Novel unsymmetrical PCP′ pincer ligands and their palladium(II) complexes
摘要:
Synthetic routes towards novel PCF pincer ligands were devised. Ligand 1-((Pr2POCH2)-P-i)-3-((Bu2PCH2)-P-t)(C6H4) is prepared in a three step synthesis from 1,3-benzenedimethanol and 1-((Pr2PO)-P-i)-3-((Bu2PCH2)-P-t)(C6H4,) is accessible in three steps from 3-hydroxybenzylalcohol. Both their palladium(II) complexes are prepared in good yields but are distinctly different since [PdCl{(C6H3)(OPPr2i)-2-(CH2PBu2t)-6}] possesses two five-membered palladacycles, whereas [PdCl{(C6H3)(CH2PBu2t)-2-(CH2OPPr2i)-6}] is unusual for a pincer complex in that it contains both five- and six-membered palladacycles. Both compounds also represent the first examples of pincer complexes where one donor is a phosphinite and the other is a phosphine. The X-ray structures of these complexes were solved and are discussed. The data reveal that an increase in the metallacycle ring-size leads to changes in bond lengths, but more importantly to significant increases in the bond angles. (C) 2003 Elsevier B.V. All rights reserved.
Novel unsymmetrical PCP′ pincer ligands and their palladium(II) complexes
摘要:
Synthetic routes towards novel PCF pincer ligands were devised. Ligand 1-((Pr2POCH2)-P-i)-3-((Bu2PCH2)-P-t)(C6H4) is prepared in a three step synthesis from 1,3-benzenedimethanol and 1-((Pr2PO)-P-i)-3-((Bu2PCH2)-P-t)(C6H4,) is accessible in three steps from 3-hydroxybenzylalcohol. Both their palladium(II) complexes are prepared in good yields but are distinctly different since [PdCl{(C6H3)(OPPr2i)-2-(CH2PBu2t)-6}] possesses two five-membered palladacycles, whereas [PdCl{(C6H3)(CH2PBu2t)-2-(CH2OPPr2i)-6}] is unusual for a pincer complex in that it contains both five- and six-membered palladacycles. Both compounds also represent the first examples of pincer complexes where one donor is a phosphinite and the other is a phosphine. The X-ray structures of these complexes were solved and are discussed. The data reveal that an increase in the metallacycle ring-size leads to changes in bond lengths, but more importantly to significant increases in the bond angles. (C) 2003 Elsevier B.V. All rights reserved.