摘要:

1972 1433Crystal and Molecular Structure of [N"-ethylenebis(sa1 icy1 idenei min-ato)]pyridine(vinyl)cobalt(iii). Evidence of trans- and cis-Influence inOctahedral ComplexesBy M. Calligaris, G. Nardin, and L. Randaccio," lstituto di Chimica, Universita di Trieste, 341 27 Trieste, ItalyThe crystal structure of the title compound has been determined from three-dimensional X-ray data by conventionalFourier methods. The crystals areorthorhombic,space group Pnma, withZ = 4, and cell dimensionsa = 15.902(5).b = 17.871 (1 0), c = 6.746(4) A. After an anisotropic block-diagonal least-squares refinement R was 0.070for 91 7 reflections. The cobalt atom has a distorted octahedral co-ordination polyhedron. The ' salen ' ligandoccupies the four equatorial positions whereas the vinyl group and the pyridine molecule occupy the two axialpositions [Co-C 1.93(2) and Co-N 2.1 2(1) 81.The complex has an umbrella-shape conformation with apparentm symmetry because of the statistical disorder of the vinyl group and ethylene bridge in the mirror plane. Com-parison of the cobalt-axial-ligand bond lengths with those of analogous compounds provides further evidence oftrans- and cis-influence in such octahedral complexes.THE three aspects of the trans-effect of a ligand in octa-hedral complexes, i.e. kinetic, thermodynamic, andground-state, have been widely studied.l Recently anincreasing amount of experimental data has beenreported on the last two aspects, because they can bemore simply rationalised, and the simple electronicmodel, which has been suggested to explain the trans-influence in square planar2 complexes, has been ex-tended to octahedral complexe~.~The octahedral cobalt complexes having as equatorialligands quadridentate Schiff bases like bae t andsalen $ revealed themselves a suitable system to studytrans- and cis-influence because it is possible to obtainseries of strictly related compounds, where more re-liable comparisons can be carried out.Recently we have reported evidence of trans-in-fluence in this type of ~omplex.~The results of the structure of [NN'-ethylenebis-(salicylideneiminato)] p yridine (vinyl) cobalt (111) determin-ation, related to those previously reported, give furtherevidence of trans-influence.Furthermore, the analysisof the structural data of this and analogous compoundssuggests the possibility of cis-influence of the differentquadridentate ligands on the axial bonds.EXPERIMENTALCrystal Data.-C,,H,,CoN,O,, M = 431.4, Orthorhombic,a = 15.902 & 0.005, G = 6.746 fF(000) = 896.Mo-K-, radiation, h = 0-71069 A; ~ ( M o -I<%) = 17.8 cm-l. Space group Pnma (0:;) from struc-ture determination. Cell parameters were determinedProin precession photographs and after alignment of thecrystal on a Hilger and Watts four-circle diffractometer,were refined by the least-squares method of Busing andLevy,5 by use of twelve high-angle reflections scannedmanually on all four circles with a small receivercollimator.Intensity Measurements.