Syntheses, structures and reactions of a series of β-diketiminatoyttrium compounds

Abstract

This paper describes the synthesis and selected reactions of a series of crystalline mono(β-diiminato)yttrium chlorides 3a, 3b, 4a, 4b, 5a, 5b, 5c and 9. The X-ray structure of each has been determined, as well as of [YCl(L⁴4)₂] (6), [Y(L¹1)₂OBu^t] (7) and [Y{CH(SiMe₃)₂}(thf)(μ-Cl)₂Li(OEt₂)₂(μ-Cl)]₂ (8). The N,N′-κ²-β-diiminato ligands were [{N(R)C(Me)}₂CH]⁻ [R = C₆H₄Prⁱ-2 (L¹1); R = C₆H₄Bu^t-2 (L²2); R = C₆H₃Prⁱ₂-2,6 (L³3)], [{N(SiMe₃)C(Ph)}₂CH)]⁻ (L⁴4) and [{N(C₆H₃Prⁱ₂-2,6)C(H)}₂CPh]⁻ (L⁵5). Equivalent portions of Li[L^x] and YCl₃ in Et₂O under mild conditions yielded [Y(μ-Cl)(L^x)(μ-Cl)₂Li(OEt₂)₂]₂ [L^x = L¹1 (3a) or L²2 (3b)] and [Y(μ-Cl)(L³3)(μ-Cl)Li(OEt₂)₂(μ-Cl)]₂ (4a) or its thf (instead of Et₂O) equivalent 4b. Each of the Li(OEt₂)₂Cl₂ moieties is bonded in a terminal (3) or bridging (4) mode with respect to the two Y atoms; the difference is attributed to the greater steric demand of L³3 than L¹1 or L²2. Under slightly more forcing conditions, YCl₃ and Li(L²2) (via3b) gave the lithium-free complex [YCl₂(L²2)(thf)₂] (5b). Two isoleptic compounds 5a and 5c (having in place of L²2 in 5b, L³3 and L⁵5, respectively) were obtained from YCl₃ and an equivalent portion of K[L³3] and Na[L⁵5], respectively; under the same conditions using Na[L⁴4], the unexpected product was [YCl(L⁴4)₂] (6) (i.e. incorporating only one half of the YCl₃). A further unusual outcome was in the formation of 8 from 3a and 2 Li[CH(SiMe₃)₂]. Compound [Y(L⁵5){N(H)C₆H₃Prⁱ₂-2,6}(thf)(μ₃-Cl)₂K]₂·4Et₂O (9), obtained from 5c and K[N(H)C₆H₃Prⁱ₂-2,6], is noteworthy among group 3 or lanthanide metal (M) compounds for containing MClKCl (M = Y) moieties.