Coupling of Diazomethane and a Carbonyl Ligand To Give a New

George Ferguson,'' W. John Laws,lb Masood Parvez,la and Richard J. Puddephatt" lb. Chemistry Department, The University of Guelph, Guelph, Ontario, ...
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Organometallics 1983,2, 276-280

276

Coupling of Diazomethane and a Carbonyl Ligand To Give a New Metallacycle: Crystal Structure of the Complex [Mn2(CO) &C (0)CH2N2)(p-Ph2PCH2PPh2)2].2CH2C12 George Ferguson,'' W. John Laws,lb Masood Parvez,la and Richard J. Puddephatt"lb Chemistry Department, The University of Guelph, Guelph, Ontario, Canada, N1G 2W1, and Department of Chemistry, University of Western Ontario, London, Ontario, Canada, N6A 567 Received August 3, 1982

Reaction of diazomethane with [Mn2(CO)4(p-CO)(p-dppm)z] (I,dppm = Ph2PCH2PPh2) gives [Mnz(CO)4(~-C(0)CH2Nz)(p-dppm)z] (11). The strusture of I1 was established by our X-ray analysis. Crystals of (II).2(CH2C12)are triclinic of space group P1 with two formula units in a cell of dimensions a = 12.549 (6)A, b = 13.447 (2) A, c = 19.140 (6) A, a = 104.34 (2)O, p = 95.99 (3)O, and y = 111.11(2)'. The structure was solved by the heavy-atom method and refined by full-matrix least-squares calculations to a final R value of 0.087 for 4360 reflections with I > 30(Z). The diazomethane ligand has reacted to bridge asymmetrically via nitrogen the Mn atoms of the [Mn,(CO),(dppm),] moiety and also to form a C-C bond with an adjacent CO ligand, yielding a planar five-membered MnC2N2ring. The manganese stereochemistry is derived from octahedral geometry with the addition of a Mn-Mn bond. Principal bond lengths are as follows: Mn-Mn = 2.898 (2) A; Mn-N = 1.894 and 1.967 (7)A; Mn-P = 2.287-2.295 (2) A; Mn-C (terminal carbonyl) = 1.764-1.809 (12) A; Mn-C (bridging carbonyl) = 1.826 and 2.524 (8)A; Mn-C(ring) = 2.001 (9) A; N=N = 1.238 (9) A. The spectroscopic data (IR and 'H and 31PNMR) are fully consistent with the above structure and show that the molecule is not fluxional in solution. However, the long C-C bond of the metallacycle is cleaved on thermolysis or photolysis of 11, and complex I is reformed. n

Introduction T h e reactions of diazoalkanes with transition-metal complexes have been the subject of intensive research over the past few years., It is generally believed t h a t diazoalkane complexes, for which several bonding modes are possible, are formed first but only rarely are such complexes An example of particular relevance to the present work is the complex [ M ~ ( T J ~ - C ~ H ~ ) ( C O ) ~ ( N ~ C (C02Me)2)]in which the metal-diazoalkane bonding is of the form t

M-N=N

'C9,

with presumably carbanion character of the carbon centera2 More commonly, dinitrogen is lost t o give an alkylidene that may then insert into a metal-metal, metal-hydrogen, or metal-phosphorus bond or that may combine with coordinated carbon monoxide, alkyne, alkene, or other ligands to give more complex derivatives.2r"8 Catalytic cyclopropanation of alkenes may result from such reaction^.^ There are few examples known in which the diazoalkane itself undergoes insertion reactions, b u t two relevant examples are shown in eq 1 a n d 2.loJ1 (1) (a) University of Guelph. (b) University of Western Ontario. (2) For an excellent review of early work see: Herrmann, W. A. Angew. Chem., Int. Ed. Engl. 1978,17,800; J. Organomet. Chem. 1975,84, C25. Herrmann, W. A.; Kriechbaum, G.; Liegler, M. L.; Wulknitz, P. Chem. Ber. 1981,114, 276. (3) Schramm, K. D.; Ibers, J. A. J . Am. Chem. SOC.1978,100, 2932. (4) Chisholm, M. H.; Folting, K.; Huffman, J. C.; Ratermann, A. L. J. Chem. SOC.,Chem. Commun. 1981, 1229. (5) Messerle, L.; Curtis, M. D. J. Am. Chem. SOC.1980, 102, 7789. (6) Claws, A. D.; Shapley, J. R.; Wilson, S. R. J.Am. Chem. SOC.1981, 103, 7387. (7) Schultz, A. J.; Williams, J. M.; Calvert, R. B.; Shapley, J. R.; Stucky, G. D. Inorg. Chem. 1979, 18, 319 and references therein. (8) &am, K. A.; Frew, A. A,; Lloyd, B. R.; ManojloviE-Muir, Lj.; Muir, K. W.; Puddephatt, R. J. J. Chem. SOC.,Chem. Commun., in press. (9) Nakamura, A.; Konishi, A.; Tsujitani, R.; Kudo, M.; Otsuka, S. J . Am. Chem. SOC. 1978, 100, 3449. (10) Herrmann, W. A.; Ziegler, M. L.; Weidenhammer, K.; Biersack, H.; Mayer, K. K.; Minard, R. D. Angew. Chem., Int. Ed. Engl. 1976,15, 164. Herrmann, W. A,; Ziegler, M. L.; Weidenhammer, K. Ibid. 1976.15, 368. (11)Gambarotta, S.;Basso-Bert, M.; Floriani, C.; Guastini, G. J. Chem. SOC.,Chem. Commun. 1982, 374.

