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Title: Linear MgCp*2 vs Bent CaCp*2: London Dispersion, Ligand-Induced Charge Localizations, and Pseudo-Pregostic C–H···Ca Interactions

Journal Article · · Inorganic Chemistry
ORCiD logo [1]; ORCiD logo [2];  [3];  [3];  [4];  [1];  [5];  [2];  [1];  [6]; ORCiD logo [1]; ORCiD logo [1]
  1. Univ. Bremen (Germany)
  2. Freie Univ. Berlin (Germany)
  3. Univ. of Western Australia (Australia)
  4. Univ. of Warsaw (Poland)
  5. Freie Univ. Berlin (Germany); Bundesinstitut für Risikobewertung, Berlin (Germany)
  6. Univ. of Chicago, Argonne, IL (United States)
+ Show Author Affiliations

In the family of metallocenes, MgCp*2 (Cp* = pentamethylcyclopentadienyl) exhibits a regular linear sandwich structure, whereas CaCp*2 is bent in both the gas phase and solid state. Bending is typically observed for metal ions which possess a lone pair. Here, we investigate which electronic differences cause the bending in complexes lacking lone pairs at the metal atoms. The bent gas-phase geometry of CaCp*2 suggests that the bending must have an intramolecular origin. Geometry optimizations with and without dispersion effects/d-type polarization functions on MCp2 and MCp*2 gas-phase complexes (M = Ca, Mg) establish that attractive methyl···methyl London dispersion interactions play a decisive role in the bending in CaCp*2. A sufficient polarizability of the metal to produce a shallow bending potential energy curve is a prerequisite but is not the reason for the bending. Concomitant ligand-induced charge concentrations and localizations at the metal atoms are studied in further detail, for which real-space bonding and orbital-based descriptors are used. Here, low-temperature crystal structures of MgCp*2 and CaCp*2 were determined which facilitated the identification and characterization of intermolecular pseudo-pregostic interactions, C–H···Ca, in the CaCp*2 crystal structure.

Research Organization:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC); National Science Foundation (NSF)
Grant/Contract Number:
AC02-06CH11357; NSF/CHE-1346572
OSTI ID:
1437474
Journal Information:
Inorganic Chemistry, Vol. 57, Issue 9; ISSN 0020-1669
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
ENGLISH
Citation Metrics:
Cited by: 12 works
Citation information provided by
Web of Science

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
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