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Systematics of BX3 and BX2+ complexes (X = F, Cl, Br, I) with neutral diphosphine and diarsine ligands

Systematics of BX3 and BX2+ complexes (X = F, Cl, Br, I) with neutral diphosphine and diarsine ligands
Systematics of BX3 and BX2+ complexes (X = F, Cl, Br, I) with neutral diphosphine and diarsine ligands
The coordination chemistry of the neutral diphosphines, R2P(CH2)2PR2 (R = Me or Et) and o-C6H4(PR?2)2 (R? = Me or Ph), and the diarsine, o-C6H4(AsMe2)2, toward the Lewis acidic BX3 (X = F, Cl, Br, and I) fragments is reported, including several rare complexes incorporating BF3 and BF2+. The studies have revealed that the flexible dimethylene linked diphosphines form [(BX3)2{?-R2P(CH2)2PR2}] exclusively, confirmed by multinuclear NMR (1H, 11B, 19F{1H}, and 31P{1H}) and IR spectroscopy and microanalytical data. Crystallographic determinations of the four BX3 complexes with Et2P(CH2)2PEt2 confirm the 2:1 stoichiometry and, taken together with the spectroscopic data, reveal that the Lewis acid behavior of the BX3 fragment toward phosphine ligands increases in the order F ? Cl ? Br < I. The first diphosphine- and diarsine-coordinated dihaloboronium cations, [BX2{o-C6H4(EMe2)2}]+ (E = P, As), are obtained using the rigid, preorganized o-phenylene linkages. These complexes are characterized similarly, and the data indicate that the complexes with o-C6H4(AsMe2)2 are much more labile and readily decomposed than the phosphine analogues. X-ray crystallographic studies on [BX2{o-C6H4(PMe2)2}][BX4] (X = Cl, Br), [BI2{o-C6H4(PMe2)2}][I3], and [BCl2{o-C6H4(AsMe2)2}][BCl4] confirm the presence of distorted tetrahedral coordination at boron through a chelating diphosphine or diarsine and two X ligands, with d(B–P) revealing a similar increase in Lewis acidity down group 17. Comparison of d(B–P) and d(B–As) reveals an increase of ca. 0.08 Å from P to As. Reaction of BCl3 with the diphosphine dioxide Ph2P(O)CH2P(O)Ph2 gives the ligand-bridged dimer [(BCl3)2{Ph2P(O)CH2P(O)Ph2}], while using either BF3 gas or [BF3(SMe2)] gives a mixture containing both [(BF3)2{?-Ph2P(O)CH2P(O)Ph2}] and the unexpected difluoroboronium salt, [BF2{Ph2P(O)CH2P(O)Ph2}][B2F7] containing a chelating phosphine oxide. The structure of the latter was confirmed crystallographically.
0020-1669
8852-8864
Burt, Jennifer
4f8a0b68-2fb3-4136-98ff-70dfe1acba98
Emsley, James
9d219d5e-28c0-4a8c-bf3d-1f78cd707c17
Levason, William
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Reid, Gill
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Tinkler, Iain
0657dcf9-a94e-4e3f-94d3-d603fd34a0c2
Burt, Jennifer
4f8a0b68-2fb3-4136-98ff-70dfe1acba98
Emsley, James
9d219d5e-28c0-4a8c-bf3d-1f78cd707c17
Levason, William
e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd
Reid, Gill
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Tinkler, Iain
0657dcf9-a94e-4e3f-94d3-d603fd34a0c2

Burt, Jennifer, Emsley, James, Levason, William, Reid, Gill and Tinkler, Iain (2016) Systematics of BX3 and BX2+ complexes (X = F, Cl, Br, I) with neutral diphosphine and diarsine ligands. Inorganic Chemistry, 55 (17), 8852-8864. (doi:10.1021/acs.inorgchem.6b01375).

Record type: Article

Abstract

The coordination chemistry of the neutral diphosphines, R2P(CH2)2PR2 (R = Me or Et) and o-C6H4(PR?2)2 (R? = Me or Ph), and the diarsine, o-C6H4(AsMe2)2, toward the Lewis acidic BX3 (X = F, Cl, Br, and I) fragments is reported, including several rare complexes incorporating BF3 and BF2+. The studies have revealed that the flexible dimethylene linked diphosphines form [(BX3)2{?-R2P(CH2)2PR2}] exclusively, confirmed by multinuclear NMR (1H, 11B, 19F{1H}, and 31P{1H}) and IR spectroscopy and microanalytical data. Crystallographic determinations of the four BX3 complexes with Et2P(CH2)2PEt2 confirm the 2:1 stoichiometry and, taken together with the spectroscopic data, reveal that the Lewis acid behavior of the BX3 fragment toward phosphine ligands increases in the order F ? Cl ? Br < I. The first diphosphine- and diarsine-coordinated dihaloboronium cations, [BX2{o-C6H4(EMe2)2}]+ (E = P, As), are obtained using the rigid, preorganized o-phenylene linkages. These complexes are characterized similarly, and the data indicate that the complexes with o-C6H4(AsMe2)2 are much more labile and readily decomposed than the phosphine analogues. X-ray crystallographic studies on [BX2{o-C6H4(PMe2)2}][BX4] (X = Cl, Br), [BI2{o-C6H4(PMe2)2}][I3], and [BCl2{o-C6H4(AsMe2)2}][BCl4] confirm the presence of distorted tetrahedral coordination at boron through a chelating diphosphine or diarsine and two X ligands, with d(B–P) revealing a similar increase in Lewis acidity down group 17. Comparison of d(B–P) and d(B–As) reveals an increase of ca. 0.08 Å from P to As. Reaction of BCl3 with the diphosphine dioxide Ph2P(O)CH2P(O)Ph2 gives the ligand-bridged dimer [(BCl3)2{Ph2P(O)CH2P(O)Ph2}], while using either BF3 gas or [BF3(SMe2)] gives a mixture containing both [(BF3)2{?-Ph2P(O)CH2P(O)Ph2}] and the unexpected difluoroboronium salt, [BF2{Ph2P(O)CH2P(O)Ph2}][B2F7] containing a chelating phosphine oxide. The structure of the latter was confirmed crystallographically.

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BX3 diphosphine 25_07_2016 final revised.pdf - Accepted Manuscript
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Accepted/In Press date: 10 June 2016
e-pub ahead of print date: 5 August 2016
Published date: 6 September 2016
Organisations: Organic Chemistry: SCF, Magnetic Resonance

Identifiers

Local EPrints ID: 401727
URI: http://eprints.soton.ac.uk/id/eprint/401727
ISSN: 0020-1669
PURE UUID: fdf041cf-76b9-4085-97f0-c8280bc6e97d
ORCID for William Levason: ORCID iD orcid.org/0000-0003-3540-0971
ORCID for Gill Reid: ORCID iD orcid.org/0000-0001-5349-3468

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Date deposited: 20 Oct 2016 13:19
Last modified: 10 Dec 2019 06:22

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