-Intensity data were collectedon a Hilger and Watts four-circle diffractometer by use ofPIIo-K, radiation utilising the method of balance filters,5.bae = Dianion of bis(acety1acetone) ethylenedi-imine. 1 salen = Dianion of bis(salicyla1dehyde)ethylenedi-imine.b = 17.871 -& 0.010,0.004 A, U = 1916.8 A,, D, = 1.50, 2 = 4, D, = 1.495,G. Costa, G. Mestroni, A. Puxeddu, and E. Reisenhofer,J . Chew. SOC. ( A ) , 1970, 2870, and references therein.for a maximum 28 angle of 50". The 8, w scan techniquewas used with a scan rate of 1" min-1 for a constant scanwidth of 1-4". The background radiation was countedfor 15 s at both extremes of the scan range with both thecrystal and counter stationary. Reflections for whichI , < 3 Q (I,) were rejected, the remainder being correctedfor Lorentz polarisation factors.A total of 917 reflectionswas obtained. No correction for absorption (pR ca. 0.3),extinction, or anomalous dispersion of the cobalt atom wasapplied.Structure Determination and Re$nement.-The structurewas solved by conventional Patterson and Fourier methodsassuming the Pnma space group which was suggested bythe vector distribution on the three-dimensional Pattersonmap. The carbon atoms of the ethylene bridge and thoseof the vinyl group clearly appeared disordered. In factthe electron-density maps show that the vinyl group liesout of the crystallographic mirror plane, and the ethylenebridge is located in two symmetrical arrangements, eachcarbon atom having an occupancy factor F of 0.5.This suggests the possibility that, because of small dis-torsion from exact mirror symmetry of the molecule, thestructure could belong to the non-centrosymmetric spacegroup Pna2, (after interchanging of b and c axes).There-fore an isotropic full-matrix least-squares refinement hasbeen carried out adopting both space-groups. After fivecycles, acceptable values of bond lengths and angles wereobtained only for the centrosymmetric space group. Infact the corresponding bond lengths of the two chemicallyequivalent halves of the molecule were quite differentafter the non-centrosymmetric refinement and oftenmeaningless, e.g. in the pyridine molecule the N-C distanceswere 1.26 and 1.44 A, whereas the C-C distances rangedfrom 1-19 to 1.56 A, A further anisotropic refinementwas then carried out in space group Pnma, with all atomstreated anisotropically except for the carbon atoms of theethylene and vinyl groups.The contribution of thehydrogen atoms of the carbon atoms with occupancy factor1.0 was then included and held constant ( B = 5.0 A2)in the last refinement which reduced Iz to 0.070. Theminimised function was X(wIFol - IF,()2. The expressionused for the weighting factor was w = ( A + BIFol +2 R. McWeeny, R. Mason, and A. D. C. Towl, Discuss. FaradayR. Mason and A. D. C. Towl, J . Claem. SOC. ( A ) , 1970, 1601.M. Calligaris, D. Minichelli, G. Nardin, and L. Randaccio,W. R. Busing and H. A. Levy, Acta Cryst., 1967, 22, 457.SOC., 1969, 47, 20.J. Chew. SOC. ( A ) , 1971, 27201434 J.C.S.DaltonICIF,(2)-1 where A = 0.11, B = 7-94 x and C = and 8. programme of our own design (unpublished) was1-35 x were chosen to maintain w(lF,I - IFcl)2 used to calculate best molecular planes. Least-squaresessentially constant over all ranges of IFo/. The finalatomic parameters are listed in Table 1, together with theirestimated standard deviations as derived from the residualsand the diagonal elements of the inverse matrix of the last Description Of the StT'ztCtZtT'e.