Znorg. Chem. 1980,19, 3306-3316
3306
.
of the arsolane ring species, this influence of methyl substitution on ring stability is consistent with that observed for arsenium ion stability. All of the arsenic-containing ions in these aminoarsolanes can be assigned structures in which arsenic is monovalent/ divalent or divalent/trivalent. No major peaks in the spectra can be assigned structures containing the As=O bond or trivalent/tetravalent arsenic. Such results are in agreement with those of Freryen and Maller24i43for 2-substituted 1,3,2dioxarsenanes and esters of arsenious acid and may be related to the thermodynamic stability of the As=O bond.43 Freryen and Merller" observed that the main fragmentation route for the [M - R]' ion in the substituted 1,3,2-dioxarsenanes was caused by the loss of CHIO and that, in some cases, the molecular ion directly eliminated aldehyde. Such 1 elimination is not observed for OCH2CH20AsN(C2HS)2 and I OCH,CH,OASN(~-C,H,)~but appears to be an important process in the fragmentation of the methyl and ethyl derivatives of the 2-(dialkylamino)-4,4,5,5-tetramethyl-l,3,2-dioxarsolanes. t
I
(43) Froyen, P.; Moller, J. Org. Mass Spectrom, 1973, 7, 73.
Acknowledgment. The support from the Research Corp. and the University College Committee on Faculty Research Grants at the University of Alabama in Birmingham is acknowledged. The assistance of Dr. R. King at the University of Florida in obtaining the mass spectra is greatly appreciated.
. .
Registry No. OCH2CH20AsCI, 3741-33-1;OCH2CH20AsN(CH3)2, 27262-85-7; O C H ~ C H ~ O A S N ( C ~ H34713-88-7; ~)~, OCH2CH20AsN(n-C3H7),, 74466-67-4; , I O C ( C H ~ ) ~ C ( C H ~ ) ~ O A54128-06-2; SCI, OC(CH~)~C(CH,)~OASI N(CH3)2, 57938-74-6;O C ( C H J ~ C ( C H ~ ) ~ O A S N ( C 74466~H~)~, I Q 7 74466-69-6;[OC(C68-5; OC(CH~)~C(CH~)~OASN(~-C~H~)~, r H ~ ) ~ C ( C H ~ ) ~ O A S ]74466-70-9; [OC(CH~)~C(CH~)~OAS]~, ~NH, NCH3, 74466-71-0;O C ( C H ~ ) ~ C ( C H ~ ) ~ ~ A S N H (74466~-C~H~), , 14849-23-1; AQ72-1;OCH~CH~OASOCH~CH~OASOCH,CH,O, [N(n-C4Hg)],, 3690-32-2;(n-C3H7)2NH,142-84-7;n-C4H9NH2, 109-73-9; CH3NH2, 74-89-5; "3, 7664-41-7.
. .
-
.
Supplementary Material Available: A listing of infrared and mass spectral data (4pages). Ordering information is given on any current masthead page.
