Late transition metal complexes of a new P–N ligand Ph2PCH2N(H)C5H3(Cl-5)N: synthesis and structural studies

Abstract

A new functionalised pyridylphosphine Ph₂PCH₂N(H)C₅H₃(Cl-5)N 1 has been synthesized from Ph₂PCH₂OH and 2-H₂NC₅H₃(Cl-5)N. Reaction of 1 with aqueous H₂O₂ gave Ph₂P(O)CH₂N(H)C₅H₃(Cl-5)N 2. The crystal structures of 1 and 2 reveal, in both cases, dimer pair formation through N–H···N_pyridyl or N–H···OP intermolecular hydrogen bonding respectively. Chloro bridge cleavage of either [{RuCl(μ-Cl)(η⁶-p-MeC₆H₄Prⁱ)}₂], [{RhCl(μ-Cl)(η⁵-C₅Me₅)}₂] or [{Pd(C₁₂H₁₂N)(μ-Cl)}₂] with two equivalents of 1 gave the mononuclear complexes [RuCl₂(η⁶-p-MeC₆H₄Prⁱ)1] 3, [RhCl₂(η⁵-C₅Me₅)1] 4 or [PdCl(C₁₂H₁₂N)1] 5 (P trans to N) respectively. The chloro complexes [AuCl(1)] 6, [PtCl₂(1)₂] 7 and [PdCl₂(1)₂] 8 were prepared by substitution of tht (tetrahydrothiophene) (or cod) from [AuCl(tht)] or [MCl₂(cod)] (M = Pt or Pd). In 3–8 only P-ligation of 1 was observed. Chloride abstraction from either 3–5 or 7, 8 using Ag[BF₄] gave the cationic complexes [RuCl(η⁶-p-MeC₆H₄Prⁱ){Ph₂PCH₂N(H)C₅H₃(Cl-5)N-P,N}][BF₄] 9, [RhCl(η⁵-C₅Me₅){Ph₂PCH₂N(H)C₅H₃(Cl-5)N-P,N}][BF₄] 10, [Pd(C₁₂H₁₂N){Ph₂PCH₂N(H)C₅H₃(Cl-5)N-P,N}][BF₄] 11 and cis-[M{Ph₂PCH₂N(H)C₅H₃(Cl-5)N-P,N}₂][BF₄]₂ (M =  Pt 12 or Pd 13) in which 1 chelates through both P and N_pyridyl donor atoms. All complexes were characterised by a combination of multinuclear NMR, IR spectroscopy and elemental analyses. Furthermore the crystal structures of 5–7 and 12 have been determined and reveal several types of N–H···X (X = N, F or Cl; inter- or intra-molecular) hydrogen bonding contacts. The structure of 12 represents an extremely rare, crystallographically characterised, M–P–C–N–C–N six-membered metallacyle.