Parish James D, Snook Michael W, Johnson Andrew L
Department of Chemistry, University of Bath. Claverton Down, Bath, BA2 7AY, UK.
Dalton Trans. 2021 Oct 12;50(39):13902-13914. doi: 10.1039/d1dt02480a.
We have successfully prepared and structurally characterized a family of eight tin(II) heteroleptic complexes, [Sn(NR)(ON)] (NR = NMe (1a-d) or N(SiMe) (2a-d); = 1 or 2) and four homoleptic systems, [Sn(κ-ON)] (3a-d) from a series of aminoalcohols and fluorinated aminoalcohols (H{ON}) having a different number of methyl/trifluoromethyl substituents at the α-carbon atom, [HOC(R)(R)CHNMe] (R = R = H (H{dmae}) (a); R = H, R = Me (H{dmap}) (b); R = R = Me (H{dmamp}) (c); R = R = CF (H{Fdmamp}) (d)). The synthetic route used reactions of either [Sn{N(SiMe)}] or [Sn(NMe)] with one or two equivalents of the aminoalcohols (a-d) in dry aprotic solvents leading to elimination of amines and formation of the Sn(II) species 1a-d, 2a-d and 3a-d respectively. All complexes were thoroughly characterized by NMR spectroscopy (H, C, F, and Sn) as well as single-crystal X-ray diffraction studies. In all case the solid state molecular structures of the complexes have been unambiguously established: the solid state structures 1a-b and 1c are dimeric with central {SnN} cores resulting from bridging {μ-NMe} units, in which the Sn(II) atoms are four-coordinate. In contrast, the solid state structures of complexes 1c and 2a-c possess similarly dimeric structures, with four-coordinate Sn(II) atoms, in which the oxygen atoms of the {ON} ligand bridge two Sn(II) centres to form dimers with a central {SnO} core. Uniquely in this study, 2d, [Sn(κ-O,N-OCMeCHNMe){N(SiMe)}] is monomeric with a three coordinate Sn(II) centre. The homoleptic complexes 3a-d are all isostructural with monomeric four-coordinate structures with disphenoidal geometries. Solution state NMR studies reveal complicated ligand exchange processes in the case of the heteroleptic complexes 1a-d and 2a-d. Contrastingly, the homoleptic systems 3a-d show no such behaviour. While complexes 1a-d and 2a-d displayed either poor thermal stability or multistep thermal decomposition processes, the thermal behaviour of the homoleptic complexes, 3a-d, was investigated in order to determine the effects, if any, of the degree of fluorination and asymmetry of the aminoalkoxide ligands on the suitability of these complexes as ALD precursors for the deposition of SnO thin films.
我们已经成功制备并对一族八个异配体锡（II）配合物[Sn(NR)(ON)]（NR = NMe (1a - d) 或 N(SiMe) (2a - d)； = 1 或 2）以及四个均配体体系[Sn(κ - ON)] (3a - d)进行了结构表征，这些配合物由一系列在α - 碳原子上具有不同数量甲基/三氟甲基取代基的氨基醇和氟化氨基醇（H{ON}）合成，[HOC(R)(R)CHNMe]（R = R = H (H{dmae}) (a)；R = H，R = Me (H{dmap}) (b)；R = R = Me (H{dmamp}) (c)；R = R = CF (H{Fdmamp}) (d)）。所采用的合成路线是在干燥的非质子溶剂中，使[Sn{N(SiMe)}]或[Sn(NMe)]与一当量或两当量的氨基醇（a - d）反应，分别导致胺的消除并形成锡（II）物种1a - d、2a - d和3a - d。所有配合物均通过核磁共振光谱（H、C、F和Sn）以及单晶X射线衍射研究进行了全面表征。在所有情况下，配合物的固态分子结构均已明确确定：配合物1a - b和1c的固态结构是二聚体，具有由桥连{μ - NMe}单元形成的中心{SnN}核，其中Sn(II)原子为四配位。相比之下，配合物1c和2a - c的固态结构具有类似的二聚体结构，Sn(II)原子为四配位，其中{ON}配体的氧原子桥连两个Sn(II)中心形成具有中心{SnO}核的二聚体。在本研究中独特的是，2d，[Sn(κ - O,N - OCMeCHNMe){N(SiMe)}]是具有三配位Sn(II)中心的单体。均配体配合物3a - d均具有同构的单体四配位结构，呈双楔形几何形状。溶液态核磁共振研究揭示了异配体配合物1a - d和2a - d情况下复杂的配体交换过程。相反，均配体体系3a - d没有表现出这种行为。虽然配合物1a - d和2a - d表现出较差的热稳定性或多步热分解过程，但对均配体配合物3a - d的热行为进行了研究，以确定氨基醇盐配体的氟化程度和不对称性（如果有的话）对这些配合物作为用于沉积SnO薄膜的ALD前驱体的适用性的影响。