CPh2

While the reaction of diazomethane with the complex was [Mn2(CO)5(p-dppm)2J (I, dppm = Ph2PCH2PPh2)12-'6 studied, we discovered a 1:l adduct of formula [Mn2(CO),(CH,N,)(p-dppm),] (11). This complex is shown to have a unique metallacyclic unit formed by a new type of coupling of diazomethane with a carbonyl ligand, and its synthesis, structure, and properties form the basis for this article.

Experimental Section 'H and 31P(1H) NMR spectra were recorded by using a Varian XL 100 spectrometer at 100.1 and 40.5 MHz, respectively. Chemical shifts are quoted with respect to Me4& or (MeO),PO, respectively. IR and mass spectra were recorded by using a Beckman IR 4250 and Varian MAT 311 spectrometers, respectively. [ Mn2(CO)S(p-dppm)z] (I) was prepared by the literature method13 and purified by chromatography on Florisil eluting with CH2Cl2:mp 228-234 "C dec; IR v(C0) (cm-', Nujol) 1942 (m), 1930 (s), 1860 (s), 1835 (m), 1645 (m); NMR (CH,Cl,) 6 3.51 (PCH,P), S(31P) 75.9, 59.5.14 (12) Commons, C. J.; Hoskins, B. F. Aust. J . Chem. 1975, 28, 1663. (13) Colton, R.; Commons, C. J. Aust. J. Chem. 1975, 28, 1673. (14) Caulton, K. G.; Adair, P. J. Organomet. Chem. 1976, 114, C11. (15) Balch, A. L.; Benner, L. S. J. Organomet. Chem. 1977, 135,339. (16) Aspinall, H. C.; Deeming, A. J. J. Chem. SOC.,Chem. Commun. 1981. 724.

0276-7333/83/2302-0276$01.50/00 1983 American Chemical Society

Organometallics, Vol. 2, No. 2, 1983 277

Coupling of C H a 2 and CO To Give A New Metallacycle

C

CG5 14

c73

c7

Figure 1. Stereoview of I1 with our numbering scheme.

