The reaction of [UO2I2(THF)3] with KC5R5 (R = H, Me) or K2C8H8 in pyridine gave crystals of [{UO2(py)5}{KI2(py)2}]∞ (1), which were desolvated under vacuum into pulverulent [UO2(py)2.2KI2] (2). Similar reactions with [UO2(OTf)2] afforded [UO2(py)2.3K(OTf)2] (3) as a powder and crystals of [{UO2(py)5}2{K3(OTf)5}·py]∞ (4·py), which were also obtained together with crystals of [{UO2(py)5}2{K(OTf)2(py)2}][OTf]·py (5·py) by treating [UO2(OTf)2] with KC4Me4P. Crystals of 6·py, the thallium analogue of 5·py, were isolated from the reaction of [UO2(OTf)2] and TlC5H5. Treatment of [UO2I2(THF)3] with LiCH2SiMe3 in pyridine afforded crystals of [{UO2(py)5}{LiI(py)2}][I] (7) while [UO2(OTf)2] reacted with the alkyllithium reagent in acetonitrile to give crystals of [{UO2(py)5}{Li2(OTf)3}]∞ (8) in pyridine. The crystal structures of 1, 4·py, 5·py, 6·py, 7 and 8 revealed the presence of U![[double bond, length as m-dash]](https://www.rsc.org/images/entities/char_e001.gif)
O→M interactions (M = Li, K, Tl), and the rich diversity of these structures, from dinuclear (7) to 3D polymeric (4), is related to the distinct coordination numbers of the M+ ion and ligation modes of the bridging iodide and triflate ligands as well as the presence of UO→M interactions. The mononuclear complexes [UO2(OTf)(THF)n] (9) and [UO2(OTf)(Et2O)0.5] (10) were respectively obtained by reaction of [UO2(OTf)2] with KC5R5 in THF or LiCH2SiMe3 in Et2O, and were transformed into [UO2(OTf)(py)2] (11) in pyridine. Treatment of [UO2I2(THF)3] with TlC5H5 in pyridine afforded crystals of [UO2(py)5][I]·py (12·py) which were desolvated under vacuum into the powder of [UO2I(py)2.5] (14). The same reaction in THF gave [UO2I(THF)2.7] (13) in powder form. Crystals of [UO2(CyMe4BTBP)(py)][OTf]·1.5py (15·1.5py) and the powder of [UO2I(CyMe4BTBP)] (16) were obtained by treating [UO2(CyMeBTBP)X2] (X = OTf, I) with KC5Me5 or TlC5H5, respectively. The uranyl(V) chloride and nitrate compounds [UO2Cl(py)3] (17) and [UO2(NO3)(py)3] (18) were prepared by reaction of the uranyl(VI) precursors with TlC5H5 in pyridine; complex 18 was also obtained by treating 13 with TlNO3. Crystals of the neutral mononuclear complex [UO2(OTf)(py)4] (19) were isolated from reaction of [UO2(OTf)2] with Me3SiC5H5 in acetonitrile. Similar reaction with [UO2Cl2(THF)2]2 in pyridine gave crystals of [UO2Cl2(py)3]. The crystal structures of 12·py, 15·1.5py and 19 were determined; the structure of 15 was compared with that of the uranyl(VI) counterpart. All the uranyl(V) compounds are remarkably stable in pyridine solution; the IR absorption at 816 cm−1 is attributed to the νasym(UO) of the ubiquitous [UO2(py)5]+ species.
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