Mixed-Metal Cluster Chemistry. 27. Coupling of Diphenylbuta-1,3-diyne and CO at Tungsten–Triiridium Cluster Cores 1 Gulliver T. Dalton, 2 Anthony C. Willis, 3 and Mark G. Humphrey 2,4 Received February 7, 2004 Reactions of WIr 3 (CO) 11 (g-C 5 H 4 R) (R@H, Me) and excess diphenylbuta-1,3-di- yne in refluxing toluene afford a large number of products in each case, one of which has been identified as [WIr 3 {l 4 -g 7 -C(Ph)C(CB CPh)C(Ph)CC(H)CC 6 H 4 C(O)-2}(CO) 7 (g-C 5 H 4 R)] [R@H (10 %) (1), Me (6 %)] by a single-crystal X-ray diffraction study of 1. The structure of 1 reveals a unique ten-electron-donating ligand which has formed from combination of two diphenylbuta-1,3-diyne units and one carbonyl group, addition of the latter having presumably proceeded by orthometallation of one phenyl group, followed by formal insertion of the car- bonyl into the Ir-phenyl linkage. Crystal data for 1.CH 2 Cl 2 : space group P2 1 /n, a ¼ 8.6081(1) A ˚ , b ¼ 39.3638(5) A ˚ , c ¼ 12.3935(2) A ˚ , b ¼ 100.4889(5)°, V ¼ 4129.33(10) A ˚ 3 , Z ¼ 4, R ¼ 0.030, R w ¼ 0.026 for 4982 reflections [I > 2.00r(I)]. KEY WORDS: Tungsten; iridium; carbonyl; cyclopentadienyl; cluster. INTRODUCTION The chemistry of metal clusters with alkynes has been of enduring interest [1]. Considerably fewer reports describe the cluster chemistry of 1,3-diynes [38]. Many of these studies report coordination of intact 1,3-diynes [2–9], or transformations of diynes similar to those undergone by mono-ynes 1 Dedicated to Professor Michael Bruce on the occasion of his 65th birthday, in recognition of his outstanding contributions to cluster chemistry. 2 Department of Chemistry, Australian National University, Canberra ACT 0200, Australia. 3 Research School of Chemistry, Australian National University, Canberra ACT 0200, Australia. 4 To whom correspondence should be addressed. E-mail: Mark.Humphrey@anu.edu.au 291 1040-7278/04/0900-0291/0 Ó 2004 Plenum Publishing Corporation Journal of Cluster Science, Vol. 15, No. 3, September 2004 (Ó 2004)