[Mn,(CO)Jcc-C(O)CH,N,Hrc-dPPm),I(11). This was prepared by reaction of complex I (2.5150 g, 2.471 X mol) in CH2C12 (100 d) with ethereal CH2N2(105 mL of 0.60% solution, 1.482 X mol). The color of the solution slowly changed from red to yellow-orange over a period of 1day at rmm temperature. The mixture was purified by chromatography on Florisil (100-200 mesh). Elution with CH2C12gave complex I (0.2273 g, 2.231 X 10-4mol, 9.0%) and then with 20% CH30H/CH2C12gave complex I1 (1.9448 g, 1.835 X mol, -74%), recovered as an orange solid, which was recrystallized from CH2C12/pentane. The initially formed solvated crystals lost CH2C12rapidly to give the product as an orange powder: mp 197.5-199.5 "C; IR v(C0) (cm-l, Nujol) W 1960 (m), 1920 (s), 1858 (s), 1818 (m), 1610 (m); NMR (CH2C12) Figure 2. View of the manganese coordination with bond lengths 6 2.76 (PCH2P),4.81 (CH2N),integration 42, 6t31P)53.7, 56.4; (A). Estimated standard deviations are as follows: Mn-Mn = parent ion ( m / e 1060) not observed, m / e (assignment) 1018 (P 0.002 A; Mn-P = 0.002 A; Mn-N = 0.007 A; Mn-C = 0.008-0.012 - CH2N2), 962 (P - CH2N2 - ZCO), 934 (P - CH2N2 - 3CO), 884 A; P-C = 0.006-0.009 A; C-O, N-N, C-C, and C-N = 0.004-0.013 (P- CH2N2- 2c0 - C6H6). Anal. Calcd for CMHaMn2N20p4: A. C, 63.4; H, 4.3; N, 2.6. Found: C, 63.5; H, 4.35; N, 2.6. Thermal and Photochemical Decomposition of 11. A sowhich also showed the presence of two CH2C12molecules of lution of complex II(0.047 g) in benzene (15 d), in a closed vessel solvation. Initial refinement?' by full-matrix least-squares calfitted with a vacuum tap and a serum cap, was heated at 80 "C culations with isotropic thermal parameters lowered R to 0.160. for 1day. Analysis of the gas phase by GC showed C2H6 as the In subsequent refinement cycles to save computer time, the phenyl major volatile organic product. The residue was chromatographed rings were constrained to be regular hexagons (with C-C = 1.395 on Florisil to give a mixture of complex I (0.01 g) and I1 (0.03 g), A) and refined isotropically;the other non-hydrogen atoms were identified by comparison with authentic samples. Heating in an allowed anisotropic vibration. When R was 0.10, a difference open vessel gave more rapid conversion to I. synthesis revealed electron density maxima in positions anticiSimilarly photolysis (Xe lamp, Pyrex filter) of complex I1 in pated for the hydrogen atoms of 1. In subsequent refinement CH2C12occurred slowly to give ethane and complex I. cycles, the hydrogen atoms were included in geometrically Crystallographic Studies. Recrystallization of I1 from diidealized positions (C-H = 0.95 A) but not refined; only an overall chloromethane afforded large single crystals of what was later isotropic thermal parameter was refmed for hydrogen. The solvent shown to be the bis(dichlor0methane)solvate. The crystals lost molecules showed evidence of disorder (diffuse electron density solvent rapidly and were very unstable in air; for the data colmaxima, abnormal geometry, and abnormally large thermal palection a suitable crystal was coated with several thin layers of rameters), and their hydrogen atoms were not located. In the epoxy resin within seconds of its being removed from the mother final rounds of calculations a weighting scheme of the form w = liquor. 1/ [2(29] was employed. Scattering factors used in the calculations Crystal data: I'V~~(CO)~(OCCH~N&(P~~PCH~PP~&~~CH~C~~, were taken from ref 18 and 19, and allowance was made for CMHaMn2N20jP4-2CH2C12; M,= 1088.8; triclinic; a = 12.549 (6) anomalous dispersion.m Refinement converged with R = 0.087 A, b = 13.447 (2) A, c = 19.140 (6) A; a = 104.34 (2)", /3 = 95.99 and R, = ( C W A ~ / C W F=~0.107. ) ' / ~ A final difference map (2)", y = 111.11 (2)"; U = 2851.4 A3, 2 = 2; D = 1.27 g ~ m - ~ , showed no chemically significant maxima. Final fractional coF(000)= 1260; Mo Ka radiation; X = 0.71069 X;(Mo Ka) = 8.1 ordinates and their estimated standard deviations are in Table cm-l. Space group PI or P1; Pi assumed and confirmed by I, and details of molecular dimensions are in Table 11. Tables analysis. of calculated hydrogen coordinates and thermal parameters and After preliminary photographic studies, accurate unit-cell a listing of observed and calculated structure amplitudes have constants and crystal orientation matrix were determined on an been deposited as supplementary material. Figure 1is a stereoview Enraf-Nonius Cad-4 diffractometer by a least-squares treatment of 1, and Figure 2 shows the main coordination geometry with of the setting angles of 25 reflections with B in the range 10-15'. principal dimensions. Intensity data were collected by the w-28 scan method using monochromatized Mo K a radiation. The intensities of three Discussion reflections, chosen as standards, were monitored at regular inWith the aim of synthesizing complexes with the Mn2tervals and decreased by 11.7% over the course of the data collection; this decay was corrected for by appropriate scaling. (p-C&) grouping, a study of reactions of diazoalkanes with Intensities of 5302 reflections were measured, of which 4360 had Colton's complex [Mn,(CO)&dppm),] (I), having an I > 3a(I) and were used in structure solution and refmement. Data were mrrectedfor Lorentz, polarization factors, and for absorption. (17)Sheldrick, G.M.SHELX, a program system for crystal structure Maximum and minimum values of the transmission coefficients determination, University of Cambridge, England, 1976. are 0.7228 and 0.5613, respectively. (18)Cromer, D. T.;Mann,J. B.Acta Crystallogr., Sect. A 1968,A24, The coordinates of the atoms of the Mn2P4fragment were 321-323. deduced from a careful examination of the three-dimensional (19)Stewart, R.F.;Davidson, E. R.; Simpson, W. T. J. Chem. Phys. Patterson function, and the remaining non-hydrogen atoms were 1965,42,3175-3187. located from subsequent heavy-atom phased electron density maps (20)Cromer, D.T.;Liberman, D. J. Chem. Phys. 1970,53,1891-1898.

