Coordination and coupling of alkylidene groups on a triosmium cluster framework. Crystal structure of Os3(CO)10(.mu.-CO)(.mu.-CHSiMe3)

Novel butterfly tungsten-osmium carbido cluster Complexes from the reaction of Os3(CO)10(NCME)2 CPW(CO)3(CH2SMe)

“…Full matrix least-squares refinement with 50 atoms and 362 parameters gave "B (eq) is the mean of the principal axes of the thermal ellipsoid. (16) 4.3(12) 0.2918 (15) 3.0(10) 0ù1120(141 3.3(111 0.0460 (15) 2.7(10) 0.1511 (16) 3.8(11) 0.2831(141 3.0(10) 0.2500 (19) 7.1(18) 0.2381(2(I) 6.0(15) 0.1459 (18) 3.9(13) 0.1041(171 5.2(13) 0.1705(20) 5.8(16) 0.1972 (12) 4.4(9) 0.0296 (11) 4.8(9) 0.4454 (11) 5.2( 10 "B (eq) is the mean ot" the principal axes of the thermal ellipsoid.…”

“…The methylene ligand is asymmetrical with Os(1)-C( 14) bond (2.09(2) Ä) and is substantially shorter than that of W-C( 14) bond (2.21(2)Ä). The M-C bond distances are in the range observed for the M-C (alkylidene) distances of CpWOs3(IL-O)(/I-H)(II-CHTol)" (W-C=2.08Ä and Os-C=2.24Ä) [4] and the Os-C distances of Os3(CO)ll(/l-CHSiM%) (2.16-2.19)(2)A) [15], which possess unsymmetrical and symmetrical alkylidene group, respectively.…”

Bridging ligands formed by decarbonylation of keten and by decarboxylation of diketen and vinylene carbonate at triosmium clusters

“…(2) react with the more reactive of triosmium clusters such as and CH,O ligands. Some or all of these are implicated in Interestingly the keten group which was cleaved in the formation of (4) is reformed on heating (4) in refluxing heptane (2 h) to give (5) in excellent yield (Scheme At one stage we considered that (3) might have been formed from some diketen (1) that had escaped decomposition in the cracking to keten, but, since [OS,(CO),,(M~CN)~] does not react with (1) at room temperature, compound (3) is not formed in this way. However, the bis-acetonitrile compound with an excess of (1) in refluxing benzene (3 h) does give compound (3) (1 8 %).…”

“…Compound (6) is closely related to (4), containing a p-CO and a p-alkylidene group, and moreover (4) and (6) are isomeric but these do not interconvert at temperatures lower than those at which they convert into other compounds. While compound (4) readily converts into (5) (Scheme I), its isomer ing octane) does it slowly convert with associated decomposition into the dihydride (7)$ with no indication of any compound (5) being formed. The source of the extra two hydrogen atoms was not established but, since yields of (7) are relatively low (38% after 1.5 h in refluxing octane), all the hydrogen atoms in (7) could have originated from (6).…”

“…Scheme 1 keten at a triosmium cluster as in the formation of [Os,H,-(CO),(C=CH,)] from ethylene., However, allowing [OS,(CO)~,-(MeCN),] to react with keten in dichloromethane at room temperature rapidly gave the red compound [OS,(CO)~,allene compound (3) is probably derived from allene which is an impurity in keten formed by cracking (1) at 550 "C. Rather than cleaving a C-H bond of keten to give [Os3H(CO),,-(p-CH=C=O)] the C-C bond of keten is broken. Compound (4) was previously prepared by acidifying [OS,(CO)~~(CHO)]or by treating [0s3( CO),,( MeCN) ] with diazomet hane.4~5Interestingly the keten group which was cleaved in the formation of (4) is reformed on heating (4) in refluxing heptane (2 h) to give(5) in excellent yield (Scheme At one stage we considered that (3) might have been formed from some diketen (1) that had escaped decomposition in the cracking to keten, but, since [OS,(CO),,(M~CN)~] does not react with (1) at room temperature, compound (3) is not formed in this way. However, the bis-acetonitrile compound with an excess of (1) in refluxing benzene (3 h) does give…”