摘要:

How Ghee Ang,* Lip Lin Koh, Siau Gek Ang, Sek Yeo Ng and Guo Ying YangDepartment of Chemistry, National University of Singapore, Lower Kent Ridge Road,Singapore I 19260, Republic of SingaporeReaction of the linear triosmium carbonyl cluster [Os,H(CO), 1(q2-C6F5"NC6F5)] with [0s3(C0), '-(NCMe)] in hexane at 60 "C under vacuum afforded the 'spiked' tetraosmium cluster [Os,(p-H)(CO),,(q2-C,F,"NC,F,)] 1. Reaction with [Os,(CO), ,(NCMe),] in CH,Cl, at room temperature gave the 'spiked'hexaosmium cluster [OS6(p-H)(CO)21(NCMe)(~2-c6F5~~Nc6F5)] 2. Cluster 2 is reactive and converts intothe 'spiked' pentaosmium cluster [Os,(p-H)(CO), 7(q2-C,F5"NC,F5)] 3 and a known cluster [os5(co)16]respectively when heated with and without C,F,N=~NHC,F,. Clusters 1 and 3 were characterized by single-crystalX-ray crystallography.The structure of 1 consists of a triangular unit with a Os(CO),(q2-C6F,NNNC6F,)portion 'spiked' equatorially to it. The two nitrogen atoms in the triazenide ligand occupy an axial and anequatorial position in the Os(C0),(q2-C6F,NNNC6F,) group. The hydride ligand bridges, in a cis manner, the0s-0s edge where the OS(CO),(~~-C,F,NNNC,F,) portion is attached. The structure of 3 adopts a '4 + 1spiked' geometry hitherto unknown. Its metal core consists of a planar 'kite-like' Os, unit with theOs(CO),(q 2-C,F,NNNC,F5) portion 'spiked' to one of the equatorial co-ordination sites of an osmium atom.The two nitrogen atoms in the triazenide ligand and the hydride are bonded as in cluster 1. Based upon 13CNMR studies, the structure of cluster 2 in solution was also deduced to have a 'spiked' feature with the lineartriosmium fragment Os,(CO), l(q2-C6F5"NC6F5) bound to one atom in the osmium triangle at anequatorial co-ordination site.The transformation of cluster 2 and the formation of cluster 1 are also brieflydiscussed.Pyrolysis and redox reactions of carbonyl clusters have beenshown to give a variety of products with high nuclearity.'However, these reactions presented difficulties in efficientseparation and mechanism studies. Recently, a stepwise build-up of carbonyl clusters has been achieved via 'metal hydridecoupling' reaction of a metal complex e.g. [Os,H,(CO),,] (n =1-3) with clusters containing labile ligand(s) e.g. MeCN., Wehave also reported the synthesis of a novel Os, cluster [Os,(p-H)(CO), 9(p-CO)(r12-C,F,NNNc6F5)],3 as shown in Scheme1.Studies have shown that it is formed via a 'spiked' isomericresulting from 'metal hydride coupling' reactions betweenthe unstable linear cluster [OS~H(CO)~~(NCM~)(~~-C,F,-"NC,F,)] and the triangular cluster [Os,(CO),,(NCMe),].These findings stimulated us to explore systematically theapplication of the linear triosmium cluster [Os,H(CO), '(q2-C6F,"NC,F,)], obtained from the reaction of C,F,N=NNHC,F, with [Os,(CO), l(NCMe)],4 in the synthesis of'spiked' clusters and their transformation from open to closedclusters. We present here the study of 'metal hydride coupling'reactions of the linear triosmium cluster [Os,H(CO), ,(q2-C,F,"NC,F,)] with [OS,(CO),~-,(NCM~),] (n = 1 or 2),together with the reactivities of the adduct [Os,(p-H)-(CO),,(NCMe)(q2-C6F,N"C6F5)].intermediate [ o S 6 ( p-H)(C0)2 (NCMe)(q 2-C6F5"NC6F5)]Results and DiscussionReaction of [ os,H(co), l(q2-C6F,"NC6F,)] withTreatment of the linear cluster [Os,H(CO), 1(q2-c6F5-"NC,F,)] with an equivalent amount of [Os3(c0), '-(NCMe)] in hexane at 60 "C under vacuum provided a majorproduct [Os,(p-H)(CO) 14(q2-C6F5~"C6F5)] 1, isolated