## Abstract

Computations describe the dependence of the H_{2}M=Si triplet electronic structure on the α-substituent. Whereas silylidenes H _{2}C=Si and H_{2}Si=Si benefit from a π^{1}p ^{1} triplet state, the electronegative nitrogen of HN=Si prefers an n^{1}p^{1} triplet. CCSD(T) and B3LYP calculations predict R_{2}Si=Si triplet silylenes are stabilized by π-donor/σ- acceptor R substituents which compensate for electron deficiency in the singly occupied π orbital of the π(1)p(1) triplet state. (NH_{2}) _{2}Si=Si, (OH)_{2}Si=Si, F_{2}Si=Si, (NH _{2})HSi=Si, and (OH)HSi=Si all are triplet ground states. In particular, (NH_{2})_{2}Si=Si and (OH)_{2}Si=Si have singlet-triplet energy gaps (ΔE_{S-T} = E_{T} - E _{S}) of -10.2 and -10.3 kcal/mol, respectively. More practical results are achieved via cyclization of (NH_{2})_{2}Si=Si, which eliminates the probability of rearrangement. Unsaturation of the resulting cyclic structure to give (NHCHCHNH)Si=Si leads to a more favorable triplet silylene with a ΔE_{S-T} value of -19.6 kcal/mol. Similar to the common approach of bulky substitution in the synthesis of singlet Arduengo-type N-heterocyclic silylenes, triplet (NRCH_{2}CH_{2}NR)Si=Si and (NRCHCHNR)Si=Si could be experimentally achievable.

Original language | English (US) |
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Pages (from-to) | 5027-5032 |

Number of pages | 6 |

Journal | Organometallics |

Volume | 30 |

Issue number | 18 |

DOIs | |

State | Published - Sep 26 2011 |

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