Note New tetrahedrane complexes from molybdenum alkynyls and Co 2 (CO) 8 Julio Pe ´rez a, *, Lucı ´a Riera a , Vı ´ctor Riera a , Santiago Garcı ´a-Granda b , Esther Garcı ´a-Rodrı ´guez b , David George Churchill c , Melvyn Rowen Churchill c , Thomas S. Janik d a Departamento de Quı ´mica Orga ´nica e Inorga ´nica /I.U.Q.O.E.M., 33071 Oviedo, Spain b Departamento de Quı ´mica Fı ´sica y Analı ´tica, Facultad de Quı ´mica, Universidad de Oviedo-C.S.I.C., 33071 Oviedo, Spain c Department of Chemistry, State University of New York, Buffalo, NY 14260-3000, USA d State University of New York College at Fredonia, Fredonia, NY, 14063, USA Received 21 March 2002; accepted 14 May 2002 This paper is dedicated to Professor Rafael Uso ´n, a pioneer of organometallic chemistry in Spain Abstract The molybdenum alkynyl complexes [Mo(C Å/CPh)(h 3 -allyl)(CO) 2 (bipy)] (1) and [Mo(C Å /CH)(h 3 -allyl)(CO) 2 (N /N)] (N  /N / 2,2?-bipyridine, 2a; 1,10-phenanthroline, 2b) react with dicobalt octacarbonyl to give the new tetrahedrane trimetallic complexes [Co 2 (CO) 6 (m-h 2 :h 2 -M  /C Å /CPh)], M/{Mo(h 3 -C 3 H 5 )(CO) 2 (bipy)} (3) and [Co 2 (CO) 6 (m-h 2 :h 2 -M  /C Å /CH)], M/{Mo(h 3 - C 3 H 5 )(CO) 2 (N  /N)} (N /N /bipy, 4a; phen, 4b), respectively. These new compounds were characterized by analytical (C, H, N), spectroscopic (IR, 1 H NMR) and crystallographic (single crystal X-ray diffraction) means. # 2003 Elsevier Science B.V. All rights reserved. Keywords: Tetrahedrane complexes; Molybdenum alkynyls; Crystal structures 1. Introduction The reactions of acetylenes with [Co 2 (CO) 8 ] to afford [(m-h 2 :h 2 -R 1  /C Å /C  /R 2 )Co 2 (CO) 6 ] complexes are classi- cal processes in organometallic chemistry. In some instances, the stability of the products allowed the derivatization of the R substituents, and a subsequent demetallation step afforded the new acetylenes [1]. On the other hand, [(m-h 2 :h 2 -R 1 /C Å /C  /R 2 )Co 2 (CO) 6 ] com- plexes react with CO, olefins and acetylenes to afford C  /C coupled products with high regioselectivity [2]. Similar [(m-h 2 :h 2 -R /C Å /C  /ML n )Co 2 (CO) 6 ] compounds can be obtained by reaction of metal alkynyl complexes [3], L n M /C Å /C /R, with [Co 2 (CO) 8 ], although this chemistry has been much less studied. The first com- pounds of this kind, namely, the complexes [(m-h 2 :h 2 - CpFe(CO)(L)  /C Å /C  /R)(Co 2 (CO) 6 )] (R /Me, Ph; L / CO, PMe 2 Ph) were reported by Yamazaki in 1972 [4], and the structure of the derivative with R /Ph, L /CO was determined by X-ray diffraction by Bruce in 1986 [5]. Riera found that complexation to the {Co 2 (CO) 6 } unit stabilized the otherwise difficult to obtain trans geometry of the alkynyl [Mn(C Å /CPh)(CO) 4 (PCy 3 )], which could be liberated by treatment with [I(py) 2 ]BF 4 [6]. We have recently reported the preparation of new alkynyl complexes [Mo(C Å /CR)(h 3 -allyl)(CO) 2 (N  /N)] (R /H, Ph; N  /N /2,2?-bipyridine, 1,10-phenanthro- line) [7]. Their reactions with [Co 2 (CO) 8 ], as well as the crystallographical characterization of two products, are the subject of this paper. 2. Experimental 2.1. General procedures All manipulations were carried out under dinitrogen using standard Schlenk techniques. Solvents were dis- * Corresponding author. Tel.:  /34-98-5102-985; fax:  /34-98-5103- 446 Inorganica Chimica Acta 347 (2003) 189  /193 www.elsevier.com/locate/ica 0020-1693/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved. PII:S0020-1693(02)01442-1