as[OS3(CO),,(NCMe)Ian orange solid (1 5.1 %) after thin-layer chromatography(TLC). Cluster 1 was characterized by spectroscopy (Table I )and microanalysis. Its IR absorption in the carbonyl regionshows multiple peaks for terminal carbonyl groups.The band at1263 cm-' is characteristic for a bidentate triazenide ligand.The 'H NMR spectrum shows the presence of bridging hydrideat 6 -19.21, while the 19F NMR spectrum exhibits the samechemical shifts for the two C,F, groups, indicating asymmetrical arrangement of the triazenide ligand.Reaction of [ Os,H(CO),,(~*-C,F,NNNC6F,)] withAddition of [Os,H(CO), l(q2-C6F,"NC,F5)] to a solutionof [0s3(C0),,(NCMe),] in CH2Cl, at room temperatureafforded an orange compound [O~,(p-H)(co)~ 1(NCMe)(q2-terminal CO stretching, consistent with the proposed structurebased upon ' ,C NMR studies (Tables 1 and 2).As for cluster 1,the band at 1252 cm-' is due to the bidentate triazenide ligand.,The 'H NMR spectrum shows a singlet at 6 - 16.8, attributedto a bridging metal hydride. The symmetrical arrangement ofthe triazenide ligand is also shown by the identical chemicalshifts of the two C,F, groups in the I9F NMR spectrum.[OS3(CO)i o(NCMe), IC6F5"NC6FS)] 2 (37.0%). Its IR spectrum shows OnlyCarbon-13 NMR study of cluster 2To elucidate the structure of cluster 2, 13C-(1H) and l3C-'HNMR spectra (Fig.1) were recorded and they display tworesonances of relative intensity four, one resonance of intensitytwo and eleven of intensity one due to the carbonyl ligands(Table 2). The proton-coupled spectrum reveals ,J( I3C-'H)coupling on resonances j, f, g, i, h and e. A tentative assignmentof these resonances is shown in Fig. 1 and Table 2. The peak atJ. Chem. SOC., Dalton Trans., 1996, Pages 4083-4088 408\I/\ I /\ 2 (L' = CO, L2= MeCN)(ii )1L' = L~ = M~CNN1=2N2=0 '@ (iii )Scheme 10s-0s bonds formed; N , = number of Os(CO), units eliminated(i) CH,Cl,, room temperature; (ii) C6F,N=NNHC,F,, hexane, 60-70 OC, vacuum; (iii) toluene, 90 "C, vacuum.N , = Number of newTable 1 Spectroscopic data for osmium clustersNMR (6,CDCl,)Cluster 1~ 19F1 - 19.21 (s)23 - 14.14 ( s )-75.2 (m, 4 F), -81.0 (m, 2 F),-85.8 (m, 4 F)-75.4 (m, 4 F), -81.9 (m, 2 F),- 85.7 (m, 4 F)-74.8 (m, 2 F), -75.4 (m, 2 F),-80.7 (m, 1 F), -81.7 (m, 1 F),- 85.4 (m, 4 F)- 16.8 (s, 1 H), 2.57 (s, 3 H)IR (cm-', CH,Cl,)V(C0) V(C6F5) v( triazenide)2 I34w, 2094w, 2075vs, 2056vs, 15 14m, 992w 1263m203 lm, 2022m, 2005m, 1968w,1944w21 19w, 2095m, 2077w, 2053w, 1514m, 990w 1252m2063m, 203 1 s, 2021 vs21 18w, 2126w, 2098s, 2079m, 1515m, 991w 1252m206 1 s, 2042s, 2026sthe highest field (6 167.80) remains as a broad singlet in theproton-coupled spectrum and can therefore be assigned to thecarbonyl carbon (COa) trans to the Os-Os bond at the end ofthe linear portion with the triazenide ligand.This broadening ispresumably due to the coupling between 13C and "N nuclei.The peak at 6 179.05, which also remains broad in the proton-4084 J. Chem. SOC., Dalton Trans., 1996, Pages 4083-408i fbI I 4 I190 180 1706Fig. 1 Proton-coupled (upper) and decoupled (lower) I3C NMR spectra in the carbonyl region for cluster 2Table 2 Carbon-1 3 NMR data for cluster 26 (CD,CI,,downfield from SiMe,)197.38194.62189.99189.47186.93184.19181.78179.05175.12172.54172.02170.58169.67167.802J( 'H-I3C)/Hz2.872.8600005.03br3.370012.693.82brAssignment1mnheacoupled spectrum but has the intensity of two nuclei, can beassigned to the two carbonyl carbon nuclei (Cob) at the sameosmium atom of the linear portion.The