Monomeric InC6H3-2,6-Trip2 (trip = -C6H2-2,4,6-i-Pr3) and its manganese complex (η5-C5H5)(CO)2MnInC6H3-2,6-Trip2

Full text of DOI:10.1021/ja973479c

2202
J. Am. Chem. Soc. 1998, 120, 2202-2203
Compound 1 was obtained12 by treatment of InCl with (Et2O)-
LiC6H3-2,6-Trip2 in THF at ca. -78 °C. The bright-orange,
Monomeric InC6H3-2,6-Trip2 (Trip )
-C6H2-2,4,6-i-Pr3) and Its Manganese Complex
(η5-C5H5)(CO)2MnInC6H3-2,6-Trip2: One-Coordinate
Indium in the Solid State
12a
very air-sensitive crystals of 1 display considerable thermal
stability and decompose only above 216 °C. Its structure13 (Figure
1) consists of well-separated InC6H3-2,6-Trip2 monomers (shortest
In‚‚‚In distance ) 6.890(2) Å) which have an In-C bond length
of 2.260(7) Å. The In is displaced slightly (by ca. 0.23 Å) from
the averaged plane of the C(1) ring. There are no close
interactions between In and other atoms as indicated by the
distances In‚‚‚centroid C(7) or C(13) rings ) ca. 3.90 Å, In‚‚‚H-
(i-Pr, CH3) ) 3.30 and 3.40 Å. The In-C bond is longer than
the In-C σ-bonded distances (range ca. 2.11 f 2.17 Å) in In-
(III) derivatives of bulky ligands such as Mes*(-C6H2-2,4,6-t-
Bu3), -C6H3-2,6-Mes2, or -C6H3-2,6-Trip2,14 but is almost identical
to the In-C distance(2.250(5) Å) in [In{C(SiMe3)3}]4.9b A similar
lengthening has been noted in its Ga(I) analogue [Ga{C(SiMe3)3}]415
whose Ga-C bonds average ca. 0.1 Å longer than those in
sterically crowded Ga(III)-C compounds.14,16 Furthermore, it is
notable that the Ga-C distance in the vapor-phase structure of
monomeric Ga{C(SiMe3)3}17 remains essentially unchanged from
that seen in [Ga{C(SiMe3)3}]4.15 Similarly, the In-N distances
Scott T. Haubrich and Philip P. Power*
Department of Chemistry, UniVersity of California
DaVis, California 95616
ReceiVed October 6, 1997
Although the major oxidation state of the group 13 elements
(i.e., B-Tl) is III, the univalent state becomes more stable with
increasing atomic number so that Tl(I) is dominant in that
element’s chemistry.1 In(I) is more unstable and readily dispro-
portionates to give In(O) and In(III) products. Nonetheless, there
is widespread interest2 in its compounds as well as those of its
less stable Ga(I) and Al(I) congeners.3 A range of organometallic4-6
and related7,8 derivatives of In(I) have been synthesized. In the
solid state, the organometallic compounds are associated and have
a polymeric zig-zig arrangement in {In(C5H5)}∞,5c a hexameric
structure in {In(C5Me5)}6,5a,b and a weakly In-In bonded structure
in dimeric [In{C5(CH2Ph)5}]2.6 In the vapor phase, however, In(η5-
C5H4Me)5c and In(η5-C5Me5)5b are monomers. The related
trispyrazolylborate complexes In(pz)3BH (pz ) 3-phenylpyra-
zolyl,7 3,5-di-tert-butylpyrazolyl,8a or 3-tert-butylpyrazolyl8b), in
which In is coordinated by three N donors, are monomeric in the
crystal phase. At present, however, there are no structures of a
one-coordinate In(I) species in either the vapor or solid states. In
fact, molecular In(I) derivatives of monodentate ligands of any
12a
(12) Under anaerobic and anhydrous conditions (Et2O)LiC6H3-2,6-Trip2
(1.00 g, 1.78 mmol) in THF (15 mL) at ca. -78 °C was added dropwise to
a suspension of InCl (0.267 g, 1.78 mmol) at ca. -78 °C with rapid stirring.
