V = 6863.8(9) A3, Z = 8, m(Mo-Ka) = 0.729 mmꢁ1, 8664 total
reflections, 2460 independent (Rint
2, C60H106BCuLiNO8P2: monoclinic, P21/c,
=
0.0409) with I
a
4
= 11.9146(9),
2s(I);
b = 21.3858(16), c = 24.4619(18) A, b = 92.5560(10)1, V =
6226.8(8) A3, Z = 8, m(Mo-Ka) = 0.905 mmꢁ1, 72625 total reflec-
tions, 14800 independent (Rint
= 0.0841) with I 4 2s(I);
3, C39H63BCuNP2: monoclinic, P21/c, a = 10.186(5), b = 17.079(8),
c = 22.083(7) A, b = 98.24(4)1, V = 3802(3) A3, Z = 4, m(Mo-Ka) =
0.685 mmꢁ1, 31590 total reflections, 7306 independent (Rint = 0.0990)
with I
17.548(3), b = 30.333(5), c = 12.818(3) A, V = 6823(2) A3, Z = 8,
4 2s(I); 4, C34H58BCuOP2: orthorhombic, Fdd2, a =
Fig.
3
13C{1H} signal (left) and 31P{1H} signal (right) for
m(Mo-Ka) = 0.758 mmꢁ1, 3639 total reflections, 2005 independent
13
[Ph2BPtBu2]CuQ CPh2 (8-13C).
ꢀ
(Rint = 0.0385) with I 4 2s(I); 5, C34H59BCuN2P2Si2: trigonal, R3c, a
= 21.4508(13), c = 47.633(3) A, V = 18981(2) A3, Z = 15, m(Mo-Ka)
=
= 0.561 mmꢁ1, 37667 total reflections, 3067 independent (Rint
though it is certainly within the range typically observed for
terminal metal carbene complexes.5,14 As further evidence for
the presence of the ‘‘CPh2’’ carbene functionality in 8, we
observed quantitative carbene transfer to CO to generate
ketene Ph2CQCQO and [Ph2BPtBu2]Cu(CO) upon exposure
of solutions of 8 to excess carbon monoxide (Scheme 1).
Carbene transfer to CO is also characteristic of the Ni and
Cu carbenes of Hillhouse and Warren, respectively.5,12 Com-
plex 8 did not readily transfer its carbene unit to olefins such as
1-hexene or styrene.
0.0834) with I 4 2s(I); 6, C49H72BCuN2P2: monoclinic, P21/c, a =
11.6975(16), b = 17.955(2), c = 23.035(3) A, b = 91.707(4)1, V =
4836.1(12) A3, Z = 4, m(Mo-Ka) = 0.550 mmꢁ1, 22763 total reflec-
tions, 6798 independent (Rint
=
0.1309) with
I 4 2s(I). 7,
C56H70BCuN2P2: monoclinic, P21/c,
a
=
12.0749(11), b =
22.347(2), c = 19.2412(18) A, b = 104.625(2)1, V = 5023.8(8) A3,
Z = 4, m(Mo-Ka) = 0.536 mmꢁ1, 42567 total reflections, 11402
independent (Rint = 0.0617) with I 4 2s(I). CCDC 659790–659796.
For crystallographic data in CIF or other electronic format see DOI:
10.1039/b713687k
1 Selected reviews: W. Kirmse, Angew. Chem., Int. Ed., 2003,
42, 1088; H. M. L. Davies and S. A. Panaro, Tetrahedron, 2000,
56, 4871; M. P. Doyle and D. C. Forbes, Chem. Rev., 1998, 98,
911.
Whereas Warren’s b-diketiminato copper carbene complex
is stable at room temperature, complex 8 loses Ph2CQCPh2
even at ꢁ30 1C. This fact has thus far precluded its crystal-
lization from solution. The b-diketiminato CuQCPh2 species
degrades similarly upon thermolysis.5
2 For recent advances see, for example: M. R. Fructos, T. R.
Belderrain, M. C. Nicasio, S. P. Nolan, H. Kaur, M. M. Dı
Requejo and P. J. Perez, J. Am. Chem. Soc., 2004, 126, 10846, and
references therein.
3 Selected examples: J. Barluenga, L. A. Lo
Tomas, S. Garcıa-Granda, C. Alvarez-Rua and J. Borge, Angew.
