An official website of the United States government
Abstract Organofunctionalized tetranuclear clusters [(MIICl)2(VIVO)2{((HOCH2CH2)(H)N(CH2CH2O))(HN(CH2CH2O)2)}2] (1, M=Co,2: M=Zn) containing an unprecedented oxometallacyclic {M2V2Cl2N4O8} (M=Co, Zn) framework have been prepared by solvothermal reactions. The new oxo‐alkoxide compounds were fully characterized by spectroscopic methods, magnetic susceptibility measurement, DFT and ab initio computational methods, and complete single‐crystal X‐ray diffraction structure analysis. The isostructural clusters are formed of edge‐sharing octahedral {VO5N} and trigonal bipyramidal {MO3NCl} units. Diethanolamine ligates the bimetallic lacunary double cubane core of1and2in an unusual two‐mode fashion, unobserved previously. In the crystalline state, the clusters of1and2are joined by hydrogen bonds to form a three‐dimensional network structure. Magnetic susceptibility data indicate weakly antiferromagnetic interactions between the vanadium centers [Jiso(VIV−VIV)=−5.4(1); −3.9(2) cm−1], and inequivalent antiferromagnetic interactions between the cobalt and vanadium centers [Jiso(VIV−CoII)=−12.6 and −7.5 cm−1] contained in1.
more »
« less
Electronic Structure of trans‐ [V II Cl 2 (E(CH 3 ) 2 CH 2 CH 2 E(CH 3 ) 2 ) 2 ], E=N, P
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
- PAR ID:
- 10555571
- Publisher / Repository:
- ECS Publishing
- Date Published:
- Journal Name:
- European Journal of Inorganic Chemistry
- ISSN:
- 1434-1948
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract We introduce the heterocumulene ligand [(Ad)NCC(tBu)]−(Ad=1‐adamantyl (C10H15),tBu=tert‐butyl, (C4H9)), which can adopt two forms, the azaalleneyl and ynamide. This ligand platform can undergo a reversible chelotropic shift using Brønsted acid‐base chemistry, which promotes an unprecedented spin‐state change of the [VIII] ion. These unique scaffolds are prepared via addition of 1‐adamantyl isonitrile (C≡NAd) across the alkylidyne in complexes [(BDI)V≡CtBu(OTf)] (A) (BDI−=ArNC(CH3)CHC(CH3)NAr), Ar=2,6‐iPr2C6H3) and [(dBDI)V≡CtBu(OEt2)] (B) (dBDI2−=ArNC(CH3)CHC(CH2)NAr). ComplexAreacts with C≡NAd, to generate the high‐spin [VIII] complex with a κ1‐N‐ynamide ligand, [(BDI)V{κ1‐N‐(Ad)NCC(tBu)}(OTf)] (1). Conversely,Breacts with C≡NAd to generate a low‐spin [VIII] diamagnetic complex having a chelated κ2‐C,N‐azaalleneyl ligand, [(dBDI)V{κ2‐N,C‐(Ad)NCC(tBu)}] (2). Theoretical studies have been applied to better understand the mechanism of formation of2and the electronic reconfiguration upon structural rearrangement by the alteration of ligand denticity between1and2.more » « less
-
Abstract Discovery of new materials with enhanced optical properties in the visible and UV‐C range can impact applications in lasers, nonlinear optics, and quantum optics. Here, the optical floating zone growth of a family of rare earth borates,RBa3(B3O6)3(R= Nd, Sm, Tb, Dy, and Er), with promising linear and nonlinear optical (NLO) properties is reported. Although previously identified to be centrosymmetric, the X‐ray analysis combined with optical second harmonic generation (SHG) assigns the noncentrosymmetricPspace group to these crystals. Characterization of linear optical properties reveals a direct bandgap of ≈5.61–5.72 eV and strong photoluminescence in both the visible and mid‐IR regions. Anisotropic linear and nonlinear optical characterization reveals both Type‐I and Type‐II SHG phase matchability, with the highest effective phase‐matched SHG coefficient of 1.2 pm V−1at 800‐nm fundamental wavelength (for DyBa3(B3O6)3), comparable to β‐BaB2O4(phase‐matchedd22≈ 1.9 pm V−1). Laser‐induced surface damage threshold for these environmentally stable crystals is 650–900 GW cm−2, which is four to five times higher than that of β‐BaB2O4, thus providing an opportunity to pump with significantly higher power to generate about six to seven times stronger SHG light. Since the SHG arises from disorder on the Ba‐site, significantly larger SHG coefficients may be realized by “poling” the crystals to align the Ba displacements. These properties motivate further development of this crystal family for laser and wide bandgap NLO applications.more » « less
-
Not, available (Ed.)Abstract Described here is a direct entry to two examples of 3d transition metal catalysts that are active for the cyclic polymerization of phenylacetylene, namely, [(BDI)M{κ2‐C,C‐(Me3SiC3SiMe3)}] (2‐M) (BDI=[ArNC(CH3)]2CH−, Ar=2,6‐iPr2C6H3;M=Ti, V). Catalysts are prepared in one step by the treatment of [(BDI)MCl2] (1‐M,M=Ti,V) with 1,3‐dilithioallene [Li2(Me3SiC3SiMe3)]. Complexes2‐Mhave been spectroscopically and structurally characterized and the polymers that are catalytically formed from phenylacetylene were verified to have a cyclic topology based on a combination of size‐exclusion chromatography (SEC) and intrinsic viscosity studies. Two‐electron oxidation of2‐Vwith nitrous oxide (N2O) cleanly yields a [VV] alkylidene‐alkynyl oxo complex [(BDI)V(=O){κ1‐C‐(=C(SiMe3)CC(SiMe3))}] (3), which lends support for how this scaffold in2‐Mmight be operating in the polymerization of the terminal alkyne. This work demonstrates how alkylidynes can be circumvented using 1,3‐dianionic allene as a segue into M−C multiple bonds.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/ejic.202400395