278 Organometallics, Vol. 2, No. 2, 1983

Ferguson

Table I. Final Fractional Coordinates ( X104)with Estimated Standard Deviations in Parentheses X Y z atom X Y

atom

1444 3178 1565 1228 3360 3006 62 -1231 0 1633 -1069 1743 5571 4210 3185 1474 763 -78 1661 4636 36 20 26 90 1331 2031 1585 -1403 5 59 161 -618 -1737 -2077 -1298 -179 2486 2382 3104 3930 4034

2795 (1) 1908 (1) 31 22 (1) 2451 (1) 2178 (1) 1496 (1) 722 (6) 1543 ( 9 ) 437C ' 6 ) 5498 ( 7 ) 2690 ( 4 ) 4363 ( 4 ) 1644 ( 4 ) 3423 ( 4 ) 358 ( 4 ) 1812 ( 4 ) 1237 ( 5 ) 2736 ( 5 ) 3755 ( 6 ) 1766 ( 5 ) 2874 ( 5 ) 850 (5) 607 ( 5 ) 2429 ( 5 ) 1548 (5) 1074 (22) 4815 (13) 3192 ( 3 ) 2572 ( 3 ) 2627 ( 3 ) 3302 ( 3 ) 3922 ( 3 ) 3867 (3) 3981 ( 3 ) 4205 ( 3 ) 4853 ( 3 ) 5277 ( 3 ) 5054 ( 3 )

2331 (1) 2879 (1) 4136 ( 2 ) 504 ( 2 ) 4701 ( 2 ) 1062 ( 2 ) 6575 ( 9 ) 5705 (13) 7413 ( 9 ) 9109 (11) 1554 ( 6 ) 2389 ( 7 ) 3622 (6) 3130 ( 5 ) 2945 ( 5 ) 2353 ( 5 ) 2127 ( 7 ) 1867 ( 7 ) 2383 ( 8 ) 3345 ( 7 ) 2989 ( 6 ) 2754 ( 7 ) 2274 ( 1 0 ) 4836 ( 7 ) 76 ( 7 ) 6278 (27) 9179 (31) 4208 ( 6 ) 4092 ( 6 ) 4034 ( 6 ) 4093 ( 6 ) 4208 ( 6 ) 4266 ( 6 ) 5193 ( 4 ) 6217 ( 4 ) 7039 ( 4 ) 6836 ( 4 ) 5811 ( 4 )

unusual 4-electron bridging carbonyl ligand,12J3was initiated. The reaction of excess diazomethane with I occurs slowly a t room temperature and more rapidly if acid catalysis16 is employed. T h e product is not a methylene complex however but is a new type of metallacycle (11) formed according to eq 3. F

o-p

P

A

D

P = Ph2PCY22Ph2

Since the structure could not be deduced from the spectroscopic data, a structure determination by X-ray methods was undertaken. T h e crystal structure of (11)2(CH2C1J contains discrete molecules separated by normal van der Waals distances. Figure 1 is a stereoview of the structure of 11, and Figure 2 shows details of the manganese environment with principal bond lengths. The structure of I1 is very similar to that reportedI2 for [Mn2(CO)5(dppm)2](I) but with the additional uniquez1 feature of a diazomethane ligand t h a t bridges the Mn atoms and also forms a C-C single bond to what had been a carbonyl carbon atom in I. T h e stereochemistry a t each manganese may be regarded as being derived from octahedral geometry with the (21) 'Crystor"-The Cambridge Crystallographic Data Base at NRC Ottawa.

3312 ( 5 ) -281 ( 5 ) -1070 ( 5 ) -2243 (5) -2627 ( 5 ) -1838 (5) -665 (5) 2013 (5) 2943 ( 5 ) 3546 (5) 3219 (5) 2289 (5) 1686 ( 5 ) 4561 ( 5 ) 4585 ( 5 ) 5483 ( 5 ) 6356 (5) 6332 (5) 5435 (5) 3564 ( 5 ) 2746 ( 5 ) 2967 (5) 4004 (5) 4821 (5) 4601 (5) 3053 (4) 4103 (4) 4207 (4) 3261 (4) 2211 (4) 2107 (4) 4060 ( 5 ) 5090 ( 5 ) 5895 (5) 5671 (5) 4641 ( 5 ) 3836 (5)

