摘要:
1973 697Crystal Structure of Di-p-tropolonato-bis[aquo(tropolonato)nickel( II)]By Roger J. Irving,' Michael L. Post, and David C. Povey, Departments of Chemistry and Chemical Physics,Crystals of the title compound are monoclinic, a = 9.720(7), b = 18.888(17), c = 7-146(3) 8, /3 = 97.97(5)".Z = 4, space group P2,/n. The structure was determined from diffractometer data by the heavy-atom method andrefined by full-matrix least squares to R 0.082 for 11 91 observed reflections. The molecule exists as a centrosym-metric dimer and contains two types of tropolone ligand : one co-ordinated to one nickel atom only, the other,co-ordinated both to the first nickel atom, and to a second nickel via a bridging oxygen atom. This, together witha co-ordinated water molecule gives the nickel atoms six-co-ordination.There is evidence for hydrogen bonding,via the water molecule, between adjacent dimers.University of Surrey, GuildfordTROPOLONE displays the characteristic properties of ap-diketone in its ability to form a wide range of co-ordination compounds with transition meta1s.l Likeacetylacetone , tropolone forms an anhydrous , pre-sumably polymeric compound with nickel, [NiTd,(T = tropolonate ion) but unlike [Ni(acac),], whichreacts with water to give Ni(acac),(H,O),, [NiT,],gives the unusual monohydrate NiT,(H,O) , which isthe subject of this investigation.EXPERIMENTALLight green needle crystals were obtained from a solu-tion of the compound (0.05 g) in methanol-water (100 ml,CvystaZ Data.-C,4H12Ni0,, M = 3 18.95, Monoclinic,3 : 1 v/v).= 9.720(7), b = 18-888(17), G = 7*146(3) A, p =U = 1299 A,, D, = 1.630, 2 = 4, D , = 1.64, 07-97(5)",(by flotation in aqueous zinc chloride), F(000) = 688,Cu-K, radiation, A = 1.5418 A; ~(CU-K,) = 24 cm-l.Systematic absences; OkO k = 2n + 1, lzOZ 12 + I =292 + 1.A crystal of dimensions 0.6 x 0-12 x 0.16 mm, parallelto a, b, and G respectively, was selected for the investiga-tion.Unit-cell and space-group data were obtained fromoscillation and Weissenberg photographs. The crystalwas then mounted with the a axis parallel to the instru-mental axis of a paper-tape controlled Siemens' four-circle diffractometer (A.E.D.) equipped with a scintillationcounter and pulse-height discriminator. The unit-cellparameters were refined by a least-squares treatment ofthe 8 values of 26 reflections. The intensities of 1993symmetry-independent reflections (sin O)/A < 0.61 weremeasured with Cu-K, radiation by the 8-20 technique,the scan ranges increasing linearly from 0.66" at 8 10" to1-10' at 8 65".The scan speed was 1" min-l in 8 andeach reflection was scanned twice (one full and two halfscans). The background was measured at both the be-ginning and end of each scan range for the same time asthat for the full scan across the peak. A reference reflection(0,2,0) was monitored after every 20 data reflections. Theintensity of this reflection decreased by 9% during the com-plete period of data collection. As a check on the longterm stability of both electronics and crystal, a set of fivereflections (0,1,1, 0, 1, I, 0,7,2, 0,5,2, and 1,4,1) was measuredevery 250 data deflections.They showed no significantchange, apart from the 9% decrease in intensity.Integrated net intensities were calculated from therelationship: whereSpace group, P2,/n.Inet = [(I1 + I, + I,) - (I, + Id)],D. W. Thompson, Structure and Bonding, 1971, 9, 27.2 ' International Tables for X-Ray Crystallography,' vol. 111,Iiynoch Press, Birmingham, 1962.I, and I, are the intensities for the half-peak