Organometallic chemistry in supercritical water: metallorganic products of the CpCo-catalyzed cyclotrimerization of acetylenes

Cyclotrimerization of t-butylacetylene or phenylacetylene with CpCo(CO)(2) as catalyst in supercritical water yields the isomeric 1,3,5-tris-substituted- (1: R=Ph, 1a: R=bu(t)) and 1,2,4-tris-substituted benzene derivatives (2: R=Ph, 2a: R=bu(t)). The identification of the organometallic products obtained under these conditions is described. The formation of all possible isomers of the corresponding CpCo(bis-substituted-cyclobutadiene) (3, 4), CpCo(bis-substituted-CpCobaltacyclopentadiene) (5, 6, 7) and CpCo (bis-substituted-cyclopentadienone) (8, 9, 10) via GC-MS is reported. Two of three isomers of CpCo (bis-substituted-cyclopentadienone) (8, 9 (R = Ph), 8a, 9a (R = bu(t))) were separated and characterized in substance. The structures of 8, 9, 8a and 9a were elucidated by single crystal X-ray diffraction. 8 crystallizes in the orthorhombic space group P2(1)2(1)2(1) (No.19) with a = 840.5(1), b = 1105.9(2), c = 1767.2(3) pm, V = 1642.8(1) x 10(6) pm(3), Z=4, D-calc = 1.441 g cm(-3), R-1 = 0.0501 (I> 3 sigma), wR(1) = 0.0529 (I> 3 sigma). 9 crystallizes in the orthorhombic space group Pna2(1) (No.33) with a = 1086.7(1), b = 4726.0(1), c = 1668.5(1) pm, V = 8427.3(1) x 10(6) pm(3), Z = 20, D-calc = 1.404 g cm(-3), R-1 = 0.0705 (I> 2 sigma), Rw = 0.1321 (all data on F-2). 8a crystallizes in the monoclinic space group P2(1)/c (No. 14) with a = 1441.6(3), b = 1241.3(1), c = 3672.6(6) pm, beta = 92.39(2)degrees, V = 6566(2) x 10(6) pm(3), Z = 16, D-calc = 1.280 g cm(-3), R-1 = 0.082 (I> 2 sigma), Rw = 0.144 (all data on F-2). 9a crystallizes in the monoclinic space group P2(1)/c (No. 14) with a = 669.3(1), b = 1335.7(1), c = 1843.1(1) pm, beta = 94.78(1)degrees, V = 1641.9(1) x 10(6) pm(3), Z = 4, D-calc = 1.28 g cm(-3), R-1 = 0.0622 (I > 2 sigma), Rw = 0.1185 (all data on F-2). (C) 1998 Elsevier Science S.A. All rights reserved.