An official website of the United States government
Abstract Coordination complexes of general formulatrans‐[MX2(R2ECH2CH2ER2)2] (MII=Ti, V, Cr, Mn; E=N or P; R=alkyl or aryl) are a cornerstone of coordination and organometallic chemistry. We investigate the electronic properties of two such complexes,trans‐[VCl2(tmeda)2] andtrans‐[VCl2(dmpe)2], which thus representtrans‐[MX2(R2ECH2CH2ER2)2] where M=V, X=Cl, R=Me and E=N (tmeda) and P (dmpe). These VIIcomplexes haveS=3/2 ground states, as expected for octahedral d3. Their tetragonal distortion leads to zero‐field splitting (zfs) that is modest in magnitude (D≈0.3 cm−1) relative to analogousS=1 TiIIand CrIIcomplexes. This parameter was determined from conventional EPR spectroscopy, but more effectively from high‐frequency and ‐field EPR (HFEPR) that determined the sign ofDas negative for the diamine complex, but positive for the diphosphine, which information had not been known for anytrans‐[VX2(R2ECH2CH2ER2)2] systems. The ligand‐field parameters oftrans‐[VCl2(tmeda)2] andtrans‐[VCl2(dmpe)2] are obtained using both classical theory andab initioquantum chemical theory. The results shed light not only on the electronic structure of VIIin this environment, but also on differences between N and P donor ligands, a key comparison in coordination chemistry.
more »
« less
Structures and Energetics of E 2 H 3 + (E = As, Sb, and Bi) Cations
- Award ID(s):
- 2153978
- PAR ID:
- 10486152
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- The Journal of Physical Chemistry A
- Volume:
- 128
- Issue:
- 3
- ISSN:
- 1089-5639
- Format(s):
- Medium: X Size: p. 563-571
- Size(s):
- p. 563-571
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract The gas-phase reaction of O + H 3 + has two exothermic product channels: OH + + H 2 and H 2 O + + H. In the present study, we analyze experimental data from a merged-beams measurement to derive thermal rate coefficients resolved by product channel for the temperature range from 10 to 1000 K. Published astrochemical models either ignore the second product channel or apply a temperature-independent branching ratio of 70% versus 30% for the formation of OH + + H 2 versus H 2 O + + H, respectively, which originates from a single experimental data point measured at 295 K. Our results are consistent with this data point, but show a branching ratio that varies with temperature reaching 58% versus 42% at 10 K. We provide recommended rate coefficients for the two product channels for two cases, one where the initial fine-structure population of the O( 3 P J ) reactant is in its J = 2 ground state and the other one where it is in thermal equilibrium.more » « less
