Organometallics 1982, 1, 1429-1432 amplitudes and calculated structure factors in Table OMllM100##fnt The computer programs used in this analysis are listed in ref 23. (Canada) for Acknowledgment. We thank financial support (R.J.P.),NATO for a travel grant (R.J.P. (22) Supplementary material. (23) The Enraf-Nonius Software Package for the CAD-4F diffractometer: CAD4 Data Processing Program (M. B. Humthouse),a local version of G. M. Sheldricks SHELX system, CEOM molecular functions program (P. R. Mallinson), and ORTEP (C. K. Johnson),adapted for the local ICL 2976 computer by P. R. Mallinson and K. W. Muir.
1429
and M.P.B.), and the University of Glasgow for a studentship (A.A.F.). Registry Na. Ia, 63911-00-2;Ib, 82864-97-9;IIa, 74587-82-9;IIb, 82864.99-1; 111, 78064-41-2; IV, 69215-82-3; 68851-46-7; VI, 64387-54-8; VII, 81533-22-4; [PhH2(p-H)(p-dppm)2]C1,63910-98-5; Pt, 7440-06-4: carbon monoxide, 630-08-0: hydrogen. 1333-74-0:dimethylphenylphosphine, 1486-28-8; methanithiil, 74-93-1.
v,
Supplementary Material Available: Listings of observed and calculated and atom fractional coordinates (Table v; 32 pages). Ordering information is given
on any current masthead page.
Comparative Reactivities of the Cyclopolyarsines (C,H,As), and (CH,As),. The Crystal and Molecular Structure of trans-I ,2-( 1,2-Diphenyldiarsino) bis[ (y5-cyclopentadienyl)dicarbonyliron], [CpFe(co),],( C6H5As), Arnold L. Rheingold,’ Michael J. Foley, and Patrick J. Sullivan Department of Chemistry, University of Delaware, Newark, Delaware 197 1 1 Received July 1, 1982
The bis metal-substituted diarsine species [CpFe(CO)2]2(C6H&s)2 (31, synthesized from [CpFe(CO)2]2 and c-(C&~AS)~, crystallizes in the centrosymmetricmonoclinic space group R1c [c”,, No. 141 with a = 6.534 (2) A, b = 11.191 (2) A, c = 17.529 (5) A, /3 = 99.60 (2) A, V = 1263.9 (6) and p = 1.73 g for 2 = 2 (mol wt 657.98). Diffraction data were collected with a Nicolet R3 diffractometer, and the structure was refined to RF = 6.60% for 1579 reflections with 3’ < 28 < 45’ (Mo K a radiation). The molecule is as the tetrasubstituted diarsine trans-l,2-(1,2-diphenyldiarsino)bis[(~5-cyclopentadienyl)dicarbonyliron]; such it represents the f i s t example of a new class of bridged dinuclear metal complexes. The As-Fe bond distance, 2.450 (2) A, is long in keeping with the formal one-electron As donation to Fe. The As-As‘ bond distance, 2.456 (2) A, is within the range of ’normal” As-As single bonds. In comparison, replacement produces as the primary Fe-As-containing product of (c&&)6for (CH3As),in reactions with [CpFe(CO)2]z (4), identified by its spectroscopic a four-membered, diiron-bridging chaii [Fe(CO)Cp]z[p-catena-(CH3As)4] properties. Accompanying the formation of 4 under open system conditions in refluxing hexane with UV irradiation is a substantial yield of [CpFe(CO)],(-55%).
13,
Introduction Understanding how main-group elements bridge transition-metal centers is a major goal in inorganic chemistry. Such bridges often possess desirable structural characteristics for the design of binuclear and cluster catalysts. The extraordinary structural diversity of transition-metal carbonyl derivatives of catenated organophosphinidene and arsinidene groups (RP or RAs) makes them particularly rewarding subjects for study. Our studies of the products of the reactions of cyclopentadienylmetal carbonyls with polyorganocyclopolyarsines have shown that a characteristic feature of these reactions is ring cleavage and reformation of the resulting chain into a variety of lengths (from two to nine atoms) and configuration^.'-^ We have also been interested in determining what effects the organic substitution on the cycloarsine precursor has in controlling the course of these reactions. West has studied the reactions of Fe(CO), with three cyclopolyarsines: (CH~AS)~, (C&j&)6, and (cfl&)q.3dh the first two cases, the rings were cleaved and shortened to form (1) Rheingold, A. L.; Churchill, M. R. J.Organomet. Chem., in press.
(2) Rheingold, A. L.; Foley, M. J.; Sullivan, P. J. J.Am. Chem. Soc., in press. (3) Elmes, P. S.;West, B. 0. J. Organomet. Chem. 1971, 32, 365. (4) Gatehouse, B. M. J. Chem. SOC.,Chem. Commun. 1969,948. (5) Elmes, P. S.; Leverett, P.; West, B. 0. J. Chem. Soc., Chem. Commun. 1971, 747.
