Treatment of [{Ti(h 5 -C 5 Me 5 )(m-NH)} 3 (m 3 -N)] with alkali metal bis(trimethylsilyl)amido reagents in toluene afforded the complexes [M(m 3 -N)(m 3 -NH) 2 {Ti 3 (h 5 -C 5 Me 5 ) 3 (m 3 -N)}] 2 (M Li (2), Na, (3), K (4)). The molecular structures of 2 and 3 have been determined by X-ray crystallographic studies and show two azaheterometallocubane cores [MTi 3 N 4 ] linked by metal ± nitrogen bonds. Reaction of the lithium derivative 2 with chlorotrimethylsilane or trimethyltin chloride in toluene gave the incomplete cube nitrido complexes [Ti 3 (h 5 -C 5 Me 5 ) 3 (m-NH) 2 (m-NMMe 3 )(m 3 -N)] (M Si (5), Sn (6)). A similar reaction with indium(i) or thallium(i) chlorides yielded cube-type derivatives [M(m 3 -N)(m 3 -NH) 2 {Ti(h 5 -C 5 Me 5 )} 3 (m 3 -N)] (M In (7), Tl (8)).Keywords: alkali metals´cubanesń itrido complexes´titanium[a] Dr.

4a-Aza-10a-boraphenanthrene has been synthesized in only four steps from commercially available materials with a remarkable overall yield of 62%. In contrast to other BN-isosteres of phenathrene, this isomer is weakly fluorescent, which has been explained by means of computational studies that found a low energy conical intersection for the nonradiative deactivation of the excited state. Moreover, a completely regioselective functionalization of 4a-aza-10a-boraphenanthrene at C-1 by reaction with activated electrophiles has been achieved.

Following the track of the useful titanocene [Ti( 5 -C5H5)2Cl] reagent in organic synthesis, the related half-sandwich titanium(III) derivatives [Ti( 5 -C5R5)Cl2] are receiving increasing attention in radical chemistry of many catalyzed transformations. However, the structure of the active titanium(III) species remains unknown in the literature. Herein, we describe the synthesis, crystal structure, and electronic structure of titanium( III) aggregates of composition [{Ti( 5 -C5Me5)Cl2}n]. The thermolysis of [Ti( 5 -C5Me5)Cl2Me] (1) in benzene or hexane at 180 ºC results in the clean formation of [{Ti( 5 -C5Me5)Cl(-Cl)}2] (2), methane and ethene. The treatment of 1 with excess pinacolborane in hexane at 65 ºC leads to a mixture of 2 and the paramagnetic trimer [{Ti( 5 -C5Me5)(-Cl)2}3] (3). The Xray crystal structures of compounds 2 and 3 show Ti-Ti distances of 3.267(1) and 3.219(12) Å, respectively. Computational studies (CASPT2//CASSCF and BS DFT methods) for dimer 2 reveal a singlet ground state and a relatively large singlet-triplet energy gap. Nuclear magnetic resonance (NMR) spectroscopy of 2 in aromatic hydrocarbon solutions and DFT calculations for several [{Ti( 5 -C5Me5)Cl2}n] aggregates are consistent with the existence of an equilibrium between the diamagnetic dimer [{Ti( 5 -C5Me5)Cl(-Cl)}2] and a paramagnetic tetramer [{Ti( 5 -C5Me5)(-Cl)2}4] in solution. In contrast, complex 2 readily dissolves in tetrahydrofuran to give a green-blue solution from which blue crystals of the mononuclear adduct [Ti( 5 -C5Me5)Cl2(thf)] (4) were grown.

