Tantalum(I) alkyne complexes: Ta(CO)/sub 2/(eta/sup 2/-RC=CR)(I)L/sub 2/
Excess alkyne reacts with Ta(CO)/sub 3/(I)L/sub 3/ to form Ta(CO)/sub 2/(eta/sup 2/-RC=CR)(I)L/sub 2/ complexes (L = PMe/sub 3/ and RCCR = PhCCPh (3), PhCCH (4), HCCH (5), Ph/sub 2/PCCPPh/sub 2/ (6); L = P(OMe)/sub 3/ and RCCR = PhCCPh (7)). These octahedral d/sup 4/ tantalum alkyne adducts have been characterized by /sup 1/H, /sup 13/C, and /sup 31/P NMR, as well as by infrared and visible spectroscopy. Low-field acetylenic proton and carbon resonances are compatible with a four-electron donor alkyne description for these complexes. Variable-temperature /sup 13/C NMR studies of /sup 13/CO enriched Ta(CO)/sub 2/(PhCCH)(I)(PMe/sub 3/)/sub 2/ revealed a ..delta..Gdouble dager of 16 kcal/mol for alkyne rotation about the C-C midpoint of the tantalum-alkyne axis. The X-ray crystal structure of Ta(CO)/sub 2/(PhCCPh)(I)(PMe/sub 3/)/sub 2/ has been determined. (Crystal data: monoclinic, P2/sub 1//c; a = 12.304 (4) A, b = 30.971 (8) A, c = 13.967 (5) A; ..beta.. = 96.91 (3)/sup 0/; Z = 8.) The molecule adopts a distorted octahedral geometry with trans carbonyl ligands and trans PMe/sub 3/ ligands. The alkyne is trans to iodide to complete the coordination sphere, and the C-C axis is parallel to the OC-Ta-CO axis. Average metal-ligand bond distances for the two independent molecules in the unit cell are Ta-I, 2.88 (1) A; Ta-C (alkyne), 2.06 (6) A; and Ta-CO, 1.98 (9) A. There is a definite pyramidal distortion of the four equatorial ligands away from the alkyne ligand toward the trans iodide.
- Research Organization:
- Univ. of North Carolina, Chapel Hill (USA)
- OSTI ID:
- 7004941
- Journal Information:
- Organometallics; (United States), Journal Name: Organometallics; (United States) Vol. 7:2; ISSN ORGND
- Country of Publication:
- United States
- Language:
- English
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ABSORPTION SPECTROSCOPY
ALKYNES
BOND ANGLE
BOND LENGTHS
CARBON 13
CARBON ISOTOPES
CARBONYLS
CHEMICAL PREPARATION
CHEMISTRY
COHERENT SCATTERING
COMPLEXES
CRYSTAL STRUCTURE
DATA
DIFFRACTION
DIMENSIONS
ELECTROCHEMISTRY
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGEN 1
HYDROGEN ISOTOPES
INFORMATION
ISOTOPES
LENGTH
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
RESONANCE
SCATTERING
SPACE GROUPS
SPECTROSCOPY
STABLE ISOTOPES
SYNTHESIS
TANTALUM COMPLEXES
TRANSITION ELEMENT COMPLEXES
X-RAY DIFFRACTION