Electronic Structure of Ru2(II,II) Oxypyridinates: Synthetic, Structural, and Theoretical Insights into Axial Ligand Binding
详细信息 查看全文
- 作者：Tristan R. Brown ; Brian S. Dolinar ; Elizabeth A. Hillard ; Rodolphe Cl茅rac ; John F. Berry
- 刊名：Inorganic Chemistry
- 出版年：2015
- 出版时间：September 8, 2015
- 年：2015
- 卷：54
- 期：17
- 页码：8571-8589
- 全文大小：865K
- ISSN：1520-510X
文摘
Reduction of (4,0)-Ru2(chp)4Cl (1) (chp = 6-chloro-2-oxypyridinate) with Zn or FeCl2 yields a series of axial ligand adducts of the Ru2(II,II) species Ru2(chp)4(L), with L = tetrahydrofuran (2), dimethyl sulfoxide (DMSO; 3), PPh3 (4), pyridine (5), or MeCN (6). Zn reduction in noncoordinating solvents such as toluene or CH2Cl2 leads to the dimeric species [Ru2(chp)4]2 (7) or [Ru2(chp)4]2(ZnCl2) (8), whereas addition of strongly 蟽-donating ligands such as CO causes cleavage of the Ru鈥揜u bond. Density functional theory (DFT) models of these complexes, the axially free species, and the axial adducts of several other potential ligands (H2O, NH3, CH2Cl2, S-bound DMSO, N2, and CO) indicate that these compounds can be divided into three distinct categories, based on their Ru鈥揜u bond length and electronic structure. Compounds 2, 3, 5, 6, 7, and 8, the hypothetical axially free species, and adducts of H2O and NH3 fit in Category 1 with a (未*)2(蟺*)2 ground state, as indicated by their electronic spectra, magnetic properties, and Ru鈥揜u bond distances. However, compound 4 and the CH2Cl2 adduct (Category 2) show a pseudo-Jahn-Teller distortion and spectroscopic signs of 未*/蟺* orbital mixing suggestive of a new electronic ground state intermediate between the (未*)2(蟺*)2 and (未*)1(蟺*)3 configurations. Category 3 consists of the hypothetical adducts of N2, S-bound DMSO, and CO, all of which are predicted to have a (未*)1(蟺*)3 configuration. Electronic spectra were recorded and assigned using time-dependent DFT, allowing assignment of a band in the 10鈥?00鈥?3鈥?00 cm鈥? range as the 未 鈫?蟺* transition. The axial ligand鈥檚 蟺-acid character heavily influences the 未*鈭捪€* gap, and thereby the ground-state electronic configuration, but not the axial ligand binding strength, which is dictated more by the 蟽-donor character of the ligands. Thus, this work greatly expands the number of axial ligand adducts known for Ru2(II,II) complexes supported by N,O-donor ligands and provides a predictive theoretical framework for their stability and electronic structures.