Contribution from the School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801, and the Research School of Chemistry, The Australian National University, Canberra, A.C.T., Australia
Metal Complexes of Diiminodiphosphines. Structural and Reactivity Patterns JOHN C. JEFFERY, THOMAS B. RAUCHFUSS,* and PAUL A. TUCKER
Received June 4, 1980 The coordination chemistries of ~,N'-bis[o-(diphenylphosphino)bnzylidene]ethylenediamine (en=P2) and the corresponding 1,3-diaminopropane derivative (tn=P2) have been explored for the metals nickel, copper, and silver, and these results provide fundamental information on this novel class of metal complexes. The ligands function as tetradentate chelating agents for these metal ions as inferred from spectroscopic data and proven by the X-ray structure of [Cu(en=P2)]C1O4.CH2CI2, the first iminophos hine chelate thus characterized. The crystals are triclinic, of space group Pi,with a = 14.140(3) A, 6 = 24.926 (5) ,c = 11.430(3) A, a = 94.45(l)", /3 = 81.91 (l)", y = 97.42,')l( and Z = 4. The complex adopts a severely distorted tetrahedral geometry, and this strain is manifested in its reactivity. The four-coordinate complexes M(en=P2)z (M = Cu or Ag, z = l+; M = Ni, z = 2+) all react with additional ligands L (M = Ag or Cu, L = tert-butyl isocyanide (t-BuNC); M = Ni, L = Br-), affording five-coordinate adducts in the case of Ni(I1) and Ag(1). Crystals of the derivative [Cu(en=P2)(t-BuNC)]C104, examined by X-ray methods show the metal to be tetrahedrally coordinated. The first coordination sphere contains only one imine functionality in addition to the isocyanide and the two phosphine moieties. The crystals are orthorhombic, of space group P222,with a = 30.232 (9)A, b = 16.144 (4) A, c = 8.450 (2) A, and Z = 4. The complex is a unique example of a nine-membered chelate ring bound to a tetrahedral complex and is formed by the displacement of an internal donor of the chelate. All complexes are dynamic on the N M R time scale (-80 to 35 "C), and mechanisms consistent with the spectroscopic and X-ray data are presented. The electrochemical behavior of the complexes demonstrate the interconvertability of the [M(en=P2)]' unit containing the metal ion in the d8, d9, and dIo configurations for M = Ni or Cu. The impact of the additional methylene group in the tn=P2 complexes vs. the en=P2 analogues is assessed chemically and electrochemically.
8:
Introduction A characteristic of the coordination chemistry of chelating &$tertiary phosphines and arsines) is their distinctive ability to stabilize metal ions in a variety of uncommon oxidation states and geometries.' The adaptive nature of these ligands is a desirable attribute, from both theoretical2and applied (e.g., catalysis3) perspectives. Imino ligands, particularly the 192d i i m i n e ~are , ~ also known to stabilize metal ions in a variety of low and high oxidation states, and their metal complexes are powerful catalysts in both biological (e.g., corrins, porphyrins) and industrial roles (e.g,, phthalocyanins). ~~i~~ a *To whom correspondence should be addressed at the University of Illinois.
fusion of these ligand types, the iminophosphines hold promise to provide a new and readily available source of ligands which retain many of the aforementioned properties of imines and phosphines. A variety of iminophosphinesW and irninoarsinesl0 Warren, L. F.; Bennett, M. A. Inorg. Chem. 1976, 15, 3126-3140. Bernstein, p, K,; Gray,H.B. Inorg, (-hem. 1972, 11,3035-3 039. 5491-5494, Fryzuk, B. N.; Bosnich, B. J . Am, Chem, sot. 1978, For instance see: Staal, L. H.; Oskam, A,; Vrieze, K.; Roosendahl, E.; Schenk, H. Inorg. Chem. 1979, 18, 1634-1640. ( 5 ) Sacconi, L.; Speroni, G. P.; Morassi, R. Inorg. Chem. 196% 7, (1) (2) (3) (4)
1521-1525.
(6) DuBois, T. D. Inorg. Chem. 1972, 11, 7 18-722. (7) Riker-Nappier, J.; Meek, D. W. J. Chem. Soc., Chem. Commun. 1974, 442-443.
0020-1669/80/13 19-3306$01.OO/O 0 1980 American Chemical Society
Inorganic Chemistry, Vol. 19, No. 11, 1980 3307
Metal Complexes of Diiminodiphosphines have been prepared although so far their coordination chemistry has been restricted to the derivatives of divalent metal . ions. Prior to the work of one of us9 these ligands were synthesized from the condensation of organic carbonyls with aminophosphines or aminoarsines. As part of a broader program concerned with exploring the synthetic utility of the carbonyl phosphines, e.g., o-(diphenylphosphino)benzaldehyde, we have prepared derivatives in which the formyl group has been converted to an imine; this methodology enjoys distinct advantages over-the previously reported route to these imino containing hybrid ligands in both synthetic versatility and convenience. Herein we report a study of the stereochemical and reactivity patterns of metal complexes of two diiminodiphosphines including the first crystallographic examination of this class of coordination compounds. We also describe a novel substitution pattern for metal complexes of polydentate ligands which was uncovered in the course of these studies. T h e results reported herein represent the basis for the design and synthesis of more complex and stereoselective ligands applicable to asymmetric catalysis.