-'rhe results Of the x-raycycle of the refinement. The numbering scheme for the analysis show that the crystal consists of discreteatoms is shown in Figure 1. Observed and calculated molecules with distorted octahedral stereochemistryplane equations were calculated according to ref.9.DISCUSS1oNTABLE 1Fractional atoniic co-ordinates and thermal parameters * with their estimated standard deviations in parenthesesX0*1701(1)0*1429(4)0.1 989(5)0*2956(6)0*1355(5)0.1030 (6)0.0906( 7)0.1115(8)0*1459( 7)0*1571(5)0*1900( 6)0.336766)0.41 74(6)0*4593(8)0.2 102( 12)0.2491 (12)0.057 6 (9)0*0052( 14)0.08680.06540.09830.16610.20980.4481Y0-25000.32 1 3 (4)0-3207 (5)0.25000.3941(5)0*4367(5)0.51 26(6)0*5469(6)0*5085(6)0*4296(6)0-3912(7)0.3 142 (6)0*3156(6)0.25000*2799( 10)0.2034( 11)0.231 8(8)0.2 840 ( 12)0.40860.54550.60670.53860.42580.3686z0-0531(3)0-2437( 11)-0.1412(9)- 0*0537( 16)- 0.1 1 1 1 ( 14)-0*2683(16)- 0*2508(20)- 0.0730(23)0*0784(20)0.06 5 8 ( 1 6)0-2320( 15)- 0*0905( 14)- 0.1 620( 16)-0*1969(21)0-4463( 32)0-4099(29)0.1478 (24)0.204 1 (34)- 0.4079- 0.3746- 0.05600-21210.3578-0.1920B,,2.07 (5)3*57(26)4*00(34)2.44(36)2*82( 35)3.64( 42)5.55 (60)6*85( 67)5-2 8 (5 1)3*36(38)3.01(37)3.25 (37)2*64(52)B/A24.17 (38)4.29 (42)2.95(37)5.08( 9 1)5.05.08.05.05.06.03*37(45)B223-7 3( 7)4-05(29)5.06( 40)3.03(43)3.7 l(45)4-02 (55)3*88(48)4.67 (52)4.82 (46)7*16( 65)4*40(4)5.03 (48)7*08( 104)3.75(44)B,,1 * 88 (6)2-51 (26)2*14(31)4*40( 50)4-9 1 (52)6.67( 67)9.1 4( 99)6-91(79)4*48(53)3*55(46)4.20( 49)4- 18(47)2.74( 43)3.49(75)B1200.77(22)1-49(31)00.1 8(32)-0*16(34)- 0*44(43)- 0.05(46)- 0*37(40)0.22(34)0.55 (40)-0.45(35)- 1.13(36)0B130*16(6)- 0.41 (22)- 0.77(28)- 0*24(34)0-40( 40)0*12( 41)0.96(54)0.20( 72)0.43 (53)0.35( 40)0.14 (35)- 0.27(35)- 0*12(37)0.88 (5 1 )B2300.3 6 (24)- 0*78(31)0O*12( 39)0*55(42)0.36 (56)0*58(59)- 1*79(66)- 1.87(46)- l.Ol(48)0.36(34)1 a25 (44)0F0.51.01.00.51.01.01.01.01.01.01.01.01.00.30.50.60.50.5* Anisotropic temperature factors are defined by the expression: exp[-&(Bllh2a*2 + B22k2b*2 + B3312~*2 + B,,hka*b* +-2Bl,hZa*c* + 2B2,klb*c*)].structure factors are listed in Supplementary PublicationNo.SUP 20373 (6 pp., 1 microfiche).*Atomic scattering factors were calculated accordingto the expression f(x) = A exp (-ax2) + B exp (-bx2) +C, where x = sin O/A and the constants were those givenin ref.6.\C(CfU2'FIGURE 1 Numbering scheme for the atomsCaZcuZations.