1969, 37 I I ; b) G. V. Ponomarev, R. P. Evstigneeva, N. A. Preobrazhenskii, J. Org. Chem. USSR 7(1971) 167. [5] Procedure (all operations carried out under argon): A mixture of 20 mL methanol (p.a.) and 0.5 mL acetic acid (p.a.) was evaporated down to 10 mL and cooled to room temperature, treated with 0.7 mL 35% formaldehyde-H,O solution and finally 147 mg (1.55 mmol) 3, and stored in the dark at room temperature. The fine crystals filtered off after 3 h were washed with methanol and dried over PaOlo at 50 "C in a vacuum. Yield 157 mg (94%) 4, colorless needles, thin-layer chromatographically and 'H-NMR spectroscopically pure (recrystallization from CHC13/CH,0H on exposure to air leads to decomposition): m.p. 234-235°C (dec.); Rr=0.53 (silica gel-TLC; CHdYbenzene I :0.5); IR (KBr): 3444.7 (N-H), 3429 (N-H), 3395 (assoc. N-H), 3368 c m -' (assoc. N-H); MS (inlet system temperature ca. 140°C); m/z=428 ( M + ; l0Oo/o); 'H-NMR (CDCII): 6 = 1.95 ( s ; 24H), 3.69 (5; SH), 6.91 ( s ; 4H). Angew. Chem. Int. Ed. Engl. 21 (1982) No. 10 1, L, = ,LloCp(CO), 3 , L m = Co(C0)2P(OCH3)3 2, L, = S1Cp 4 , L, = K i C p 5 , X = C H , L, = WCp(CO)2, M = C O 6 , X = S, L m = M O C~( C O )~, M = F e 7, X = P P h , L, = Fe(CO),, :M = C o (cob Angew. Chem. inf. Ed. Engl. 21 (1982) No. I0