New superhindered polydentate polyphosphine ligands P(CH2CH 2PtBu2)3, PhP(CH2CH 2PtBu2)2, P(CH2CH 2CH2PtBu2)3, and their ruthenium(II) chloride complexes

Article abstract of DOI:10.1021/ic2027169

The synthesis and characterization of the extremely hindered phosphine ligands, P(CH₂CH₂P^tBu₂)₃ (P²P₃^tBu, 1), PhP(CH₂CH ₂P^tBu₂)₂ (PhP²P ₂^tBu, 2), and P(CH₂CH₂CH ₂P^tBu₂)₃ (P³P ₃^tBu, 3) are reported, along with the synthesis and characterization of ruthenium chloro complexes RuCl₂(P ²P₃^tBu) (4), RuCl₂(PhP ²P₂^tBu) (5), and RuCl₂(P ³P₃^tBu) (6). The bulky P²P ₃^tBu (1) and P³P₃^tBu (3) ligands are the most sterically encumbered PP₃-type ligands so far synthesized, and in all cases, only three phosphorus donors are able to bind to the metal center. Complexes RuCl₂(PhP²P₂ ^tBu) (5) and RuCl₂(P³P₃ ^tBu) (6) were characterized by crystallography. Low temperature solution and solid state ³¹P{¹H} NMR were used to demonstrate that the structure of RuCl₂(P²P ₃^tBu) (4) is probably analogous to that of RuCl ₂(PhP²P₂^tBu) (5) which had been structurally characterized.