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Octanuclear Zinc Phosphates with Hitherto Unknown Cluster Architectures: Ancillary Ligand and Solvent Assisted Structural Transformations Thereof

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Title Octanuclear Zinc Phosphates with Hitherto Unknown Cluster Architectures: Ancillary Ligand and Solvent Assisted Structural Transformations Thereof
 
Creator DAR, AA
SEN, S
GUPTA, SK
PATWARI, GN
MURUGAVEL, R
 
Subject OPEN-FRAMEWORK ZINCOPHOSPHATE
EFFECTIVE CORE POTENTIALS
ZIRCONIUM-PHOSPHATE
MOLECULAR-SIEVES
CRYSTAL-STRUCTURES
TITANIUM PHOSPHATES
METAL PHOSPHATES
HYDROTHERMAL SYNTHESIS
TEMPERATURE SYNTHESIS
AUXILIARY LIGANDS
 
Description Structural variations in zinc phosphate cluster chemistry have been achieved through a careful selection of phosphate ligand, ancillary ligand, and solvent medium. The use of 4-haloaryl phosphates (X-dippH(2)) as phosphate source in conjunction with 2-hydroxypyridine (hpy) ancillary ligand in acetonitrile solvent resulted in the isolation of the first examples of octameric zinc phosphates [Zn-8(X-dipp)(8)(hpy)(4)(CH3CN)(2)(H2O)(2)}center dot 4H(2)O (X = Cl 2, Br 3) and not the expected tetranuclear D4R cubane clusters. Use of 2,3-dihydroxypyridine (dhpy) as ancillary ligand, under otherwise similar reaction conditions with the same set of phosphate ligands and solvent, resulted in isolation of another type of octanudear zinc phosphate clusters {[(Zn-8(X-dipp)(4)(X-dippH)(4)(dhpyH)(4)(dhpyH(2))(2)(H2O)(2)]center dot 2solvent} (X = Cl, solvent = MeCN 4; Br, solvent = H2O 5), as the only isolated products. X-ray crystal diffraction studies reveal that 2 and 3 are octanudear clusters that are essentially formed by edge fusion of two D4R zinc phosphates. Although 4 and 5 are also octanudear clusters, they exhibit a completely different cluster architecture and have been presumably formed by the ability of 2,3-dihydroxypyridine to bridge zinc centers in addition to the X-dipp ligands. Dissolution of both types of octanuclear clusters in DMSO followed by crystallization yields D4R cubanes [Zn(X-dipp)(DMSO)](4) (X = Cl 6, Br 7), in which the ancillary ligands such as hpy, H2O, and CH3CN originally present on the zinc centers of 2-5 have been replaced by DMSO. DFT calculations carried out to understand the preference of Zn-8 versus Zn-4 clusters in different solvent media reveal that use of CH3CN as solvent favors the formation of fused cubanes of the type 2 and 3, whereas use of DMSO as the solvent medium promotes the formation of D4R structures of the type 6 and 7. The calculations also reveal that the vacant exoduster coordination sites on the zinc centers at the bridgehead positions prefer coordination by water to hpy or CH3CN. Interestingly, the initially inaccessible D4R cubanes [Zn(X-dipp)(hpy)](4)center dot 2MeCN (X = Cl 8, Br 9) could be isolated as the sole products from the corresponding DMSO-decorated cubanes 6 and 7 by combining them with hpy in CH3CN.
 
Publisher AMER CHEMICAL SOC
 
Date 2016-01-15T06:06:15Z
2016-01-15T06:06:15Z
2015
 
Type Article
 
Identifier INORGANIC CHEMISTRY, 54(19)9458-9469
0020-1669
1520-510X
http://dx.doi.org/10.1021/acs.inorgchem.5b01308
http://dspace.library.iitb.ac.in/jspui/handle/100/17889
 
Language en