Theoretical Prediction of Vertical Transition Energies of Diaminosilylenes and Aminosubstituted Disilenes MASAE TAKAHASHI, 1 MITSUO KIRA, 2 KENKICHI SAKAMOTO, 1,2 THOMAS MÜLLER, 3 YITZHAK APELOIG 4 1 Photodynamics Research Center, RIKEN (The Institute of Physical and Chemical Research), 519-1399, Aoba, Aramaki, Aoba-ku, Sendai 980-0845, Japan 2 Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan 3 Institut für Anorganische Chemie der Goethe Universität Frankfurt, Federal Republic of Germany 4 Department of Chemistry and Lise Meitner-Minerva Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Haifa, Israel Received 12 February 2001; accepted 23 April 2001 Dedicated to Professor Paul von R. Schleyer ABSTRACT: Vertical electronic transition energies of diaminosilylenes and their dimers (disilenes and nitrogen-bridged) were investigated by ab initio and density functional calculations. A good linear correlation was found between the observed UV transition energies of various silylenes and disilenes and those of model compounds calculated using the CIS and TD–DFT methods. On the basis of these computations the experimental UV absorption maximum observed for the dimer of (i-Pr 2 N) 2 Si: (λ max 439 nm at 77 K), could be assigned to an Si—Si bonded dimer with an unusually long Si—Si distance of 2.472 Å, and the isomeric amino-bridged cyclic dimer could be discarded. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1536–1541, 2001 Keywords: silylenes; disilenes; UV spectra; TD–DFT; CIS; quantum mechanical calculations Correspondence to: M. Takahashi Contract/grant sponsor: German–Israeli Foundation for Sci- entific Research Journal of Computational Chemistry, Vol. 22, No. 13, 1536–1541 (2001) © 2001 John Wiley & Sons, Inc.