School of Chemistry, PO Box 23, Monash University, VIC 3800, Australia.
Dalton Trans. 2010 Oct 7;39(37):8788-95. doi: 10.1039/c0dt00589d. Epub 2010 Aug 12.
The preparation of a series of amidinato and guanidinato zinc halide complexes incorporating ligands of varying steric bulk is described, and their thermal stabilities compared. Salt elimination reactions between [M(Giso)] (M = K or Li; Giso = (ArN)(2)CNCy(2), Ar = 2,6-diisopropylphenyl, Cy = cyclohexyl) and ZnX(2) (X = I or Br) have yielded the monomeric complexes [(Giso)ZnI] and [(Giso)Zn(mu-Br)(2)Li(OEt(2))(2)]. Both have been crystallographically characterised and the former shown to slowly decompose in solution at ambient temperature to give the carbodiimide, ArN[double bond, length as m-dash]C[double bond, length as m-dash]NAr. In contrast, reactions between alkali metal complexes of a less bulky guanidinate, [M(Priso)] (Priso = (ArN)(2)CNPr(i)(2)) and ZnX(2) have yielded [(IZn)(2)(mu-NPr(i)(2)){mu-N,N'-(NAr)(2)CH}] and [(Priso)Zn(mu-Br)(2)Li(OEt(2))(2)]. The latter decomposes in solution at ambient temperature, generating ArN[double bond, length as m-dash]C[double bond, length as m-dash]NAr, which was also produced in the preparation of the former. Analogies are drawn between the decomposition of [(Priso)Zn(mu-Br)(2)Li(OEt(2))(2)] and the carbonic anhydrase catalysed dehydration of bicarbonate. Two bulky amidinato zinc complexes, [{(Piso)Zn(mu-Br)}(2)] and [Zn(Piso)(2)] (Piso = (ArN)(2)CBu(t)) have been prepared, structurally characterised and shown to be markedly more thermally stable than the zinc guanidinate compounds. Attempts to reduce several of the zinc(ii) halide complexes to dimeric zinc(i) compounds were so far unsuccessful, in all cases leading to the deposition of zinc metal.
描述了一系列包含不同空间位阻配体的酰胺基和胍基锌卤化物配合物的制备，并比较了它们的热稳定性。[M(Giso)]（M = K 或 Li；Giso = (ArN)(2)CNCy(2)，Ar = 2,6-二异丙基苯基，Cy = 环己基）和 ZnX(2)（X = I 或 Br）之间的盐消除反应生成了单核配合物[(Giso)ZnI]和[(Giso)Zn(mu-Br)(2)Li(OEt(2))(2)]。两者均已进行了晶体学表征，并且前者在环境温度下在溶液中缓慢分解，生成碳二亚胺，ArN[双键，长度为 m-dash]C[双键，长度为 m-dash]NAr。相比之下，空间位阻较小的胍基配体[M(Priso)]（Priso = [(ArN)(2)CNPr(i)(2)](-）与 ZnX(2)的碱金属配合物之间的反应生成了[(IZn)(2)(mu-NPr(i)(2)){mu-N,N'-(NAr)(2)CH}]和[(Priso)Zn(mu-Br)(2)Li(OEt(2))(2)]。后者在环境温度下的溶液中分解，生成 ArN[双键，长度为 m-dash]C[双键，长度为 m-dash]NAr，该化合物也在前者的制备过程中产生。[(Priso)Zn(mu-Br)(2)Li(OEt(2))(2)]的分解与碳酸酐酶催化的碳酸氢盐脱水之间存在相似性。制备了两个大位阻的酰胺基锌配合物[{(Piso)Zn(mu-Br)}(2)]和[Zn(Piso)(2)]（Piso = (ArN)(2)CBu(t)化合物，但迄今为止均未成功，所有情况下均导致锌金属的沉积。