4990 ( 4 ) -487 (5) -847 ( 5 ) -1 524 (5) -1842 ( 5 ) -1482 ( 5 ) -805 ( 5 ) -53 (4) 647 ( 4 ) 190 ( 4 ) -967 ( 4 ) -1667 ( 4 ) -1210 ( 4 ) 5796 ( 5 ) 6874 ( 5 ) 7708 ( 5 ) 7464 (5) 6386 (5) 5552 ( 5 ) 5381 ( 6 ) 5729 ( 6 ) 6250 ( 6 ) 6424 ( 6 ) 6076 ( 6 ) 5555 ( 6 ) 483 ( 4 ) 966 ( 4 ) 567 ( 4 ) -315 ( 4 ) -798 ( 4 ) -399 ( 4 ) 632 ( 3 ) 1429 ( 3 ) 1089 ( 3 ) -47 (3) -844 ( 3 ) -505 ( 3 )

et al.

z

4405 ( 3 ) 2310 ( 3 ) 1638 (3) 1568 ( 3 ) 2168 ( 3 ) 2839 ( 3 ) 2910 ( 3 ) 2999 ( 3 ) 3595 (3) 3983 ( 3 ) 3776 ( 3 ) 3180 (3) 2792 ( 3 ) 2924 ( 3 ) 3156 ( 3 ) 3727 ( 3 ) 4066 ( 3 ) 3833 (3) 3262 ( 3 ) 1459 ( 4 ) 1163 ( 4 ) 617 ( 4 ) 366 ( 4 ) 661 ( 4 ) 1208 (4) 539 (3) 328 ( 3 ) -396 ( 3 ) -910 (3) -699 ( 3 ) 26 ( 3 ) 1949 (3) 2438 ( 3 ) 2757 ( 3 ) 2589 ( 3 ) 2100 ( 3 ) 1781 ( 3 )

addition of a Mn-Mn bond, 2.898 (2) A. The manganese atoms and those of the carbonyl and diazomethane ligands form an equatorial plane and, as in I, the phosphine ligands occupy trans axial sites. T h e angle between the Mn2P, plane and that of manganese and equatorial ligands is 89.8'. The manganese atom Mn(1) (Figure 2) forms two normal Mn-C bonds to terminal carbonyl groups (Mn(l)-C(l) = 1.76 (1) A, Mn(l)-C(2) = 1.81 (1)A, a Mn-N bond to the bridging diazo ligand (Mn-N = 1.894 (7) A), and there is also a much weaker interaction to a semibridging equatorial carbonyl Mn-C(4) = 2.524 (8) A. The resulting trans effects are marked, with Mn-C(l) (trans to M n - G (4)) shorter than Mn-C(2) (trans to N(1)). The equatorial environment a t Mn(2) is quite different from that a t Mn(1). There is one terminal carbonyl (Mn(2)-C(3) = 1.782 (10) A), the bridging carbonyl (Mn(2)-C(4) = 1.826 (9) A), and the bridging diazomethane (Mn(2)-N(l) = 1.967(7) A), and the remaining carbonyl ligand has been incorporated into the five-membered MnC2N2 ring (Mn(2)-C(5) = 2.001 (9) A). The Mn-N distances are significantly different with the shorter Mn-N bond being to Mn(l), the manganese atom with only a weak interaction to the bridging carbonyl C(4). In the five-membered MnC2N2ring the N-N distance 1.238 (9) 8, is consistent with it being a double bond. In 11, the bridging carbonyl group is much more asymmetric than was observed in I (compare Mn-C = 1.826 (9) and 2.524 (8) A and Mn(2)-C-O = 159.9 (7)O with the corresponding data for I, 1.93 (3) and 2.01 (3) 8, and 173 (3)O), but the observed geometry for I1 indicates a significant Mn(l)-C(4) interaction.

