3-Center-4-Electron Bonding in [(silox)2Mo=NtBu]2(μ-Hg) Controls Reactivity while Frontier Orbitals Permit a Dimolybdenum π-Bond Energy Estimate

Description:

Article describing research on 3-center-4-electron bonding in [(silox)2Mo=NtBu]2(mu-Hg).

Creator(s):
Creation Date: May 18, 2005
Partner(s):
UNT College of Arts and Sciences
Collection(s):
UNT Scholarly Works
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Rosenfeld, Devon C.

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Wolczanski, Peter T.

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University of North Texas

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Buda, Corneliu

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Cundari, Thomas R., 1964-

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Publisher Info:
Publisher Name: American Chemical Society
Place of Publication: [Washington, DC]
Date(s):
  • Creation: May 18, 2005
Description:

Article describing research on 3-center-4-electron bonding in [(silox)2Mo=NtBu]2(mu-Hg).

Degree:
Department: Chemistry
Note:

Reprinted with permission from the Journal of the American Chemical Society. Copyright 2005 American Chemical Society.

Note:

Abstract: Na/Hg reduction of (silox)2Cl2Mo=NtBu (3) afforded C2h [(silox)2Mo=NtBu]2(mu-Hg)(12-Hg), which consists of two distorted trigonal monoprisms with Hg at the each apex (d(MoHg)= 2.6810(5) A). Calculations reveal 3c4e bonding in the linear MoHgMo linkage that renders 12-Hg susceptible to nucleophilic cleavage. Exposure to PMe3 and pyridine rapidly (<5 min) affords (silox)2(tBuN)MoLn (L = PMe3, n = 1 (1-PMe3); py, n = 2 (1-py2)), while poorer nucleophiles (L = C2H4, 2-butyne) yield adducts (e.g., 1-C2H4 and 1-C2Me2) after prolonged heating. The HOMO and LUMO of 12-Hg are "stretched" pi and pi* orbitals from which four states arise: 1Ag (GS), 3Bu, 1Bu, and 1Ag. DeltaE = E(1Bu)- E(3Bu)= 2K, where K is the exchange energy. Magnetic studies indicate E(3Bu)- E(1Ag) approximately 550 cm-1 (calcd 1744 cm-1), and a UV-vis absorption at 10 000 cm-1 is assigned to 1Ag --> 1Bu, permitting K to be evaluated as 4725 cm-1. With the pi --> pi* transition in Schrock's [Mo(NAr)(CH2tBu)(OC6F5)]2 (4) assigned at 528 nm, this estimation places its pi-bond energy as {E(pi2 --> pi1pi*1 in 4)- E(1Ag --> 1Bu in 12-Hg)}+ E(1Ag --> 3Bu in 12-Hg)= 27 kcal/mol.

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2 p.

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Subject(s):
Keyword(s): pme | pi-bond | orbital | c2h | energy estimate | frontier orbital | bonds | frontiers | reactivity | deltae | adduct
Source: Journal of the American Chemical Society, 2005, Washington DC: American Chemical Society, pp. 8262-8263
Partner:
UNT College of Arts and Sciences
Collection:
UNT Scholarly Works
Identifier:
  • DOI: 10.1021/ja051070e
  • ARK: ark:/67531/metadc77136
Resource Type: Article
Format: Text
Rights:
Access: Public
Citation:
Publication Title: Journal of the American Chemical Society
Volume: 127
Page Start: 8262
Page End: 8263
Pages: 2
Peer Reviewed: Yes