Synthesis and characterisation of yttrium complexes supported by the beta-diketiminate ligand {ArNC(CH3)CHC(CH3)NAr}(-) (Ar=2,6-(Pr2C6H3)-C-i)

Reaction Of YI3(THF)(3.5) with one equivalent of the potassium beta-diketiminate (BDI) complex [HC{C(CH3)NAr)(2)K] (1) (Ar = 2,6-(Pr2C6H3)-C-i) affords the monomeric, mono-substituted yttrium BDI complex [HC{CH3)NAr}(2)YI2(THF)] (2) in good yield. Reaction of 2 with DME affords [HC{C(CH3)NAr}(2)YI2(DME)] (3) in quantitative yield, which is monomeric also. Reaction of the primary terphenyl phosphane Ar*PH2 (Ar* = 2,6-(2,4,6-(Pr3C6H2)-C-i)(2)C6H3) with potassium hydride, and recrystallisation from hexane, affords the potassium primary terphenyl phosphanide complex [{Ar*P(H)K(THF)}(2)] (4) in high yield. Compound 4 is dimeric in the solid state, constructed around a centrosymmetric K2P2 four-membered ring, the coordination sphere of potassium is supplemented with an eta(6) K...C-aryl interaction. The reaction of 2 with one molar equivalent of 4 in THF affords the THF ring-opened compound [HC{C(CH3)NAr}(2)Y{O(CH2)(4)P(H)Ar*}(1)(THF)] (5). Compound 5 is formed as a mixture of endo(OR) (5a) and exO(OR) (5b) isomers (5a : 5b = similar to 2: 1) which may be separated by fractional crystallisation from hexane-toluene to give pure 5a. Attempted alkylation of 3 with two equivalents of KCH2Si(CH3)(3) affords the potassium yttriate complex [Y{mu-eta(5):eta(1)-ArNC(CH3)=CHC(=CH3)NAr}(2)K(DME)(2)](6) in moderate yield; 6 contains two dianionic dianilide ligands, which are derived from C-H activation of a backbone methyl group, each bonded eta(5) to yttrium in the solid state. The reaction of 3 with one equivalent of KC, affords [{HC(C[CH3]NAr)(2)YI(mu-OCH3)}(2)] (7), derived from C-O bond activation of DME, as the only isolable product in very low yield. Compounds 2, 3, 4, 5a, 6, and 7 have been characterised by single crystal X-ray diffraction, NIMR spectroscopy and CHN microanalyses.