Alkaline-Earth Derivatives of Diphenylphosphine-Borane

Louis J. Morris; Michael S. Hill; Mary F. Mahon; Ian Manners; Brian O. Patrick

doi:10.1021/acs.organomet.0c00008

Alkaline-Earth Derivatives of Diphenylphosphine-Borane

Louis J. Morris, Michael S. Hill, Mary F. Mahon, Ian Manners, Brian O. Patrick

Research output: Contribution to journal › Article

Abstract

Treatment of β-diketiminato (BDI = HC{C(CH₃)Ndipp)}₂ where dipp = 2,6-iPr₂C₆H₃) magnesium butyl [(BDI)MgBu] (I) and calcium hexamethyldisilazide [(BDI)Ca{N(SiMe₃)₂}] (II) complexes with equimolar quantities of diphenylphosphine-borane, Ph₂PH·BH₃, results in the formation of the respective alkaline earth (Ae) phosphidoborane derivatives [(BDI)Mg(Ph₂PBH₃)]₂ (6a) and [(BDI)Ca(Ph₂PBH₃)] (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 Ph₂PH·BH₃, allowing the crystallization of the dimeric Mg and trimeric Ca phosphidoborane species [(BDI)Mg(H)(H₃BPPh₂)Mg(BDI)] (8) and [{(BDI)Ca}₃(H)(H₃BPPh₂)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(H₃BPPh₂)·THF] (6b) and [(BDI)Ca(H₃BPPh₂)·THF] (7b). Addition of Ph₂PH·BH₃ to compound 6a results in BH₃ transfer to eliminate Ph₂PH and generate the phosphinodiboronate complex [(BDI)Mg{(H₃B)₂PPh₂}]₂ (10) in preference to dehydrocoupling of the phosphidoborane and phosphine-borane reagents.

Original language	English
Journal	Organometallics
Early online date	19 Feb 2020
DOIs	https://doi.org/10.1021/acs.organomet.0c00008
Publication status	E-pub ahead of print - 19 Feb 2020

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Organic Chemistry
Inorganic Chemistry

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Morris, L. J., Hill, M. S., Mahon, M. F., Manners, I., & Patrick, B. O. (2020). Alkaline-Earth Derivatives of Diphenylphosphine-Borane. Organometallics. https://doi.org/10.1021/acs.organomet.0c00008

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title = "Alkaline-Earth Derivatives of Diphenylphosphine-Borane",

abstract = "Treatment of β-diketiminato (BDI = HC{C(CH3)Ndipp)}2 where dipp = 2,6-iPr2C6H3) magnesium butyl [(BDI)MgBu] (I) and calcium hexamethyldisilazide [(BDI)Ca{N(SiMe3)2}] (II) complexes with equimolar quantities of diphenylphosphine-borane, Ph2PH·BH3, results in the formation of the respective alkaline earth (Ae) phosphidoborane derivatives [(BDI)Mg(Ph2PBH3)]2 (6a) and [(BDI)Ca(Ph2PBH3)] (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 Ph2PH·BH3, allowing the crystallization of the dimeric Mg and trimeric Ca phosphidoborane species [(BDI)Mg(H)(H3BPPh2)Mg(BDI)] (8) and [{(BDI)Ca}3(H)(H3BPPh2)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(H3BPPh2)·THF] (6b) and [(BDI)Ca(H3BPPh2)·THF] (7b). Addition of Ph2PH·BH3 to compound 6a results in BH3 transfer to eliminate Ph2PH and generate the phosphinodiboronate complex [(BDI)Mg{(H3B)2PPh2}]2 (10) in preference to dehydrocoupling of the phosphidoborane and phosphine-borane reagents.",

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AB - Treatment of β-diketiminato (BDI = HC{C(CH3)Ndipp)}2 where dipp = 2,6-iPr2C6H3) magnesium butyl [(BDI)MgBu] (I) and calcium hexamethyldisilazide [(BDI)Ca{N(SiMe3)2}] (II) complexes with equimolar quantities of diphenylphosphine-borane, Ph2PH·BH3, results in the formation of the respective alkaline earth (Ae) phosphidoborane derivatives [(BDI)Mg(Ph2PBH3)]2 (6a) and [(BDI)Ca(Ph2PBH3)] (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 Ph2PH·BH3, allowing the crystallization of the dimeric Mg and trimeric Ca phosphidoborane species [(BDI)Mg(H)(H3BPPh2)Mg(BDI)] (8) and [{(BDI)Ca}3(H)(H3BPPh2)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(H3BPPh2)·THF] (6b) and [(BDI)Ca(H3BPPh2)·THF] (7b). Addition of Ph2PH·BH3 to compound 6a results in BH3 transfer to eliminate Ph2PH and generate the phosphinodiboronate complex [(BDI)Mg{(H3B)2PPh2}]2 (10) in preference to dehydrocoupling of the phosphidoborane and phosphine-borane reagents.

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