Improved Synthesis of Bis(borano)hypophosphite Salts

Anstey, Mitchell R.; Corbett, Michael T.; Majzoub, Eric H.; Cordaro, Joseph Gabriel

doi:10.1021/ic101326c

Cited by 15 publications

(23 citation statements)

References 34 publications

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“…Phosphinodiboranates are congeners of aminodiboranates and differ only in that they contain a bridging phosphido linker between the two BH 3 groups instead of an amido linker (Chart ). Like aminodiboranates, phosphinodiboranate salts with different substituents attached to phosphorus have been known for over half a century, − but f-element coordination complexes with these ligands were unknown until the first compounds were reported with P , P -di- tert -butylphosphinodiboranate (H 3 BP t Bu 2 BH 3 – , t Bu-PDB) by us in a communication last year . Phosphinodiboranates join a series of phosphinate and related ligands with other second-row donor groups (i.e., O, , NR, − and CH 2 − ) that have been used in f-element separations and coordination chemistry (Chart ).…”

Section: Chelating Borohydrides: Review Of Phosphinodiboranatesmentioning

confidence: 99%

Chelating Borohydrides for Lanthanides and Actinides: Structures, Mechanochemistry, and Case Studies with Phosphinodiboranates

et al. 2019

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In this Forum Article, we review the development of chelating borohydride ligands called aminodiboranates (H 3 BNR 2 BH 3 − ) and phosphinodiboranates (H 3 BPR 2 BH 3 − ) for the synthesis of trivalent f-element complexes. The advantages and history of using mechanochemistry to prepare molecular borohydride complexes are described along with new results demonstrating the mechanochemical synthesis of M 2 (H 3 BP t Bu 2 BH 3 ) 6 , where M = U, Nd, Tb, Er, and Lu (1−5). Multinuclear NMR, IR, and singlecrystal X-ray diffraction data are reported for 1−5 alongside complementary density functional theory calculations to reveal differences in their structure and reactivity with and without tetrahydrofuran. The results demonstrate how mechanochemistry can be used to access f-element complexes with chelating borohydrides in improved and reproducible yields, which is an important step toward investigating the properties of lanthanide and actinide phosphinodiboranate complexes with different phosphorus substituents. The relevance of these results is contextualized by a discussion of structural factors known to influence the volatility of f-element borohydrides and applications that require the development of volatile f-element complexes.

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Section: Chelating Borohydrides: Review Of Phosphinodiboranatesmentioning

confidence: 99%

Chelating Borohydrides for Lanthanides and Actinides: Structures, Mechanochemistry, and Case Studies with Phosphinodiboranates

et al. 2019

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“…More recently, in situ nuclear magnetic resonance studies by Conradi et al 1 were performed using a high-pressure cell that prevented the decomposition of NaAlH 4 during heating of the sample up to and through the melt. This study identified a new phase containing 27 Al with a shift of about 12 ppm higher than the 27 Al in I4 1 /a NaAlH 4 . This new species was labeled S105 due to its shift from the 27 Al standard (see Table S1 in Supporting Information).…”

Section: Introductionmentioning

confidence: 79%

First-Principles Study of Structural Prototypes for NaAlH₄: Elevated Pressure Polymorph in Symmetry Fmm2 Leads to a Single-Step Decomposition Pathway

2013

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In situ high-temperature X-ray diffraction and hightemperature and pressure nuclear magnetic resonance studies of the complex metal hydride NaAlH 4 have strongly suggested an intermediate phase or phases. In order to search for these phases, structural prototypes of NaAlH 4 were generated using the method of prototype electrostatic ground states (PEGS). Structural motifs included tetrahedral [AlH 4 ] − and [AlH 6 ] 3− octahedral anions. Structures were produced with Al−H coordination numbers from 4 to 6 and were examined for thermodynamic stability. We present a high-temperature phase in symmetry Fmm2 that is lower in total free energy than all currently known structures, including a structure presented in space group Cmcm, due to low rotational barriers for [AlH 4 ] − anions. The Na−Al−H phase diagram, calculated in the harmonic approximation, indicates that at higher pressures, the I4 1 /a NaAlH 4 phase transforms to Fmm2 symmetry, which then decomposes directly into NaH and Al, eliminating the Na 3 AlH 6 intermediate. The transition to Fmm2 is predicted to occur near 320 K at calculated pressures of about 1−2 bar. We also present calculations of NMR 27 Al and 23 Na chemical shifts for the structural prototypes. These results indicate a monotonic decrease of the 27 Al chemical shift with increasing Al−H coordination number with an unambiguous identification of an Al/H ratio of 1:4 for the unknown high-temperature phase S105 identified by Conradi and coworkers (Conradi, M. S. et al.

