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(beta-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(L4)(2)] (6), [Y(L1)(2)OBu(t)] (7) and [Y{CH(SiMe(3))(2)}(thf)(mu-Cl)(2)Li(OEt(2))(2)(mu-Cl)](2) (8). The N,N'-kappa(2)-beta-diiminato ligands were [{N(R)C(Me)}(2)CH](-) [R = C(6)H(4)Pr(i)-2 (L1); R = C(6)H(4)Bu(t)-2 (L2); R = C(6)H(3)Pr(i)(2)-2,6 (L3)], [{N(SiMe(3))C(Ph)}(2)CH)](-) (L4) and [{N(C(6)H(3)Pr(i)(2)-2,6)C(H)}(2)CPh](-) (L5). Equivalent portions of Li[L(x)] and YCl(3) in Et(2)O under mild conditions yielded [Y(mu-Cl)(L(x))(mu-Cl)(2)Li(OEt(2))(2)](2) [L(x) = (L1(3a)) or (L1(3b))] and [Y(mu-Cl)(L3)(mu-Cl)Li(OEt(2))(2)(mu-Cl)](2) (4a) or its thf (instead of Et(2)O) equivalent 4b. Each of the Li(OEt(2))(2)Cl(2) 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 L3 than L1 or L2. Under slightly more forcing conditions, YCl(3) and Li(L2) (via 3b) gave the lithium-free complex [YCl(2)(L2)(thf)(2)] (5b). Two isoleptic compounds 5a and 5c (having in place of L2 in 5b, L3 and L5, respectively) were obtained from YCl(3) and an equivalent portion of K[L3] and Na[L5], respectively; under the same conditions using Na[L4], the unexpected product was [YCl(L4)(2)] (6) (i.e. incorporating only one half of the YCl(3)). A further unusual outcome was in the formation of 8 from 3a and 2 Li[CH(SiMe(3))(2)]. Compound [Y(L5){N(H)C(6)H(3)Pr(i)(2)-2,6}(thf)(mu(3)-Cl)(2)K](2).4Et(2)O (9), obtained from and K[N(H)C(6)H(3)Pr(i)(2)-2,6], is noteworthy among group 3 or lanthanide metal (M) compounds for containing MClKCl (M = Y) moieties.