The solution was stirred at ca. -78 °C for 1.5 h and then warmed to ca. -10
°C. After an additional 1 h of stirring, the volatile materials were removed
under reduced pressure at -10 °C. The solid residue was extracted with ca.
35 mL of cold hexane (ca. -10 °C). The solution was allowed to come to
ambient temperature, where the dark precipitates (presumably In metal and
LiCl) were allowed to settle. The orange-brown supernatant solution was then
filtered through Celite. The filtrate was concentrated to incipient crystallization
(ca. 20 mL) and stored at ca. -20 °C for 24 h to afford the product 1 as
bright orange crystals: yield 0.37 g, 0.61 mmol, 34%; mp 216-220 °C (dec).
LDI MS: m/e ) 596.8. UV (λmax, ꢀ): 280 nm, sh; 440 nm, 320; 368 nm,
760. Anal. Calcd for C36H49In: C, 72.47; H, 8.28; In, 19.25. Found: C, 72.38;
H, 8.36; In, 19.11. 1H NMR (C6D6): δ 1.17 (d, 12H, J ) 6.9 Hz, p-CH-
(CH3)2); 1.25 (d, 12H, J ) 7.2 Hz, o-CH(CH)3)2), 1.27 (d, 12H, J ) 7.2 Hz,
o-CH(CH3)2); 2.85 (sept, 2H, J ) 6.9 Hz, p-CH(CH3)2); 3.15 (sept, 4H, J )
7.2 Hz, o-CH(CH3)2); 7.19 (br s, 2H, m-C6H3); 7.25 (s, 4H, m-Trip), 7.26 (t,
1H, p-C6H3). 13C{1H} NMR (C6D6): δ 24.76 (o-CH(CH3)2), 24.99 (o-CH-
(CH3)2); 30.49 (p-CH(CH3)2); 30.82 (p-CH(CH3)2); 34.74 (o-CH(CH3)2);
121.00 (m-Trip); 126.93 (p-C6H3); 128.83 (m-C6H3); 137.73 (o-C6H3); 144.21
(p-Trip); 147.60 (o-Trip); 148.40 (i-Trip); 206.92 (i-C6H3). Mn(η5-C5H5)(CO)3
(0.07 g, 0.34 mmol, Strem) in THF (5 mL) at ca. 25 °C was irradiated for 1
h with a UV lamp in a quartz Schlenk tube. The resultant bright red solution
of (η5-C5H5)Mn(CO)2THF12b was treated with 1 (0.20 g, 0.34 mmol) via a
solids addition tube. After 12 h of stirring, the volatile materials were removed
under reduced pressure. The residue was extracted with hexane (ca. 10 mL),
and the orange solution was filtered through Celite. Concentration to ca. 4
mL and storage at -20 °C for 48 h gave 2 as orange crystals: yield 0.12 g,
46%; mp 200 °C (dec). Anal. Calcd for C43H54InMnO2: C, 66.84; H, 7.04.
Found: C, 67.10; H, 7.09. IR (Nujol, cm-1): 1940 s, 1864 s (CO). 1H NMR
(C6D6): δ 1.15 (d, 12H, J ) 7.0 Hz, p-CH(CH3)2; 1.26 (d, 12H, J ) 7.1 Hz,
o-CH(CH3)2), 1.28 (d, 12H, 7.1 Hz, o-CH(CH3)2); 2.81 (sept, 2H, J ) 7.0
Hz, p-(CH3)2), 3.12 (sept, 4H, J ) 7.1 Hz, 4.72 (s, 5H, η5-C5H5), 7.12 (d, 2H,
JHH ) 7.7 Hz, m-C6H3), 7.24 (s, 4H, m-Trip), 7.28 (t, 1H, JHH ) 7.3 Hz,
p-C6H3). (a) Schiemenz, B.; Power, P. P. Organometallics 1996, 15, 958. (b)
Strohemeier, W.; Hillman, H. Chem. Ber. 1965, 98, 1598.