[Fe(CO)312[r-(RAs)41(1); with (C6F5As),, [Fe(C0)41[T*(AsC~F,)~] (2) was obtained. In the study we now report, we compare the reactions of (C6H5As)6and (CH3A~)6 with [CpFe(CO)2]2. In the former case we obtain a diarsine derivative, trans-1,2(1,2-diphenyldiarsino)bis(cyclopentadienyldicarbonyliron), [CpFe(C0)2]2(AsC6H5)2 (3), which is the first example of a new class of arsenic-bridged dinuclear complexes. An X-ray crystallographic structure is included. In the latter case, an analogue of 1 containing a four-membered, RAs chain bridged complex is obtained: [CpFe(CO)][p(CH3As4)](4) along with up to 55% yield of [CpFe(CO)I4. Structurally confirmed examples of complexes containing two linked RA5 units are surprisingly few and are limited to three-membered heterocycles, e.g., the AszFe
2 &-A = 2 . 3 8 8 ( 7 ) A
5 &-AS= 2.371 A
(6) Huttner, G.; Schmid, H.-G.; Frank, A.; Orama, 0. Angew. Chem. 1976, 88, 255.
0276-7333/82/2301-1429$01.25/0 0 1982 American Chemical Society
Rheingold, Foley, and Sullivan
1430 Organometallics, Vol. 1, No. 11, 1982 Table I. Crystal and Refinement Data
c
formula cryst system space group a, .K b, c, '4
P , deg v, A 3
z
mol wt p(calcd), g cm-' temp, "C crystal dimens, m m ; color radiation diffractometer abs coeff, cm-' scan speed, deglmin 26 scan range, deg scan technique data collected scan width, deg weighting factor ( g ) b unique data unique data with (F,)' > 3o(F0I2 std reflctns RF RWF
Table 11. Atomic Fractional Coordinates for [CPFe(CO),12(C,H,A5)2 atom X Y z
20As2Fe204 monoclinic P ~ , / c[C&, NO. 141 6.534 (2)* 11.191 ( 2 ) 17.529 ( 5 ) 99.60 ( 2 ) 1263.9 ( 6 ) 2 657.98 1.729 25 0.20 x 0.25 X 0.32; dark red graphite-monochromated Mo Ka ( h = 0.710 73 A ) Nicolet R3 37.70 variable, 3.0-15.0 3 . 0 < 20 < 45.0 2e/e ih,ik,+l 2.0 + A ( @ , - a 2 ) 0.0001 1880 reflctns ( 3 9 2 3 collected) 1579 2
3
3/97 6.60% 5.75%
Unit-cell parameters were obtained from the angular W-' = settings of 25 reflections with 26 = 25-30'. o 2 ( F o )-k g(F0l2.
Experimental Section A. P r e p a r a t i o n of [CpFe(CO)zAs(C6H5)]z (3). [CpFe(co),]J (0.50 g, 1.41 "01) and c-(c6H&): (0.50 g, 0.55 mmol) were combined in a heavy-wall Pyrex tube with 25.0 mL of dried toluene. The contents were thoroughly degassed, and the tube was sealed under vacuum and heated a t 90 "C for 24 h in a dark oven. The oven was then switched off and the reaction tube left in the oven undisturbed for 24 h while being cooled to room temperature. Examination of the tube revealed the presence of crystallographic grade crystals that were removed by filtration and washed with cold hexane. Compound 3 was obtained as a dark red, air-stable solid (mp 195 "C) that is only slightly soluble in common organic solvents: 'H NMR Cp 4.50 (5), C6H6, 7.23 ppm (5); IR (KBr) carbonyl 2020 (s), 1945 cm-' ( 8 ) . Column chromatography on deactivated alumina failed to reveal any other products present in significant quantities. B. Reactions of [CpFe(CO)z]zand c-(AsCH& 1. Thermal Reaction. Equimolar quantities (2.0 mmol) of [CpFe(CO)z]zand (CH,As): were combined with 20 mL of toluene in a heavy-wall Pyrex tube, the contents were degassed, and the tube was flame sealed under vacuum and heated to 90 "C for 36 h. (Below 95" no apparent reaction occurred, above 95O extensive decomposition occurred.) The progress of the reaction was monitored by 'H NMR by observing changes in a n identically prepared and manipulated sample in a medium wall, 5-mm NMR tube. After the reaction tube was cooled and opened, the contents were chromatographed by using a low-pressure column on alumina (highly deactivated) and eluted with a 90/10 (v/v) C6&-CHC13 mixture. In addition to starting material (
