Synthesis and structure of rhodium complexes containing a photolabile {eta}{sup 2}-carbodiimide ligand. 1,3-dipolar cycloaddition of phenyl azide to Tp{prime}Rh(CNR){sub 2} (Tp{prime} = hydrotris(3,5-dimethylpyrazolyl)borate)

Journal Article · Wed Apr 01 04:00:00 EST 1992 · Organometallics

DOI:https://doi.org/10.1021/om00040a020· OSTI ID:539387

Hessell, E T; Jones, W D ^[1]

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1. Univ. of Rochester, NY (United States)

The 1,3-dipolar cyloaddition of phenyl azide to the metal-coordinated isocyanide ligands in Tp{prime}Rh(CNR){sub 2} (Tp{prime} = hydrotris (3,5-dimethylpyrazolyl) borate, R = neopentyl, methyl, 2,6-xylyl; 1a-c) or Cp*Rh(CN-neopentyl){sub 2} (Cp* = {eta}{sup 5}-1,2,3,4,5-pentamethylcyclopentadienyl; 3) in hexane produces the complexes Tp{prime}Rh(CNR)({eta}{sup 2}-PhN{double_bond}C{double_bond}NR) (R = neopentyl, methyl, 2,6-xylyl; 2a-c) and Cp*Rh(CNR)({eta}{sup 2}-PhN{double_bond}C{double_bond}N-neopentyl) (4), respectively, in high yield. The reaction is regiospecific with respect to coordination of the unsymmetrical carbodiimide ligand. Reaction of 2,4-xylyl azide with Tp{prime}Rh(CN-2-tolyl){sub 2} (1d) gives by X-ray diffraction. Complex 2d crystallizes from toluene in the triclinic space group PI with a = 10.962 (6) {Angstrom}, b = 11.238 (4) {Angstrom}, c = 8.691 (14) {Angstrom}, {alpha} = 96.95 (5){degrees}, {beta} = 104.02 (5){degrees}, {gamma} = 101.00 (4){degrees}, V = 2159 (5) {Angstrom}{sup 3}, and Z = 2. The structure of 2d confirms the bidentate bonding of the carbodiimide and shows that the nitrogen of the carbodiimide arising from the azide is coordinated to rhodium. Photolysis of 2a in benzene produces Tp{prime}Rh(H)(Ph)(CN-neopentyl) (5) along with free PhN{double_bond}C{double_bond}N-neopentyl with a quantum yields of 1.0 {+-} 0.03, whereas complex 4 is photochemically unreactive in benzene solution. The conversion of 2a to 5 can also be effected thermally, although the rate is slow at 100 {degrees}C. Photolysis of 2a in the solid state results in an intramolecular reaction to give Tp{prime}Rh(H)(2-(N{double_bond}C{double_bond}N-neopentyl)C{sub 6}H{sub 4})(CN-neopentyl) (7). Addition of excess neopentyl isocyanide to 2a gives the azametallacyclobutane complex Tp{prime}RhC({double_bond}N-neopentyl)N(Ph)C({double_bond}N-neopentyl)(CN-neopentyl) (8). 51 refs., 5 figs., 4 tabs.

• Sponsoring Organization: USDOE
• DOE Contract Number: FG02-86ER13569
• OSTI ID: 539387
• Journal Information: Organometallics, Journal Name: Organometallics Journal Issue: 4 Vol. 11; ISSN ORGND7; ISSN 0276-7333
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
BENZENE
BOND ANGLE
HEXANE
IMIDES
LIGANDS
ORGANOMETALLIC COMPOUNDS
PHOTOLYSIS
RHODIUM COMPLEXES
SYNTHESIS
X-RAY DIFFRACTION