9
kind are quite rare and limited to the complexes [In{C(SiMe3)3}]4
and [In{OC6H2-2,4,6-(CF3)3}]2.10 The former species was shown
to have a tetrahedrane9 In4 arrangement (In-In ) 3.002(1) Å9b)
with an In-C distance of 2.250(5) Å.9b The structure of [In-
{OC6H2-2,4,6-(CF3)3}]210 involves the two metals bridged by two
aryloxides which results in unique two-coordination for In. It is
now shown that, by use of the crowding o-terphenyl ligand -C6H3-
2,6-Trip2 (Trip ) -C6H2-2,4,6-i-Pr3),11 the monomeric compound
InC6H3-2,6-Trip2 (1), which has a unique one-coordinate solid-
phase structure, can be synthesized and characterized.
(1) Cotton, F. A.; Wilkinson, G. AdVanced Inorganic Chemistry, 5th ed.;
Wiley: New York, 1988; p 208.
(2) Tuck, D. G. Chem. Soc. ReV. 1993, 22, 269.
(3) Dohmeier, C.; Loos, D.; Schno¨ckel, H. Angew. Chem., Int. Ed. Engl.
1996, 35, 129.
(4) Schmidbaur, H. Angew. Chem., Int. Ed. Engl. 1985, 24, 893.
(5) (a) Beachley, O. T., Jr.; Blom, R.; Churchill, M. R.; Fettinger, J.; Pazik,
J. C.; Victoriano, L. J. Am. Chem. Soc. 1986, 108, 4666. (b) Beachley, O. T.,
Jr.; Blom, R.; Churchill, M. R.; Faegri, K., Jr.; Fettinger, J. C.; Pazik, J. C.;
Victoriano, L. Organometallics 1989, 8, 346. (c) Beachley, O. T., Jr.; Pazik,
J. C.; Glassman, T. E.; Churchill, M. R.; Fettinger, J. C.; Blom, R.
Organometallics 1988, 7, 1051. (d) Beachley, O. T., Jr.; Lees, J. F.; Glassman,
T. E.; Churchill, M. R.; Buttrey, L. A. Organometallics 1990, 9, 2488. (e)
Beachley, O. T., Jr.; Lees, J. F.; Rodgers, R. D. J. Organomet. Chem. 1991,
418, 165.
(13) Crystallographic data for 1 (130 K) and 2 (170 K) with Mo KR (λ )
0.710 73 Å) radiation: 1, a ) 7.926(3) Å, b ) 16.282(7) Å, c ) 25.661(8)
Å, Z ) 4, space group Pna21, R1 ) 0.066 for 2118 I > 2(σ)I data; 2, a )
9513(2) Å, b ) 9.831(2) Å, c ) 21.083(4) Å, R ) 86.65(3)°, â ) 81.40(3)°,
γ ) 89.32(3)°, Z ) 2, space group P1h, R ) 0.047 for 7034 I > 2(σ)I data.
(14) (a) Petrie, M. A.; Power, P. P.; Dias, H. V. R.; Ruhlandt-Senge, K.;
Waggoner, K. M.; Wehmschulte, R. Organometallics 1993, 12, 1086. (b)
Schultz, S.; Pusch, S.; Pohl, E.; Dielkus, S.; Herbst-Irmer, R.; Miller, A.;
Roesky, H. W. Inorg. Chem. 1993, 32, 3343. (c) Rahbarnoohi, H.; Heeg, M.
J.; Oliver, J. P. Organometallics 1994, 13, 2123. (d) Robinson, G. H.; Li,
X.-W.; Pennington, W. T. J. Organomet. Chem. 1995, 501, 399. (e) Cowley,
A. H.; Isom, H. S.; Decken, A. Organometallics 1995, 14, 2589. (f) Li, H.-
W.; Robinson, G. H.; Pennington, W. T. Main Group Chem. 1996, 1, 301.
(g) Rahbarnoohi, H.; Wells, R. L.; Liable-Sands, L. M.; Rheingold, A. L.
Organometallics 1996, 15, 3998.
(6) Schumann, H.; Janiak, C.; Gorlitz, F.; Loebel, J.; Dietrich, A. J.
Organomet. Chem. 1991, 418, 165.
