COMMUNICATIONS 1066  WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001 1433-7851/01/4006-1066 $ 17.50+.50/0 Angew. Chem. Int. Ed. 2001, 40, No. 6 Formation of Super Wires of Clusters by Self- Assembly of Transition Metal Cluster Anions with Metal Cations Takayuki Nakajima, Atsushi Ishiguro, and Yasuo Wakatsuki* The self-assembly approach to the construction of supra- molecules or extended frameworks based on coordination complexes is one of the major current research areas in inorganic and organometallic chemistry. [1] In the vast majority of such compounds, the molecular building blocks are held together by strong metal ± (linking ligand) ± metal bonding interactions or weaker forces such as hydrogen bonding between ligands coordinating to the different metal units. In some cases, however, the metal ds stacking force of square- planar complexes can lead to stacklike, one-dimensional (1D) metal ± metal bonds in the solid state. Thus, there has been a series of reports on (Pt ± Pt) 1 chains in which metal ± metal separations indicative of weak interactions or of discrete bonds have been found. [2] A similar 1D stacking polymer [{Ru(CO) 4 } 1 ] has been structurally characterized by powder diffraction, [3] and a 1D Rh  Rh polymeric complex has been prepared by the electrochemical reduction of an Rh II ± Rh II dimer that only has acetonitrile ligands. [4] This reaction has been explained as a radical polymerization of an unstable [Rh I;II 2 ] species generated at the electrode. Crystals of a nonstacked zigzag chain of Co ± Cu atoms have been prepared by a simpler route, that is, the reaction of Na[Co(CO) 4 ] with CuCl. [5] Herein we report a new class of 1D complexes that consist of high-nuclearity cluster species and have infinite, heteroleptic metal ± metal bonded chains. This unprecedented ªsuper wireº has been prepared by alternative self ordering of anionic cluster complexes with a cationic metal species. In 1983, Heaton and co-workers reported an interesting observation from NMR spectrocopy which was that on addition of Ag  ions to a solution of [Rh 6 C(CO) 15 ] 2 , the oligomeric species [Ag n {Rh 6 C(CO) 15 } n ] n (n > 3) is formed, although the crystals that they isolated were from a structur- ally simpler sandwich-type complex [Ag{Rh 6 C(CO) 15 } 2 ] 3 . [6] Therefore, it appeared interesting to us to examine a similar reaction of the analogous ruthenium clusters because the Ru 6 core is hexagonal whereas the Rh 6 core has a trigonal prismatic structure. It was known that the reactions of high- nuclearity ruthenium cluster anions with Ag [7] and Cu  ions [7a, 8] gave sandwich-type complexes such as the rhodium complex isolated by Heaton. However, almost all of these isolated ruthenium products are stabilized by the inclusion of a chloride ligand from the [PPN]Cl (PPN  N(PPh 3 ) 2  ) used in the reactions. We wondered what the product would be if chloride is excluded from the reaction system, thus, we attempted the reaction of the hexanuclear dianionic ruthenium cluster [PPN] 2 [Ru 6 C(CO) 16 ] ([PPN] 2 1) in THF, with an equivalent of AgNO 3 at room temperature. Over 12 h a characteristic n Ä (CO) band at 1998 cm 1 in the IR spectrum gradually increased while that of 1 at 1973 cm 1 disappeared completely, during this time the solution remained homogeneous. On evaporation of the solvent the crude micro-crystals obtained in 97 % yield had the composition [PPN][AgRu 6 C(CO) 16 ] ([PPN]2). This complex is soluble in acetone and probably has an oligomeric structure in solution as observed by Heaton for the rhodium complex. [4] The solid-state IR spectrum of [PPN]2 is very similar to that in solution: it shows the n Ä (CO) band, though broader than the corresponding peak in solution, at 1999 cm 1 (KBr). Dark red crystals grown from acetone/methanol have the X-ray structure shown in Figure 1. Figure 1. Crystal packing of {[PPN]2} 1 viewed along a) the b axis and b) the c axis. The infinite chains of alternating ruthenium clusters and silver ions are separated from each other by layers of PPN cations (Figure 1a). The view along the polymer-chain axis (Fig- ure 1 b) indicates that the Ru cluster and PPN are comparable in size which probably aids the crystal packing of {[PPN]2} 1 . Looking closer at this rigid metal chain (Figure 2), one notices that the bridging silver atom has a distorted tetrahedral orientation, the dihedral angle Ag-Ru12-Ru13/Ag-Ru12*- Ru13* being 49.98. There is a point of inversion at the carbido center of the Ru 6 core, as well as at the silver atom, so that only three Ru atoms and one Ag atom are crystallographically independent. The Ag Ru12 and Ag Ru13 bond lengths are 2.9185(4) and 2.9425(4) , respectively. The edge bridged by the silver atom, Ru12 Ru13, is 3.046(1) , which is distinctly longer than the five independent Ru  Ru bonds (av. 2.907 ). The polymeric complex with the PPh 4 cation {[PPh 4 ]2} 1 was [*] Dr. Y. Wakatsuki, Dr. T. Nakajima, Dipl.-Chem. A. Ishiguro RIKEN (The Institute of Physical and Chemical Research) Wako-shi, Saitama 351-0198 (Japan) Fax: ( 81) 484-62-4665 E-mail : waky@postman.riken.go.jp