Chemisorption of Exchange‐Coupled [Ni2L(dppba)]+ Complexes on Gold by Using Ambidentate 4‐(Diphenylphosphino)benzoate Co‐Ligands1. Issue 24 (17th April 2013)

• Record Type: Journal Article
• Authors: Golecki, Matthias; Lach, Jochen; Jeremies, Alexander; Lungwitz, Frank; Fronk, Michael; Salvan, Georgeta; Zahn, Dietrich R. T.; Park, Jaena; Krupskaya, Yulia; Kataev, Vladislav; Klingeler, Rüdiger; Büchner, Bernd; Mahns, Benjamin; Knupfer, Martin; Siles, Pablo F.; Grimm, Daniel; Schmidt, Oliver G.; Reis, Andreas; Thiel, Werner R.; Breite, Daniel; Abel, Bernd; Kersting, Berthold
• Is Part Of: Chemistry. Volume 19:Issue 24(2013)
• Page Start: 7787
• Page End: 7801
• Publication Date: 2013-04-17
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201300496
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A new strategy for the fixation of redox‐active dinickel(II) complexes with high‐spin ground states to gold surfaces was developed. The dinickel(II) complex [Ni<sub>2</sub>L(Cl)]ClO<sub>4</sub> (<bold>1</bold>ClO<sub>4</sub>), in which L<sup>2−</sup> represents a 24‐membered macrocyclic hexaaza‐dithiophenolate ligand, reacts with ambidentate 4‐(diphenylphosphino)benzoate (dppba) to form the carboxylato‐bridged complex [Ni<sub>2</sub>L(dppba)]<sup>+</sup>, which can be isolated as an air‐stable perchlorate [Ni<sub>2</sub>L(dppba)]ClO<sub>4</sub> (<bold>2</bold>ClO<sub>4</sub>) or tetraphenylborate [Ni<sub>2</sub>L(dppba)]BPh<sub>4</sub> (<bold>2</bold>BPh<sub>4</sub>) salt. The auration of <bold>2</bold>ClO<sub>4</sub> was probed on a molecular level, by reaction with AuCl, which leads to the monoaurated Ni<sup>II</sup><sub>2</sub>Au<sup>I</sup> complex [Ni<sup>II</sup><sub>2</sub>L(dppba)Au<sup>I</sup>Cl]ClO<sub>4</sub> (<bold>3</bold>ClO<sub>4</sub>). Metathesis of <bold>3</bold>ClO<sub>4</sub> with NaBPh<sub>4</sub> produces [Ni<sup>II</sup><sub>2</sub>L(dppba)Au<sup>I</sup>Ph]BPh<sub>4</sub> (<bold>4</bold>BPh<sub>4</sub>), in which the Cl<sup>−</sup> is replaced by a Ph<sup>−</sup> group. The complexes were fully characterized by ESI mass spectrometry, IR and UV/Vis spectroscopy, X‐ray crystallography (<bold>2</bold>BPh<sub>4</sub> and <bold>4</bold>BPh<sub>4</sub>), cyclic voltammetry, SQUID magnetometry and HF‐ESR spectroscopy. Temperature‐dependent magnetic susceptibility measurements reveal a ferromagnetic coupling <italic>J</italic>=+15.9 and +17.9 cm<sup>−1</sup> between the two Ni<sup>II</sup> ions in <bold>2</bold>ClO<sub>4</sub> and <bold>4</bold>BPh<sub>4</sub> (H=−2 <italic>J</italic>S<sub>1</sub>S<sub>2</sub>). HF‐ESR measurements yield a negative axial magnetic anisotropy (<italic>D</italic><0), which implies a bistable (easy axis) magnetic ground state. The binding of the [Ni<sub>2</sub>L(dppba)]ClO<sub>4</sub> complex to gold was ascertained by four complementary surface analytical methods: contact angle measurements, atomic‐force microscopy, X‐ray photoelectron spectroscopy, and spectroscopic ellipsometry. The results indicate that the complexes are attached to the Au surface through coordinative AuP bonds in a monolayer.</p> </abstract>