Experimental Section IH nuclear magnetic resonance spectra were recorded variously on a 90-MHz Jeol Minimar, 90-MHz Varian EM390, or 100-MHz HA 100 spectrometer. 31PNMR spectra (Bruker 90 or a Varian XLlOO spectrometer) were always 'H decoupled. Microanalyses were obtained at both The Australian National University and the University of Illinois with the in-house services. o-(Diphenylphosphin0)benzaldehyde was prepared according to Schiemenz and Kaack," by using commercially available o-bromobenzaldehyde (Fluka, Aldrich) and diphenylphosphinous chloride (Aldrich). tert-Butyl isocyanide was prepared by using a modified literature methodi2 by Mr. Horst Neumann at The Australian National University or purchased from Strem Chemicals. All compounds reported in the Experimental Section gave satisfactory microanalyses for CHNP; these data are contained in the supplementary material. (See the paragraph at the end of this paper regarding supplementary material.) N ~ - B i s [ o - ( d i p h e n y I p h o s p h i n o ) b e n z y l i d een==P2 (1). o-Ph2PC6H4CH0,29 g (0.1 mol), and 3.3 mL of freshly distilled ethylenediamine (0.05 mol) were refluxed with stirring in 300 mL of absolute ethanol for 90 min. After this time, the cream-colored slurry was cooled to 0 OC for 12 h and filtered; the product was rinsed with EtOH and air-dried. The yield was 25.5 g (85%). While this material was satisfactory for the preparation of complexes, it was necessary to recrystallize a small portion from CH2C12/EtOHto obtain an analytically pure sample. Four-Coordinate en=P2 Complexes. [CU(M~CN)~]C~O,, 314 mg (0.97 mmol), was dissolved in 25 mL of MeCN. A solution of 610 mg (1.01 mmol) of en=Pz in 10 mL of CH2C12was added, and the solution instantly changed from colorless to dark orange. The solution was then diluted with 100 mL of Et20. After 2 h, the crystals of [Cu(en=PZ)]C1O4 (2) were collected and washed with Et20. The yield was 700 mg (60%). The silver(1) (3) and nickel(I1) (4) fluoroborates were prepared similarly. The MeCN solution of the nickel complex is brown, while the CH2C12solutions of the same compound are yellow, suggesting that the brown coloration is due to [Ni(MeCN)(en=P2)] 2+, [Cu(tn=P2)lC104 (5). A sample of 960 mg of PCHO (3.33 mmol) and 140 gL of 1,3-diaminopropane (tn) (1.66 mmol) were refluxed in 30 mL of absolute EtOH, yielding after evaporation an oily product which was redissolved in ca. 80 mL of CH2C12. A solution of 545 mg of [ C U ( M ~ C N ) ~ ] C(1.66 ~ O ~mmol) in ca. 50 mL of MeCN was (8) Cabral, J. deO.; Cabral, M. F.; Drew, M. G. B.; Nelson, S.M.; Rogers, A. Inorg. Chim. Acta 1977, 25, L77-19. (9) Rauchfuss, T. B. J . Organomet. Chem. 1978,162, C19-21. (10) Chiswell, B.; Lee, K. W. Inorg. Chim. Acra 1973, 7,49-59, 509-516, 517-523; 1972, 6, 583-590. Lee, K. W. Ph.D. Thesis, University of
Table I. Crystal and Data Collectiona Details for [Cu(en=P,)]ClO,CH,C, and [Cu(en=P,)(t-BuNC)]ClO,
empirical formula fw a, A b, A c, '4 a,deg
P, deg 7,degg vc, A
P ~ I , g~w3 ~ , ~
Z
Pcalcd, g cmm3
space group scan speed, deg min-I scan width: deg
[Cu(en=P,)] C10,. CH,Cl,
[Cu(en=P,)(t-BuNC)]C10,