scans, I ,is the intensity for the full-peak scan and Iz and I, arethe backgrounds a t each end of the peak scan.Each intensity was corrected for the variation of thereference reflection by the relationshipI c = Inet x IR/[(Ia + Ib)/2]where I, is the corrected intensity, I n is the intensityof the reference reflection at the start of the measurementsand I,, I b are the intensities of the reference reflection a tthe beginning and end of each block of 20 reflections inwhich the measurement occurred.The intensities wereassigned a variation of 0 2 ( I ) , from the equation:a2(I) = I, + I, + I, + I 4 + I,A reflection was classified as unobserved if I/a(I) < 2.0 andits intensity was replaced by ~(1). Of the 1993 reflections,802 were classified as unobserved. The intensities and theirstandard deviations were corrected for Lorentz and polaris-ation factors and placed on an approximately absolutescale by means of a Wilson plot. No absorption or ex-tinction corrections were applied.Structure Determination and Refinement.-The structurewas determined by Fourier methods.A three-dimen-sional Patterson map gave the co-ordinates of the nickelatom and a structure factor calculation gave R 0.42.From an electron-density map phased on the nickel atoms,the remaining light atoms (excluding hydrogen) were found.A structure factor calculation on these atoms, includingan overall isotropic temperature factor of B 4.5 A,, gaveR 0.28.Positional and isotropic thermal parameters and anoverall scale factor all refined by full-matrix least squaresdecreased R to 0.18. At this point, a Cruickshank weight-ing scheme (w-1 = A + BIF,I + CIFO2], with A = 6.0,B = 1.2, and C = 0.004) was applied to maintain themean wA2 approximately constant for different ranges ofF,.Several more cycles of weighted least squares reducedR to 0.11 and introduction of anisotropic thermal para-meters further reduced R to 0.086.A three-dimensional diff erence-Fourier map revealedthe positions of the hydrogen atoms. Two further cyclesof least squares, including the hydrogen atoms, decreasedR to its final value of 0.082. The hydrogen atoms were notrefined and were allocated isotropic temperature factorsof 5-0 A2.Allcalculations were performed on an Atlas computer ofthe S.R.C. Computing Laboratory, Hanvell by use of theprogram system ' X-Ray ',3 and as ICL 1905 F computera t the University of Surrey.' X-Ray '63,' program system, J. M. Stewart, University ofMaryland Technical Report, TR 64 6.Atomic scattering factors were taken from ref.2J.C.S. DaltonFinal positional and thermal parameters for all atomsexcluding hydrogen are listed in Tables 1 and 2. Hydrogenpositional parameters and their associated carbon-hydrogenTABLE 1Atomic co-ordinates ( x lo4), with estimated standarddeviations in parenthesesAtom X Y 2Ni 5533(1) 4527(1) 67 3 3 (2)4825(7) 3667 (3) 5154(9)4661 (7) 3969(3) 8648(8)7 5 12 (8) 4149(4) 7 1 32 (9)628 9 (7) 4957(3) 4509(8)6038(7) 4589(4) 8 1 25 (8)408 3 ( 10) 3248(4) 5975(11)3940( 10) 3430(4) 7945(ll)3 07 6 (1 3) 3078(5) 909 8 ( 1 4)2182( 12) 2499(5) 8713 (15)1 897 (1 2) 2097(5) 7095 (16)2491 (1 1) 2171(5) 6454( 16)3463(11) 2657(5) 4954( 14)8 137 (1 2) 4222(5) 5 7 13 ( 14)7419( 11) 4664(4) 4131 (1 1)7801 (1 1) 4747(5) 2351(14)9024(13) 4506 (5) 1637( 15)01 62 (1 3) 4134(6) 2521(17)0331 (12) 3 8 8 3 (6) 43 19 (1 8)9480( 13) 3 9 19 (6) 5741 (16)omOM0 (3)O(4)0 (5)C(1)C(2)(33) c (4)C(5)C(6)C(7)C(8)C(9)C(10)C(11)C(12)CP3)C(14)TABLE 2Thermal parameters * in [NiT,(H,O)], : anisotropicparameters (A2 x 10)Ni 467 295 282 