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“…Although several examples of alkali-metal phosphinodiboronate derivatives and related f-block complexes have been reported, − the majority contain alkyl-substituted phosphorus centers. Compound 10 is, to the best of our knowledge, only the second crystallographically characterized example of the [(H 3 B) 2 PPh 2 ] − anion, with the only direct precedent provided by the report of Wagner and co-workers of [(18-crown-6)K{(H 3 B) 2 PPh 2 }] ( 11 ) .…”

Section: Resultsmentioning

confidence: 99%

Alkaline-Earth Derivatives of Diphenylphosphine–Borane

et al. 2020

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Treatment of β-diketiminato (BDI = HC{C(CH 3 )Ndipp)} 2 where dipp = 2,6-iPr 2 C 6 H 3 ) magnesium butyl [(BDI)MgBu] (I) and calcium hexamethyldisilazide [(BDI)Ca{N(SiMe 3 ) 2 }] (II) complexes with equimolar quantities of diphenylphosphine− borane, Ph 2 PH•BH 3 , results in the formation of the respective alkaline earth (Ae) phosphidoborane derivatives [(BDI)Mg(Ph 2 PBH 3 )] 2 (6a) and [(BDI)Ca(Ph 2 PBH 3 )] (7a). Although satisfactory single crystals of 7a could not be obtained, 6a was crystallographically characterized and both compounds display similar NMR spectra. The dimeric Ae-hydride complexes [(BDI)AeH] 2 (IIIa, Ae = Mg; IIIb, Ae = Ca) react with substoichiometric quantities of Ph 2 PH•BH 3 , allowing the crystallization of the dimeric Mg and trimeric Ca phosphidoborane species [(BDI)Mg(H)(H 3 BPPh 2 )Mg(BDI)] (8) and [{(BDI)Ca} 3 (H)-(H 3 BPPh 2 ) 2 ] (9). In the absence of coordinating Lewis bases, compounds 6a, 7a, 8, and 9 display dynamic solution-state behavior (in benzene and toluene), while addition of THF furnishes the monomeric adducts [(BDI)Mg(H 3 BPPh 2 )•THF] (6b) and [(BDI)Ca-(H 3 BPPh 2 )•THF] (7b). Addition of Ph 2 PH•BH 3 to compound 6a results in BH 3 transfer to eliminate Ph 2 PH and generate the phosphinodiboronate complex [(BDI)Mg{(H 3 B) 2 PPh 2 }] 2 (10) in preference to dehydrocoupling of the phosphidoborane and phosphine−borane reagents.Article pubs.acs.org/Organometallics

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Improved Synthesis of Bis(borano)hypophosphite Salts

Cited by 15 publications

References 34 publications

Chelating Borohydrides for Lanthanides and Actinides: Structures, Mechanochemistry, and Case Studies with Phosphinodiboranates

Chelating Borohydrides for Lanthanides and Actinides: Structures, Mechanochemistry, and Case Studies with Phosphinodiboranates

First-Principles Study of Structural Prototypes for NaAlH₄: Elevated Pressure Polymorph in Symmetry Fmm2 Leads to a Single-Step Decomposition Pathway

Alkaline-Earth Derivatives of Diphenylphosphine–Borane

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Improved Synthesis of Bis(borano)hypophosphite Salts

Cited by 15 publications

References 34 publications

Chelating Borohydrides for Lanthanides and Actinides: Structures, Mechanochemistry, and Case Studies with Phosphinodiboranates

Chelating Borohydrides for Lanthanides and Actinides: Structures, Mechanochemistry, and Case Studies with Phosphinodiboranates

First-Principles Study of Structural Prototypes for NaAlH4: Elevated Pressure Polymorph in Symmetry Fmm2 Leads to a Single-Step Decomposition Pathway

Alkaline-Earth Derivatives of Diphenylphosphine–Borane

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First-Principles Study of Structural Prototypes for NaAlH₄: Elevated Pressure Polymorph in Symmetry Fmm2 Leads to a Single-Step Decomposition Pathway