Molecular Nitrides with Titanium and Rare-Earth Metals

Abstract

A series of titanium-group 3/lanthanide metal complexes have been prepared by reaction of [{Ti(η(5)-C(5)Me(5))(μ-NH)}(3)(μ(3)-N)] (1) with halide, triflate, or amido derivatives of the rare-earth metals. Treatment of 1 with metal halide complexes [MCl(3)(thf)(n)] or metal trifluoromethanesulfonate derivatives [M(O(3)SCF(3))(3)] at room temperature affords the cube-type adducts [X(3)M{(μ(3)-NH)(3)Ti(3)(η(5)-C(5)Me(5))(3)(μ(3)-N)}] (X = Cl, M = Sc (2), Y (3), La (4), Sm (5), Er (6), Lu (7); X = OTf, M = Y (8), Sm (9), Er (10)). Treatment of yttrium (3) and lanthanum (4) halide complexes with 3 equiv of lithium 2,6-dimethylphenoxido [LiOAr] produces the aryloxido complexes [(ArO)(3)M{(μ(3)-NH)(3)Ti(3)(η(5)-C(5)Me(5))(3)(μ(3)-N)}] (M = Y (11), La (12)). Complex 1 reacts with 0.5 equiv of rare-earth bis(trimethylsilyl)amido derivatives [M{N(SiMe(3))(2)}(3)] in toluene at 85-180 °C to afford the corner-shared double-cube nitrido compounds [M(μ(3)-N)(3)(μ(3)-NH)(3){Ti(3)(η(5)-C(5)Me(5))(3)(μ(3)-N)}(2)] (M = Sc (13), Y (14), La (15), Sm (16), Eu (17), Er (18), Lu (19)) via NH(SiMe(3))(2) elimination. A single-cube intermediate [{(Me(3)Si)(2)N}Sc{(μ(3)-N)(2)(μ(3)-NH)Ti(3)(η(5)-C(5)Me(5))(3)(μ(3)-N)}] (20) was obtained by the treatment of 1 with 1 equiv of the scandium bis(trimethylsilyl)amido derivative [Sc{N(SiMe(3))(2)}(3)]. The X-ray crystal structures of 2, 7, 11, 14, 15, and 19 have been determined. The thermal decomposition in the solid state of double-cube nitrido complexes 14, 15, and 18 has been investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) measurements, as well as by pyrolysis experiments at 1100 °C under different atmospheres (Ar, H(2)/N(2), NH(3)) for the yttrium complex 14.

Heterometallic Cube‐Type Molecular Nitrides

“…). [79] The crystal structures of several isomorphous chloride complexes showed ). [80] Analogous treatment of 1 with bis(cyclopentadienyl) derivatives ).…”

Pentamethylcyclopentadienyl-Supported Rare-Earth-Metal Benzyl, Amide, and Imide Complexes

“…Since rare-earth-metal ions have the tendency to assemble into stable di- or polynuclear complexes with bridging imido ligands, ,− such oligomerization can be counteracted by the use of bulky ancillary ligands, like β-diketiminato (nacnac) or tris­(pyrazolyl)­borato. , Moreover, bulky chelating ligands were shown to favorably stabilize the highly polarized LnNR bond. ,− Surprisingly, only a few fully characterized cyclopentadienyl-supported rare-earth-metal imide complexes have been described. Hessen and co-workers could isolate a scandium imide complex by insertion of benzonitrile into a Sc–diene bond (Chart , A ). , Another approach exploits the insertion of alkyl/​arylnitriles into the Ln–H bond of hydrides ( B ) …”

Heterometallic complexes with cube-type [MTi3N4] cores containing Group 10 metals in a variety of oxidation states

“…18 We have noted an analogous shift in many adducts of 1 with a tridentate chelate coordination of the NH groups to the metal centers. [7][8][9] However, the resonances for the ipso carbon of the C 5 Me 5 groups (δ = 116.9-115.3) in the 13 C{ 1 H} NMR spectrum are shifted slightly upfield with respect to that found for 1 (δ = 117.1). 18 This shift of the ipso carbon is unusual in complexes derived from 1 and indicates an increased electron density at the titanium centers upon coordination of the metalloligand.…”

“…The trinuclear complex 1 is capable of acting as a neutral tridentate ligand through the NH imido groups toward many transition, 7 lanthanides, 8 and main-group 9 metals in a manner similar to other well-known facially coordinating trinitrogen six-electron donor ligands such as tris(pyrazolyl)methanes, 10 1,4,7-triazacyclononanes, 11 and 1,3,5triazacyclohexanes. 12 The great versatility of the metalloligand 1 is illustrated by the possibility of stabilizing complexes with metals in low (e.g., Mo 0 and Ir I ) or high oxidation 4…”

“…On the basis of this similarity, we have intensively examined the incorporation of a variety of metal fragments into the preorganized structure of 1 to uncover a new family of heterometallic imido-nitrido compounds with cube-type [MTi 3 N 4 ] cores. The trinuclear complex 1 is capable of acting as a neutral tridentate ligand through the NH imido groups toward many transition, 7 lanthanides, 8 and maingroup 9 metals in a manner similar to other well-known facially coordinating trinitrogen six-electron donor ligands such as tris-( pyrazolyl)methanes, 10 1,4,7-triazacyclononanes, 11 and 1,3,5triazacyclohexanes. 12 The great versatility of the metalloligand 1 is illustrated by the possibility of stabilizing complexes with metals in low (e.g., Mo 0 and Ir I ) or high oxidation states (e.g., Ti IV and Ta V ).…”