C, ,H 36Cl,CuN, 0, P, 85 2.6 14.140 (3) 24.926 (5) 11.430 (3) 94.45 (1) 81.91 (1) 97.42 (1) 3947.8 1.44 (1) 4 1&1 P1 (Ci, NO. 2) 2.0
C,, H, ClCuN,O, P, 850.8 30.232 (9) 16.144 (4) 8.450 (2) 90 90 90 4124.2 1.37 (1) 4 1.37 P2,2,2, (Di, No. 19) 0.9
(20 - 0.91428 0.9 + A) 50 15 041 9076
+
(0.8
+ 0.34 tan e)
max 20, deg 45 data collected 6246 unique data with 2848 I >3 4 ) a Intensities were measured with graphite-monochromated Mo Kor radiation (20, = 12.16", A(Mo Kor) = 0.710 69 A, tube takeoff angle = 3") with use of 6/20 scan mode with stationary backgrounds (10 s) at each end of the peak scan. By flotation. A is the angular separation of the Ka, and Ka, components of the diffracted beam. added to the CHzC12solution, producing a yellow-orange solution which was then diluted with 300 mL of Et20 and 500 mL of petroleum ether (bp 100 "C). After cooling of the solution for 1 h, the crystalline precipitate was collected and recrystallized from CHzC12 by the addition of ether, yielding 1.09 g (84%). [Ni(tn=P2)](BFJ2 (6). A sample of 870 mg of PCHO (3 mmol) and 110 mg of 1,3-diaminopropane(tn) (1.5 mmol) was refluxed in 30 mL of EtOH for 3 h. After cooling of the solution to room temperature, 535 mg of [Ni(H20),](BF4), (1.5 mmol) was added, and the orange solution was refluxed for 1 h. The cooled solution was filtered, and the solid was extracted with acetone, filtered, and evaporated. This material was recrystallized by dissolution of the solid in methanol/acetone (1 :1) and dilution with Et20. The yield was 740 mg (53%). [Cu(en=P2)( t-BuNC)p04 (7) and [Ag(en=P2)(t-BuNC)pF4(8). An excess of t-BuNC (- 5 drops) was added to a solution of 100 mg of [Ag(en=P2)]BF4 in CH2C12(10 mL), resulting in the rapid formation of a pale yellow color. The solution was then slowly diluted with hexane, yielding cream crystals. The yield was 93 mg (84%). The copper complex [Cu(en=P2)(t-BuNC)]C104 was prepared similarly. [NiBr(en=P2)]Br (9). A sample of 604 mg of en=P2 (0.5 mol) in 10 mL of CH2C12was added to a stirred solution of NiBr2.3H20 (0.5 mmol) in 20 mL of EtOH. The brown solution was stirred for 1 h, filtered, rinsed with 10 mL of CH2ClZ,and diluted with 175 mL of E t 2 0 with stirring to give brown crystals. Recrystallization from CH2ClZ/Et20yielded 675 mg (82%) of red-brown crystalline complex. Electrochemistry. The instrumentation has been described previ~usly.'~Measurements on the en=P2 complexes were made by using a Pt working electrode and lo-' M solutions of the metal complexes in a 0.1 M acetone solution of tetraethylammonium perchlorate. Measurements on the tn=P2 complexes were made by using an Au electrode and working in 0.1 M acetonitrile solution of tetramethylammonium tritluoromethylsulfonate. The reference electrode in all cases was Ag/AgCl (0.1 M LiCl in MeCN). Collection and Reduction of X-ray Intensity Data. [Cu(en= PJUO4. Crystals of [Cu(en=P2)] [C104]CH2C12were obtained from CH2C12/hexaneand were coated with a thin film of Araldite to inhibit loss of solvent. The crystal used for data collection was a well-developed parallelepiped with (OlO),{OOl),and (110)faces and maximum
-
Oueensland. 197 1.
