5046
(15)
(16) (17) (18)
Measured by a Bruker 360-MHz instrument. J. M. van der Veen, J. Org. Chem., 28, 564 (1963). R. U. Lemieux and J. 13. Steven, Can. J. Chem., 44, 249 (1966). A. Schweiger, J. Chromatogr., 9,374 (1962). Solvent system: ethyl acetatelpyridinelH,O (2:1:2, both phases); visualization with ganisidine phthalate. GLC of the Me&?derivatives of sugars present in the acid hydrolysateof Q’ nucleoside showed a 2:l ratio of peaks corresponding to the mannose and galactose derivatives. The steric bulk of the protonated amino function is larger than the nonprotonated form due to greater solvation of the ammonium ion? Y. Kuchino, H. Kasai, K. Nihei. and S.Nishimura, Nucleic Acids Res., 3 , 393 (1976). R. J.’Suhadolnik and T. Uematsu, J. Biol. Chem., 245, 4365 (1970)
H. Kasai, K. Nakanishi*
b
Department of Chemistry, Columbia University New York, New York 10027 R. D. Macfarlane, D. F. Torgerson Cyclotron Institute, Texas A & M University College Station, Texas 77843 Z. Ohashi, J. A. McCloskey Department of Biopharmaceutical Sciences University of Utah, Salt Lake City, Utah 84112
Nig(CO)&-
PC6H5)6
Figure 1. View of the N ~ ~ ( C O ) & . L ~ - P Cfragment ~ H ~ ) ~of the phenylphosphido-bridged molecule. All atoms are represented by 25% thermal ellipsoids. The phenyl rings have been omitted for clarity. The entire molecule possesses crystallographic Ci- 1 symmetry, while the fragment ideally conforms to cubic 0,symmetry.
cm-I. Its proton NMR spectrum (JEOL MH-100) in CS2 (with Me4Si as internal standard) showed sharp resonances H. J. Gross characteristic of a diamagnetic compound with overlapping Max-Planck-Institut Fur Biochemie phenyl resonances centered at 6 1.5. 0-8033 Martinsried, West Germany An x-ray structural determinatio@ revealed the existence of N ~ ~ ( C O ) ~ ( P L ~ -as PC a discrete ~ H ~ ) ~molecule which with S. Nishimura* the neglect of the phenyl rings ideally conforms to cubic oh Biology Division, National Cancer Center symmetry, although an inversion center is the only crystalloResearch Institute, Tokyo, Japan graphically required molecular symmetry element. The moReceived May 25, 1976 lecular configuration (Figure l ) consists of a cube of nickel atoms with each square tetranickel face symmetrically capped by a phenylphosphido ligand. The additional coordination of one terminal carbonyl group, which is directed outward along one of the nickel cube’s body-diagonals, results in a tetraheSynthesis and Structural Characterization of a New dral-like ligand environment of one carbonyl and three phosType of Metal Cluster System, N ~ s ( C ~ ) S ( ~ ~ - P C ~ H & , phorus atoms about each nickel atom. Each nickel atom then attains a noble-gas electronic configuration through a twoContaining a Completely Bonding Metal Cube. A electron donation from the terminal carbonyl ligand, a oneTransition Metal Analogue of Cubane, CSHS electron donation from each of the three phenylphosphido liSir: gands, and electron-pair Ni-Ni bonds with the three adjacent nickel atoms. This completely bonding (electron precise) hoWe wish to report the preparation and structural analysis monuclear metal cube may be considered to be the first tranof N ~ ~ ( C O ) & L ~ - Pwhich C ~ H not ~ ) ~only establishes the sition metal analogue of the CgH8 hydrocarbon7 denoted as completely bonding metal cube as a basic structural unit in “cubane”. Three octacopper cubane complexes, the [Cus(itransition metal chemistry but also provides the first example MNT)6I4-, [ C U ~ ( D E D ) ~ ]and ~ - ,[ C U ~ ( D T S ) ~tetraanions, ]~of a M&(p~q-X)6 type of metal cluster system. This work was have previously been found from structural analyses8a-c to a result of systematic studies designed to produce new transipossess a [M&* - X)12J4- type structure based upon a metal tion metal cluster systems (with different MO electronic cube with edge-bridged X ligands. This geometry arises from configurations) containing bridging main group ligands from the 12 sulfur atoms of the six bidentate sulfur ligands in each the preformed metal cluster [Ni3(C0)3(p2-CO)3ln2- ( n = 2,’ tetraanion being arranged in a distorted icosahedral array such 32) and [Pt3(CO)3(p2-CO)31n2- ( n = 2, 3,4, 5)3 dianions. that each Cu( 1) is trigonally coordinated to three sulfur atoms The synthesis of Nig(Co)~(p2-PC6H5)6was accomplished from different ligands with a sulfur atom linked to two copper by the addition of 0.28 g (1.6 mmol) of C6H5PC12 to a susatoms along each of the 12 octacopper cube edges. Whereas pension of 0.85 g (1.0 mmol) of [NMe4]2[Ni3(CO),(pza conformity to the EAN rule by each Cu( 1) would effectively C0)3]2 in 40 ml of dry THF.4 The mixture immediately correspond to a two-thirds electron-pair Cu-Cu bond along changed from a bright orange-red to a deep purple color. After each of the 12 cube edges, an alternative bonding model sug1.5 h of stirring under N2, the solvent was removed under gested from MO calculations8d involves no net Cu-Cu intervacuum and the residue washed three times with 15-ml poraction~.~ tions of hexane. About 15 mg (ca. 20% yield based on P) of black plate-like crystals of Ni8(C0)8(p4-PC&)6 were sepThe Ni8P6 core in Nis(Co)s(p4-PC6H5)6 may be viewed arated by the slow diffusion of heptane into a saturated toluene as the result of the interpenetration of a nonbonding P6 octasolution. Dark-red octahedral-shaped crystals of another hedron by a bonding Nig cube. The Ni atoms are ca. 2.6 A compound also were isolated, but their unstable nature (as well apart, while the P-P distance along any of the three octahedral as small yield) has prevented adequate characterization to date. axes is 4.9 A. The result is that each phosphorus atom lies Attempts to separate the compounds by elution from a silica approximately 1.1 A out of its square Ni4 face. This octamegel column were unsuccessful due to extensive decomposition. tal-hexaligand architecture has a reciprocal structural relaThe infrared spectrum for Nig(C0)8(p4-PC6H5)6 in CS2 extionship to the hexametal-octaligand [Mo6Cls]4+ type hibited a very sharp carbonyl stretching frequency at 2020 structure,1° which may be viewed to evolve from a bonding Journal of the American Chemical Society f 98:16 f August 4, 1976
5047 M06 octahedron interpenetrating a nonbonding Cl8 cube with Acknowledgments. We wish to thank the National Science the Mo-Mo and Cl--Cl distances being such that the molybFoundation (No. GP-19175X) for their financial support. The denum atoms project by only 0.1 A outside the nonbonding Cls use of the UNIVAC 11 10 computer at the Academic Comcube. puting Center, University of Wisconsin (Madison), was made available through partial support of the National Science Three other compounds, in addition to