two peaks at 6 189.99and 189.47, both of which have intensity four and remain assinglets in the proton-coupled spectrum, can be assigned to thecarbonyl groups (CO' and Cod) on the other two osmiumatoms in the linear portion, where rotation about the 0s-0sbonds in solution is presumably fast on the NMR time-scalerendering the rotamers indistinguishable. The peak at 6 170.58with the largest value of 2J('3C-'H) in the proton-coupledspectrum can be assigned to the carbonyl carbon (COh) trans tothe hydride.The peaks at 6 197.38 and 194.62, which have thesmallest values of 'J(13C-'H), 2.87 and 2.86 Hz, respectively,are tentatively assigned to the carbonyl groups (COj and CO')at the axial sites of the 0 s atoms attached to the bridginghydride. The peaks at 6 175.12 and 169.67 with 'J(13C--lH) of3.37 and 3.82 Hz, respectively are tentatively assigned to thecarbonyl carbon nuclei (CO' and COe) cis to the hydride, andthat at 6 181.78 with 2J('3C-'H) of 5.03 Hz to the carbonylcarbon (Cog) at the axial site. As the chemical shift of the COcarbon trans to the 0s-0s bond is at relatively high field, thepeaks at 6 172.54 and 172.02, which remain as singlets in theproton-coupled spectrum, can be assigned to the equatorialcarbonyl carbon nuclei (CO" and CO") on the osmium atomwithout a bridging hydride.The singlets at F 186.93 and 184.19are at relatively low field and can be assigned to the axialcarbonyl carbon nuclei (COk and CO') on the same osmiumatom. Although the assignment of the CO groups in this clusteris tentative due to limited literature data on the magnitude of2J('3C-'H) coupling constants in such systems, the pattern ofthe 3C NMR spectra are fully consistent with an 'equatoriallyspiked' arrangement of the linear fragment Os3(CO)' l(q2-C,F,NNNC,F,) on the triangular portion Os3(p-H)-(CO),o(NCMe).Reactivity of cluster 2Cluster 2 was converted into a dark red cluster [Os,(pH)-(CO), ,(q'-C,F,~"C,F,)] 3 (34.5%) when heated with anequivalent amount of C,F,N=~NHC6F, in hexane at 60-70 "C under vacuum.As for cluster 1, the IR spectroscopic datareveal the bidentate co-ordination mode for the triazenideJ. Chem. SOC., Dalton Trans., 1996, Pages 4083-4088 408Table 3 Selected interatomic distances (A) and angles (") for cluster 1Os( 1)-0s(2)Os(4)-N( 1 1N( 1 t N ( 2 )Os( I)-C( 1 1)Os( 1 )-C( 13)OS(2)-c(22)Os(2)-C(24)Os( 3)-C( 32)OS( 1)-0~(4)OS( 3)-C( 34)0~(4)-C(42)N( 1 tc( 106)OS( 1)-0~(2k0~(3)OS(~)-OS( 1 t O ~ ( 3 )Os(2)-0s( 1 kOs(4)0~(4)-N( 1 t N ( 2 )Os( l)-Os(4)-c(42)OS( 1)-0~(4)-C(43)2.850(2)2.880(2)1.18(5)1.87(4)1.90(6)1.87(5)2.02(4)2.01 (4)1.97(4)1.37(5)2.19(3)1.93(3)63.9( 1)58.8(1)166.7( 1)9 7.9( 24)175.8( 1 1)87.8( 1 1)Os( 1 )-Os(3)Os(2)-Os(3)0~(4)-N(3)N(2)-N(3)Os( 1)-C( 12)OS(2)-C(21)Os(2)-C(23)OS( 3)-C( 3 1 )0~(3)-C(33)0~(4)-C(43)Os(4)-C(41)N( 3 )-C( 306)3.042(2)2.899(2)2.16(3)1.34(5)1.91(4)1.83(4)1.87(5)2 .O 1 (4)1.86(5)1.92(5)2.03(4)1.40( 5)Os( l)-Os(3)-Os(2) 57.3( 1)Os(3)-Os(ljOs(4) 108.2(1)N(l)-N(2 j N ( 3 ) 110.7(33)Os(4jN( 3)-N(2) 95.2( 22)OS(l)-OS(3)-C(32) 11 5.5( 11)Os( 1 )-Os(4)-C(41) 84.3( 13)F( 103)F(301)3)F(302) 6Fig.2 Molecular structure of compound 1 showing the atom labelling.The C atoms of the CO and C6F5 groups bear the same numbering asthe corresponding 0 or F atomsligand and the presence of terminal carbonyl ligands (Table 1).The resonance of the bridging hydride ligand was seen at 6-14.14 in the 'H NMR spectrum.The arrangement of thetriazenide ligand is also symmetrical as shown by the identicalchemical