ORGANOMETALLIC CHEMISTRY OF [W-2(OCH(2)TBU)(8)] (M=M) - SUBSTRATE UPTAKE AND ACTIVATION AT A TUNGSTEN-TUNGSTEN DOUBLE-BOND

The compound [W-2(OCH2-tBu)(8)] reacts in hydrocarbon solvents with et hyne, ethene, allene, carbon monoxide, and benzophenone to give 1:1 ad ducts [W-2(OCH(2)tBu)(8)(mu-C2H2)] (1), [W-2(OCH(2)tBu)(8)(eta(2)-C2H4 )] (2), [W-2(OCH(2)tBu)(8)(mu,eta(1),eta(3)-C3H4)] (3), [W-2(OCH(2)tBu )(8)(CO)] (4), and [W-2(OCH(2)tBu)(8)(eta(2)-OCPh2)] (5), respectively . These compounds have been characterized by variable-temperature H-1 and C-13 NMR studies, infrared spectroscopy, elemental analysis, and f or 1 and 3 by single-crystal X-ray crystallography. Compound 1 contain s a nonperpendicular and nonparallel mu-C2H2 ligand in the solid-state with W-C=2.07(1) and 2.43(1) Angstrom, and W-W and C-C=2.623(1) and 1 .34(1) Angstrom, respectively. However, in solution the mu-C2H2 ligand sees two equivalent tungsten nuclei on the NMR time-scale, even at lo w temperatures. In the mu,eta(1),eta(3)-allene adduct 3, the W-W dista nce of 2.917(2) Angstrom implies a loss of M-M bonding in favor of W-2 -to-allene bonding: W1-eta(1)-C=2.11(1), W2-eta(3)-C=2.24 to 2.35 Angs trom. [W-2(OCH(2)tBu)(8)] and Ph2C=S react in hydrocarbon solvents to give products from the cleavage of the C=S bond, namely [(tBuCH(2)O)(4 )W=S] and [(tBuCH(2)O)(4)W=CPh2]. A derivative of the latter, [(Ph2C=( tBuCH(2)O)(EtO)(2)W(mu-OEt)](2) (6), has been characterized by a singl e-crystal X-ray study. The W-W distance of 3.485(1) Angstrom is consis tent with the lack of a W-W bond, while W-C=1.967(6) Angstrom is typic al for a W-alkylidene distance. [W-2(OCH(2)tBu)(8)] reacts with KH and [18]crown-6 in tetrahydrofuran to give {K+([8]crown-6)[W-2(mu-H)(OCN( 2)tBu)(8)](-)} (7), and with Ph3P=CH2 to give [W-2(mu-CH2)(OCH(2)tBu)( 8)] (8) and Ph3P. These results are compared with related reactions in volving [W-2(OR)(6)](M=M) compounds and with the organometallic chemis try of M=M-bonded species such as [Cp-2Re-2(CO)(4)] and [Os-2(CO)(8)] .