The synthesis and characterisation of a number of group nine complexes containing the recently reported ligand, diphenyl-2-(3-methyl)indolylphosphine, is presented herein. The complexes [RhCl(COD){PPh(2)(C(9)H(8)N)}] (1), [IrCl(COD){PPh(2)(C(9)H(8)N)}] (2), [RhCl(NBD){PPh(2)(C(9)H(8)N)}] (3) and [Rh(COD)(MeCN){PPh(2)(C(9)H(8)N)}]BF(4) (4) (where COD = 1,5-cyclooctadiene, NBD = 2,5- norbornadiene) have been structurally characterised by X-ray crystallography. The complex [Rh(2)(COD)(2){N(Me)[double bond, length as m-dash]C(H)Ph)}{PPh(2)(C(9)H(8)N)}][BF(4)](2) (8) was also isolated and structurally characterised. Complex 8 contains a '[Rh(COD)]' fragment coordinated to the aromatic ring of the indolyl group, providing the first example of a eta(6) coordination mode for this ligand. The synthesised complexes were investigated for their activity in the catalytic transfer hydrogenation of ketones and found to be moderately active catalysts.

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Low‐valent titanium species were prepared by reaction of [TiCp*X3] (Cp*=η5‐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*(μ‐H)}2{(μ‐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 σ‐accepting (Z‐type) ligands. Analogous reactions of [TiCp*X3] with LiBH4 (2 and 3 equiv.) in tetrahydrofuran at room temperature and at 85 °C lead to the titanium(III) compounds [{TiCp*(BH4)(μ‐X)}2] (X=Cl, Br) and [{TiCp*(BH4)(μ‐BH4)}2], respectively. The treatment of [TiCp*Me3] with 4 and 5 equiv. of BH3(thf) produces the diamagnetic [{TiCp*(BH3Me)}2(μ‐B2H6)] and paramagnetic [{TiCp*(μ‐B2H6)}2] complexes, respectively.

The treatment of [{Ti(η(5)-C5Me5)}4(μ3-N)4] with NH3BH3 leads to the paramagnetic imidonitrido complex [{Ti(η(5)-C5Me5)}4(μ3-N)3(μ3-NH)], which can also be obtained by stepwise proton and electron transfer with HOTf and [K(C5Me5)].

Several azaheterometallocubane complexes containing [MTi3N4] cores have been prepared by the reaction of [{Ti(eta5-C5Me5)(mu-NH)}3(mu3-N)] (1) with zinc(II) and copper(I) derivatives. The treatment of 1 with zinc dichloride in toluene at room temperature produces the adduct [Cl2Zn{(mu3-NH)3Ti3(eta5-C5Me5)3(mu3-N)}] (2). Attempts to crystallize 2 in dichloromethane gave yellow crystals of the ammonia adduct [(H3N)Cl2Zn{(mu3-NH)Ti3(eta5-C5Me5)3(mu-NH)2(mu3-N)}] (3). The analogous reaction of 1 with alkyl, (trimethylsilyl)cyclopentadienyl, or amido zinc complexes [ZnR2] leads to the cube-type derivatives [RZn{(mu3-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N)}] (R = CH2SiMe3 (5), CH2Ph (6), Me (7), C5H4SiMe3 (8), N(SiMe3)2 (9)) via RH elimination. The amido complex 9 decomposes in the presence of ambient light to generate the alkyl derivative [{Me3Si(H)N(Me)2SiCH2}Zn{(mu3-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N)}] (10). The chloride complex 2 reacts with lithium cyclopentadienyl or lithium indenyl reagents to give the cyclopentadienyl or indenyl zinc derivatives [RZn{(mu3-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N)}] (R = C5H5 (11), C9H7 (12)). Treatment of 1 with copper(I) halides in toluene at room temperature leads to the adducts [XCu{(mu3-NH)3Ti3(eta5-C5Me5)3(mu3-N)}] (X = Cl (13), I (14)). Complex 13 reacts with lithium bis(trimethylsilyl)amido in toluene to give the precipitation of [{Cu(mu4-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N)}2] (15). Complex 15 is prepared in a higher yield through the reaction of 1 with [{CuN(SiMe3)2}4] in toluene at 150 degrees C. The addition of triphenylphosphane to 15 in toluene produces the single-cube compound [(Ph3P)Cu{(mu3-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N)}] (16). The X-ray crystal structures of 3, 8, 9, and 15 have been determined.