Nis(CO)s(p4PC6H5)6, are now known to possess pentacoordinate phosFoundation and the Wisconsin Alumni Research Foundation phorus or arsenic atoms bonded to four transition metal atoms. administered through the University Research Committee. These are Co4(CO)s(ll2-CO)2(p4-Pc6Hs)z,l' its arsenic analogue Co4(CO)8(p2-CO)2(p4-Asc6H5)2,'2 and the Supplementary Material Available: A listing o f atomic coordinates (3 pages). Ordering information i s available on any current masthead [ C O ~ ( C O ) ~ ( P ~ - C O ) (pq-PC6Hs)2](~~-H) monoanion.I3 In page. each case, a square-pyramidal coordination is observed for either the phosphorus or arsenic atoms with four metals References and Notes comprising the basal plane and with a phenyl ligand at the apex. J. C. Calabrese. L. F. Dahl, A. Cavalieri, P. Chini, G. Longoni, and S.MartProminent structural features for N ~ S ( C O ) ~ ( F ~ - P C ~ H S ) ~inenoo. J. Am. Chem. Soc.. 96. 2616 (1974). (a) L:D. Lower, L. F. Dahl, G. Longoni, and P: Chini, Abstracts of Papers, include the following: (1) the electron-pair Ni-Ni distances 170th National Meeting of the American Chemical Society, Chicago, Ill., Aug 1975, INOR 68; (b) L. D. Lower, G. Longoni, P. Chini. and L. F. Dahl. vary from 2.636 (3) to 2.681 (3) AI4 with the mean value of submitted for publication. 2.648 A being similar to the mean electron-pair Co-Co (un(a) G. Longoni, Ph.D. Thesis, lstituto di Chimica, Generale ed Inorganica, bridged) distance of 2.697(2) A observed" in C04Universitadegli Studi, Milan, Italy, 1971; (b) J. C. Calabrese, L. F. Dahl, P. Chini, G. Longoni, and S. Martinengo, J. Am. Chem. SOC.,96,2614 (1974); (CO)s(l12-C0)2(p4-PC6H5)2; (2) the Ni-P distances range (c) J. C. Calabrese, L. D. Lower, G. Longoni, S. Martinengo, P. Chini, and from2.172 (5) to2.192(5)Awiththemeanvaheof2.183A L. F. Dahl, submitted for publication. The use of a larger relative amount of CBH5PCIzcaused precipitation of being comparable with the mean value of 2.242 A for the a copious quantity of NiCIz. corresponding distances in Co4(CO)s(11z-C0)2(114-Pc6Hs)2; (a) Ni8(CO)&4-PC6H&: orthorhombic: Pcab (nonstandard setting of (3) the P atoms lie ca. 1.1 A out of their respective Ni4 planes P b ~ a 4 ~ ' ~ ) ; a = 2 0 . 4 8 9 ( 1b3=) ,16.861(11),c = 14.485(6)A: V=5004 A3: P&d = 1.82 vs. Pcalcd = 1.78 g/cm3 for z = 4. Each molecule is rewith Ni-P-Ni angles of range 74.1 (2)-76.1 (2)' and of mean quired to possess C, - site symmetry such that one-half molecule value 75'. The corresponding mean Co-P-Co angle for the comprises the crystallographically independent unit. Least-squares refinement unbridged edges of C O ~ ( C O ) ~ ( C ~ ~ - C ~ ) ~ ( ~is~74'; ~ - P C ~ H S ) * gave R l ( F ) = 6.2% and Rz(F) = 6.3% for 1505 independent diffractometry data with I 1 2u(/). (4)the P-Ni-P bond angles are of range 103.4 (2)-105.7 (2)' For computation of distances and bond angles, atomic coordinates will and mean value 105', while the P-Ni-CO bond angles are of appear following these pages in the microfilm edition of this volume of the journal. See paragraph at end of paper. range 107.6 (6)-121.9 (6)' and mean value 114'; (5) the four (a) P. E. Eaton and T. W. Cole, Jr., J. Am. Cbem. SOC.,86, 3157 (1964); crystallographically independent carbonyl groups are nearly (b) E. B. Fleischer, ibid., 86, 3889 (1964). (a) L. E. McCandlish, E. C. Bissell. D. Coucouvanis, J. P. Fackler, and