Potassium and Yttrium Complexes of a Rigid Bis‐Phosphido POP‐Donor Ligand

Dilithiation of 4,5‐dibromo‐2,7‐di‐tert‐butyl‐9,9‐dimethyl‐xanthene (XBr2) followed by addition of 2 equiv. of (2,4,6‐triisopropylphenyl)dichlorophosphine (TrippPCl2) afforded 4,5‐bis[(2,4,6‐triisopropylphenyl)chlorophosphino]‐2,7‐di‐tert‐butyl‐9,9‐dimethylxanthene (XP2Cl2), which was reduced to 4,5‐bis[(2,4,6‐triisopropylphenyl)phosphino]‐2,7‐di‐tert‐butyl‐9,9‐dimethylxanthene (H2XP2) using excess LiAlH4. Deprotonation of H2XP2 with excess KH in DME provided the dipotassium salt, [K2(XP2)(dme)n] (1; n = 2.5–4), and stirring 1 in THF followed by recrystallization from hexanes yielded tetrametallic [K4(XP2)2(THF)4] (2) which features a central K4P4 cage. Reaction of [YI3(THF)3.5] with [K2XP2(dme)2.5] afforded a mixture of products including [(XP2)YI(THF)2] (3) and (PTripp)3; pure 3 could be isolated in low yield by extraction with a minimum volume of hexanes or O(SiMe3)2. In the solid state, 3 adopts a face‐capped trigonal bipyramidal coordination geometry with a planar xanthene backbone and an angle of 85° between the P(1)/C(4)/C(5)/P(2) and P(1)/Y/P(2) planes.

Potassium and Yttrium Complexes of a Rigid Bis‐Phosphido POP‐Donor Ligand Journal Articles