1 96 6Atom Bll B22 B33 B12 B13 B230(1) 458 213 217 -13 115 -41O(2) 280 202 186 -11 106 1O(4) 292 231 180 42 71 37C(l) 117 245 179 91 23 10C(2) 222 183 206 97 53 44C(3) 503 298 280 -111 105 43C(4) 326 354 390 -78 99 9O(3) 378 319 235 -41 62 23O(5) 380 265 250 -32 65 -48C(6) 269 240 436 -27 52 -3C(6) 200 292 475 -22 62 -85C(7) 216 315 296 -26 59 -93C(8) 295 231 264 -41 49 -3248 152 2 8 -31C(11) 365 461 330 -151 131 -21284 550 399 52 53 -12220 451 592 93 143 -43C(14) 288 404 378 5 13 -32E[!b) ”z! 354 276 -30 147 -11* Temperature factors are in the form: e~p*-~(BllhZa*2 +B22k2b*z + B3,Z2c*2 + 2BI2hka*b* + 2B,,hla t + 2B2,klb*c*TABLE 3Atomic co-ordinates ( x lo3) and bond lengths (A)for the hydrogen atomsX32317511420035470790406 1132968Y333222172194269496464437374369205096898643636413203610948669 1H(n)-C(n)1.101.011.020.960.961-030.911.251.020.94DISCUSSIONA perspective drawing of the whole molecule, ex-cluding hydrogen atoms, is shown in Figure 1.Themolecule is dimeric, the centre of symmetry inherent inthe space group lying midway between the two nickelatoms of each dimer.FIGURE 1 A perspective drawing of the dimer1 1 k 4 $ ? 33s0 12FIGURE 2 Bond distances (A).Mean Q = Ni-Ni’ 0.004,Ni-O 0.006, C-0 0.009, C-C 0.009Figures 1-3 show that there are two types of tropo-to one nickel atom only and one (ligand B) which alsoco-ordinates to the first nickel atom and to the secondvia a bridging oxygen atom, O(4). With one ligand ofbond lengths are listed in Table 3.publication No. SUP 20610 (11 pp., 1 microfiche).*(A), 1970, Issue No. 20.Final observed andcalculated structure factors are listed in supplementary lone ligand in the : One (kand A) “-Ordinating* For details see Notice to Authors No. in J .sot1973 699each type, and one water molecule, co-ordinated through0 ( 5 ) , to each nickel atom, a six-co-ordination is attainedby the latter.The bond lengths and ligand angles of the asymmetricunit of the complex are shown in Figures 2 and 3,together with the atom numbering scheme used. Thenickel-nickel distance (3.11 A) is too long for anymetal-metal interaction to occur, and is longer than thecorresponding distance in many other, associated, nickelcomplexes where the shorter Ni-Ni distance is structuredetermining. In tetrakis(2-aminoethanethio1ato)tri-nickel (11) ,4 bis (monothiobenzoato)nickel(II) ,5 and bis-(dithiophenylacet ato)nicke1(11) ,6 the Ni-Ni distancesare 2.73, 2-49, and 2-56 A. The possibility of dimerformation in the nickel tropolonate complex, to takeadvantage of metal-me t a1 interaction can, theref ore,be excluded.5(l)dll4*3 113.9 '012)O(5)Ni' hg./( 4 ) 0 113.9 113.6,0(3)12The nickel-oxygen distances exhibit a variationwhich appears to be real.The longer Ni-O(5) distance,for the co-ordinated water molecule indicates that it isnot bonded as strongly to the nickel atom as are thetropolone molecules and this is in keeping with thechemical behaviour of the compound.The atom O(4) forms bonds of unequal length to thetwo nickel atoms which it bridges. If one considers thesteric requirements of the bridging tropolone ligand,the ' bite ' of the ligand (the ' bite ' is the distancebetween the chelating oxygen atoms of one ligand), doesnot exceed 2-60 A in this structure, or in any of theC.H. Wei and L. F. Dahl, Inorg. Chem., 1970, 9, 1878.5 N. Bonamico, G. Dessey, and V. Fares, Chem. Comm., 1969,N. Bonamico, G. Dessey. andV. Fares, Chem. Comm., 1969,7 H. Shimanouchi and Y . Sasada, Tetrahedron Letters, 1970,FIGURE 3 Bond angles ("). Mean Q = 0.2-0.9"697.1106.28, 2421.published structures of tropolone compounds. From ageometrical consideration of the Ni-0 distance (meanca. 