title: Isolated heterometallic Cr7Ni rings grafted on Au(111) surface.
abstract: A study of the deposition of heterometallic antiferromagnetically coupled rings onto gold surfaces is reported. Two new {Cr7Ni} rings, [NH2nPr2][Cr7NiF8(3-tpc)16] (1) (where 3-tpc=3-thiophenecarboxylate) and [nBuNH2CH2CH2SH] [Cr7NiF8(O2CtBu)16] (2) have been made and structurally characterized. They have been deposited from the liquid phase on Au(111) and the adsorbed molecules compared by means of scanning tunneling microscopy (STM) and X-ray photoemission spectroscopy (XPS). In both cases a two-dimensional distribution of individually accessible {Cr7Ni} heterometallic rings on the gold surface has been obtained, exploiting the direct grafting of sulfur-functionalized clusters. There is a competition between the chemisorption of the {Cr7Ni} clusters and a thiolic self-assembled monolayer (SAM) formed by free ligands. In 2, the presence of a single sulfur ligand should force the molecule to graft with the ring axis normal to the surface. The cluster stability in the STM images and the S-2p energy positions demonstrate, for both functionalizations, the strength of the grafting with the gold surface.
authors.affiliation: CNR-INFM-S3 National Research Centre and Dipartimanto di Fisica, Università di Modena e Reggio Emilia, Via G. Campi 213/A, 41100 Modena, Italy. valdis@unimo.it
authors.forename: Valdis
authors.initials: V
authors.lastname: Corradini
authors.forename: Roberto
authors.initials: R
authors.lastname: Biagi
authors.forename: Umberto
authors.initials: U
authors.lastname: del Pennino
authors.forename: Valentina
authors.initials: V
authors.lastname: De Renzi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Gambardella
authors.forename: Marco
authors.initials: M
authors.lastname: Affronte
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Muryn
authors.forename: Grigore A
authors.initials: GA
authors.lastname: Timco
authors.forename: Richard E P
authors.initials: RE
authors.lastname: Winpenny