Coupling of C H a , and CO To Give A New Metallacycle

Organometallics, Vol. 2, No. 2, 1983 279

Table 11. Principal Interatomic Distances ( A ) and Angles (deg) and Some Mean Plane Data for 1 a. Bo]nd Distances 2.898 (2) P( 11)-C( 7) 1.836 (9) Mn( 1)-Mn( 2) O( 1)-C( 1) P(ll)-C(ll) 1.816 (8) 2.294 (2) Mn( 1)-P( 11) O( 2)-C( 2) 1.823 (6) P(ll)-C(21) 2.287 (2) Mn( 1)-P( 12) O( 3)-C( 3) 1.837 (8) P( 12)-C( 8) 1.894 (7) Mn( 1)-N( 1) O( 41474) 1.825 (6) P( 12)-C( 31) 1.764 (10) Mn( 1)-C( 1) 0(5)-C( 5) 1.827 (6) P(12)-C(41) 1.809 (12) Mn( 1)-C( 2) N(l)-N(2) 2.524 (8) Mn(l)...C(4) P( 21)-C( 7) N( 2)-C( 6) 1.840 (8) 2.295 (2) C( 5)-C( 6) Mn( 2)-P( 21) 1.841 ( 6 ) P( 21)-C( 51) C1( 1)-C( 9) 2.295 (2) h!h( 2)-P( 22) 1.823 (7) P( 21)-C(61) 1.967 (7) Mn( 2)-N( 1) C1( 2)-C(9) 1.829 (8) P( 22)-C( 8) Cl( 3)-C( 1 0 ) 1.781 (10) Mn( 2)-C( 3) 1.821 (6) P( 22)-C(71) C1(4)-C(1 0 ) 1.826 (9) Mn( 2)-C( 4) 1.843(6) p( 22)-C( 81) Mn( 2)-C( 5) 2.001 (9) Aromatic C-C Constrained To Be 1.395 A b. Bond Angles 92.6 (1) 90.8 (1) Mn( 1)-Mn( 2)-P( 21) Mn( 2)-Mn( 1)-P( 11) 92.6 (1) Mn( 1)-Mn( 2)-P( 22) 90.8 (1) Mn( 2)-Mn( 1)-P( 12) 40.4 (2) 4 2 3 (2) Mn( 1)-Mn( 2)-N( 1) Mn( 2)-Mn( 1)-N( 1) 153.6 ( 3 ) 141.2 (3) Mn( 1)-Mn( 2)-C( 3) Mn( 2)-Mn( 1)-C( 1) 59.6 (3) 128.7 (3) Mn( 1)-Mn( 2)-C(4) Mn( 2)-Mn( 1)-C( 2) 120.3 (3) 38.6 ( 2 ) Mn( 1)-Mn( 2)-C( 5) Mn( 2)-Mn( 1)-C( 4) 173.1 (1) P( 21)-Mn( 2)-P( 22) 177.3 (1) P(l1)-Mn(l)-P(l2) 90.6 (2) 89.7 (2) P( 21)-Mn( 2)-N( 1) P( 11)-Mn( 1)-N( 1) 88.0 (3) 88.3 (3) P( 21)-Mn( 2)-C( 3) P( 11)-Mn( 1)-C( 1) 93.7 (2) 90.7 ( 3 ) P( 21)-Mn( 2)-C(4) P( 11)-Mn( 1)-C( 2) 86.4 (2) 91.8 (2) P( 21)-Mn( 2)-C( 5) P( 11)-Mn( l)-.C( 4) 90.4 (2) 90.0 ( 2 ) P( 22)-Mn( 2)-N( 1) P( 12)-Mn( 1)-N( 1) 89.3 (3) 89.0 (3) P( 22)-Mn( 2)-C( 3) P( 12)-Mn( 1)-C( 1) 92.8 (2) 90.1 (3) P( 22)-Mn( 2)-C( 4) P( 12)-Mn( 1)-C( 2) 87.1 (2) 90.8 ( 2 ) P( 22)-Mn( 2)-C( 5) P( 12)-Mn( l)-..C(4) 165.9 (3) 98.8 (4) N( 1)-Mn( 2)-C( 3) N( 1)-Mn( 1)-C( 1) 100.0 (3) 171.0 (4) N( 1)-Mn( 2)-C( 4 ) N( 1)-Mn( 1)-C( 2) 79.9 (3) 80.9 (3) N( 1)-Mn( 2)-C( 5) N( l)-Mn(l)...C(4) 94.1 (4) 90.2 (4) C( 3)-Mn( 2)-C( 4) C( 1)-Mn( 1)-C( 2) 86.1 (4) 179.7 ( 2 ) C( 3)-Mn( 2)-C( 5) C( 1)-Mn( 