Matrix isolation infrared observation of the HSiN 2 and H 2 SiN 2 complexes using a 121 nm vacuum-ultraviolet photolysis source Jay C. Amicangelo, C. T. Dine, D. G. Irwin, C. J. Lee, N. C. Romano, N. L. Saxton

Schematic of Matrix-Isolation Apparatus –Hydrogen lamp (H 2 /Ar) photolysis source (121 nm) –Evanson-Broida cavity, 2450 MHz, 40 W –Mixture of SiH 4 & N 2 (1:100); 2 – 3 mmol/hr; 12 K SiH 4 :N 2

SiH 4 + N 2 deposition  no H-lamp photolysis SiH 4 Asym. Stretch SiH 4 Deg. Bend SiH 4 :N 2 1:100, 12 K, 10 minutes

SiH 4 + N 2 deposition with H-lamp photolysis SiH 4 SiH 4 :N 2 1:100, 12 K, 4 hours Si 2 H 6 H2OH2O CO 2 N2N2 SiN 2 No H-lamp H-lamp Si 3 H 8 Si(N 2 ) 2 Si 2 H 2

SiH 4 + N 2 H-lamp photolysis –Vis & UV photolysis (Hg-Xe lamp) –30 K anneal ● H-Lamp vis photo UV photo 30 K anneal ● ▲ ▲

SiH 4 + N 2 H-lamp photolysis –20 K, 25 K, 30 K anneal ● H-Lamp 20 K anneal 25 K anneal 30 K anneal ● ▲ ▲ ●

SiH 4 + N 2 H-lamp photolysis –Isotopic variations SiH N 2 SiD N 2 SiH N 2 SiD N 2 H N

SiH 4 + N 2 H-lamp photolysis –Isotopic variations SiD N 2 No H-lamp SiD N 2 H-lamp Spectral Subtraction

SiH 4 + N 2 H-lamp photolysis –Isotopic variations SiH N 2 SiD N 2 SiH N 2 SiD N 2 H N N

SiH 4 + N 2 H-lamp photolysis –20 K, 25 K, 30 K anneal ● H-Lamp 20 K anneal 25 K anneal 30 K anneal ● ▲ ▲ ●

SiH 4 + N 2 H-lamp photolysis –25 K Annealed & Isotopic variation

Peaks involving nitrogen  N–N stretch cm cm -1 Peak involving hydrogen  Si–H stretch & 2009 cm cm -1 Theoretical Calculations for H x SiN 2 –B3LYP/aug-cc-pVTZ –Full geometry optimization –Frequency analysis (scaled by )

H 2 SiN 2 complex Theoretical frequencies & interaction energy –N–N stretch = 2238 cm -1 (expt = 2274 cm -1 ) –Si–H asymm stretch = 2008 cm -1 –Si–H symm stretch = 2001 cm -1 –H 2 Si + N 2 → H 2 SiN 2  E = − 25.2 kJ/mol 1.97 Å 1.10 Å CsCs 1.51 Å (expt = 2014 cm -1 ) 96.1° 86.8° 167.9° 1A′1A′ ● ● (expt = 2009 cm -1 )

HSiN 2 complex Theoretical frequency & interaction energy –N–N stretch = 2021 cm -1 (expt = 2024 cm -1 ) –Si–H stretch = 1981 cm -1 (expt = 2007 cm -1 ) –HSi + N 2 → HSiN 2  E = − 46.3 kJ/mol 1.85 Å 1.12 Å CsCs 1.52 Å 86.4° 170.7° ▲ ▲ 2A″2A″

Acknowledgements Undergraduate Students Chris Dine Nancy Saxton Dan Irwin Natalie Romano Cynthia Lee Funding Penn State Erie Research Corporation Cottrell Award Petroleum Research Fund Type G Award