(7) Frazer, A.; Piggott, B.; Hursthouse, M. B.; Mazid, M. J. Am. Chem.
Soc. 1994, 116, 4127.
(8) (a) Kuchta, M. C.; Dias, H. V. R.; Bott, S. G.; Parkin, G. Inorg. Chem.
1996, 35, 943. (b) Dias, H. V. R.; Huai, L.; Jin, W.; Bott, S. G. Inorg. Chem.
1995, 34, 1973.
(9) (a) Schluter, R. D.; Cowley, A. H.; Atwood, D. A.; Jones, R. A.;
Atwood, J. L. J. Coord. Chem. 1993, 30, 215. (b) Uhl, W.; Graupner, R.;
Layh, M.; Schu¨tz, U. J. Organomet. Chem. 1995, 493, C1-C5.
(10) Scholz, M.; Noltemeyer, M.; Roesky, H. W. Angew. Chem., Int. Ed.
Engl. 1989, 28, 1382.
(15) Uhl, W.; Miller, W.; Layh, M.; Schwarz, W. Angew. Chem., Int. Ed.
Engl. 1992, 31, 1364.
(11) (a) Schiemenz, B.; Power P. P. Angew. Chem., Int. Ed. Engl. 1996,
35, 2150. (b) Grigsby, W. J.; Power, P. P. J. Am. Chem. Soc. 1996, 118,
7981. (c) Su, J.; Li, X.-W.; Crittendon, R. C.; Robinson, G. H. J. Am. Chem.
Soc. 1997, 119, 5471.
(16) (a) Meller, A.; Pusch, S.; Pohl, E.; Ha¨ming, L.; Herbst-Irmer, R. Chem.
Ber. 1993, 126, 2255. (b) Li, H.-W.; Pennington, W. T.; Robinson, G. H.
Organometallics 1995, 14, 2109. (c) Crittendon, R. C.; Li, X.-W.; Su, J.;
Robinson, G. H. Organometalics 1997, 16, 2443.
S0002-7863(97)03479-3 CCC: $15.00 © 1998 American Chemical Society
Published on Web 02/20/1998

Communications to the Editor
J. Am. Chem. Soc., Vol. 120, No. 9, 1998 2203
Figure 1. Computer-generated drawing of 1 with H atoms not shown.
Selected bond distances (Å) and angles (deg): In-C(1) ) 2.260(7), C(1)-
C(2) ) 1.39(2), C(2)-C(3) ) 1.42(2), C(3)-C(4) ) 1.44(2), C(4)-C(5)
) 1.35(2), C(5)-C(6) ) 1.39(2), C(1)-C(6) ) 1.42(2), In-C(1)-C(2)
) 121.9(14), In-C(1)-C(6) ) 120.2(14), C(2)-C(1)-C(6) ) 117.5-
(6), C(1)-C(2)-C(7) ) 115(2), C(1)-C(6)-C(13) ) 118(2).
Figure 2. Computer-generated drawing of 2 with H atoms not shown.
Selected bond distances (Å) and angles (deg): In-C(1) ) 2.155(3), In-
Mn(1) ) 2.4102(9), Mn-C(37) ) 1.785(4), Mn-C(38) ) 1.774(4), Mn-
C(η5-C5H5) ) 2.115(3)-2.311(4), O(2)-C(37) ) 1.168(5), O(1)-C(38)
) 1.167(5), Mn-centroid(η5-C5H5) ) 1.757, C(1)-In(1)-Mn(1) )
175.39(9), C(37)-Mn(1)-C(38) ) 91.7(2), In(1)-C(1)-C(2) ) 123.8-
(2), In(1)-C(1)-C(6) ) 114.7(2), C(2)-C(1)-C(6) ) 121.4(3).
in monomeric In(I) trispyrazolylborates may be as much as ca.
0.2 Å longer than those in related In(III) trispyrazolylborate
species.8 Thus, it seems that the longer In-C bond in 1 is
consistent with known structural data for monomeric or weakly
associated Ga(I) or In(I) species.
