Catalyst-Free Syntheses of [2]Rotaxanes Utilizing a Pentacoordinated Hydrosilane as an End-Capping Agent

Hydrosilylation of RN=CH Imino-Substituted Pyridines without a Catalyst

Treatment of the neutral pyridine-based ligands L¹ -L³ , bearing either one or two RN=CH imine moieties {where L¹ and L² are N,N-chelating ligands 2-(RN=CH)C₅ H₄ N (R=Ph (L¹ ) or R=2,4,6-Ph₃ C₆ H₂ (L² )) and L³ is the N,N,N-chelating ligand 2,6-(RN=CH)₂ C₅ H₃ N (R=2,6-iPr₂ C₆ H₃ )}, with HSiCl₃ yielded N→Si-coordinated silicon(IV) amides 2-{Cl₃ SiN(R)CH₂ }C₅ H₄ N (1, R=Ph; 2, R=2,4,6-Ph₃ C₆ H₂ ) and 2-{Cl₃ SiN(R)CH₂ }-6-(RN=CH)C₅ H₄ N (3, R=2,6-iPr₂ C₆ H₃ ). The organosilicon amides 1-3 are the products of spontaneous hydrosilylation of the RN=CH imine moiety induced by N→Si coordination of the proposed N,N-chelated chlorosilanes L¹ →SiHCl₃ (1 a), L² →SiHCl₃ (2 a), and L³ →SiHCl₃ (3 a). Furthermore, the reaction of L³ with an excess of HSiCl₃ provided the intramolecularly coordinated chlorosilicon diamide cyclo-{(C₅ H₃ N)-1,3-(CH₂ NR)₂ }SiCl₂ (4) (R=2,6-iPr₂ C₆ H₃ ) as the product of spontaneous reduction of both RN=CH imine moieties. The compounds have been characterized by NMR spectroscopy (1-4) and single-crystal X-ray diffraction analysis (1, 3, and 4). The mechanism of the hydrosilylation of the second RN=CH imine moiety in 3 by an excess of SiHCl₃ has also been studied. The experimental work is supplemented by DFT calculations.

Spontaneous Double Hydrometallation Induced by N→M Coordination in Organometallic Hydrides of Group 14 Elements

Our attempts to synthesise N→M intramolecularly coordinated diorganometallic hydrides L2MH2 [M=Si (4), Ge (5), Sn (6)] containing the CH=N imine group (in which L is C,N-chelating ligand {2-[(2,6-iPr2C6H3)N=CH]C6 H4}(-)) yielded 1,1'-bis(2,6-diisopropylphenyl)-2,2'-spriobi[benzo[c][1,2]azasilole] (7), 1,1'-bis(2,6-diisopropylphenyl)-2,2'-spriobi[benzo[c][1,2]azagermole] (8) and C,N-chelated homoleptic stannylene L2Sn (10), respectively. Compounds 7 and 8 are an outcome of a spontaneous double hydrometallation of the two CH=N imine moieties induced by N→M intramolecular coordination (M=Si, Ge) in the absence of any catalyst. In contrast, the diorganotin hydride L2SnH2 (6) is redox-unstable and the reduction of the tin centre with the elimination of H2 provided the C,N-chelated homoleptic stannylene L2Sn (10). Compounds 7 and 8 were characterised by NMR spectroscopy and X-ray diffraction analysis. Because the proposed N→M intramolecularly coordinated diorganometallic hydrides L2MH2 [M=Si (4), Ge (5), Sn (6)] revealed two different types of reduction reactions, DFT calculations were performed to gain an insight into the structures and bonding of the non-isolable diorganometallic hydrides as well as the products of their subsequent reactions. Furthermore, the thermodynamic profiles of the different reaction pathways with respect to the central metal atom were also investigated.

Synthesis of a phosphine imide bearing a hydrosilane moiety, and its water-driven reduction to a phosphine

Reaction of a hydrosilane bearing a phosphine imide moiety with water caused hydrolytic oxidation of the Si–H moiety accompanied by reduction of the phosphine imide moiety.