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Hydride transfer to gold: yes or no? Exploring the unexpected versatility of Au···H-M bonding in heterobimetallic dihydrides

Hydride transfer to gold: yes or no? Exploring the unexpected versatility of Au···H-M bonding in heterobimetallic dihydrides
Hydride transfer to gold: yes or no? Exploring the unexpected versatility of Au···H-M bonding in heterobimetallic dihydrides
The potential for coordination and H-transfer from Cp2MH2 (M = Zr, W) to gold(I) and gold(III) complexes was explored in a combined experimental and computational study. [(L)Au]+ cations react with Cp2WH2 giving [(L)Au(κ2-H2WCp2)]+ (L = IPr (1), cyclic (alkyl)(amino)carbene (2), or phosphines PPh3 (3) and Dalphos-Me (4) [IPr = 1,3-bis(diisopropylphenyl)imidazolylidene; Dalphos-Me = di(1-adamantyl)-2-(dimethylamino)phenyl-phosphine], while [Au(DMAP)2]+ (DMAP = p-dimethylaminopyridine) affords the C2-symmetric [Au(κ-H2WCp2)2]+ (5). The Dalphos complex 4 can be protonated to give the bicationic adduct 4H, showing Au(I)…H+-N hydrogen bonding. The gold(III) Lewis acid [(C^N-CH)Au(C6F5)(OEt2)]+ binds Cp2WH2 to give an Au-H-W σ-complex. By contrast, the pincer species [(C^N^C)Au]+ adds Cp2WH2 by a purely dative W→Au bond, without Au···H interaction. The biphenyl-based chelate [(C^C)Au]+ forms [(C^C)Au(µH)2WCp2]+, with two 2-electron-3-centre W-H…Au interactions and practically no Au-W donor acceptor contribution. In all these complexes strong but polarised W-H bonds are maintained, without H-transfer to gold. On the other hand, the reactions of Cp2ZrH2 with gold complexes led in all cases to rapid H-transfer and formation of gold hydrides. Relativistic DFT calculations were used to rationalize the striking reactivity and bonding differences in these heterobimetallic hydride complexes along with an analysis of their characteristic NMR parameters and UV-Vis absorption properties.
bridging ligands, density functional calculations, gold, hydrides, tungsten
0947-6539
Rocchigiani, Luca
928f4dfb-8d8f-4902-830c-3a752e6e9259
Klooster, Wim
64dc0111-f415-4226-9189-45764c0933d9
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Hughes, David L.
d3b8245e-976a-47e6-8fe6-6ebcf38e2255
Hrobárik, Peter
60eae956-3239-4406-a78c-8c31939d1608
Bochmann, Manfred
ec2bb201-23cc-4f91-aa80-258e6c8cc9fb
Rocchigiani, Luca
928f4dfb-8d8f-4902-830c-3a752e6e9259
Klooster, Wim
64dc0111-f415-4226-9189-45764c0933d9
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Hughes, David L.
d3b8245e-976a-47e6-8fe6-6ebcf38e2255
Hrobárik, Peter
60eae956-3239-4406-a78c-8c31939d1608
Bochmann, Manfred
ec2bb201-23cc-4f91-aa80-258e6c8cc9fb

Rocchigiani, Luca, Klooster, Wim, Coles, Simon J., Hughes, David L., Hrobárik, Peter and Bochmann, Manfred (2020) Hydride transfer to gold: yes or no? Exploring the unexpected versatility of Au···H-M bonding in heterobimetallic dihydrides. Chemistry - A European Journal. (doi:10.1002/chem.202000016).

Record type: Article

Abstract

The potential for coordination and H-transfer from Cp2MH2 (M = Zr, W) to gold(I) and gold(III) complexes was explored in a combined experimental and computational study. [(L)Au]+ cations react with Cp2WH2 giving [(L)Au(κ2-H2WCp2)]+ (L = IPr (1), cyclic (alkyl)(amino)carbene (2), or phosphines PPh3 (3) and Dalphos-Me (4) [IPr = 1,3-bis(diisopropylphenyl)imidazolylidene; Dalphos-Me = di(1-adamantyl)-2-(dimethylamino)phenyl-phosphine], while [Au(DMAP)2]+ (DMAP = p-dimethylaminopyridine) affords the C2-symmetric [Au(κ-H2WCp2)2]+ (5). The Dalphos complex 4 can be protonated to give the bicationic adduct 4H, showing Au(I)…H+-N hydrogen bonding. The gold(III) Lewis acid [(C^N-CH)Au(C6F5)(OEt2)]+ binds Cp2WH2 to give an Au-H-W σ-complex. By contrast, the pincer species [(C^N^C)Au]+ adds Cp2WH2 by a purely dative W→Au bond, without Au···H interaction. The biphenyl-based chelate [(C^C)Au]+ forms [(C^C)Au(µH)2WCp2]+, with two 2-electron-3-centre W-H…Au interactions and practically no Au-W donor acceptor contribution. In all these complexes strong but polarised W-H bonds are maintained, without H-transfer to gold. On the other hand, the reactions of Cp2ZrH2 with gold complexes led in all cases to rapid H-transfer and formation of gold hydrides. Relativistic DFT calculations were used to rationalize the striking reactivity and bonding differences in these heterobimetallic hydride complexes along with an analysis of their characteristic NMR parameters and UV-Vis absorption properties.

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Accepted/In Press date: 26 February 2020
e-pub ahead of print date: 26 February 2020
Keywords: bridging ligands, density functional calculations, gold, hydrides, tungsten

Identifiers

Local EPrints ID: 438440
URI: http://eprints.soton.ac.uk/id/eprint/438440
ISSN: 0947-6539
PURE UUID: 5c3d596b-aadb-4399-b945-671441f79524
ORCID for Simon J. Coles: ORCID iD orcid.org/0000-0001-8414-9272

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Date deposited: 10 Mar 2020 17:31
Last modified: 19 May 2020 00:31

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