2.05 A), and the angular relationships in the triangleformed by Ni-O(4)-Ni', it is apparent that equalsharing of the bridging oxygen atom could only occurif the Ni-Ni' distance was very much closer to 3 Athan it is in nickel tropolonate. It is incorrect to as-sume, therefore, that unequal sharing of the atom,0(4), is due to any inherent weakness of the tropoloneligand to form bridged complexes.The carbon-carbon bond lengths are in good agree-ment with those reported for other tropolone complexesand with tropolone itself .' The mean carbon-carbonbond length is 1.401 A for ring A, and 1.396 A for ring B.The very much longer C(1)-C(2) and C(S)-C(9) distances,probably indicate that these bonds are not appreciablyinvolved in the electron delocalisation experienced bythe remainder of the ring.The mean C-H distance(1.04 8) (Table 3) is in fair agreement with reportedvalues .*99TABLE 4Angles (") subtended at the NiII atomO( 1)-Ni-O(2) 79.44 * 0 (3)-Ni-O (4) 79-11 *94.79 O( 1)-Ni-O( 3) 92.16 0 (3)-Ni-0 (5)O( 1)-Ni-O( 4) 90.96 O( 3)-Ni-O( 4') 160-860 (1)-Ni-0 (6) 171-98 0(4)-Ni-0(5! 86.43O( 1)-Ni-0 (4') 86-30 0 (4)-Ni-O (4 ) 81.840 (2)-Ni-0 (3) 101.55 0 (5)-Ni-0 (4') 85.8388-12 0 (2)-Ni-0(4) 170-390(2)-Ni-0(6) 103.02 0 (6)-Ni-Ni' 84.8698-16 0(2)-Ni-0(4') 96.920 (1)-Ni-Ni'Ni-O( 4)-Ni'* Angles subtended by the ligands.TABLE 5Oxygen-oxygen distances (A) in the co-ordinationpolyhedronO(1) * - * O(2) 2.588 * O(2) * * O(4') 3-079 *0(1) * * * O(3) 2.973 O(2) * * * O(5) 3.2120 ( 1 ) * * * O(4; 2-891 O(3) * O(4) 2.577 *0 ( 1 ) * - O(4 ) 2-838 O(3) * * * 0(5! 3.0410(1) - * * O(5) 2.862 O(4) * * * O(4 ) 2-699O(2) * - O(3) 3.131 O(4) * * O(5) 2-814* Ligand ' bite ' distances.The co-ordination stereochemistry experienced by thenickel atom is considerably distorted octahedral.Theprimed numerals in Figure 1 denote the centrosym-metrically related atoms. The 0-Ni-0 angles are givenin Table 4 and the oxygen-oxygen distances in the co-ordination polyhedron in Table 5 . The angles sub-tended by the chelating oxygen atoms are ca. 79", andthis is due to the rigid co-ordination system of tropolone.Table 6 lists equations of best mean planes and de-viations and atoms from these.Both ligands A and B exhibit folding about the linesdefined by the respective co-ordinating oxygen atoms.Thus, for ligand A, the plane defined by 0(1), C(1), C(2),O(2) is at an angle of 8" to the plane 0(1), Ni, O(2).For ligand B, the corresponding angle is 15". In the* V. W. Day and J. L. Hoard, J . Amer. Chem. SOC., 1970, 92,3626.9 J.J. Park, D. M. Collins, and J. Id. Hoard, J . Amcr. Chmz.SOC., 1970, 92, 3636700 J.C.S. DaltonTABLE 6Equations of test planes in the form PX + Qy + l?,z = swhere x , y, and z are fractional co-ordinates. Devi-ations (A) of atoms from the planes are given in squa,rebracketsP Q R SPlane (1) :C(1)--(7), 0(1)* O(2) -7.042 11.375 -1.655 -0.1663[ 0(1) -0.087, O(2) 0.033, C(l) 0.004, C(2) 0.022, c(3) O.004,C(4) -0.030, C(6) -0-040, C(6) 0.022, C(7) 0.071, Ni- 0.306)Plane (2) :-6.909 11,506 -1.784 -0.1885[C(1) -0.033, C(2) 0.005, C(3) 0.018, C(4) -0.001, C(5)C(1)-(7)-0.024, C(6) 0-008, C(7) 0.031, Ni -0.3731Plane (3) :c(8)-(14)J 0(3)J 0(4) 4.168 15.698 2.089 11.2360[0(3) 0.109, O(4) -0.103, C(8) 0.030, C(9) -0.033, C(10)0.048, C(11) 0.067, C(12) -0.002, C(13) -0.068, C(14)-0.058, Ni 0.4211Plane (4) :C(8)-(14) 4-054 15.985 1.932 11.2070[C(8) 0-056, C(9) -0.063.C(10) 0.002, C(11) 