Synthesis and coordination studies of new aminoalcohol functionalized tertiary phosphines

Durran, Sean E., Smith, Martin B., Slawin, Alexandra M. Z., Gelbrich, Thomas, Hursthouse, Michael B. and Light, Mark E. (2001) Synthesis and coordination studies of new aminoalcohol functionalized tertiary phosphines. Canadian Journal of Chemistry, 79 (5-6), 780-791.

Abstract

The synthesis of two new aminoalcohol functionalized tertiary phosphines o-Ph2PCH2N(H)C6H4(OH) (I) and o-Ph2PCH2N(H)C6H4(CH2OH) (II) are reported. Oxidation with aqueous H2O2 gave the corresponding phosphine oxides o-Ph2P(O)CH2N(H)C6H4(OH) (III) and o-Ph2P(O)CH2N(H)C6H4(CH2OH) (IV) (P-31 NMR evidence only). The ligating ability of I, II and, in several cases, the known ligand 2,3-Ph2PCH2N(H)C5H3N(OH) (V), was investigated with a range of late transition-metal precursors. Accordingly, reaction of 2 equiv of I (or II) with [MCl2(cod)] (M = Pd or Pt, cod = cycloocta-1,5-diene) gave the corresponding dichloro metal(II) complexes [MCl2(I)(2)] (M = Pd 1; M = Pt 2) and [MCl2(II)(2)] (M = Pd 3; M = Pt 4) in which I (and II) P-coordinate. Solution NMR studies reveal that 2 and 4 are exclusively cis whereas 1 and 3 are present as a mixture of cis and (or) trans isomers [4.7:1 (for 1); 2.2:1 (for 3)]. Reaction of 2 equiv of II with [Pt(CH3)(2)(cod)] gave the neutral complex [Pt(CH3)(2)(II)(2)] (5) whose X-ray structure confirmed a cis disposition of "hybrid" ligands. In contrast, reaction of I with [Pt(CH3)(2)(cod)] gave initially [Pt(CH3)(2)(I)(2)] (6) which, upon standing, afforded several products possibly reflecting an increased acidity of the phenolic groups of ligated I. Chloro bridge cleavage reactions of [{Ru(mu -Cl)Cl(p-cymene)}(2)] or [{Rh(mu -Cl)Cl{C-5(CH3)(5)}}(2)] with I (or II) proceeds smoothly and gave the mononuclear complexes [RuCl2(p-cymene)I] (7), [RuCl2(p-cymene)II] (8), [RhCl2{C-5(CH3)(5)}I] (9), and [RhCl2{C-5(CH3)(5)}II] (10) in good yield. X-ray crystallography confirms both ruthenium complexes bear P-coordinated I (or II) ligands. Molecules of 7 are linked into linear chains via O-H . . . Cl-coord intermolecular hydrogen bonding, a feature absent in the closely related compound 8. Reaction of [AuCl(tht)] (tht = tetrahydrothiophene) with 1 equiv of I (or II) gave the corresponding gold(I) complexes [AuCl(I)] (11) and [AuCl(II)] (12). Bridge cleavage of the cyclometallated palladium(II) dimers [{Pd(mu -Cl)(C similar toN)}(2)] [C similar toN = C,N-C6H4CH2N(CH3)(2), C,N-C10H6N(CH3)(2), C,N-C6H4N=NC6H5] with V (or I) gave the neutral complexes [PdCl(C similar toN)V] (13-15) (or [PdCl(C9H12N)I] (16)), respectively. Chloride abstraction from 13 (or 15) with Ag[BF4] gave the cationic complexes [Pd(C similar toN)V][BF4] (17) (or 18) in which V P,N-pyridyl-chelates to the palladium(II) metal centre. The X-ray structures of 13 and 18 have been determined and confirm the expected coordination environments. An array of intra- and intermolecular H-bonding contacts are also observed. All compounds have been characterized by a combination of spectroscopic and analytical studies.

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Contributors

Author: Mark E. Light

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