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The unsymmetrical benzamidinate ligand [PhC(NSiMe3)(NAr)]− (Ar = 2,6-Me2C6H3), denoted L−, and its lithium derivative [LiL(TMEDA)] (1) (TMEDA = N,N,N′,N′-tetramethylethylenediamine) have been prepared. Treatment of 1 with MCl2 (M = Mn, Co, Fe or Ni) afforded the corresponding divalent transition metal benzamidinates with interesting molecular structures. The reaction of two equivalents of 1 with MnCl2 or CoCl2 afforded the centrosymmetric binuclear complexes [(ML2)2·(TMEDA)] (M = Mn 2, Co 5). On the other hand, the reaction of FeCl2 with 1, in an appropriate stoichiometric ratio, led to the mononuclear mono(benzamidinate) [FeL(Cl)(TMEDA)] (3) and the bis(benzamidinate) [FeL2(TMEDA)] (4) complexes. The addition of two equivalents of 1 to NiCl2 yielded the mononuclear [NiL2] (6). X-Ray crystallography revealed that the κ2-benzamidinate ligand L− is bonded to the metal centre of these complexes in an unsymmetrical fashion. The TMEDA ligand in 2–5 exhibits different coordination modes. It acts as a chelating ligand in 3, as a monodentate ligand in 4, and as an unusual N,N′-bridging ligand in 2 and 5.

Two hundred four strains of Streptococcus pneumoniae isolated in Hong Kong from January 1993 to May 1995 were analyzed for their antibiotic susceptibilities and epidemiological patterns. The ages of the patients from whom the strains were isolated from 1 month to 93 years (median, 53 years); the male-to-female ratio was 2.8, with a predominance of males in the pediatric group. Fifty-nine (28.9%) strains showed reduced penicillin susceptibility, including 40 (19.6%) with frank penicillin resistance (MIC > 1 microgram/ml). Tetracycline resistance alone was found in 28.4% of strains. Isolates with reduced penicillin susceptibility were more common in children than adults (40 versus 23.9%, P = 0.02), and penicillin resistance rates were significantly higher in hospitalized patients than in outpatients (39.5 versus 12.5%; p < 0.001). Penicillin resistance was significantly associated with resistance to ceftriaxone, erythromycin, and tetracycline (P < 0.01) but not with ofloxacin or vancomycin (P = 0.5). Among eight different patterns of resistance to three or more antibiotics, the commonest one (14.2%) was multiple resistance to penicillin, chloramphenicol, ceftriaxone, erythromycin, and tetracycline. Emergence of multiple-antibiotic-resistant S. pneumoniae reflects changes in the pneumococcus itself and the general indiscriminate use of antibiotics in treatment of respiratory infections in Hong Kong.