ISSN:
0044-2313
Keywords:
Octa-μ3-chloro-hexazido-octahedromolybdate(2-)
;
Octa-μ3-bromo-hexazido-octahedromolybdate(2-)
;
Synthesis
;
Crystal Structure
;
Vibrational Spectra
;
Normal Coordinate Analysis
;
Force Constants
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Synthesis, Crystal Structure, and Spectroscopic Properties of the Cluster Anions [(Mo6X8i)(N3)6a]2-; Xi = Cl, BrBy treatment of [(Mo6X8i)Y6a]2-; Xi, Ya = Cl, Br; with AgNO3 in ethanol/dichloromethane and addition of NaN3 the octa-μ3-halogeno-hexazido-octahedro-hexamolybdate(2-) anions [(Mo6X8i)(N3)6a]2- are formed. X-ray structure determinations have been performed on single crystals of (n-Bu4N)2[(Mo6Cl8i)(N3)6a] (1) (monoclinic, space group P 21/n, a = 14.592(5) Å, b = 12.314(5) Å, c = 17.039(5) Å, β = 101.183(5)°, Z = 2), (n-Bu4N)2[(Mo6Br8i)(N3)6a] (2) (monoclinic, space group P 21/n, a = 14.595(6) Å, b = 12.416(5) Å, c = 16.960(3) Å, β = 100.74(3)°, Z = 2) and (Ph3P=N=PPh3)2 [(Mo6Br8i)(N3)6a] (3) (triclinic, space group P 1, a = 11.092(4) Å, b = 13.161(8) Å, c = 14.341(11) Å, α = 78.085(6)°, β = 82.821(5)°, γ = 84.379(4)°, Z = 1). Whereas the cluster anions of the (n-Bu4N) salts reveal a regular geometry, the (Ph3P=N=PPh3) cation causes strong distortions of the cluster kernel with variation of the Mo-Mo and Mo-Bri 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-Bu4N) cluster salts are assigned by normal coordinate analyses based on a modified valence force field. The valence force constants are fd(Mo—Mo) = 1.53 (Cli), 1.46 (Bri), fd(Mo—Cli) = 1.09, fd(Mo-Bri) = 0.96, fd(Mo-N1) = 2.09 (Cli), 2.36 (Bri) mdyne/Å, respectively.
Notes:
Bei der Umsetzung von [(Mo6X8i)Y6a]2-; Xi, Ya = Cl, Br; mit AgNO3 in Ethanol/Dichlormethan und anschließender Zugabe von NaN3 entstehen Octa-μ3-halogeno-hexazido-octahedro-hexamolybdat(2-)-Anionen [(Mo6X8i)(N3)6a]2- Röntgenstrukturanalysen sind an Einkristallen von (n-Bu4N)2[(Mo6Cl8i)(N3)6a] (1) (monoklin, Raumgruppe P 21/n, a = 14,592(5) Å, b = 12,314(5) Å, c = 17,039(5) Å, β = 101,183(5)°, Z = 2), (n-Bu4N)2[(Mo6Br8i)(N3)6a] (2) (monoklin, Raumgruppe P 21/n, a = 14,595(6) Å, b = 12,416(5) Å, c = 16,960(3) Å, β = 100,74(3)°, Z = 2) und (Ph3P=N=PPh3)2[(Mo6Br8i)(N3)6a] (3) (triklin, Raumgruppe P 1, a = 11,092(4) Å, b = 13,161(8) Å, c = 14,341(11) Å, α = 78,085(6)°, β = 82,821(5)°, γ = 84,379(4)°, Z = 1) durchgeführt worden. Während die Clusteranionen in den (n-Bu4N)-Salzen eine regelmäßige Geometrie aufweisen, verursacht das Kation in der (Ph3P=N=PPh3)-Verbindung starke Verzerrungen des Clusterkerns mit einer Variation der Bindungslängen Mo-Mo bzw. Mo-Bri um bis zu 8%. Unter Verwendung der röntgenographisch ermittelten Molekülparameter werden die bei 10 K registrierten IR- und Raman-Spektren der (n-Bu4N)-Clustersalze durch Normalkoordinatenanalysen auf der Basis eines modifizierten Valenzkraftfeldes zugeordnet. Die Valenzkraftkonstanten betragen für fd(Mo-Mo) = 1,53 (Cli) bzw. 1,46 (Bri), fd(Mo-Cli) = 1,09, fd(Mo—Bri) = 0,96, fd(Mo—N1) = 2,09 (Cli) bzw. 2,36 (Bri) mdyne/Å.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19976230102
