The divalent calcium and ytterbium compounds M(C(SiHMe(2))(3))(2)THF(2) contain beta-agostic SiH groups, as determined by spectroscopy and crystallography. Upon thermolysis, HC(SiHMe(2))(3) is formed. However, the SiH groups are hydridic. The compounds M(C(SiHMe(2))(3))(2)THF(2) react with 1 and 2 equiv of the Lewis acid B(C(6)F(5))(3) to form MC(SiHMe(2))(3)HB(C(6)F(5))(3))THF(2) and M(HB(C(6)F(5))(3))(2)THF(2), respectively. These species contain the anion [HB(C(6)F(5))(3)](-) from hydride abstraction rather than [(Me(2)HSi)(3)CB(C(6)F(5))(3)](-) from alkyl abstraction. The 1,3-disilacyclobutane byproduct initially suggested beta-elimination [as the dimer of the silene Me(2)Si horizontal lineC(SiHMe(2))(2)], but the other products and reaction stoichiometry rule out that pathway. Additionally, Yb(C(SiHMe(2))(3))(2)THF(2) and the weak Lewis acid BPh(3) react rapidly and also give the H-abstracted products. Despite the strong hydridic character of the SiH groups and the low-coordinate, Lewis acidic metal center in M(C(SiHMe(2))(3)THF(2) compounds, beta-elimination is not an observed reaction pathway.

A series of organometallic compounds containing the tris(dimethylsilyl)methyl ligand are described. The potassium carbanions KC(SiHMe2)3 and {KC(SiHMe2)3TMEDA}2 are synthesized by deprotonation of the hydrocarbon HC(SiHMe2)3 with potassium benzyl. {KC(SiHMe2)3TMEDA}2 crystallizes as a dimer with two types of three-center-two-electron K-H-Si interactions: side-on coordination of SiH (∠K-H-Si = 102(2)°) and more obtuse K-H-Si structures (∠K-H-Si ≈ 150°). The divalent calcium and ytterbium compounds M{C(SiHMe2)3}2L (M = Ca, Yb; L = 2THF, TMEDA) are prepared from MI2 and 2 equiv of KC(SiHMe2)3. Low 1JSiH coupling constants in the NMR spectra, low-energy νSiH bands in the IR spectra, and short M-Si distances and small M-C-Si angles in the crystal structures suggest β-agostic interactions on each C(SiHMe2)3 ligand. The IR assignments of M{C(SiHMe2)3}2L (L = 2THF, TMEDA) are supported by DFT calculations. The compounds M{C(SiHMe2)3}2L react with 1 or 2 equiv of B(C6F5)3 to give the 1,3-disilacyclobutane {Me2SiC(SiHMe2)2}2 and MC(SiHMe2)3HB(C6F5)3L or M{HB(C6F5)3}2L, respectively. In addition, M{C(SiHMe2)3}2L compounds react with BPh3 to give β-H abstracted products. The compounds M{C(SiHMe2)3}2THF2 react with SiMe3I to yield Me3SiH and disilacyclobutane as the products of β-H abstraction, while M{C(SiHMe2)3}2TMEDA and Me3SiI form a mixture of Me3SiH and the alkylation product Me3SiC(SiHMe2)3 in a 1:3 ratio.

A series of homoleptic rare-earth silazido compounds and their silica-grafted derivatives were prepared to compare spectroscopic and catalytic features under homogeneous and interfacial conditions. Trivalent tris-(silazido) compounds Ln{N(SiHMe 2 )tBu} 3 (Ln = Sc (1), Y (2), Lu (3)) are prepared in high yield by salt metathesis reactions. Solution-phase and solid-state characterization of 1− 3 by NMR and IR spectroscopy and X-ray diffraction reveals Ln↼H−Si interactions. These features are retained in solventcoordinated 2·Et 2 O, 2·THF, and 3·THF. The change in spectroscopic features characterizing the secondary interactions (ν SiH , 1 J SiH ) from the unactivated SiH in the silazane HN(SiHMe 2 )tBu follows the trend 3 > 2 > 1 ≈ 2·Et 2 O > 2·THF ≈ 3· THF. Ligand lability follows the same pattern, with Et 2 O readily dissociating from 2·Et 2 O while THF is displaced only during surface grafting reactions. 1 and 2·THF graft onto mesoporous silica nanoparticles (MSN) to give Ln{N(SiHMe 2 )tBu} n @MSN (Ln = Sc (1@MSN), Y (2@MSN)) along with THF and protonated silazido as HN(SiHMe 2 )tBu and H 2 NtBu. The surface species are characterized by multinuclear and multidimensional solid-state (SS) NMR spectroscopic techniques, as well as diffuse reflectance FTIR, elemental analysis, and reaction stoichiometry. A key 1 J SiH SSNMR measurement reveals that the grafted sites most closely resemble Ln·THF adducts, suggesting that siloxane coordination occurs in grafted compounds. These species catalyze the hydroamination/bicyclization of aminodialkenes, and both solution-phase and interfacial conditions provide the bicyclized product with equivalent cis:trans ratios. Similar diastereoselectivities mediated by catalytic sites under the two conditions suggest similar effective environments.

