Heteropolymetalate Clusters of the Subvalent Main Group Elements Bi^III and Sb^III

Abstract

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).

Syntheses and Crystal Structures of dmso‐Coordinated Tungstoantimonates(III) and ‐bismuthates(III)

“…The IR spectra of 1a-4a are very similar to their precursors Na-X 2 W 22 /KNa-X 2 W 22 Fe 2 [11,12] and Ru(bpy) 3 Cl 2 [36] superimposed on each other, which implies that the Krebs-type POM frameworks are maintained in compounds 1a-4a.…”

“…20 Fe 2 ) were synthesized according to the literature and characterized by IR spectra. [11,12] All other reagents were used as purchased without further purification. Deionized water was used throughout.…”

“…For example, we tested if 1-4 can also be isolated from the mixed solutions with dmso/H 2 O (1:1, v/v) in the absence of Rubpy, but the results indicated that no products were obtained. We also tested a two-step procedure: (1) [11,12] in which two [B-β-XW 9 O 33 ] 9-fragments are connected by two WO 2 and two WO 2 (OH) groups. Comparison of the structures of 1 and 2 with that of X 2 W 22 indicates that dmso groups replace the oxygen atoms of WO 2 and hydroxy group of WO 2 (OH) leading to dmso-coordinated polytungstates.…”

“…In addition, the novel WO 2 (dmso) groups were found in 1 and 2, as shown in Figure 2. 12-(X = Sb III , Bi III ) [11,12] suggests that two W11-OT bond lengths in 1 and 2 do not indicate any hydroxy groups. This observation allows the conclusion that the two protonated W-OH groups in […”

Polyoxometalates: Powerful Catalysts for Atom‐Efficient Cyclopropanations

“…[47] As each cobalt cation in the latter complex bears three water molecules instead of a single one, its catalytic activity could be improved, as already suggested. [47][48][49] One asset of multi-vacant POMs is their ability to coordinate several active metallic sites, so that synergistic effects could arise, provided that they are not too distant from each other. We thus included the study of…”