-All calculations were performed on anIBM 7044 computer, using programmes described in refs. 7* For details see Notice to Authors No. 7 in J . Chem. SOG. ( A ) ,1970, Issue No. 20 (items less than 10 pp. are sent as full sizecopies).II F. H. Moore, Ada Cryst., 1963, 16, 1169.A. Immirzi, Ricerca sci., 1967, 10, 846.around the cobalt atom, The salen ligand occupiesthe four equatorial positions, whereas the vinylgroup and the pyridine molecule occupy the axialpositions. The crystallographic mirror plane relatesthe two salicylaldimine residues of the equatorialligand and half the pyridine molecule, the whoIecompound attaining the apparent 992 symmetry bystatistical disorder of the vinyl group and ethylenebridge in the mirror plane.The equatorial donoratoms are exactly coplanar, the cobalt atom beingslightly displaced (0.016 A) towards the vinyl group.The crystallographic independent salicylaldimine residueis nearly planar (50.04 A), the angle between itsplane and the equatorial co-ordination plane being 8.4".Therefore the two halves of the equatorial ligand arebent towards the vinyl group at an angle of 16.8".This umbrella-shape conformation is very similar tothat found in the five-co-ordinated [Co(salen) (py)] ,lo inwhich the angle between the two halves of the salenligand was 28.8".These values of the bending are8 V. Albano, A. Domenicano, and A. Vaciago, Gazzetta, 1966,9 V. Schomaker, J. Waser, R. F. Marsh, and G. Bergman,10 M. Calligaris, D. Minichelli, G. Nardin, and L. Randaccio,96, 922.Acta Cryst., 1959, 12, 600.J. Chem. SOC. ( A ) , 1970, 24111972easily interpreted in terms of different inter-ligandrepulsion in the five- and six-co-ordinate species.The plane passing through the pyridine molecule isnearly perpendicular to the equatorial plane (88.5")and parallel to the N(1)-N(1') direction as in the [Co-(salen) (py)] compound.lO Conversely the ethylenebridge is found in a nearly gauche conformation with atorsional angle around the C-C bond of 44.9". It seemsa general rule that for salen and bae cobalt complexesthe ethylene bridge prefers a nearly gauche conformationin the octahedral species, whereas an eclipsed conform-ation is more easily assumed in the square planar andsquare pyramidal complexes.Table 2 lists a series ofsalen and bae cobalt derivatives together with the tor-sional angle around H,C-CH, bond and the type ofstereochemistry around the cobalt atom.FIGURE 2 A side view of the moleculeThe vinyl group is disordered in such aTway that onehalf group is arranged above one salicyaldimine ring, thedihedral angle between the planes through Co, C(D),C(10) and N(l), Co, C(9) being 43.5". The mirrorsymmetry relates the geometrical arrangement in theother half of the complex. A side view of the moleculeis shown in Figure 2.Bond lengths and angles are reported in Table 3together with their estimated standard deviations.The values of the interatomic bond distances in thesalen ligand are in agreement, within experimental errors,with the mean values recently reported for a series ofsalen cornplexes.ll The Co-C(sj2) bond length is1.93(2) A.Correction from sP2 to sfi3 carbon a-covalentradius gives a value of 1-95 A which must be comparedwith the average Co-C(sP3) bond length found in othersalen organometallic derivatives (2-00 A). Becauseof the low accuracy of the carbon atom location thisdifference does not appear significant. However wenote that the same difference is found in the corre-sponding bae organocobalt derivatives [Co-C (vinyl)1-89 A and Co-C(sp3) 1.95 A].12trans- and cis-In$ztence.