GeH ₃ ‐substituierte Carbonylmetallate und Carbonyl(cyclopentadienyl)‐metallate mit V, Nb, Cr, Mo, W, Re, Co und Ni Präparative und röntgenographische Untersuchungen

Abstract

KGeH3 reagiert mit verschiedenen Metallcarbonylen und Cyclopentadienylmetallcarbonylen unter Substitution einer CO‐Gruppe und Bildung von GeH3‐substituierten Metallaten [M(CO)3(⊖5‐C5H5)GeH3]⊖ [M: V (1), Nb (2)], [M(CO)5GeH3]⊖ [M: Cr (3), Mo (4), W (5)], [Re(CO)2(η5‐C5H5)GeH3]⊖ (6), [Ni(CO)3GeH3]⊖ (7), [Ni(CO)2(PPh3)GeH3]⊖ (8) und [Co‐(CO)(η5R5)GeH3]⊖ [R: H (9), Me (10)]. Die so gebildeten K‐Salze sind sehr luftempfindlich und meist ziemlich thermolabil. Umsetzung mit [PPh4]Br in wäßriger Lösung ergibt die etwas stabileren und besser kristallisierenden Phosphonium‐Salze. Sie wurden elementaranalytisch und spektroskopisch (IR, 1H‐NMR) charakterisiert und im Falle von 1, 4, 5, 7 und 8 auch röntgenographisch untersucht. Auffallend sind ihre kurzen Ge–Metall‐Abstände, obgleich wegen Fehlordnungsproblemen meist keine große Genauigkeit erreichbar war.

Synthetic, Structural, and Theoretical Investigations of Alkali Metal Germanium Hydrides—Contact Molecules and Separated Ions

“…GeA C H T U N G T R E N N U N G (SiMe 3 ) 4 , [27,45] RbOtBu, [46] and CsOtBu [46] were prepared according to literature procedures. [18]Crown-6, [15]crown-5, [12]crown-4, and D 2 O were obtained commercially. [18]Crown-6 was purified by solvation in freshly distilled diethyl ether and stirred with finely cut sodium metal for one day.…”

“…After filtration from excess metal, the crown was recrystallized from hexanes. [15]crown-5 and [12]crown-4 were stored over molecular sieves (4 ) in the dry-box. H 2 O/D 2 O was degassed by passing argon gas through the solution for 12 h. THF/D 2 O and THF/H 2 O stock solutions of known concentration were prepared shortly before use.…”

“…Previous transition-metal germyl derivatives display GeÀH chemical shifts between d = 2 and 4 ppm, thus in agreement with the signals observed for compounds 1-5. [10,12] The analysis of chemical shifts indicates smaller values for the contact molecules 1 and 4, with those for the separated ions closely clustered together, suggesting that the ion association observed in the solid state might be conserved in solution. This observation is in contrast to the tris(trimethylsilyl)silanides and germanides, for which virtually identical chemical shifts are observed for contact molecules and separated ions in the presence of an aromatic solvent, suggesting the formation of separated ions in all cases.…”

“…[30] In accordance with this result, 1.5 equivalents of [18]crown-6 were utilized in the reaction mixture, but only the contact molecule 4 and uncoordinated crown were isolated. The formation of the separated ions 2, 3, and 5 is the result of the small diameter of the crown cavity relative to the alkali metal diameter, as demonstrated with the combination of either [12]crown-4 or [15]crown-5 and potassium, or [18]crown-6 and cesium. With the large alkali metals located above the cavity of the crown, the small GeH 3 À ligand is unable to provide the necessary coordinative saturation.…”

“…GeH 3 À was found to replace one carbonyl functionality, affording A C H T U N G T R E N N U N G [NA C H T U N G T R E N N U N G (CH 3 ) 4 ][h-CH 3 C 5 H 4 Mn(CO) 2 GeH 3 ], [10] [PPh 4 ][Cr(CO) 5 A C H T U N G T R E N N U N G GeH 3 ], [11] [PPh 4 ][V(Cp)(CO) 2 GeH 3 ] ( C p= cyclopentadienide), [12] [PPh 4 ][M(CO) n GeH 3 ] (M= Mo, n = 5; M = W, n = 5; M = Ni, n = 3), [12] and [PPh 4 ][Mo(CO) 2 PPh 3 GeH 3 ]. [12] Replacement of the initially formed potassium salts by the larger PPh 4 + or NMe 4 + ions afforded complexes with increased stability. However, in analogy with the alkali metal species mentioned above, geometrical details of the GeH 3 À moieties were not available, due to difficulties in locating the hydrogen atoms.…”