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Is Single-4-Ring the Most Basic but Elusive Secondary Building Unit That Transforms to Larger Structures in Zinc Phosphate Chemistry?

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Title Is Single-4-Ring the Most Basic but Elusive Secondary Building Unit That Transforms to Larger Structures in Zinc Phosphate Chemistry?
 
Creator DAR, AA
SHARMA, SK
MURUGAVEL, R
 
Subject OPEN-FRAMEWORK STRUCTURES
ZIRCONIUM-PHOSPHATE
MOLECULAR-SIEVES
METAL PHOSPHATES
HYDROTHERMAL SYNTHESIS
TEMPERATURE SYNTHESIS
TITANIUM PHOSPHATES
ASSISTED SYNTHESIS
IRON PHOSPHATE
ION-EXCHANGE
 
Description Haloaryl phosphates (X-dippH(2), X = Cl, Br, I) react with zinc acetate in the presence of collidine or 2-aminopyridine (2-apy) to yield zinc phosphate clusters [Zn(X-dipp)(collidine)]4 (X = Cl (1), Br (2), I (3)) and [Zn(X-dipp)(2-apy)](4)center dot 2MeOH (X = Cl (4), Br (5), I (6)), respectively. Single-crystal X-ray diffraction studies reveal that collidine and 2-apy capped zinc phosphates 1-6 exist as discrete tetrameric zinc phosphate molecules, exhibiting a cubane-shaped D4R core. In contrast, when the same reaction has been carried out in the presence of 4-cyanopyridine (4-CNpy), polymeric zinc phosphates {[Zn-4(X-dipp)(4)(4-CNpy)(2)(MeOH)(2)]center dot 2H(2)O}(n) (X = Cl (7), Br (8), I (9)) have been isolated. Compounds 7-9 are square-wave-shaped, one-dimensional polymers composed of fused S4R repeating units. The common structural motif found both in D4R cubanes 1-6 and polymers 7-9 is the S4R building block, which presumably undergoes further fusion because of the coordinative unsaturation at zinc and the simultaneous presence of free P=O. The closed shell cubanes 1-6 are obviously formed by a face-to-face dimerization involving two S4R units in which the two P=O groups are in cis-configuration. On the other hand, the one-dimensional (1-D) square-wave polymers 7-9 are formed from a face-to-face association of S4R building units in which the two P=O groups are in a trans-configuration. In order to stabilize these elusive S4R zinc phosphates, the reaction between Cl-dippH2 and zinc acetate was carried out in the presence of excess imidazole as an ancillary ligand (1:1:4), although only an imidazole decorated cubane cluster [Zn(Cl-dipp)(imz)]4.2MeOH (10) was isolated. The chelating N,N'-donor 1,10-phenanthroline ligand was used to eventually isolate cyclic S4R phosphate [Zn(mu(2)-Cl-dipp)(1,10-phen)(OH2)](2)center dot MeOH center dot H2O (11). The change of Zn2+ source to zinc nitrate and the phosphate source to 2,6-dimethylphenyl phosphate (dmppH2) led to the isolation of another polymeric phosphate [Zn(dmpp)(MeOH)](n) (12), with a zigzag backbone, formed through an edge-to-edge to polymerization of S4R building units with P=O groups in trans-configuration. The isolation of four different structural types of zinc phosphates A-D in the present study can be rationalized in terms of fusion of S4R rings in a variety of ways to either produce discrete clusters or 1-D polymers.
 
Publisher AMER CHEMICAL SOC
 
Date 2016-01-15T06:04:13Z
2016-01-15T06:04:13Z
2015
 
Type Article
 
Identifier INORGANIC CHEMISTRY, 54(10)4882-4894
0020-1669
1520-510X
http://dx.doi.org/10.1021/acs.inorgchem.5b00495
http://dspace.library.iitb.ac.in/jspui/handle/100/17885
 
Language en