Synthesis and Selected Properties of New Complex Cation Decorated Polyoxotantalates

Abstract

Diffusion-based room temperature syntheses using K8{Ta6O19}·16H2O, d-block metal (M) salts (M = Cu, Zn, or Cd), and the macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane (cyclam) led to crystallization of the three new polyoxotantalates with the composition K4{[Cu­(cyclam)]2Ta6O19}·18H2O (I), K4{[Zn­(cyclam)]2Ta6O19}·18H2O (II), and {[Cd­(cyclam)]4Ta6O19}·19H2O (III). The latter two compounds represent the first polyoxotantalates (POTas) with Zn2+ and Cd2+ centered amine complexes and also the first POTas synthesized using a macrocyclic amine. Compounds I and II are isostructural with two complexes attached to the anionic cluster via Cu–O–Ta respectively Zn–O–Ta bonds. Despite that these two compounds are isostructural, the geometry of the M2+ complexes differs significantly with Cu2+ in a square-pyramidal and Zn2+ in a trigonal-bipyramidal environment. In the structure of III, the Cd2+ cations are in the rare hepta-coordinated monocapped trigonal prismatic geometry covalently linked to the anionic core via Cd–O–Ta bonds. While compounds I and II are quite stable under ambient conditions, III shows a fast loss of crystal water molecules. Temperature-dependent in situ XRD measurements were performed with I demonstrating stepwise structural rearrangements caused by water release.

Polyoxotantalate chemistry: from synthetic strategies to structural diversity and applications

“…Two years later, three new POTas with the formula K 4 [{Zn(cyclam)} 2 Ta 6 O 19 ]·18H 2 O, K 4 [{Cu(cyclam)} 2 Ta 6 O 19 ]·18H 2 O and [{Cd(cyclam)} 4 Ta 6 O 19 ]·19H 2 O were obtained by the reaction of d-block metal (M) salts (M = Zn, Cu, or Cd), cyclam (cyclam = 1,4,8,11-tetraazacyclotetradecane) and K 8 [Ta 6 O 19 ]·16H 2 O in liquid phase diffusion at room temperature. 64 The first two compounds are isomorphic, both of which are polyoxoanion [Ta 6 O 19 ] 8− coordinated with two complexes (Fig. 4i).…”

“…4c). 63 In the same year, the first inorganic-organic hybrid three-dimensional POTa [Cu(en) 64 The first two compounds are isomorphic, both of which are polyoxoanion [Ta 6 O 19 ] 8− coordinated with two complexes (Fig. 4i).…”

Two resistance-switchable hybrid polyoxotantalates based on {Co2Ta12} clusters

“…[29][30][31] To date, only a tiny number of POTas have been discovered. [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] The reasons for the limited development of POTas include the chemical inertness of the tantalite species, the lack of soluble POTa precursors, the narrow reaction pH range (10)(11)(12), the low aqueous solubility of the common [Ta 6 O 19 ] 8− precursor, and the chemical incompatibility between POTas and other metal cations. It is worth noting that POTas have been shown to have significant application value in the fields of virology, photocatalysis, proton conductivity and base catalysis.…”

Two binuclear Ni-inserted polyoxotantalates based on {NiTa10O32} units with catalytic activity

“…In 1953, the first POTa {Ta 6 O 19 } was reported by Lindqvist, 8 and then, a few other POTas were obtained by Nyman, Casey, Liu, Su, Hu and Zheng's groups, such as {Re(CO) 3 Ta 6 O 19 }, {Mn(CO) 3 Ta 6 O 19 }, 9 {Ta 10 O 28 }, 10 {Ti 2 Ta 8 O 28 }, {Ti 12 Ta 6 O 44 }, 11 {P 8 W 60 Ta 12 (H 2 O) 4 (OH) 8 O 236 }, {P 2 W 15 O 59 (TaO 2 ) 3 }, 12 {Ta 18 P 12 W 90 (OH) 6 (H 2 O) 2 O 360 }, 13 {[Cu(en) 2 ] 4 Ta 6 O 19 }, 14 {[Cu(en) 2 ] 3 [Cu(en)(H 2 O) 2 Cu(en)(Ta 6 O 19 )] 2 }, 15 and {[Cu(cyclam)] 2 Ta 6 O 19 }. 16 Our group has also explored the chemistry of POTas and discovered a series of structurally novel compounds such as {P 4 (TaO 2 ) 6 O 25 }, 17 {Se 4 (TaO 2 ) 6 (OH) 4 O 17 }, 18 {Ln(H 2 O) 6 H 4 (TaO 2 ) 6 As 4 O 24 }, 19 {CoTa 6 O 19 }, {[Co(en)] 2 Ta 12 O 38 }, 20 {Co 8 Ta 24 O 80 }, 21 {Cu 4 (bipy) 6 Ta 6 O 19 }, and {Cu 4 (phen) 6 Ta 6 O 19 }. 22 In these compounds, transition-metal or lanthanide clusters serve as pendants that decorate the surface of the POTas skeleton or act as connectors that bridge POTas units to form large aggregations.…”