The synthesis and coordination chemistry of new functionalised pyridylphosphines derived from Ph₂PCH₂OH

Condensation of Ph2PCH2OH with H2NC5H3(OH)N in methanol/toluene gave the new "hybrid" ligand Ph2PCH2N(H)C5H3(OH)N Ia, which upon phosphorylation with either ClP(O)R-2 (R=Ph, OPh) or ClPR2 afforded Ph2PCH2N(H)C5H3(X)N [X=OP(O)Ph-2 II; OP(O)(OPh)(2) III; OPPh2 IV]. Oxidation of Ia with aqueous H2O2 in thf gave Ph2P(O)CH2N(H)C5H3(OH)N V. The dichloroplatinum(II) complexes 1-4 were prepared from [PtCl2(cod)] (cod=cycloocta-1,5-diene) and Ia, II or III (2 equiv.) or IV (1 equiv.). Reaction of [AuCl(tht)] (tht=tetrahydrothiophene) with 1 equiv. of Ia gave [AuCl(Ia)] 5. Bridge cleavage of [{RuCl(mu-Cl)(eta(6)-p-cymene)}(2)], [{RuCl(mu-Cl)(eta(6)-C6Me6)}(2)] or [{MCl(mu-Cl)(eta(5)-C5Me5)}(2)] (M=Rh, Ir) with Ia-IV afforded either monometallic [MCl2(L)(PR3)] 6-11 (M=Ru, Rh or Ir; L=eta(6)-p-cymene, eta(5)-C5Me5; PR3=Ia, II or III) or P,P'-bridged bimetallic [{MCl2(L)}(2) IV] 12-15 (M=Ru, Rh or Ir; L=eta(6)-p-cymene, eta(6)-C6Me6, eta(5)-C5Me5) complexes. The neutral ruthenium(II) complexes [RuCl2(eta(6)-p-cymene){P-Ph2PCH2N(H)C5H3(X)}] (X=OH 6a; X=H 6b) undergo isomerisation in CDCl3 to give [RuCl(eta(6)-p-cymene){P,N(pyridyl)-Ph2PCH2N(H)C5H3(X)N}]Cl (X=OH 6c; X=H 6d). In contrast aged solutions (ca. 40 d) of 7-15 show no evidence (by P-31{H-1} NMR) for P,N(pyridyl)-chelation. The X-ray structures of representative compounds have been determined, and confirm, in the case of 6c/6d, a novel six-membered M-P-C-N-C-N metallacycle.