Crystalline N-formimidoyl thienamycin

Crystalline N-formimidoyl thienamycin monohydrate, having the following X-ray powder diffraction:

• ______________________________________ Peak Inten- Peak Inten- Position sity Position sity 2-.crclbar. d-Spacing 2-.crclbar. d-Spacing (CuK.alpha.) (A) I/I.sub.o (CuK.alpha.) (A) I/I.sub.o ______________________________________ 9.75 9.07 100 26.9 3.31 75 11.35 7.80 40 28.7 3.11 37 13.85 6.39 11 29.9 2.99 17 14.5 6.11 4 30.8 2.90 7 15.75 5.63 14 31.85 2.81 12 17.5 5.06 30 32.6 2.75 10 18.9 4.69 27 32.9 2.72 10 19.6 4.53 12 33.4 2.68 5 20.0 4.44 14 33.9 2.64 10 21.45 4.14 30 34.8 2.58 26 21.75 4.08 36 35.6 2.52 14 22.3 3.98 45 37.0 2.43 5 22.9 3.88 30 38.3 2.35 9 23.3 3.82 28 39.3 2.29 6 24.3 3.66 33 40.0 2.25 9 25.35 3.52 24 42.0 2.20 14 25.8 3.45 20 42.4 2.14 18 ______________________________________