´
az-
´
A computational study of 8 was undertaken to probe the
Cu–C distance by DFT methods.15 A diphenylcarbene unit
was attached to the [Ph2BPtBu2]Cu fragment taken from the
atomic coordinates in the solid-state structure of 1. Geometry
optimization calculations using various initial Cu–C distances
all gave the same optimized geometry, featuring trigonal
planar geometries at both the copper center and the carbene
carbon atom, with a Cu–C distance of 1.933 A. Significantly
shorter distances have been determined experimentally for the
previously reported MQCR2 (M = Cu, Ni) complexes
(1.834–1.859 A).5,12 It is possible that the long predicted
Cu–C distance in 8 is experimentally manifested by the
relatively small value for 2JPC and the significantly deshielded
carbene carbon atom. It must however be noted that optimiz-
ing the geometry of 8 while fixing the Cu–C distance to be
either 1.830 or 2.030 A gave structures whose energies spanned
a range of only 1.0 kcal molꢁ1, indicating that the molecule’s
potential energy surface is quite flat with regard to the Cu–C
distance.
This work was funded by BP (MC2 program) and the NSF
(CHE-0132216). N. P. M. is grateful for an NSF Graduate
Research Fellowship. J. Christopher Thomas is acknowledged
for preliminary reaction screening. John Keith gave useful
advice regarding DFT calculations, and Larry Henling pro-
vided crystallographic assistance. DFT calculations were done
at the Materials and Process Simulation Center at the Cali-
fornia Institute of Technology.
´
pez, O. Lober, M.
¨
´
´
´
Chem., Int. Ed., 2001, 126, 10085; D. S. Laitar, P. Muller and
¨
J. P. Sadighi, J. Am. Chem. Soc., 2005, 127, 17196; H. Kaur, F.
Kauer, E. D. Stevens and S. P. Nolan, Organometallics, 2004, 23,
1157.
4 B. Straub and P. Hofmann, Angew. Chem., Int. Ed., 2001, 40,
1288.
5 Y. M. Badiei and T. H. Warren, J. Organomet. Chem., 2005, 690,
5989; X. Dai and T. H. Warren, J. Am. Chem. Soc., 2004, 126,
10085.
6 Selected examples: D. M. Jenkins, T. A. Betley and J. C. Peters, J.
Am. Chem. Soc., 2002, 124, 11238; S. D. Brown, T. A. Betley and J.
C. Peters, J. Am. Chem. Soc., 2003, 125, 322; T. A. Betley and J. C.
Peters, J. Am. Chem. Soc., 2004, 126, 6252; C. E. MacBeth, J. C.
Thomas, T. A. Betley and J. C. Peters, Inorg. Chem., 2004, 43,
4645.
7 J. C. Thomas and J. C. Peters, J. Am. Chem. Soc., 2003, 125,
8870; J. C. Thomas and J. C. Peters, Inorg. Chem., 2003, 42,
5055.
8 J. C. Thomas and J. C. Peters, Polyhedron, 2004, 23, 2901.
9 E. D. Blue, A. Davis, D. Conner, T. B. Gunnoe, P. D. Boyle and P.
S. White, J. Am. Chem. Soc., 2003, 125, 9435.
10 B. F. Straub, F. Rominger and P. Hofmann, Organometallics,
2000, 19, 4305.
11 E. Glozbach and J. Lorberth, J. Organomet. Chem., 1980, 191, 371;
H. E. Zimmerman and D. H. Paskovich, J. Am. Chem. Soc., 1964,
86, 2149.
12 R. Waterman and G. L. Hillhouse, J. Am. Chem. Soc., 2003, 125,
13350; D. J. Mindiola and G. L. Hillhouse, J. Am. Chem. Soc.,
2002, 124, 9976.
13 H. Zhu, J. Chai, A. Stasch, H. W. Roesky, T. Blunk, D. Vidovic, J.
Magull, H.-G. Schmidt and M. Noltemeyer, Eur. J. Inorg. Chem.,
2004, 4046.
14 R. H. Crabtree, The Organometallic Chemistry of the Transition
Metals, Wiley-Interscience, New York, 2001.
15 B3LYP functional; LACVP** basis set for Cu atoms, 6-31G**
basis set for carbene C and P atoms; MIDI! basis set for all other
atoms. See ESIw for additional details.
Notes and references
z Details of the X-ray diffraction studies: 1, C18H28BCuNP2: ortho-
rhombic, Fdd2, a = 16.5848(13), b = 30.917(2), c = 13.3863(10) A,
ꢀc
This journal is The Royal Society of Chemistry 2008
Chem. Commun., 2008, 1061–1063 | 1063