Steric control of the reactivity of moderately hindered tris(pyrazolyl)borates with copper(II) salts

Chia, Li Mei Lindy and Radojevic, Sanja and Scowen, Ian J. and McPartlin, Mary and Halcrow, Malcolm A. (2000) Steric control of the reactivity of moderately hindered tris(pyrazolyl)borates with copper(II) salts. Journal of the Chemical Society, Dalton Trans. (2). pp. 133-140. ISSN 1477-9226, 1470-479X

Full content URL: http://dx.doi.org/10.1039/A907258F

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Item Type:Article
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Abstract

The co-ordination chemistry of the anions tris(3-phenylpyrazolyl)borate (TpPh-){,} tris(3-cyclohexylpyrazolyl)borate (TpCy-) and tris(3{,}5-diphenylpyrazolyl)borate (TpPh2-) with Cu(O2CMe)2middle dotH2O{,} CuCl2 and Cu(BF4)2middle dot6H2O has been investigated. The complex Cu(O2CMe)(TpPh) (1) transforms in solution to the B-N cleavage product Cu(O2CMe)(HpzPh)(TpPh) (2){,} whose crystal structure shows two square pyramidal Cu(II) centres in the asymmetric unit{,} each with a monodentate acetate ligand. The analogous complex Cu(O2CMe)(TpCy) (3) does not undergo this reaction. Reaction of KTpCy or KTpPh2 with one equivalent of CuCl2 in CH2Cl2 yields mixtures of CuCl(TpR) (R = Cy{,} Ph2) and CuCl(HpzR)(TpR) (R = Cy{,} 5; R = Ph2{,} 6). Reaction of Cu(BF4)2middle dot6H2O with one equivalent of KTpPh in CH2Cl2 gives Cu(HpzPh)4(BF4)2 (7) in low yield as the only isolable product. An identical reaction with KTpCy affords Cu(HpzCy)2(TpCy)BF4 (8) in moderate yield. The single crystal structure of 8middle dotCHCl3 contains a square pyramidal complex with two N-H FBF3 and one Cl3C-H FBF3 hydrogen bonds within each formula unit. Complexation of CuCl2 by two equivalents of KTpPh in MeOH affords Cu(TpPh)2 (9) in high yield. In contrast{,} identical reactions employing KTpCy or KTpPh2 yield Cu(pzCy)(HpzCy)(TpCy) (10) or 6 as the major products. The single crystal structure of 10 shows a square pyramidal Cu(II) centre with metric parameters very similar to 8; although not crystallographically located{,} the presence of a N-H N hydrogen bond between the HpzCy and pzCy- ligands can be inferred from the close approach of the pzCy pyrrolic N atoms. All complexes were characterised by FAB mass spectrometry{,} microanalysis{,} IR{,} UV/vis and EPR spectroscopies.

Keywords:Chemistry
Subjects:F Physical Sciences > F100 Chemistry
Divisions:College of Science > School of Chemistry
ID Code:13268
Deposited On:19 Mar 2014 17:57

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