MONOMERIC BIS(ETA(2)-ALKYNE) COMPLEXES OF COPPER(I) AND SILVER(I) WITH ETA(1)-BONDED ALKYL, VINYL, AND ARYL LIGANDS

Two synthetic routes to compounds [(eta(5)-C(5)H(4)SiMe(3))2Ti(C drop CSiMe(3))2]MR (abbreviated as [1 . MR]; M = Cu: R = Me (5), CH(2)SiMe( 3) (6), Et (7), (n)Bu (8), C(H)=CH2 (9), C(6)H(2)Me(3)-2,4,6 (13), C(6 )H(4)Me-4 (14), C(6)H(4)OMe-4 (15), C(6)H(4)NMe(2)-4 (16), C6H5 (17); M = Ag: R = C(6)H(2)Me(3)-2,4,6 (18)) are described. These compounds c ontain monomeric MR entities, which are eta(2)-bonded by both alkyne l igands of the organometallic 3-titanio-1,4-pentadiyne [(eta-C(5)H(4)Si Me(3))(2)Ti(C drop CSiMe(3))(2)] (1). The X-rays structures of 5, 13, and 18 have been solved. Crystals of 5 are monoclinic, space C2/c, wit h a = 19.477(1) Angstrom, b = 10.3622(6) Angstrom, c = 16.395(1) Angst rom, beta = 95.287(5)degrees, V = 3294.8(3) Angstrom(3), Z = 4, and fi nal R = 0.030 for 3232 reflections with F greater than or equal to 4 s igma(F) and 240 parameters. Crystals of 13 are orthorhombic, space gro up Pbcn, with a = 12.4290(9) Angstrom, b = 09.8770(8) Angstrom, c = 15 .532(1) Angstrom, V = 3837.2(4) Angstrom 3, Z = 4, and final R = 0.026 for 3082 reflections with I greater than or equal to 2.5 sigma(I) and 217 parameters. The mesitylcopper compound 13 is isostructural with t he mesitylsilver compound 18, and crystals of 18 are orthorhombic, spa ce group Pbcn, with a = 12.47(3) Angstrom, b = 20.00(3) Angstrom, c = 15.53(3) Angstrom, V = 3873(13) Angstrom(3), Z = 4, and final R = 0.05 5 for 2068 reflections with I greater than or equal to 2.5 sigma(I) an d 188 parameters. All compounds contain a monomeric bis(eta(2)-alkyne) M(eta 1-R) unit (M = Cu or Ag) in which the group 11 metal atom is tri gonally coordinated by the bis(eta(2)-alkyne) chelate 1 and an eta(1)- bonded monoanionic organic ligand. A bonding description of the bis(et a(2)-alkyne)M(eta(1)-R) entity (M = Cu, Ag) is discussed. The alkylcop per compounds 5-8 decompose in solution either via nucleophilic substi tution of one SiMe(3) group in 1 to eliminate RSiMe(3) or via beta-hyd ride elimination (7 and 8) to eliminate the corresponding alkene, wher eas arylcopper compounds 14-17, which lack ortho-substituents rearrang e in solution via addition of the monomeric arylcopper entity to one o f the alkynes within [1 . CuR] is not isolated, while the correspondin g addition product is favored. The X-ray structure of [(eta(5)-C(5)H(4 )SiMe(3))(2)Ti(C drop CSiMe(3))-{mu-C=C(SiMe(3))(R)}Cu], 22, which is a rare example of a 1,1-bimetallaalkene, has been solved. Crystals of 22 are pseudomerohedrally twinned and monoclinic, space group P2(1)/c, with a = 31.05(2) Angstrom, b = 14.323(3) Angstrom, c = 20.014(8) Ang strom, beta = 108.53(5)degrees, V = 8440(7) Angstrom(3), Z = 8, and fi nal R = 0.1233 for 8564 reflections with F > 4 sigma(F) and 462 parame ters.