shifts of the two C6F5 groups in the 19F NMRspectrum. When heated in toluene at 90 "C under vacuum in theabsence of C6F5N=~NHC6F5 cluster 2 was converted into aknown cluster [os5(co),6].6 On standing in CH2C12 at roomtemperature, cluster 2 can also be converted slowly into 3. Uponheating compound 3 in toluene at 90 "C cluster [os5(co)16]was also obtained as a major product. Compared with theformation of the hexaosmium cluster [Os6(p-H)(CO) &-CO)( q -C 6 F "NC 6 F 5)] which we obtained previously, thebuild-up of 0s-0s bonds on the triangular portion is dependenton the presence of labile ligands (MeCN) in the intermediates[OS6(p-H)(CO)20L1 ( L2)(q 2-C6F5NNNC6F5)] (Scheme I ).Inthe case Of [OS6(p-H)(CO)20L'(L2)(q2-c6F5NNNc6F5)] 2(L' = CO, L2 = MeCN) the presence of one labile ligandMeCN in the triangular portion allows the formation of oneadditional 0s-0s bond upon its conversion into cluster 3. In thecase of cluster 2 (L' = L2 = MeCN), where one MeCN ligandis present in the triangular part and the other at the osmiumatom attached to the triangular metal core, [Os6(p-H)-(C0)19(~-C0)(~2-C6FsNNNC6F5)] was obtained with theformation of two additional 0s-0s bonds and loss of twoMeCN ligands. Cluster 1 was obtained directly from the re-action of [Os,(CO), ,(NCMe)] with [Os,H(CO), '(q2-C6F5-"NC6F5)] in hexane at an elevated temperature of 60 "C orin a polar solvent e.g.CH2Cl, or tetrahydrofuran at roomtemperature. The intermediate 2 (L' = L2 = CO) was notobtained in either reaction. In this case, no additional metal-metal bond would be formed during the transformation.It has been suggested that in osmium cluster chemistry theaddition of a pair of electrons to a cluster is concomitant withbreaking of a metal-metal bond.' Based upon our observation,it can be concluded that the formation of a metal-metal bond isconsistent with loss of a two-electron donor ligand (e.g. MeCNor CO). This kind of process was also believed to occur in theformation of high-nuclearity carbonyl clusters via pyrolysismethods, in which co-ordinatively unsaturated species wereinvolved and condensed to the products by forming new metal-metal bonds.* This feature was also present in the trans-formation of cluster 3 to [os5(co)16], in which three new0s-0s bonds were formed with the loss of one CO (two-electron donor) and one C6F5N="HC6F, ligand (four-electron donor). It is also interesting that the formationof cluster 1 was accompanied by the elimination of twoOs(CO), units, while in the transformation of cluster 2 to 3one Os(CO), was expelled from the system and no Os(CO),was lost during the formation of [os6(p-H)(co),,(p-co)(q2-C6F5"NC6F5)].Crystal structure of cluster 1The molecular structure of compound 1 was determined bysingle-crystal X-ray diffraction analysis.Relevant bond lengthsand bond angles are given in Table 3.The structure (Fig. 2)consists of a metal-co-ordinated triangular cluster having fourmetal-metal bonds and a total of 64 electrons, in which a 17-electron portion, OS(CO)J(q2-C6F5NNNC6F5) 'spikes". thetriangular (p-H)Os,(CO), , fragment. One 0s-0s edge in theosmium triangle is bridged by a hydride ligand, while thetriazenide ligand is attached to the osmium atom co-ordinatedto the triangle. The osmium atom of the Os(CO),(C6F,-"NC6F,) ligand is positioned at a distance of 0.1623 8, abovethe plane formed by the other three osmium atoms. Thisdeviation from planarity may be the result of steric hindrancebetween the bulky C6F5 group on N(l) and the