1)-C(4) 179.8 (1) 90.1 (4) C( 4)-Mn( 2)-C( 5) C( 2)-Mn( 1)-C(4) 111.3 (3) 112.6 (3) Mn( 2)-P( 21)-C( 7) Mn(1)-P(l1)-C(7) 119.3 (2) 112.6 (3) Mn( 2)-P( 21)-C( 51) Mn(1)-P(l1)-C(l1) 118.9 (2) 122.6 (2) Mn( 2)-P( 21)-C( 61) Mn( 1)-P( 11)-C( 21) 104.4 (3) C( 7)-P( 21)-C( 51) 103.8 (2) C( 7)-P(l1)-C( 11) 101.8 (3) 102.4 (3) C( 7)-P( 21)-C(61) C( 7)-P( 11)-C( 21) 98.7 (3) 100.7 ( 3 ) C(51)-P( 21)-C( 61) C( 11)-P( 11)-C( 21) 111.4 (3) Mn( 2)-P( 22)-C( 8) 112.5 ( 3 ) Mn(l)-P(12)-C(8) 119.0 (2) Mn( 2)-P( 22)-C( 71 ) 113.1 (2) Mn( l)-P( 12)-C( 31) 119.8 (2) Mn( 2)-P( 22)-C( 81) 123.3 (2) Mn( 1)-P( 12)-C( 4 1) 101.3 (3) C( 8)-P( 22)-C( 71) 102.6 ( 3 ) C( 8)7P(12)-C( 31) 103.7 (3) C(8)-P( 22)-C( 81) 101.3 ( 4 ) C( 8)-P( 12)-C( 41) 99.0 (3) C( 71)-P( 22)-C( 81) 101.4 ( 3 ) C( 31)-P( 12)-C(41) 135.8 (7) Mn( 2)-C( 5)-O( 5) 97.3 ( 3 ) Mn( 1)-N( 1)-Mn( 2) 111.0 (6) Mn( 2)-C( 5)-C( 6 ) 137.7 ( 6 ) Mn( 1)-N(1)-N( 2) 113.2 (8) O( 51)-C( 5)-C( 6 ) 125.0 ( 6 ) Mn( 2)-N( 1)-N( 2) 111.4 (7) 112.5 ( 7 ) N( 2)-C( 6)-C( 5) N( 1)-N( 2)-C(6) 111.3 (4) P( 11)-C( 7)-P( 21) 179.1 (8) Mn( 1)-C( 1)-O( 1) 111.7 (4) P( 12)-C( 8)-P( 22) 176.8 ( 9 ) Mn( 1)-C( 2)-O( 2) 98.8 (17) 177.2 (8) C1( l)-C(9)-Cl( 2) Mn( 2)-C(3)-0( 3) 86.2 (14) 81.9 ( 3 ) C1(3)-C( lO)-Cl( 4) Mn( l)-.C(4)-Mn( 2) 118.2 (6) Mn(l).-C(4)-0(4) 159.9 (7) Mn( 2)-C( 4)-O( 4) Phenyl C-C-C Angles Constrained To Be 120' c. Torsion Angles -85.0 Mn(2)P(21)-C(51)C(52) -171.4 Mn(l)P(ll)-C(ll)C(l2) -169.7 Mn( 2)P( 21)-C(6l)C(62) 115.0 Mn( 1)P(11)-C( 21)C( 22) 84.6 Mn( 2)P(22)-C( 71)C( 72) 65.0 Mn(l)P(12)-C(31)C(32) -11.6 Mn( 2)P( 22)-C( 81)C(82) -12.8 Mn( 1)P(12)-C( 41)C(42) d. Least-Squares Planes and Deviations of Atoms from Planes ( A , XlO')' Mn,P, Plane: 0.7313X - 0.0690Y + 0.067852 = 3.9938 Mn(1) 29, Mn(2) 60, P(11) -22, P(12) -9, P(21) -23, P(22) -36 C(7)* -779, C(8)* -768 Equatorial Plane: 0.0871X + 0.9961Y + 0.01272 = 2.4948 Mn(1) 11,Mn(2) 4, N ( l ) 3, N(2)-18, C ( l ) 18, O(1)9, C(2) 1 4 , 0 ( 2 ) 4, C(3) 2 1 , 0 ( 3 ) 0, C(4)-7,0(4)-48,C(5) 11,O(5) 49,C(6)-71 Dihedral Angle between the T w o Planes Is 89.8" a An asterisk indicates that the atom was not included in the plane equation calculation.