A further notable aspect of the structure of 1 is the one-
coordination of the In center. One-coordination for a metal in
the condensed phase has been claimed previously only for the
compounds MC6H3-2,4,6-Ph3 (M ) Cu or Ag).18 However, a
subsequent investigation indicated that the structural and spec-
troscopic data for these compounds were inconsistent with their
formulation as Cu or Ag species.19 The unique one-coordinate
nature of In in 1 is undoubtedly due to the protection afforded it
by the o-Trip substituents and the presence of a nonbonded lone-
pair of electrons.
Initial investigations of the chemical properties of 1 show that
the In center can function as a Lewis base. Thus, reaction of 1
with (η5-C5H5)(CO)2Mn(THF)12b affords the complex (η5-
C5H5)(CO)2MnInC6H3-2,6-Trip2, 2, as orange crystals.12a Its
structure (Figure 2)13 shows that 1 is bound in a terminal,
monodentate fashion to the 16-electron Mn(η5-C5H5)(CO)2 frag-
ment with an Mn-In distance of 2.4102(9) Å and an almost linear
geometry (C(1)-In(1)-Mn(1) ) 175.39(9)°) at In. The In-Mn
distance is ca. 0.2 Å shorter than those in related bridged
complexes such as [Mn(CO)4{InC(SiMe3)3}]2.20 This can be
attributed to the lower coordination number at In and the terminal
nature of the ligand. The In-C(1) bond in 2 (2.155(3) Å) is ca.
0.1 Å shorter than the corresponding distance in 1. This is
consistent with previous data for the [Mn(CO)4In{C(SiMe3)3}]2
complex20 which has a shorter distance than that seen in [In-
{C(SiMe3)3}]4.9b Carbonyl stretching frequencies in 2 (ν(CO)
cm-1 ) 1940 s, 1864 s) are comparable to those of (η5-
C5H5)(CO)2Mn(THF) (1925 s, 1850 s) and (η5-C5H5)(CO)2-
MnPPh3 (1932 s, 1869 s), indicating that 1 is, for the most part,
a σ-donor with weak π-acceptor characteristics.12b This view of
its bonding properties is in harmony with the metal-ligand
bonding descriptions of (CO)4FeAl(η5-C5Me5)21 and (CO)4FeIn{3,5-
Me2(pz)BH}22 but does not support the reported FeGa triple
bonding of the Ga(I) ligand in (CO)4FeGaC6H3-2,6-Trip2.23
Acknowledgment. We thank the National Science Foundation for
financial support and Dr. Marilyn Olmstead and Dr. Mathias Senge for
help with the X-ray data collection.
Supporting Information Available: Tables of data collection
parameters, atom coordinates, bond distances, angles, anisotropic thermal
parameters and hydrogen coordinates (34 pages). An X-ray crystal-
lographic file, in CIF format, is available through the Web only. See
any current masthead page for ordering and Web access instructions.
JA973479C
(20) Uhl, W.; Kiemling, S. W.; Hiller, W.; Neumayer, M. Chem. Ber. 1996,
129, 1137.
(21) Weiss, J.; Stelzkamp, D.; Huber, B.; Fisher, R. A.; Boehme, C.;
Frenking, G. Angew. Chem., Int. Ed. Engl. 1997, 36, 70.
(22) Reger, D. L.; Mason, S. S.; Rheingold, A. L.; Haggertry, B. S.; Arnold,
F. P. Organometallics 1994, 13, 5049.
(17) Haaland, A.; Martinsen, K.-G.; Volden, H. V.; Kaim, W.; Waldho¨r,
E.; Uhl, W.; Schu¨tz, U. Organometallics 1996, 15, 1146.
(18) Lingnau, R.; Stra¨hle, J. Angew. Chem., Int. Ed. Engl. 1988, 27, 436.
(19) Haaland, A.; Rypdal, K.; Verne, H.-P.; Scherer, W.; Thiel, W. Angew.
Chem., Int. Ed. Engl. 1994, 33, 2443.
(23) Su, J.; Li, X.-W.; Crittendon, R. C.; Campana, C. F.; Robinson, G.
H. Organometallics 1997, 16, 4511.