Syntheses, Crystal Structures and Optical Limiting Properties of Three Novel Organometallic Tungsten‐Copper‐Sulfur Clusters: [PPh 4 ][(η 5 ‐C 5 Me 5 )WS 3 (CuCN) 2 ], [(η 5 ‐C 5 Me 5 )WS 3 Cu 2 (PPh 3 )(μ‐CN)] 2 and [PPh 4 ][{(η 5 ‐C 5 Me 5 )WS 3 Cu 2 (CN)(Py)} 2 (μ‐CN)]

Reactions of [PPh 4 ][(η 5 ‐C 5 Me 5 )WS 3 ] with two equivalents of CuCN in MeCN produced a novel trinuclear butterfly‐shaped cluster [PPh 4 ][(η 5 ‐C 5 Me 5 )WS 3 (CuCN) 2 ] ( 1 ) in a 70% yield. Treatment of 1 with excess PPh 3 or Py gave rise to two different hexanuclear clusters [(η 5 ‐C 5 Me 5 )WS 3 Cu 2 (PPh 3 )(μ‐CN)] 2 ( 2 ) and [PPh 4 ][{(η 5 ‐C 5 Me 5 )WS 3 Cu 2 (CN)(Py)} 2 (μ‐CN)] ( 3 ), respectively. Compounds 1 − 3 were fully characterized by spectroscopy and X‐ray crystallography. The structure of the cluster anion of 1 contains a butterfly‐like WS 3 Cu 2 fragment in which each Cu atom is coordinated to one μ‐S atom, one μ 3 ‐S atom, and one terminal CN group. The neutral compound 2 has a double butterfly‐shaped structure in which two WS 3 Cu 2 fragments are interconnected by two Cu−μ‐CN−Cu bridges. The anion of 3 adopts another type of double butterfly‐shaped structure in which the two WS 3 Cu 2 fragments are linked by a single Cu−μ‐CN−Cu bridge. Compared with C 60 in terms of the optical limiting (OL) properties measured under identical conditions, 1 and 2 exhibit a relatively good OL performance, whereas the OL effect is not observed for 3 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)