1.146 (10) 1.155 (11) 1.165 (10) 1.153 (9) 1.211 (10) 1.238 (9) 1.484 (12) 1.560 (13) 1.97 (3) 1.37 (4) 2.13 (3) 1.82 (3)

Ferguson et al.

280 Organometallics, Vol. 2, No. 2, 1983 In the Mn2P4fragment, the Mn-Mn distance 2.898 (2) than t h a t found in I (2.934 (6) A)" and is consistent with a metal-metal bond formation. The Mn-P distances are in the range 2.287-2.295 (2) A, mean 2.293 (2) A; in I, the Mn-P distances ranged between 2.234 (9) and 2.311 (9) A. The bridging carbon atoms C(7) and C(8) of the dppm ligands lie out of the Mn2P4plane (0.78 and 0.77 A) respectively on the same side as atom N(1) and remote from the bridging carbonyl C(4); an exactly similar situation was found in I. Steric crowding causes the phenyl rings to be bent away from the equatorial coordination plane; all the Mn-P-C angles are greater than tetrahedral (111.4-123.3 ( 2 ) O ) , and the C-P-C angles are all less than tetrahedral (98.7-104.4 (3)O). Other dimensions of the dppm ligand are as expected, e.g., average P-C = 1.830 (8) A. Given the molecular structure of 11, it is then possible to explain the spectroscopic data and to understand the chemistry involved. The IR spectra in the carbonyl region of complexes I and I1 are similar in many respects (experimental). However, the band in I due to the 4-electron carbonyl at 1648 cm-' is missing in 11, while new peaks arise at 1610 and 1818 cm-'. T h e 1610-cm-' peak is assigned to the C=O and N=N stretching modes of the metallacyclic ring in I1 while the 1818-cm-' peak is assigned to the semibridging carbonyl ligand. The bonding in I1 is most readily described as shown in eq 3, and the formal oxidation states of Mn(1) and Mn(2) are then 0 and +II, respectively. This is a classic situation for a semibridging carbonyl to be present, since the weak M n ( l ) - C ( 4 ) interaction allows excess electron density a t Mn(1) to be delocalized onto the carbonyl ligand. A low v(C0) of 1818 cm-I results from this extra back-bonding.22 The 'H NMR spectrum contains resonances in the expected 2:l ratio for CHzP2and CH2N protons, the former resonance showing partially resolved coupling with 31P which was lost in the 1H(31PJNMR spectrum. In principle, two resonances are expected for the CH,P2 protons since there is no plane of symmetry containing the P C P unit, but there is presumably accidental degeneracy of the CHAHBP2chemical shifts. T h a t the molecule is not fluxional on the NMR time scale is shown by the 31P{1H) NMR spectrum (Figure 3). A t 40.5 MHz, this occurs as an AA'BB' multiplet as expected for structure 11. T h e spectrum is sharp at -70 "C and the peaks broaden at room temperature, but no further broadening occurs up to +60 " C . T h e broadening is thus due to the presence of the quadrupolar manganese center and not to the onset of a fluxional p r o ~ e s s . ' ~ , * ~ The X-ray structure shows that the CHz-C(0) bond is long for a C-C single bond [C(5)-C(6) = 1.560 (13) A, cf. 1.516 ( 5 ) A in CH3CHO]. It is therefore possible to rationalize the cleavage of this bond on heating complex I1 in benzene or on photolysis of complex I1 in dichloromethane solution. In both reactions the elements of CH,N2 are lost, and complex I is reformed. I t is not clear however whether CHzNz is a product of these reactions. T h e only organic product identified was ethane, whereas diazomethane is expected to give ethylene or methane as decomposition products.

A is slightly shorter

(22) Cotton, F. A.; Wilkinson, G. "Advanced Inorganic Chemistry", 4th ed.; Wiley: New York, 1980; pp 1058-1060. (23) Preliminary results show that, in the corresponding complex derived from diazoethane, the 31P(1H} NMR spectrum contains a singlet down to -90 "C, probably indicating fluxionality in this molecule. The alternative would require accidental degeneracy of all four 31Pchemical shifts.

(a)

/ '

k

d

'

Figure 3. 31P(1H]NMR spectra of complex 11: (a) at 40.5 MHz; (b) at 162 MHz. Simulation as an AA'BB' multiplet gives Av(A,B) = 112 Hz at 40.5 MHz and 448 Hz at 162 MHz, &AB) = 80 Hz, and J(AB') = 32 Hz. T h e mechanism of formation of complex I1 could reasonably involve initial coordination of diazomethane to I as a 2-electron ligand replacing the Mn(7r-CO) bond in the usual fashion to give 111. Now the carbanionic carbon2

of the diazomethane in I11 may act as a nucleophile in attacking a terminal carbonyl ligand and hence form the metallacyclic ring. Further studies with other diazoalkanes are in progress with the aim of clarifying the mechanisms involved.23 The easy formation and cleavage of C-C bonds is perhaps the most important general feature of the chemistry of transition metallacycles, and the above reactions provide a good example of this effect.

Acknowledgment. Financial support from N.S.E.R.C. Canada (G.F. and R.J.P.) is gratefully acknowledged. Dr. G. H. Wood provided valuable assistance in searching CRYSTOR, the Cambridge Crystallographic Data Base at Ottawa. Registry No. I, 56665-73-7; 11, 83862-77-5; II.2CH2C12, 83916-58-9;CHZNZ, 334-88-3. Supplementary Material Available: Tables of hydrogen coordinates and thermal parameters and a listing of structure factor amplitudes (22 pages). Ordering information is given on any current masthead page.