SYNTHESIS AND REACTIVITY OF BIMETALLIC BRIDGING HALOALKYL COMPLEXES OF THE FORMULA [(ETA-5-C5H5)RE(NO)(PPH3)X(CH2)XM(CO)5]+BF4-(X = I, BR, CL - M = RE, MN - X = 1, 4)
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Reactions of (CO) 5 ReCH 2 OCH 3 with (CH 3 ) 3 SiI, (CH 3 ) 3 SiBr, and HCl gas give the halomethyl complexes (CO) 5 ReCH 2 X (4, 7692%; X = a, I; b, Br; c, Cl). Reactions of Na + [(CO) 5 Re] with ICH 2 F and I(CH 2 ) 4 I give (CO) 5 ReCH 2 F (4d, 73%) and (CO) 5 Re(CH 2 ) 4 I (5, 36%). Reactions of the substitution-labile dichloromethane complex [( 5 -C 5 H 5 )Re(NO)(PPh 3 )(ClCH 2 Cl)] + BF 4 (2) with 4a and 5 give bridging haloalkyl complexes [( 5 -C 5 H 5 )Re(NO) (PPh 3 )I(CH 2 ) x Re(CO) 5 ] + BF 4 (x = 1, 6a; x = 4, 7) in 6978% yields after workup. A similar reaction of 2 and (CO) 5 MnCH 2 I gives [( 5 -C 5 H 5 )Re(NO)(PPh 3 )ICH 2 Mn(CO) 5 ] + BF 4 (9), which is less stable than 6a but can be isolated in crude form. The XCH 213 C NMR resonances of 6a, 7, and 9 show diagnostic downfield shifts, and the diastereotopic XCH 2 protons give distinct 1 H NMR resonances. Reactions of 2 with 4b,c (80 to 25 C) give spectroscopically observable adducts [( 5 -C 5 H 5 )Re(NO)-(PPh 3 )XCH 2 Re(CO) 5 ] + BF 4 (X = Br, Cl). Reaction of 2 and 4d does not yield a detectable bridging fluoroalkyl complex. Addition of PPN + Br to 6a gives ( 5 -C 5 H 5 )Re(NO)(PPh 3 )(I) (78%) and 4b (82%), and similar reactions of 9 are described. 1993, American Chemical Society. All rights reserved.
