10.1021/om1002478.s001
Guibin Ma
Guibin
Ma
Michael J. Ferguson
Michael J.
Ferguson
Robert McDonald
Robert
McDonald
Ronald G. Cavell
Ronald G.
Cavell
Rare, Hexatomic, Boat-Shaped, Cross-Linked Bis(iminodiphenylphosphorano)methanediide Pincer Carbon Bridged Photoluminescent Copper Clusters Capped with Methyl or Halide Bridges
American Chemical Society
2010
protonated parent methylene bridged ligand H 2L
THF
Halide BridgesThe dimeric dilithium methanediide salt
2C
copper atoms
UV
31 P NMR spectroscopy
Gaussian DFT calculations
2 equiv
NBO
31 P NMR spectra
6L
Li 2L
Cu
cluster
AB
2010-10-11 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Rare_Hexatomic_Boat_Shaped_Cross_Linked_Bis_iminodiphenylphosphorano_methanediide_Pincer_Carbon_Bridged_Photoluminescent_Copper_Clusters_Capped_with_Methyl_or_Halide_Bridges/2723257
The dimeric dilithium methanediide salt [Li<sub>2</sub>C(Ph<sub>2</sub>PNSiMe<sub>3</sub>)<sub>2</sub>]<sub>2</sub> ([Li<sub>2</sub>L]<sub>2</sub>, L = [C(Ph<sub>2</sub>P=NSiMe<sub>3</sub>)<sub>2</sub>]<sup>2−</sup>) reacted with 6 equiv of [NEt<sub>4</sub>CuCl<sub>2</sub>] and 2 equiv of LiMe in THF or ether to give exclusively the six-copper cluster complex [Cu<sub>6</sub>L<sub>2</sub>(CH<sub>3</sub>)<sub>2</sub>] (<b>1</b>). Similarly, [Li<sub>2</sub>L]<sub>2</sub> reacted with 3 equiv of the bimetallic copper halide complexes [(cod)<sub>2</sub>Cu<sub>2</sub>X<sub>2</sub>] (X = Cl, Br, I) in the same solvent to give good yields of three halide-capped six-copper clusters [Cu<sub>6</sub>L<sub>2</sub>(X)<sub>2</sub>] (X = Cl (<b>2</b>), Br (<b>3</b>), I (<b>4</b>)) with structures very similar to that of <b>1</b>. These four hexacopper clusters (<b>1</b>−<b>4</b>) as a family show similar <sup>31</sup>P NMR spectra with an AB pattern with slightly different chemical shifts but identical coupling constants in solution. The reactivity of <b>2</b> was explored, and it was demonstrated that <b>1</b> can be quantitatively generated by addition of 2 equiv of LiMe to <b>2</b>. Moreover, the cluster [Cu<sub>6</sub>L<sub>2</sub>(O<sup>t</sup>Bu)<sub>2</sub>] (<b>5</b>) with a similar cage structure is quantitatively generated by reaction of <b>2</b> with 2 equiv of NaO<sup>t</sup>Bu in solution according to <sup>31</sup>P NMR spectroscopy. An additional copper complex with a bicopper formulation, [Cu<sub>2</sub>L(PPh<sub>3</sub>)<sub>2</sub>] (<b>6</b>), was synthesized by reaction of [Li<sub>2</sub>L]<sub>2</sub> with 2 equiv of [(NEt<sub>4</sub>)Cu(PPh<sub>3</sub>)Cl<sub>2</sub>]. We also observed a monocopper iodide complex with the doubly protonated parent methylene bridged ligand H<sub>2</sub>L, [CuI(H<sub>2</sub>L)] (<b>7</b>), as a minor component (about 10%) during the preparation of complex <b>4</b>. Complexes <b>1</b>−<b>4</b>, <b>6</b>, and <b>7</b> were characterized by X-ray crystal diffraction. All four clusters (<b>1</b>−<b>4</b>) show a rare boat-shaped conformation of hexacopper clusters assembled by cross-linking of two copper atoms via geminal substitution on one bis(iminophosphorano)methanediide ligand. Two of these units combine along with two additional copper atoms to form the boat cluster. There is extensive direct Cu−Cu bonding. The cluster is doubly capped, top and bottom, by methyl groups (<b>1</b>) or halides (<b>2</b>−<b>4,</b> X = Cl, Br, I). All of these six-copper clusters absorb and emit in the UV−vis region. The absorption bands and photoluminescent wavelengths are substituent dependent; thus, optical properties of the complex are tunable by means of substitution of the capping ligands. The spectral and bonding characteristics were explored by means of Gaussian DFT calculations and NBO analysis.