SiH 2 , a critical study.

The first four spectroscopic states of the silylene molecule SiH 2 , namely, and were examined theoretically using multireference methods coupled with very large correlation consistent basis sets. Our aim is understanding why SiH 2 has a singlet ground state ( ) as opposed to the state of the isovalent carbene CH 2 , as well as the rationalization of its geometric and bonding characteristics. The interpretational philosophy followed is based on strictly calculable quantities in an effort to reduce to a minimum the always present but not well-defined 'chemical intuitionism'. All of our calculated quantities are in excellent agreement with existing experimental results. [ABSTRACT FROM AUTHOR]