-The most important resultarising from the comparison of the axial bond lengthsl1 AT.Calligaris, G. Nardin, and L. Randaccio, Co-ovdinationChum Rev., 1972, 7, 385TABLE 2Conformation of the ethylene bridge and stereochemistryof some salen and bae cobalt complexesd(") S tereochemistry[Co(salen)], 8 38.7 Square-planar pyramid *[Co(salen)]CHCl, 6 10.8 Square-planar[Co(salen) (PY)I 0 Square-planar pyramid[CH,CH,Co(salen)], d 44.0 Square-planar pyramid *[Co,(salen),O,(dmf),1 39.5 Octahedral[(MeCOCH,) Co(sa1en) (MeOH)] 37.9 Octahedral43-0 Octahedral34.6 Octahedral [(CN-CH,)Co(salen)], f[CH,:CH)Co(salen) (py)] 0 44-9 Octahedral[PhCo(bae)(H,O)] 32.9 Octahedral[MeCo(bae)] 4 2.2 Square-planar pyramid[ (CH,:CH) Co( bae) ( H,0)] j 42.6 Octahedral[CO(bae)l,C,H, 0 Square planar[(MeO)Wsalen) (PY)l* These compounds have a dimeric structure, where strongnonbonded interactions significantly alter the overall conform-ation.a S.Briickner, M. Calligaris, G. Nardin, and L. Randaccio,Acta Cryst., B25, 1969, 1671. b W. P. Schaefer and R. E.Marsh, Acta Cryst., B25, 1969, 1675. Ref. 10. Ref. 4.M. Calligaris, G. Nardin, L. Randaccio, and A. Ripamonti,J. Chem. Soc. ( A ) , 1970, 1069; dmf = dimethylformamide.M. Cesari, C. Neri, G. Perego, E. Perrotti, and A. Zazzetta,Chem. Comm., 1970, 276. p Present work. h S. Bruckner,M. Calligaris, G. Nardin, and L. Randaccio, Chem. Comm.,1970, 152. i S. Briickner, M. Calligaris, G.Nardin, andL. Randaccio, Inorg. Chim. A d a , 1969, 8, 308. j Ref. 12.k S. Briickner, M. Calligaris, G. Nardin, and L. Randaccio,Inorg. Chim. Acta, 1968, 2, 386.TABLE 3Bond lengths (A) and angles (") with their estimatedstandard deviations in parentheses. Primed symbolsrefer to the corresponding atoms related by thecrystallographic mirror plane(a) Distancesco-0 1.878(7) C( 1)-C(6) 1-39( 1)Co-N(l) 1 -860( 8) C(2)-C(3) 1.38( 1)1*39(2)1.36(2)1.42(2)1-42(2)N(I)-C(8,1) 1-56(2) C (8,l)-C( 8,2) 1 4 2 (3)N( l)-C(8,2') 1*44(2) C( 9)-C( 10) 1 *31(3)N(2)-C(ll) 1.34(1) C( 1 1)-C( 12) 1.37(1)C( 1)-C(2) 1*40( 1) C( 12)-C( 13) 1-371 1)C(3)-C(4) Co-N (2) 2.1 2 (1)Co-C(S) 1-93(2) C( 4)-c (8)1 -32 ( 1) C(5)-C(6) 0-C(1)N(l)-C(7) 1.27(2) C(6)-C(7)(b) Angles0-co-0' 85*4(3) 0-C(1)-C(2) 1 16.8( 8)0-CO-N ( 1') 179.0(3) O-C(l)-C(6) 13 1.9 (9)O-Co-N( 1) 94.6(3) C(2)-C(l)-C(6) 119*4(9)O-co-N( 2) 88.8 (3) C (1 )-C (2)-C (3) 12 1 *6 ( 10)0-Co-C(9) 97.6(5) C(2)-C(3)-C(4) 118*4(11)0'-co-C( 9) 84*0(6) C(3)-C(4)-C(6) 121*9(10)N( 1)-Co-N( 1') 84*4(5) C(4)-C(5)-C(6) 120-7(11)N ( l)-Co-N (2) 1 18- 1 ( 10)N( l)-Co-C( 9) 1 2 3.3 ( 1 0)N(l')-Co-C(S) 83.4 (6) C (5)-C (6)-C (7) 1 1 8.6 ( 10)co-0-c ( 1) 1 2 5 q 6) N (I)-C( 7)-C( 6) 124.9( 10)Co-N ( 1 )-C (7) 127.1 (7) N( l)-C(8,1)-C(8,2) 109-0( 15)Co-N(1)--C(8,1) 108*5(8) N(l')-C(8,2)--C(8,1) 99.7(14)CO-N( 1)-C (8,2') 1 18.1 (1 0) CO<( 9)-C ( 10) 124.6 ( 13)C(7)-N(l)-C(g,l) 122.1( 10) N(B)-C(ll)-C( 12) 122.4( 10)C( 7)-N ( I)<( 8,2) 1 20-0( 10)CO-N (2)-C( 1 1) 1 1 7- 8 ( 1 1)C( 1 1 )-N (2)-C( 1 