0.030, C(12)-0.003, C(13) -0.022, C(14) -0.009, Ni 0,4271copper complex, CuT,,lO similar behaviour is reportedalthough the angles concerned are only ca. 4". CUT,was also found to exhibit carbon-carbon bond-lengthalternation around the ring, and this was thought to bedue to the loss of ligand planarity, and a resulting de-crease in electron delocalisation efficiency. NO bond-length alternation is exhibited in the nickel complexor in the complexes ThT,(DMF),8 SnT3C1,9 and SnT,-(OH) ,9 where similar ligand-folding effects also exist.The carbon rings also deviate from planarity.RingA exhibits a fold with atoms C(2), C(3), C(6), and C(7)above the mean plane of the ring and atoms C(l), C(4),and C(5) below. Ring B exhibits a twist about an axisrunning through C(12) and the mid-point of C(8)-C(9).The arrangement of adjacent molecules in the lattice,as viewed along the c axis, is shown in Figure 4, and asviewed along the a axis in Figure 5. Figure 4 showshow the tropolone rings of each molecule fit betweenthe rings of adjacent molecules. The distance betweenadjacent molecules is not (3.7 A, which is themean distance for van der Waals interaction betweenaromatic rings.ll Figure 5 shows that although thedistance between neighbouring rings is not less than thevan der Waals distance, atom 0 ( 5 ) , of the water mole-cule, approaches parts of the adjacent molecule closelyenough to indicate a much stronger interaction,which almost certainly indicates hydrogen bonding.Because the distance between O(5) and its nearestneighbour [0(2') on the next molecule] is small (2.70 A),the hydrogen bond is probably not linear.Theappearance of the difference-Fourier synthesis in thisregion shows a toroid of electron density of ca. 0.5 eA-3,surrounding the O(5) site. Unlike the ring hydrogenatoms, no definite hydrogen atom positions are apparentclose to O(5). This may indicate greater thermallo W. M. McIntyre, J. M. Robertson, and R. F. Zahrobsky,proc. Roy. Soc., 1966, A, 289, 161.motion or disorder of the water molecule although theformer is not supported by an increase in the thermalFIGURE 4 View along the c direction (five molecules), drawnon a left-handed system of axes viewed from -cbFIGURE 5 View along the a direction (two molecules)parameters for O(5). Each dimeric molecule has astrong interaction, through hydrogen bonding, to itsl1 R. C. Weast, ' Handbook of Chemistry and Physics,' 51stedn., Chemical Rubber Co., 19701973 701neighbour and this results in lines of dimers along thec direction, so close together that they almost form atrue polymeric lattice.The reason for the stability of the present complexcompared with bis(acetylacetonato)nickel(II) is probablyconnected with the ability of the tropolones of eachdimer to approach adjacent molecules in the c directionsufficiently closely to allow the terminal water moleculesto form hydrogen bonds with the closest tropoloneoxygen atoms. Such an effect would be less likely ifthe ligands were not small and compact.The present dimeric complex represents the firstconfirmed oxygen-bridged structure with tropolone.Other examples of bridge structures, such as the variousseven-co-ordinate lanthanide complexes, almost certainlyexist, and a preliminary study of the cobalt@) complexwith tropolone, shows it to be a tetramer.We thank the S.R.C. for a maintenance award (toM. L. P.), and Dr. M. F. C. Ladd for helpful comments andfor making the X-ray equipment available.[2/955 Received, 1st May, 1972
ISSN:1477-9226
DOI:10.1039/DT9730000697
出版商:RSC
年代:1973
数据来源: RSC