carbonylsCO(11) and CO(l3) on Os(1). The geometry around the Os(4)atom is close to octahedral and the orientation of theOs(CO),(C6F5"NC6F,) unit is such that the carbonylligands are staggered with respect to those bonded to Os(1)as evidenced by the torsion angles [C(41)-Os(4)-Os( 1)-C( 1 1) 49.0( 1.8), C(43)-Os(4)-Os( 1)-C( 12) - 49.7( 1.7) andN( 1)-0s(4)-0s( 1 )-C( 13) 2 9 3 1 S)"]. The unbridged Os( 1)-Os(4) bond is 2.880(2) A.The triazenide ligand occupiesboth an axial and an equatorial site of the fourth osmium atomcentre to form a Os(4)-N( l)-N(2)-N(3) four-membered ring,which is almost planar [largest deviation from the plane 0.028 1 8,for N(2)]. The presence of the hydride ligand was not locateddirectly. However it was inferred to bridge the Os(l)-Os(3)vector, which is longer than the other 0s-0s bond lengths in theosmium triangle.A singly hydrogen-bridged 0s-0s bondusually has a length around 3.0 A (e.g. 2.989(1) A in [Os3(p-H)(H)(CO),, J and 3.0185(6) 8, in [Os,(p-H)(H)(CO)lo-(PPh,)] lo). The bond length of Os(l)-Os(3) in 1 is 3.042(2) 8,,which falls within the specified range. Furthermore, the averageOs-Os-C,, angle for [OS,(CO),~] is 98.2°,9 but theOs(l)-Os(3)-C(32) angle for 1 is 115.5(11)". This difference isalso attributable to the presence of the bridging hydride.Analysis of the 0s-0s bond lengths (A) in the osmium triangle of1 shows that while most are longer than the 0s-0s distance inthe parent [Os,(CO), J, Os( I)-Os(2) is significantly shorterthan the average found in [OS,(CO),~]. This shortening of theOs(1)-Os(2) bond which is trans to the Os(l)-Os(4) bond may4086 J.Chem. SOC., Dalton Trans., 1996, Pages 4083-408Table 4 Selected interatomic distances (A) and angles (") for cluster 3OS( 1 )-OS( 2)0 ~ ( 2 ) - 0 ~ ( 3 )OS( 3)-0~( 4)OS( 5)-N( 1 )N( 1 W ( 2 )OS( l)-c( 1 1)OS(2)-C(21)OS( 1)-C( 13)OS( 2)-C( 23)0~(3)-C( 32)OS( 3)-C( 34)0~(4)-C(42)Os(S)-C(51)Os(5)-C( 53)N(3)-C(71)2.8 14( 1 )2.947( 1)3.053( 1)2.12(2)1.33(3)1.89(2)2.00(2)1.87( 1)1.93(2)1.95(2)1.95(2)1.94(2)1.89(2)1.94(2)1.44(2)0~(2)-0~(1)-0~(3) 61.3(1)OS( 1)-0~(2)-0~(3) 61.8( 1)Os(2)-0s(3)-Os(4) 58.0( 1)Os(4)-0s(2)-C(21) 132.9(5)Os(4)-Os(5)-C(51) 175.0(6)Os(4)-Os(5)-N(3) 91.8(4)0~(5)-N(l)-N(2) 98.9(11)Os( 1 )-0s(3)Os(2)-Os(4)OS(4)-0S(5)Os(5W(3)N(2)-N(3)Os( 1 )-C( 12)Os( 1 )-C( 14)OS(2)-C(22)Os(3)-C(3 1)Os(3)-C( 33)Os(4)-C(4 1 )Os(4)-C(43)Os(5)-C(52)N( 1 t c ( 6 1 )Os( 3)-0s(2)-0s(4)OS(l)-0S(3jOS(2)os(2)-0s(4jOs(3)Os( 1)-0S(2)-C(21)Os(4)-Os(5jN( 1 )N(1)-N(2wJ(3)OS(5W(3)-N(2)2.959( 1)2.91 l(1)2.869( 1)2.1 l(1)1.28(2)1.89(2)1.94(2)1.94(2)1.90(2)1.96(2)1.89(2)1.99(2)1.92(2)1.41(2)62.8( 1)56.9( 1)59.2( 1)102.5(5)88.1(4)102.6( 1 6)101.0(11)O(11Fig.3 Molecular structure of compound 3 showing the atom labelling.The C atoms of the CO and C6F, groups bear the same numbering asthe corresponding 0 or F atomsbe taken to indicate that the Os(CO),(C,F,~"C,F,) portionis a weak donor ligand and this is consistent with the electron-withdrawing property of the triazenide ligand.The fourteencarbonyl groups in 1 are all terminal with Os-C and C-0 bondlengths of 1.83(4)-2.03(4) and 1.02(5)-1.18(7) 8, respectively.Crystal structure of cluster 3The molecular structure of cluster 3 has been determined bysingle-crystal X-ray diffraction. Selected bond distances andangles are given in Table 4. This cluster could be described asbeing derived from the unusual planar tetraosmium cluster[OS,(CO),,].'