1')90.2 (3)96.6 ( 5 )C ( l)-C( 6)-C( 5 )C ( 1)-C (6)-C (7)1 14.0( 1 1)12 1.4( 6)1 17.3 (9)C( 1 1)-C ( 12)-C( 13)C( 12)-C ( 13)-C( 1 2')in this and analogous compounds is the evidence oftrans- and cis-influence in octahedral cobalt complexes.l2 S.Bruckner, M. Calligaris, G. Nardin, and L Randaccio,Inovg. Chim. Acta, 1968, 2, 4161436 J.C.S. DaltonTABLE 4Correlation between Co-X bond lengths (-4) and Co-L S2IAE values in salen octahedral cobalt complexesS21AE*Compound L X co-x (eV-l. lo-,)[ClCo(salen)], -c1 -0 1-995(13) <0*9[(MeO)Co(salen) (py) j f --OCH, -N 2.03 1 (9) <0.9I Co,( salen),O,( dmf) J - 0 2 -0 2.150(7) < 0.9[ E tCo (salen)] , b -CH,CH:, -0 2-342 (3) 1.4[ (CN.CH,)Co(salen)], f -CH,CN -N 2*092(17) 1.4(CH,:CH)Co(salen) (py)] -CH=CH, -N 2.1 19( 10) 1.5[(MeCOCH,)Co(salen) (MeOH)] f -CH,COCH, -0 2*02( 9) 1.4* Data from Ref.3.a B. C. Wang and W. P. Schaefer, personal communication. b Ref. 4. C-g See footnotes to Table 2.A simple model has been recenly suggested to explainthe trans-influence in square planar and octahedralcomplexe~.~ This is that in an X-M-L system theIvans-influencing ability of the ligand L increases withincrease of the ratio S2/AE, where S is the overlapintegral between the L o-hybrid and metal P o orbitals,TABLE 5Co-C bond lengths (A) in some organo-cobalt complexesMean cis-[(MeO,C*CH,)Co(drng),(py)] a 2.040(6) 2.04 dmg2.00 salen[EtCo(salen)J, 1 *990(7)[ (MeCOCH,) Co( salen) (MeOH)] C 1-99(2)[ (CH2:CH) Co (salen) (py)] 1*93(2)Compound Co-C Co-C(sp3) Ligand[(NC.CH,)Co(salen)], 2.02(1)bae [MeCo(bae)] 1-95(2)[PhCo( bae) ( H,0)] f 1-93(2)) 1.95[(CH,:CH)Co(bae) (H,O)] 0 1-89(1)a P.C. Lenhert, Chenz. Comm., 1967, 980. b Ref. 4.C Ref. fof Table 2. Present work. c--g Refs. i--k of Table 2.We have applied the same model to interpret thetrans-influence in the salen octahedral complexes asshown from the data of Table 4. It can be seen that inall three cases reported, the Co-X distance increaseswith the increasing of the S2/AE ratio; however theagreement between the two trends is only qualitative.The Co-C bond lengths in this and similar Complexesare listed in Table 5.The values seem t o be indicative of a cis-influence ofthe different quadridentate equatorial ligands salen,bae, and dimethylglyoximate (dmg) on the Co-C axialbond lengths, which increase in the order bae < salen <dmg. The same trend has been already observed forother properties of these c0mp1exes.l~We are grateful to Professor K. Mason for allowing us touse the Hilger and Watts diffractometer of the Depart-ment of Chemistry in the University of Sheffield, andB. Law for help in collecting data. This research has beenin part supported by C.N.R., Rome (Italy).[1/1223 Received, 19th JuZy, 19711and hE is their absolute energy separation. Thishypothesis has foundsquare planar and d6 octahedral complexe~.~l3 A. Bigotto, G. Costa, G. Mestroni, G. Pellizer, A. Puxeddu,E. Reisenhofer, L. Stefani, and G. Tauzher, Inorg. Chim. A d a ,Rev., 1970, 4, 1971.for a series Of Pt'

ISSN:1477-9226    

DOI:10.1039/DT9720001433

出版商:RSC    

年代:1972

数据来源: RSC