mo6Bri8) nahezu lagekonstante Schwingungen, während alle Moden, an denen die Xa‐Liganden beteiligt sind, charakteristische Verschiebungen aufweisen. Die wichtigsten Banden werden durch Polarisationsmessungen zugeordnet und die Bindungskraftkonstanten durch Normalkoordinatenanalysen ermittelt. Die 95MoNMR‐Signale werden mit zunehmender Elektronegativität der Xa‐Liganden zu tiefem Feld verschoben. Die Fluorverbindung liefert im 19FNMR ein scharfes Singulett bei −184,5 ppm.