The reactivity of a series of disilazido zirconocene complexes is dominated by the migration of anionic groups (hydrogen, alkyl, halide, OTf) between the zirconium and silicon centers. The direction of these migrations is controlled by the addition of two-electron donors (Lewis bases) or two-electron acceptors (Lewis acids). The cationic nonclassical [Cp2ZrN(SiHMe2)2](+) ([2](+)) is prepared from Cp2Zr{N(SiHMe2)2}H (1) and B(C6F5)3 or [Ph3C][B(C6F5)4], while reactions of B(C6F5)3 and Cp2Zr{N(SiHMe2)2}R (R = Me (3), Et (5), n-C3H7 (7), CH═CHSiMe3 (9)) provide a mixture of [2](+) and [Cp2ZrN(SiHMe2)(SiRMe2)](+). The latter products are formed through B(C6F5)3 abstraction of a β-H and R group migration from Zr to the β-Si center. Related β-hydrogen abstraction and X group migration reactions are observed for Cp2Zr{N(SiHMe2)2}X (X = OTf (11), Cl (13), OMe (15), O-i-C3H7 (16)). Alternatively, addition of DMAP (DMAP = 4-(dimethylamino)pyridine) to [2](+) results in coordination to a Si center and hydrogen migration to zirconium, giving the cationic complex [Cp2Zr{N(SiHMe2)(SiMe2DMAP)}H](+) ([19](+)). Related hydrogen migration occurs from [Cp2ZrN(SiHMe2)(SiMe2OCHMe2)](+) ([18](+)) to give [Cp2Zr{N(SiMe2DMAP)(SiMe2OCHMe2)}H](+) ([22](+)), whereas X group migration is observed upon addition of DMAP to [Cp2ZrN(SiHMe2)(SiMe2X)](+) (X = OTf ([12](+)), Cl ([14](+))) to give [Cp2Zr{N(SiHMe2)(SiMe2DMAP)}X](+) (X = OTf ([26](+)), Cl ([20](+))). The species involved in these transformations are described by resonance structures that suggest β-elimination. Notably, such pathways are previously unknown in early metal amide chemistry. Finally, these migrations facilitate direct Si-H addition to carbonyls, which is proposed to occur through a pathway that previously had been reserved for later transition metal compounds.

The new homoleptic rare earth compound [Y(C(SiHMe(2))(3))(3)] () is prepared in 82% yield by salt metathesis of YCl(3) and 3 equivalents of [KC(SiHMe(2))(3)] (); two beta-agostic Y(H-Si) interactions are observed for each C(SiHMe(2))(3) ligand in , giving six agostic interactions per yttrium(iii) center.

Homoleptic tris(alkyl) rare earth complexes Ln{C(SiHMe)} (Ln = La, 1a; Ce, 1b; Pr, 1c; Nd, 1d) are synthesized in high yield from LnITHF and 3 equiv of KC(SiHMe). X-ray diffraction studies reveal 1a-d are isostructural, pseudo-C-symmetric molecules that contain two secondary Ln↼HSi interactions per alkyl ligand (six total). Spectroscopic assignments are supported by comparison with Ln{C(SiDMe)} and DFT calculations. The Ln↼HSi and terminal SiH exchange rapidly on the NMR time scale at room temperature, but the two motifs are resolved at low temperature. Variable-temperature NMR studies provide activation parameters for the exchange process in 1a (ΔH = 8.2(4) kcal·mol; ΔS = -1(2) cal·molK) and 1a-d (ΔH = 7.7(3) kcal·mol; ΔS = -4(2) cal·molK). Comparisons of lineshapes, rate constants (k/k), and slopes of ln(k/T) vs 1/T plots for 1a and 1a-d reveal that an inverse isotope effect dominates at low temperature. DFT calculations identify four low-energy intermediates containing five β-Si-H⇀Ln and one γ-C-H⇀Ln. The calculations also suggest the pathway for Ln↼HSi/SiH exchange involves rotation of a single C(SiHMe) ligand that is coordinated to the Ln center through the Ln-C bond and one secondary interaction. These robust organometallic compounds persist in solution and in the solid state up to 80 °C, providing potential for their use in a range of synthetic applications. For example, reactions of Ln{C(SiHMe)} and ancillary proligands, such as bis-1,1-(4,4-dimethyl-2-oxazolinyl)ethane (HMeC(Ox)) give {MeC(Ox)}Ln{C(SiHMe)}, and reactions with disilazanes provide solvent-free lanthanoid tris(disilazides).

Chiral crystalline sponges with preinstalled chiral references were synthesized. On the basis of the known configurations of the chiral references, the absolute structures of guest compounds absorbed in the pores of the crystalline sponges can be reliably determined without crystallization or chemical modification.

Triangulene and its homologues are of considerable interest for molecular spintronics due to their high-spin ground states as well as the potential for constructing high spin frameworks. Realizing triangulene-based high-spin system on surface is challenging but of particular importance for understanding π-electron magnetism. Here, we report two approaches to generate triangulene trimers on Au(111) by using surface-assisted dehydration and alkyne trimerization, respectively. We find that the developed dehydration reaction shows much higher chemoselectivity thus resulting in significant promotion of product yield compared to that using alkyne trimerization approach, through cutting the side reaction path. Combined with spin-polarized density functional theory calculations, scanning tunneling spectroscopy measurements identify the septuple (S = 3) high-spin ground state and quantify the collective ferromagnetic interaction among three triangulene units. Our results demonstrate the approaches to fabricate high-quality triangulene-based high spin systems and understand their magnetic interactions, which are essential for realizing carbon-based spintronic devices.