Structural, vibrational, and solid-state NMR studies of the halogenocuprate(I) complexes [(PPh3)2CuI2]- and [(PPh3)CuI3Cu(PPh3)]-
MetadataShow full item record
Single-crystal X-ray diffraction, vibrational spectroscopy, and solid state NMR spectroscopy have been used to characterize two new types of ionic copper(1) complexes. The anion in [PPh3Me]+[(PPh3)2Cu12]c-o ntains two PPh, ligands coordinated to the copper atom of a Cu12 unit in a pseudotetrahedral arrangement, with Cu-P = 2.292 (2), 2.288 (2) A, Cu-I = 2.692 (I), 2.702 ( I ) A, P-Cu-P = 121.24 (9)", and I-Cu-I = 108.62 (4)' (monoclinic, P21/c, a = 12.138 (5) A, b = 14.776 (6) A, c = 28.197 (14) A, 0 = 103.76 (4)O, Z = 4, R = 0.040 for 4490 'observed" (I > 3 4 ) ) reflections). The far-IR spectrum shows a strong band at 118 cm-l that is assigned to the antisymmetric Cu-I stretching mode of the CUI, unit. The CPMAS ,*P NMR spectrum shows a strong singlet at 18.1 ppm (relative to 85% H3Po4) due to the cation and a weaker quartet centered at -16.7 ppm due to the coordinated PPh, in the anion, with line spacings due to Cu-P coupling of 1.08, 1.20, and 1.23 kHz. The anion in [PPh,Me]+[ (PPh,)CuI,Cu(PPh,)]- consists of an approximately D,h Cu213 unit with three iodine atoms bridging the two copper atoms and with one PPh, molecule completing a pseudotetrahedral arrangement around each copper atom. The crystallographically imposed symmetry of the ion is C,,, with the 3-fold axis passing through the P-Cu bonds. The core structural parameters are (5)O, and Cu-I-Cu = 54.88 (4)' (cubic, P2,3, a = 17.744 (IO) A, Z = 4, R = 0.036 for 1390 "observed" reflections). This is the first reported example of a binuclear copper(1) complex with three bridging ligands and is an example of an unusual bonding situation in which two coordination tetrahedra are linked by sharing a common face. This has the effect of producing an unusually short Cu-- -Cu separation of 2.50 A. The far-IR spectrum shows a band at 127 cm-' that is assigned to the doubly degenerate perpendicular Cu-I stretching mode of the CutIl unit. The CPMAS NMR spectrum shows a strong singlet at 20.1 ppm due to the cation and a broad quartet centered at -15.8 ppm due to the coordinated PPh, in the anion. The splitting pattern for this quartet does not conform to expectations for an AX spin system involving coupling between I = I / , and I = ,/, nuclei. The assignments of the ~(CU-I)I R bands in both complexes are supported by approximate normal-wordinate analyses, and the resulting Cu-I force constants are compared with the values obtained in similar analyses of related iodocopper(1) complexes.
© 1989 American Chemical Society. Self-archiving of the author-manuscript version is not yet supported by this publisher. The contents of this journal can be freely accessed online via the ACS web page 12 months after publication. Use hypertext link above to access the ACS website.