~ Its metal core consists of a planar 'kite-like'Os, unit with an osmium bound to one of the equatorial co-ordination sites of an osmium atom, a structure which has notbeen reported before (Fig. 3). As was found in [OS,(CO),~], theOs, unit in this cluster is almost planar [dihedral angle betweenthe planes Os( l)-Os(2)-0s(3) and Os(2)-Os( l)-Os(4) 2.4'1.The fifth osmium Os(5) lies essentially in this plane [deviationfrom the plane defined by Os( l)-Os(2)-0s(3) and Os(4) 0.349 A].The hydride was not located directly; however, it was inferredto bridge the Os(2)-Os(4) vector, the length [2.911(1) A] ofwhich is similar to those found in other clusters {e.g.2.989(1) 8,in [Os,(p-H)(H)(CO), ,I and 3.0185(4) A in [Os,(p-H)(H)-(CO),,(PPh,)] lo>. The location of the hydride at Os(2)-Os(4)is also confirmed by the comparison of the diequatorialangles Os(4)-Os(2)-C(21) [ 132.9(5)'] and Os(l)-Os(2)-C(21)[ 102.5(5)"]. The former is larger by 30.4'. The Os-0s unbridgedbond lengths in this cluster are only slightly different from thecorresponding ones in [Os,(CO) , ,I.The diagonal Os(2)-0s(3)bond is 2.947( 1) A and is the same as that in [Os,(CO), 3. Thebond length of Os( 1)-0s(2) [2.814( 1) A] is significantly shorterthan the average value of 2.877(3) 8, for an Os-0s bond in[OS,(CO),~], but larger than the corresponding bond lengthof 2.772(1) 8, in [Os,(CO),,]. The Os(2)-Os(4) bond length[2.911(1) A] is larger than both the average value in[Os,(CO),,] and the corresponding bond length of 2.772(1) Ain [Os,(CO), ,I. The bond length of Os( 1)-Os(3) [2.959( 1) A] isalso longer than average bond length in [Os,(CO),,] andslightly shorter than the corresponding bond length of 2.997( 1)8, in [Os,(CO),,]. Long and short Os-0s bonds are common inosmium clusters, but the cause is not well understood.In thecase of [Os,(CO),,] or its derivative [Os,(CO),,(PMe,)] theunusual bond lengths were rationalized in terms of three-centretwo-electron metal-metal bonds. Therefore, the short bondswere assigned a bond order of 1.5 and the long bond an order of0.5, consistent with an 1 %electron configuration for each metalatom. As described above, in the case of this cluster, long andshort Os-0s bonds are also observed. Although the averageunbridged bond length [2.943(1) A] is not very different fromthat in [OS,(CO),~] [2.897(1) A], the bond lengths in cluster 3are very similar, in contrast to what was observed in[OS,(CO),,]. This may be due to the presence of the bridginghydride and the 'spiked' unit OS(CO)3(~2-C6F,NNNC6F5),which may assist inthe delocalization of electrons in the wholeOs, unit and thus reduce the difference in electron density foreach metal-metal bond.The fifth osmium atom 'spikes' on the Os, unit at Os(4) at theequatorial site.The geometry around the Os(5) atom is close tooctahedral and the orientation of the Os(CO),(q2-C6F5-"NC,F,) group is such that the carbonyl ligands arestaggered with respect to those bonded to Os(4) as evidenced bythe torsion angles [ C(43)-Os( 4)-Os( 5)-C(52) 43.3( 7),C(41)-0~(4)-0~(5)-C(53) 45.2(7) and C(42)-0~(4)-0s(S)-N(3)24.8(6)"]. The bidentate triazenide ligand chelates Os(5) to forma four-membered ring Os(5)-N( 1)-N(2)-N(3), which is almostplanar [largest deviation 0.0052 A, for N(2), from the planedefined by Os(5)-N( 1)-N(2)-N(3)] and perpendicular to theplane of the Os, unit (dihedral angle between these two planes94.8').ExperimentalMethodologyThe starting materials [Os,H(CO), l(q2-C,F,"NC,FS)],4[OS,(CO),,(NCM~>~],'~ [Os,(CO), ,(NCMe)] l4 and C,F,N="HC,F, l 5 were prepared by published methods.Thesolvents