Abstract:Proceeding from the x-B-SbW,O,, fragment 1, various novel large heteropolyanions ([Na,Sb,W,,O, 3Z(H,0),]22~~ (2), [Sb,W,,0,,(OH),]'2~ ( 3 ) and (4); M"' = Fe3+, Co", Mn''. Ni") have been obtiiined in crystalline form by systematic synthesis. Their unexpected structures have been studied by X-ray diffraction: 2, 3 and 4 contain /j-SbW,l units connected to each other by Sb3 ions, WOJW0,OH groups. and WO,/M"+(H,O), groups. respectively. Structural details and especially the systematic synthesis strategy for the formation of these interesting polytungstates are discussed in order to explain the unusual behaviour of 1 in aqueous solulion under different rcaction conditions.

The heteropolyanions [Bi 2 W 22 O 74 (OH) 2 ] 12-(1) and [X 2 W 20 M 2 O 70 (H 2 O) 6 ] (14-2n)-(X ) Sb 3+ , Bi 3+ ; M n+ ) Fe 3+ , Co 2+ , Zn 2+ ) (2-7) have been synthesized as alkali metal and ammonium salts, respectively, and characterized by elemental analysis, infrared spectroscopy, and X-ray crystallography. These tungsto bismutates and antimonates reveal one common feature: the trivacant -B-XW 9 O 33 Keggin fragment as the structural building unit. Formally, the unit can be derived from the Keggin structure by removing one trimetalate fragment, W 3 O 13 , and a 60°rotation of one of the remaining W 3 O 13 subunits around the X-O W3X bond vector (the subscript indicates the element(s) bonded). The unshared pair of electrons of the respective central, pyramidally coordinated heteroatom Sb III or Bi III prevents formation of the complete spherical structure. In the presented heteropolyanions 1-7, two -B-XW 9 O 33 units are connected by two WO 2 groups. Further stabilization of this hitherto unknown bis-decatungsto ion [X 2 W 20 O 70 ] 14-is reached either by addition of two formal fac-WO 3 anti-Lipscomb's rule units to give the bis-undecatungsto bismutate [Bi 2 W 22 O 74 (OH) 2 ] 12-(1) or by addition of two M n+ (H 2 O) 3 groups (M n+ ) Fe 3+ , Co 2+ , Zn 2+ ) forming the large, transition-metal-substituted heteropolyanion clusters [X 2 W 20 M 2 O 70 (H 2 O) 6 ] (14-2n)-(X ) Sb 3+ , Bi 3+ ; M n+ ) Fe 3+ , Co 2+ , Zn 2+ ) (2-7).

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.

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