Combined Experimental and Computational Study on the Reaction Dynamics of the D1-Silylidyne(SiD) – Silane (SiH₄) System

Abstract

Small silicon hydrides have attracted extensive interest because of their role in the chemical evolution of circumstellar envelopes of evolved carbon stars and applications in surface growth processes and as transients in semiconductor manufacturing. Combined with electronic structure calculations, we demonstrate that monobridged silylidynesilylenes [(Si(μ-D)SiH 2 , Si(μ-H)SiHD, Si(μ-H)SiH 2 ] and silylsilylidyne [H 3 SiSi, H 2 DSiSi], which are nearly isoenergetic, can be prepared via molecular hydrogen loss channels in the crossed molecular beam study of the reaction of D1-silylidyne (SiD; X 2 Π) with silane (SiH 4 ; X 1 A 1 ) in a crossed molecular beams machine. Compared to the dynamics of the isovalent methylidyne (CH) − methane (CH 4 ) system, our study delivers a unique view at the intriguing isomerization processes and reaction dynamics of dinuclear silicon hydride transients, thus contributing to our knowledge on the chemical bonding of silicon hydrides at the molecular level.

Directed Gas-Phase Formation of Aminosilylene (HSiNH2;X1A′): The Simplest Silicon Analogue of an Aminocarbene, under Single-Collision Conditions

“…The reaction of the D1-silylidyne radical (SiD; X 2 Π) with D3-ammonia (ND 3 ; X 1 A 1 ) and ammonia (NH 3 ; X 1 A 1 ) were conducted exploiting a crossed molecular beams machine . The D1-silylidyne pulsed supersonic beam was formed in situ in the primary chamber by laser ablation of a rotating silicon rod with 266 nm pulses (4–8 mJ per pulse; 30 Hz) and entrainment of the ablated species in a 1:1 mixture of deuterium gas (D 2 , >99.7%; Linde) and neon (Ne; 99.999%; Matheson) released by a pulsed piezoelectric valve with 4 atm backing pressure, 60 Hz repetition rate . The D1-silylidyne beam was optimized at a unique mass-to-charge value of m / z = 31 ( 29 SiD + ) for intensity, considering the natural silicon isotope abundances ( 28 Si (92.2%), 29 Si (4.7%), 30 Si (3.1%)).…”

“…The D1-silylidyne beam was optimized at a unique mass-to-charge value of m / z = 31 ( 29 SiD + ) for intensity, considering the natural silicon isotope abundances ( 28 Si (92.2%), 29 Si (4.7%), 30 Si (3.1%)). The primary D1-silylidyne beam was first skimmed and then velocity-selected by a high stable four-slot chopper wheel (120 Hz) controlled by a precision motion system . The chopped section of the D1-silylidyne beam is defined by a peak velocity ( v p ) of 1200 m s –1 and speed ratio ( S ) of 6 (Table S1).…”

“…41 The D1-silylidyne pulsed supersonic beam was formed in situ in the primary chamber by laser ablation of a rotating silicon rod with 266 nm pulses (4−8 mJ per pulse; 30 Hz) and entrainment of the ablated species in a 1:1 mixture of deuterium gas (D 2 , >99.7%; Linde) and neon (Ne; 99.999%; Matheson) released by a pulsed piezoelectric valve with 4 atm backing pressure, 60 Hz repetition rate. 42 The D1-silylidyne beam was optimized at a unique mass-tocharge value of m/z = 31 ( 29 SiD + ) for intensity, considering the natural silicon isotope abundances ( 28 Si (92.2%), 29 Si (4.7%), 30 Si (3.1%)). The primary D1-silylidyne beam was first skimmed and then velocity-selected by a high stable four-slot chopper wheel (120 Hz) controlled by a precision motion system.…”

“…The primary D1-silylidyne beam was first skimmed and then velocity-selected by a high stable four-slot chopper wheel (120 Hz) controlled by a precision motion system. 42 The chopped section of the D1-silylidyne beam is defined by a peak velocity (v p ) of 1200 m s −1 and speed ratio (S) of 6 (Table S1). It should be noted that no higher molecular weight silicon-deuterium bearing species were detected in the primary beam in the experiment.…”