In:
Zeitschrift für Naturforschung B, Walter de Gruyter GmbH, Vol. 43, No. 12 ( 1988-12-1), p. 1598-1610
Abstract:
The 2.5-difurfurylpyrrole-O.N.O ligands 3a, b [R = CO 2 C 2 H 5 (a). COCH, (b)] are obtained by reaction of the furanes l a , b with the 2,5-bis(chloromethyl)pyrrole 2 in the presence of SnCl 4 . Proton abstraction from 3a, b with NaH affords the sodium salts 4a-Na and 4b-Na. Exchange of the chlorine bridges in [μ-ClRh(Diol)] 2 (5,5') (Diol = cyclooctadiene, norbornadiene) results in the formation of the 14-electron complexes (Diol)Rh(O.N.O) (6a,6'a). Addition of PPh 3 , yields the four-coordinated rhodium complexes (Diol)Rh(O.N.O)(PPh 3 ) (7a,7'a). These compounds are also available in a reverse reaction sequence from 5,5', PPh 3 , and 4a-Na. The mononuclear rhodium complexes RhCl(Diol)(PPh 3 ) (8,8') are isolated as intermediates. In 7a, 7'a the olefinic ligands are replaced by carbon monoxide to give the dicarbonyl rhodium complex (OC) 2 Rh(O.N.O)(PPh 3 ) (9a) being detectable only in solution. The same result is achieved upon addition of CO to the compound (OC)Rh(O.N.O)(PPh,) (11a) which results bv the reaction of [μ-ClRh(CO)(PPh 3 )] 2 (10) with 4a-Na. Oxidative addition of CH 3 I or H 2 to 6a, 6 a, 7a, 7'a or 11a was not observed. 1 H and 31 P{ 1 H} NMR investigations indicate that depending on the temperature the O.N.O ligand in the 14-electron rhodium complex 11a acts as tri- (11a-A), bi- (11a-B) and monodentate (IIa-C) ligands. respectively. 11a also reacts with PPh, to form the /ram-bis(phosphane)rhodium complex (PPh 3 ) 2 Rh(CO)(O.N.O) (12a). 12a and the analogous complexes 12b and trans-(PMe 3 ) 2 Rh(CO)(O,N.O) (14a) are obtained by action of ClRh(CO)L 2 (13) (L = PPh 3 . PMe 3 ) on 4a-Na and 4b-Na, respectively. The methylene bridges in the O.N.O ligand 3a are not oxidized, neither in the non-complexed (3a) nor in the complexed (12a) state. According to an X-ray structural analysis 14a crystallizes in the monoclinic space group P2 1 /n with Z = 4. In 6a, 6'a, 7a, 7'a, 9a, 11a, 12a, b, and 14a the O.N.O ligand is always nitrogen bonded
Type of Medium:
Online Resource
ISSN:
1865-7117
,
0932-0776
DOI:
10.1515/znb-1988-1212
Language:
English
Publisher:
Walter de Gruyter GmbH
Publication Date:
1988
detail.hit.zdb_id:
2078109-X
detail.hit.zdb_id:
124635-5
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