(11) &hiernenzy'G. P.; Kaack, H. Liebigs. Ann. Chem. 1973, 1480-1493. (12) Gokel, G. W.; Widera, R. P.; Weber, W. P. Org. Synth. 1976, 55, 96-99.
(13) Hendrickson, A. R.; Martin, R. L.; Rhoda, N. M. Inorg. Chem. 1975, 14, 2980-2985.
3308 Inorganic Chemistry, Vol. 19,No. 11, I980
Jeffery, Rauchfuss, and Tucker
Figure 1.
ORTEP drawing and numbering scheme for cation 1 of [Cu(en=P,)]+ with thermal ellipsoids drawn at the 50% probability level.
dimensions of ca. 0.3 X 0.3 X 0.2mm. Crystals are triclinic, of space group Pi. Reflection data were collected on a Picker FACS-I automatic four-circle diffractometer, by using Mo Ka radiation. Unit cell dimensions together with their estimated standard errors and the crystal orientation matrix were obtained from the least-squares analysis of the setting angles of 12 carefully centered high-angle refle~ti0ns.l~ Crystal data and details of the experimental conditions are in Table
I.
Figure 2. ORTEP drawing and numbering scheme for [Cu(en= P2)(t-BuNC)]+ with thermal ellipsoids drawn at the 50% probability level. Scheme I Oh..
P”‘ ”2
The intensities of three standard reflections were monitored periodically to check crystal and electronic stability. No significant intensity variations were observed throughout the period of data collection. Reflection intensities were reduced to values of lFol and were assigned individual estimated standard deviations (u(F,)).’~A value of 0.04 was used for the instrumental uncertainty factor @).I6 Reflection data were sorted, equivalent reflections were averaged, and reflections with I 1 30(I) were considered observed. No absorption or extinction corrections were applied to the data. The statistical R factor (R,)15for the terminal data set was 0.028 (9076 reflections). The structure was solved by using MULTAN” in conjuction with conventional Patterson techniques and was refined satisfactorily by using block-diagonal least-squares methods in space group Pi,with two independent pseudocentrosymmetrically related formula units per asymmetric unit (Z = 4). MULTAN initially gave a false solution with the two Cu cations incorrectly positioned in the asymmetric unit. Further analysis, based on the initial (false) solution, fortuitously gave a good set of structural parameters for one cation, but it became apparent that these results could not be reconciled in detail with the Patterson synthesis. MULTAN readily gave the correct solution when the derived structural parameters for the one cation were used to calculate accurate group scattering factors for both cations, which once more emphasizes the known usefulness of this approach in direct methods procedure^.'^*'^ Atomic and anomalous scattering factors were taken from ref 19. Fixed phenyl hydrogen atom contributions were included in the scattering model (C-H = 0.95 A, BH = Bc). The final R value was 0.053 ( R , = 0.068). In the last cycle of least-squares refinement, The programs contained in the Picker Corp. FACS-I Disk Operating System (1972) were used for all phases of the Picker diffractometer control and data collection. All phases of the Philips diffractometer control were by the PW1100/15 control program llCN20 (1976). Formulas used in the data reduction programs: Lp (Lorentz-polarization factor) = (cosz 2%+ cos22%,)/[(sin 2%)(1 + cosz 2%,)], where B and 8, (-6.08’) are the reflection and monochromator Bragg angles, respectively; I (net peak intensity) = [CT - ( t / t b ) ( B l + Bl)],,where CT is the total peak count in t s, and B anc! Bz are the individual background counts in [ ( t t )z(L!l + Bz)I1A;o(Fo) (the reflection esd) = [ [ ~ ( r ) / L p+] ~@~Fo~f~1~z/21F,,I: a,(Fo) (the reflection esd from counting statistics alone) = [o(Z)/2(Lp)(lF0I)]; R, (the statistical R factor) = Cu,(F,)/CIF,I; background rejection ratio = IBl - Bzl/(E1
+ Bz)’/~.