K. linear, with an Ni-C-0 range of 171 (2)- 179 (2)' (The Ni-C Knox, J. Am. Chem. Sm., 90, 7357 (1968); (b) F. J. Hollander, M. L. Caffery, and C - 0 average distances of 1.78 and 1.14 A, respectively, and D. Coucouvanis, Abstracts of Papers, 167th National Meeting of the are in agreement with expected values.); (6) the mean P-C American Chemical Society, Los Angeles, Calif., April 1974, INOR 73; (c) F. J. Hollander and D. Coucoucanis, J. Am. Cbem. Soc., 96, 5646 (1974); (phenyl) bond length of 1.8 1 (2) A is identical with that found (d) A. Avdeef, Ph.D. Thesis, Case Western Reserve University, 1973. in C O ~ ( C O ) & ~ - C O ) ~ ( ~ ~ - and P C ~is H consistent S)~ with the Hollander and Coucowanisschave argued that the small observed variations in the long Cu-Cu distances of range 2.790 (avb2.844 (av) A accompanying assignment of a single P-C bond; (7) all distances and bond the large changes in ligand geometry and steric requirements in these three angles within the three crystallographicallyindependent phenyl octacopper complexes8a-c"suggests strongly that there is an attractive rings are within experimental error of normal values. Coninteraction (bonding) between the copper atoms of the cube." (a) H. Schafer, H.-G. v. Schnering, J. Tillack, F. Kuhnen. W. Wohrle, and sideration of interplanar angles indicates that two of the phenyl H. Baumann, Z.Anorg. Allg. Chem., 353,281 (1967), and references cited rings, C6H5(l) and C6H5(3), are only 15.5' away from being therein; (b)L. R. Batemn, J. F. Blount, and L. F. Dahl, J. Am. Chem. SOC., 88, 1082 (1966), and references cited therein. parallel to each other and that they both lie nearly in the P( l ) , R. C. Ryan and L. F. Dahl, J. Am. Chem. SOC.,97,6904 (1975). P(3), P(l'), P(3') plane. The third ring, CsHs(2), lies apR. C. Ryan, J. P. O'Connor, and L. F. Dahl, to be submitted for publicaproximately in the P(2), P(3), P(2'), P(3') plane and is nearly tion. R. C. Ryan, J. P. O'Connor, and L. F. Dahl, to be submitted for publicapependicular to both C,5H5( 1) and C6H5(3). tion. The N ~ ~ ( C O ) ~ ( C L ~ molecule - P C ~ Hbelongs ~ ) ~ to a relatively Five of six independent Ni-Ni distances fall within the range of 2.636 (3) to 2.649 (3) A. There is no apparent rationalization for the sixth Ni-Ni dissmall class of organometallic complexes containing a nickel tance of 2.6811 (3) A lying significantly outside this range. polyhedron. Other structurally analyzed systems include (a) M. J. Bennett, F. A. Cotton, and B. H. C. Winquist, J. Am. Chem. SOC., Ni4[P(C2H4CN)314(112-C0)6,15a Ni4[CNC(CH3)3l7,lsb 89, 5366 (1967); (b) V. W. Day, R. 0. Day, J. S. Krlstoff, F. J. Hirsekorn. and E. L. Muetterties, ibid., 97, 2571 (1975): (c) J. L. Davidson, M. Green, Ni4(C0)4(CF3C2CF3)3,'5C the [Ni3(C0)3(112-C0)3]22- diF. G. A. Stone, and A. J. Welch, ibid., 97, 7490 (1975); (d) G. Longoni, P. anion,Ia the [Ni5(CO)&2-CO)3]2- d i a n i ~ n , 'and ~ ~ the Chini, L. D. Lower, and L. F. Dahl, ibid., 97, 5034 (1975). [Ni3(C0)3(p2-C0)3]32- dianion2 Loren D. Lower, Lawrence F. Dahl* Work is presently underway to examine the physical and Department of Chemistry, University of Wisconsin chemical properties of the Ni8(C0)&4-PC6H5)6 molecule Madison, Wisconsin 53706 and to attempt the preparation of related metal cluster systems. Received March 29, 1976
Communications to the Editor