hexane, toluene and CH2C12 for the reactions weredried by published methods. Thin-layer chromatography wasperformed in air on plates coated with silica (Merck Kieselgel60GF). Infrared spectra were recorded on a Perkin-Elmer9836 spectrometer, NMR in CDCl, on a JEOL FX 90Q FT orFT Bruker ACF 500 MHz spectrometer; 'H and I3C NMRspectra were measured with respect to SiMe, as internalreference, and 19F with respect to CF,C02H as externalreference.CrystallographyCrystal data for compounds 1 and 3 are summarized in Table 5.Diffraction intensities were collected at 298 K on a SiemensR3m/V X-ray diffractometer with graphite-monochromatizedMo-Ka radiation (A = 0.710 73 A), scan range 7.0 < 20 < 45.0for 1 and 3.5 < 20 < 50.0' for 3, indices +h, + k, _+ 1 for 1 and+h, _+ k, k 1 for 3. All computations were carried out on aMicro VAX 2000 computer using the SHELXTL PLUSprogram package.' The structures were solved by directJ.Chem. SOC., Dalton Trans., 1996, Pages 4083-4088 408Table 5 Summary of crystallographic data for compounds 1 and 3FormulaMDJg ~ r n - ~Colour, habitCrystal dimensions/mmCrystal systemSpace groupalAblACIAa/"PI"rl"u l ~ 3ZReflections collectedObserved reflections[F > 4.0o(F)]R, R' (observed data)(all data)Goodness of fitF(OO0)p( Mo-Ka)/mm-'Weighting scheme, w-lMinimum, maximumtransmission11530.12.664Orange blocks0.33 x 0.22 x 0.11MonoclinicP2,ln1 3.040( 3)18.839(4)15.652(3)C.26HFl ON 3O 140s497.5 1 (3)3812(3)4695332750.0744,0.09660.1438,0.12851.13273613.40302(F) + 0.0042F20.0370, 0.072631804.33.024Brown blocks0.35 x 0.25 x 0.15Triclinic8.975(2)12.668(3)17.619(4)82.50(3)8 5.8 3( 3)88.27(3)1980.4( 10)274795340C29HF,oN,O17Os,Pi0.0467, 0.058 10.0647,0.06711.13160416.10402(F) + 0.0016F20.1601,0.9805methods, using full-matrix, least-squares refinement (based onF ) with all non-hydrogen atoms being refined anisotropicallyexcept for the C atoms of the CO ligands and the C6F, groupsin cluster 1, and C and F atoms of the C,F, groups in cluster 3,which were refined isotropically.Owing to large deviations,seven and four observed reflections were omitted for cluster 1and 3, respectively. The bond lengths (C-C 1.38, C-F 1.32 A) ofthe C6F5 groups in 3 were fixed because of high thermalmotion. An empirical (v-scan) correction was performed ineach case.Atomic coordinates, thermal parameters, and bond lengthsand angles have been deposited at the Cambridge Crystallo-graphic Data Centre (CCDC). See Instructions for Authors,J. Chem. SOC., Dalton Trans., 1996, Issue 1 .Any request to theCCDC for this material should quote the full literature citationand the reference number 186/204.Reactions O f [Os,H(CO), l(T12-C6F5"NC6F5)]With [Os,(CO),,(NCMe)]. A mixture of [Os,H(CO), 1(q2-C6Fs"NC6Fs)] (56.0 mg, 0.045 mmol) and [0s3(c0), 1-(NCMe)] (50.0 mg, 0.054 mmol) in hexane (4 cm3) wasintroduced in a Schlenk tube (50 cm3). The system wasevacuated and the Schlenk apparatus was placed in an oil-bathat 60-70 "C for 16 h. The resultant orange solution wasevaporated to dryness and subjected to TLC, using hexane-CH,C12 (7: 3 vlv) as eluent, to give [0s4(~-H)(CO),,(q2-C6F5"NC,F,)] 1 (R, = 0.5, 12.5 mg, 15.1%) as the majorproduct (Found: C, 20.10; H, 0.20; F, 12.6; N, 2.75. Calc. forC,,HF,oN,0,40s4: C, 20.4; H, 0.05; F, 12.4; N, 2.75%).With [Os,(CO),,(NCMe),].A mixture of [Os3H(CO), l(q2-C6F5"NC,F,)] (57.0 mg, 0.046 mmol) and [oS3(co)10-(NCMe),] (50.0 mg, 0.053 mmol) in CH,Cl, (4 cm3) wasintroduced in a Schlenk tube (50 cm3). The system wasevacuated