Busing, W. R.; Levy, H. A,; J . Chem. Phys. 1957, 26, 563-571. Corfield, P. W. R.; Doedens, R. J.; Ibers, J. A. Inorg. Chem. 1967, 6, 197-204. Declerq, J. P.; Germain, G.; Main, P.; Woolfson, M. M. Acta Crystallogr. Sect. A 1973, A29, 231. Main, P. “Crystallographic Computing Techniques”; Munksgaard: Copenhagen, 1976; p 7. “International Tables for X-ray Crystallography”; Kynoch Press: Birmingham, 1974; Vol. IV.
H2y (CH2)/
+
-
CHO
PCHO
en = P,, n = 2 tn = P,, n = 3 no parameter shifted by more than 0.1 of its estimated standard deviation, and an analysis of the weighting scheme revealed no systematic dependence of wA2 on IFoI or sin 4. The highest radical peaks in the final difference maps were ca. 1.O e/A3. Final atomic coordinates are listed in Table 11. Listings of anisotropic thermal parameters and of 10IFol and 10IFcl have been deposited. The atom numbering in the cation is illustrated in Figure 1. [Cu(en=P,)( t-BuNC)Q04. Crystals, commonly six-sided needles along (OOl), were obtained by recrystallization from dichloromethane/hexane solutions. The crystal used for data collection had approximate dimensions 0.01 X 0.05 X 0.01 cm. Crystals are orthorhombic of space group P222. Intensities were measured on a Unit cell Philips P W l 100 automatic four-circle diffra~t0meter.I~ dimensions and standard errors were measured on a Picker FACS-I diffractometer as described above. Mo Ka radiation was employed for both data collection and cell measurement. Crystal data and experimental conditions are listed in Table I. Reflection data were measured in the quadrants hkl and hkl. As before, intensities of the three standard reflections which were monitored periodically remained unchanged (to within experimental error) throughout the experiment. Reflection intensities were reduced to lFol and assigned standard deviations, o(F,), as described in ref 20. Reflection data were sorted, and reflections with I C 3 4 I ) were rejected as unobserved. No absorption [p(Mo Ka) = 7.2 cm-’] or extinction corrections were applied. The statistical R factor, Rs,I5 was 0.096 for 2848 reflections. The structure was solved by conventional Patterson and Fourier techniques and was refined by full-matrix least-squares methods. Atomic scattering factors and the anomalous dispersion corrections for Cu, P, and C1 were taken from ref 19. In view of the high statistical R factor, R,, no attempt was made to include hydrogen atom contributions or to refine anisotropic thermal parameters for the carbon atoms. The final R was 0.110 (R, = 0.103). The poor intensity statistics do not allow the determination of the absolute configuration (20) As for ref 15 except that u(I) and o(F,,) are defined as in the CRSTAN program package: H. Burzlaff, R. Bohme, and M. Gomm, Institut far
Angewandte Physik, Universitat Erlangen, 1977.
