Uranium turnings react with elemental iodine in diethyl ether at room temperature, with sonication and/or stirring, over a period of days to afford UI 3, UI 4(OEt 2) 2, or UI 4(OBu (n) 2) depending on the stoichiometry or ether solvent. This is the first room temperature, and thus safe and convenient, synthesis of UI 3.
The reduction of high oxidation state metal complexes in the presence of molecular nitrogen is one of the most common methods to synthesize a dinitrogen complex. However, the presence of strong reducing agents combined with the poor binding ability of N2 can lead to unanticipated outcomes. For example, the reduction of [NPN]ZrCl2(THF) (where NPN = PhP(CH2SiMe2NPh)2) with KC8 under N2 leads to the formation of the side-on bridged dinuclear dinitrogen complex ([NPN]Zr(THF))2(mu-eta2:eta2-N2) with an N-N bond distance of 1.503(3) A; however, reduction of the corresponding titanium precursor, [NPN]TiCl2, under N2 does not generate a dinitrogen complex, rather the bis(phosphinimide) derivative, ([N(PN)N]Ti)2, is isolated in which the added N2 is incorporated between the titanium and phosphine centers. Performing the reaction under 15N2 results in the 15N label being incorporated in the phosphinimide unit. A suggested mechanism for this process involves an initially formed dinitrogen complex being over reduced to generate a species with bridging nitrides that undergoes nucleophilic attack by the coordinated phosphine ligands and formation of the P=N bond of the phosphinimide.
A new and modular route to bidentate ligands that combines an alkoxide with a saturated backbone N-heterocyclic carbene (NHC) is presented. The bi(heterocyclic) compounds are formally the addition product of a saturated NHC and the alcohol group of the N-functionalised arm. Using these compounds, the synthesis and structural characterisation of the first electropositive metal complexes of saturated N-heterocyclic carbenes has been achieved, and examples structurally characterised for the yttrium(III) and the uranyl [UO(2)](2+) cations.
The lithium complexes RP(3,5-tBu2C6H2OLi)2(THF)4, where R = Ph or i Pr, (R[OPO]Li2)2(THF)4, synthesized by reaction of the 2-bromo-4,6-di-tert-butylphenol with BuLi and the appropriate dichlorophosphine, possess solid state structures composed of lithium oxide tetragons arranged in a step-form or face sharing half-cubane arrangements. Incorporation of excess lithium aryloxide results in the formation of complexes that display an extended step-form structure, [Ph[OPO]Li2(ArOLi)]2, or a distorted cubane arrangement of tetragons, [iPr[OPO]Li3Cl(ArOLi)](THF)3.
The d (0) yttrium N-heterocyclic carbene compound YL 3 (L = OCMe 2CH 2[C{N(CHCH)NPr ( i )}]) has been made and structurally characterized. It adopts a mer configuration of the three bidentate ligands. A comparison of this with the isostructural d (1) titanium complex TiL 3 is made in order to seek experimental evidence of a pi-bonding contribution to the M-C bond. This has been augmented by DFT calculations. Experimentally, the metal radius-corrected Ti-C distance is shorter than the Y-C distance, suggesting a pi-bonding contribution in the d (1) complex, but the computational data suggest that a shorter sigma bond might simply be formed by the more strongly polarizing titanium cation. From the potassium reduction of TiL(OPr ( i )) 3, only a byproduct arising from silicone grease activation was isolable, identified as a mixed-valent, multinuclear, d (0)/d (1) cluster [Ti (III)L 2{Pr ( i )OSiMe 2O}K 2OTi (IV)(OPr ( i )) 4] 2 in which the carbene ligands are bound to the Ti (III) centers in preference to Ti (IV), with longer Ti-C distances than those found in TiL 3.
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