and refilled with N, (1 atm, 101 325 Pa). Afterstirring overnight, the resultant orange solution was evaporatedto dryness and subjected to TLC, using hexane-CH,Cl, (6:4v/v) as eluent, to give [Os,(p-H)(CO), ,(NCMe)(q2-c,F,-"NC,F,)] 2 (R, = 0.5, 36.5 mg, 37.0%) as the majorproduct (Found: C, 19.6; H, 0.20; N, 2.75. Calc. forC45H4FloN30,10~6: C, 19.55; H, 0.20; N, 2.60%).Reaction of compound 2 with C6F5N=NNHC6F5A mixture of [Os6(~-H)(CO),,(NCMe)(q2-C,F,NNN~,F~)](50.0 mg, 0.023 mmol) and C,F,N="HC,F, (8.8 mg, 0.023mmol) in hexane (4 cm3) in a Schlenk tube (50 cm3) wasdegassed and heated at 6&70 "C overnight.The resultant redsolution was evaporated to dryness and subjected to TLC, usinghexane-CH,CI, (9: 1 v/v) as eluent, to give a red compound34.5%) as the major product (Found: C, 19.3; H, 0.25; N, 2.60.Calc. for C2,HFl,N30210s,: C, 19.2; H, 0.05; N, 2.60%).[OS,(~-H)(CO)1-,(q2-C6FsNNNC,Fs)] 3 (R, = 0.35, 12.9 mg,Pyrolysis of compound 2(50.0 mg, 0.023 mmol) in toluene (4 cm3) in a Schlenk reactiontube was degassed and heated at 90 "C overnight. The resultantdark brown mixture was evaporated to dryness and subjected toTLC, using hexane-CH,Cl, (7: 3 v/v) as eluent, to give themajor cluster [os,(co)16] (R, = 0.60, 8.3 mg), characterizedby comparison of its IR spectrum with literature data6 (Found:C, 13.88.Calc. for Cl6O1,Os5: C, 13.75%).A solution of [OS6(p-H)(C0)2 1(NCMe)(q2-C,F5NNNC6F5)]AcknowledgementsWe thank the National University of Singapore for financialsupport and a research scholarship (to G. Y. Y.).References1 M. D. Vargas and J. N. Nicholls, Adu. Inorg. Chem. Radiochem.,1986,30, 123.2 J. R. Shapley, G. A. Pearson, M. Tachikawa, G. E. Schmidt, M. R.Churchill and F. J. Hollander, J. Am. Chem. SOC., 1977, 99, 8064;M. R. Churchill, F. J. Hollander, R. A. Lashewycz, G. A. Pearsonand J. R. Shapley, J. Am. Chem. SOC., 1981, 103, 2430; M. R.Churchill and F. J. Hollander, Inorg. Chem., 1981, 20, 4124; E. J.Ditzel, B. F. G. Johnson, J. Lewis, P. R. Raithby and M. J. Yaylor,J. Chem. SOC., Dalton Trans., 1985, 555; J. Lewis and J. R. Moss,J. Organomet. Chem., 1993,444, C51.3 H. G. Ang, L. L. Koh and G. Y. Yang, Chem. Commun., 1996,1075.4 H. G. Ang, L. L. Koh and G. Y. Yang, J. Chem. SOC., Dalton Trans.,5 E. Pfeiffer, A. Oskam and K. Vrieze, Transition Met. Chem., 1977,2,6 C. R. Eady, B. F. G. Johnson and J. Lewis, J. Organornet. Chem.,7 R. Mason and D. M. P. Mingos, J. Organomet. Chem., 1973,50,53.8 B. F. G. Johnson and J. Lewis, Adu. Inorg. Chem. Radiochem., 1981,9 M. R. Churchill and B. G. DeBoer, Inorg. Chem., 1977,16, 878.10 M. R. Churchill and B. G. DeBoer, Inorg. Chem., 1977,16,2397.11 V. J. Johnston, F. W. B. Einstein and R. K. Pomeroy, J. Am. Chem.12 L. R. Martin, F. W. B. Einstein and R. K. Pomeroy, J. Am. Chem.13 J. N. Nicholls and M. D. Vargas, Inorg. Synth., 1989,26,292.14 B. F. G. Johnson, J. Lewis and D. A. Pipparel, J. Chem. SOC., Dalton15 E. J. Forbes, R. D. Richardson and J. C. Tatlow, Chem. Ind.16 D. F. Shriver and M. A. Drezdzon, The Manipulation of Air-sensitiveI7 G. M. Sheldrick, SHELXTL PLUS, Siemens Analytical Instruments,1996, 1573.240.1972,37, C39; J. Chem. SOC., Dalton Trans., 1975,2606.24,225.SOC., 1987,109, 7220.SOC., 1986, 108, 338.Trans., 1981,407.(London), 1958,630.Compounds, 2nd edn., Wiley, New York, 1986, p. 90.Madison, WI, 1990.Received 8th May 1996; Paper 610322954088 J. Chem. Soc., Dalton Trans., 1996, Pages 4083-408

ISSN:1477-9226    

DOI:10.1039/DT9960004083

出版商:RSC    

年代:1996

数据来源: RSC