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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Formation of tungsten ethylidene complexes from diethyl complexes through a proton-catalyzed rearrangement of ethylene

Here, W(NAr) 2 Et 2 (Ar = 2,6-diisopropylphenyl) reacts with two equivalents of R F9 OH (OR F9 = OC(CF 3 ) 3 ) to yield W(NAr)(ArNH 2 )(OR F9 )2(C 2 H 4 ) complexes and ethane. In solution W(NAr)(ArNH 2 )(OR F9 ) 2 (C 2 H 4 ) decomposes to give R F9 OH, ethane, W(NAr)(OR F9 ) 2 (C 2 H 4 ), and W(NAr)(NHAr′)(ArNH 2 )(OR F9 ), in which Ar′ contains a dehydrogenated isopropyl group (Ar′ = (2-i-Pr)(6-CMe=CH 2 )C 6 H 3 ) coordinated to the metal. On a similar time scale W(NAr)(OR F9 ) 2 (CHCH 3 ) complexes are formed from W(NAr)(OR F9 ) 2 (C 2 H 4 ) through an ArNH 2 -catalyzed rearrangement of the ethylene ligand. W(NAr)(NHAr′)(ArNH 2 )(OR F9 ) reacts with cyclohexene to form methylenecyclohexene and complexes that contain an NHAr″ ligand where Ar″ is a disubstituted (methyl/aryl) alkylidene, (2-i-Pr)(6-CMe)C 6 H 3 ) that is tethered to the metal through the amido nitrogen. In contrast to W(NAr)(ArNH 2 )(OR F9 ) 2 (C 2 H 4 ), analogous OR F6 (OCMe(CF 3 ) 2 ) and OR F3 (OCMe 2 (CF 3 )) complexes are relatively stable at 22 °C.

Maji, Milan [University of California, Riverside, ↗
DOE OSTI2025

Proton-Catalyzed Interconversion of Tungsten(VI) Imido Isopropylidene and Propylene Complexes

Additions of two equivalents of (CF 3 ) 3 COH (R F9 OH) or (CF 3 ) 2 MeCOH (R F6 OH) to W(NAr) 2 R 2 complexes (Ar = 2,6-diisopropylphenyl, R = n-propyl or i-propyl) offer the opportunity to synthesize propylene or isopropylidene olefin metathesis-active complexes in the absence of free propylene. Propylene and isopropylidene complexes (W(NAr)(ArNH 2 )(OR F9 ) 2 (propylene) and W(NAr)(ArNH 2 )(OR F9 ) 2 (CMe 2 )) are formed at room temperature from both W(NAr) 2 (i-propyl) 2 and W(NAr) 2 (n-propyl) 2 complexes upon addition of two equivalents of R F9 OH; no W = CHCH 2 Me complexes are observed. Similar results are found for W(NAd) 2 (propyl) 2 complexes (Ad = 1-adamantyl). Both RNH 2 and RNH 2 B(C 6 F 5 ) 3 (R = Ar or Ad) catalyze the interconversion of propylene and isopropylidene complexes. Addition of R F6 OH to W(NAr) 2 R 2 or W(NAd) 2 R 2 complexes leads to mixtures that contain largely propylene complexes. Addition of (CF 3 )Me 2 COH (R F3 OH) to W(NAr) 2 (i-Pr) 2 yields only propylene complexes. One propylene complex, W(NAd)(OR F9 ) 2 (CH 2 ═CHMe)(dme), was isolated, structurally characterized, and found to react with AdNH 2 to reform W(NAd)(OR F9 ) 2 (CMe 2 )(AdNH 2 ). Furthermore, it is proposed that propylene and isopropylidene complexes interconvert through the formation of an intermediate isopropyl complex.

Alkyls↗
DOE OSTI2020

Materials Data on Pr2I5 by Materials Project

Pr2I5 crystallizes in the monoclinic P2_1/m space group. The structure is two-dimensional and consists of one Pr2I5 sheet oriented in the (-1, 0, 1) direction. there are two inequivalent Pr sites. In the first Pr site, Pr is bonded to seven I atoms to form a mixture of distorted edge and face-sharing PrI7 pentagonal bipyramids. There are a spread of Pr–I bond distances ranging from 3.23–3.37 Å. In the second Pr site, Pr is bonded to seven I atoms to form distorted edge-sharing PrI7 pentagonal bipyramids. There are a spread of Pr–I bond distances ranging from 3.18–3.45 Å. There are five inequivalent I sites. In the first I site, I is bonded in an L-shaped geometry to two equivalent Pr atoms. In the second I site, I is bonded in a distorted trigonal non-coplanar geometry to three equivalent Pr atoms. In the third I site, I is bonded in a distorted trigonal non-coplanar geometry to three equivalent Pr atoms. In the fourth I site, I is bonded in a distorted T-shaped geometry to three Pr atoms. In the fifth I site, I is bonded in a distorted T-shaped geometry to three Pr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrI2 by Materials Project

PrI2 is trigonal omega-like structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Pr is bonded to six I atoms to form edge-sharing PrI6 octahedra. There are three shorter (3.18 Å) and three longer (3.32 Å) Pr–I bond lengths. There are two inequivalent I sites. In the first I site, I is bonded in a distorted T-shaped geometry to three equivalent Pr atoms. In the second I site, I is bonded in a 3-coordinate geometry to three equivalent Pr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PrI3 by Materials Project

PrI3 crystallizes in the hexagonal P6_3/mmc space group. The structure is one-dimensional and consists of two PrI3 ribbons oriented in the (0, 0, 1) direction. Pr3+ is bonded to six equivalent I1- atoms to form distorted face-sharing PrI6 pentagonal pyramids. All Pr–I bond lengths are 3.16 Å. I1- is bonded in an L-shaped geometry to two equivalent Pr3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr3I by Materials Project

Pr3I crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Pr is bonded in a distorted see-saw-like geometry to four equivalent I atoms. There are two shorter (3.57 Å) and two longer (3.58 Å) Pr–I bond lengths. I is bonded to twelve equivalent Pr atoms to form a mixture of corner and face-sharing IPr12 cuboctahedra.

36 MATERIALS SCIENCE↗