Inorganic Chemistry, Vol. 19, No. I I, 1980 3309
Metal Complexes of Diiminodiphosphines Table 11. Atomic Coordinates for [Cu(en=P,)] ClO,CH,CI, ATUII
z/c z/c 0.64073l51
C(Z.731
0.7287911Il
ClZL41
0.47214ll1I
CIZ251 Cl220
0.e2a4141 0,79561 6 I 0.866917 I 0.9691l61 1 . O D 2 9 I t.1
Cl23ll CIZJPI c17131
0,5038 I 6 I 0.527316 I 0.40*0151 0.41 37 151 0.189zI * I 0.1232l41
0 . 0 3 I5 I 4 1
CIL341
0.0078151
U.6519Illl
ClZJ5I C12Jhl
L.1618151
0.57G915 I
cIL:I
t r 1365i41
ti(Z,I
1' ,2333 I3 I
Cl221
~ ~ 2 9 I5 'J.2314151 9 I2
C113I NIZ2)
0.91351 31
0.93116151
0.5128ILl
U.5338 i 6 I
0~61331~1 0~6713151 t.8351I41 0.9067(41 0.99119 15 I
l.01IOl51 0.94U3tbI 0.8537 151
0.90C214) 0.80601 3 I 5.8129l51
0.7486 I5 I (106297l41
o . s w a 151 0.3733 14 I 5.4152141 0.3356 I 5 I
0.2171l51 0. I764 151 0.25181'1 I
0,4734141
0.577914 I 0.5847 I5 I
0.4822l61 0.375815) 0,3709 I 5 I 0.386414 I 0.3397l51 0.2801I5I C.2714l51 0.3188151 0137bOI5 I
0.39101l51 0.30451(III 0~5697l1lll 0.214314l
0*198515l
C.rl7Z4l5I
CIZ*l C(24lI
11.5072 I 4 I
c12421
0.6271141
C(Lr31 cl2'lql
0.7075 I 5 I
c12r51 CiZ46l CI25!1 Cl2b2l Cl2531
0.8snz151
Cl264I
c12551 Cl2561 clZ6:I CI2bZI C(2631 CIZb41 Cl2651 ClLbbl CLIII
0~6654141
(r.8220151
0.78071 4 I 6,5678 I 'I1 0.11b43151 O.l(6(19151
0.5651161 U.669dl5 1
0~6718151 0 . 6 W I41
0.6793151 11.7367 151 0,75411151 0.7185ISl 0.6694
I5 I
0~030241l31
O I I I I
r).1522141
01121
-0.Li225171
01131
-0.0lZYl7l
3 l l Y I
-0.UOU6181
CLIZI
U~U1396I141
31211
0~0591l81
Ol2ZI O(231 01241
0.03511 (71
CL(II1 CLIIZI CLlZll CL(221 CIII CI2I
0.07113l61 -0.l077l41 0,771 6131 0.7523121 0.6650131
O.7322( 3 1 0.8485171 0.789217 I
0,1238 I 6 I
0*0497151 0.0856l51 0.156VI51
0.3818141 G.4363151
for the cation. In the last cycle of refinement no parameter shift exceeded 0 . 2 ~ .The function minimized, Cw(lF,I - IFc1)2,showed no appreciable dependence on IF,I or (sin B)/h. The highest residual peaks (or troughs) in the final difference m a p were ca. 2.0A-3. Final atomic parameters are listed in Table 111, and the atom numbering in the cation is illustrated in Figure 2. Tables of lOlF,,l and 101F.J (electrons) are contained in the supplementary material. Computer Programs. All calculations were carried out on the Univac 1108 computer of The Australian National University Computer Center, by using previously described programs.2' (21) Ferguson, J.; Mau, A. W.-H.; Whirnp, P.0.J. Am. Chem. SOC.1979, 101, 2363-2369.
Results and Discussion Ligands. The phosphine aldehyde, PCHO, many of its isomers, and the corresponding acetophenone derivatives were first prepared and characterized by Kaack and Schiemenz." These compounds are potentially valuable ligand percursors via elaboration of the carbonyl group by condensation and/or reductions. The tetradentate ligand N,N'-bis[o-(diphenylphosphino)benzylidene]ethylenediamine, abbreviated en=P2 (l), is easily prepared by the condensation of 2 equiv of o(dipheny1phosphino)benzaldehyde with ethylenediamine in boiling ethanol (Scheme I). This chelating agent is soluble in common organic solvents and is conveniently crystallized
3310 Inorganic Chemistry, Vol. 19, No. 11, 1980
e
n
Jeffery, Rauchfuss, and Tucker
n
m * n I "
I
N n
e w m
n r
