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Low-valent titanium species were prepared by reaction of [TiCp*X3] (Cp* = eta5-C5Me5; X = Cl, Br, Me) with LiEH4 (E = Al, B) or BH3(thf), and their structures elucidated by experimental and theoretical methods. The treatment of trihalides [TiCp*X3] with LiAlH4 in ethereal solvents (L) leads to the hydride-bridged heterometallic complexes [{TiCp*(mu-H)}2{(mu-H)2AlX(L)}2] (L = thf, X = Cl, Br; L = OEt2, X = Cl). Density functional theory (DFT) calculations for those compounds reveal an open-shell singlet ground state with a Ti-Ti bond and can be described as titanium(II) species. The theoretical analyses also show strong interactions between the Ti-Ti bond and the empty s orbitals of the Al atom of the AlH2XL fragments, which behave as sigma-accepting (Z-type) ligands. Analogous reactions of [TiCp*X3] with LiBH4 (2 and 3 equiv) in tetrahydrofuran at room temperature and at 85 ºC lead to the titanium(III) compounds [{TiCp*(BH4)(mu-X)}2] (X = Cl, Br) and [{TiCp*(BH4)(mu-BH4)}2], respectively. The treatment of [TiCp*Me3] with 4 and 5 equiv of BH3(thf) produces the diamagnetic [{TiCp*(BH3Me)}2(mu-B2H6)] and paramagnetic [{TiCp*(mu-B2H6)}2] complexes, respectively., Ministerio de Ciencia, Innovación y Universidades, Universidad de Alcalá

The solid‐state and solution configurations of the heterodimetallic complexes (Hpy)[LaEr(HL)3(NO3)(py)(H2O)] (1), (Hpy)[CeEr(HL)3(NO3)(py)(H2O)] (2), (Hpy)[CeGd(HL)3(NO3)(py)(H2O)] (3), (Hpy)[PrSm(HL)3(NO3)(py)(H2O)] (4), and (Hpy)2[LaYb(HL)3(NO3)(H2O)](NO3) (5), in which H3L is 6‐(3‐oxo‐3‐(2‐hydroxyphenyl)propionyl)pyridine‐2‐carboxylic acid and py is pyridine, were analyzed experimentally and by using DFT calculations. Complexes 3, 4, and 5 are described here for the first time, and were analyzed by using single‐crystal X‐ray diffraction and mass spectrometry. The theoretical study was also extended to the [LaCe] and [LaLu] analogues. The results are consistent with a remarkable selectivity of the metal distribution within the molecule in the solid state, enhanced by the size difference between the different ions. This selectivity was reduced in solution, particularly for ions with the most similar radii. This unique entry into 4f–4f′′ heterometallic chemistry establishes for the first time the difference between the selectivity in solution and that in the solid state, as a result of changes to the coordination that follow the dissociation of terminal ligands upon dissolution of the complexes., G.A. thanks the Generalitat de Catalunya for the prize ICREA Academia 2008 and 2013 and the ERC for a Starting Grant (258060 FuncMolQIP). The authors thank the Spanish MINECO for funding through CTQ2012‐32247, CTQ2015‐68370‐P (GA, LAB, DA, VV), CTQ2014‐52824‐R (CB, JGF, NAGB), and MAT2014‐53961‐R (OR), the Marie Curie Co‐funding of Regional, National, and International Programs (COFUND) for funding scheme 291787‐ICIQ‐IPMP, Fundação para a Ciência e Tecnologia Grant SFRH/BPD/110419/2015 (NAGB), and the Severo Ochoa Excellence Accreditation SEV‐2013‐0319 (CB). Also we thank Generalitat de Catalunya for financial support through the CERCA Program and grant no. 2014SGR409. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy under contract no. DE‐AC02‐05CH11231.