Specrrochimica Acta, zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Vol. 47A. No. 5, pp. 577-584. 1991 05~8539/91 s3.oo+o.oo tinted in Great Britain 0 1991 Pergamon Press plc zyxwvutsrqpo Infrared spectra of Pt(I1) creatinine complexes. Normal coordinate analysis of creatinine and Pt(creat)2(N02)2 N. TRENDAFILOVA* Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia 1040, Bulgaria and A. P. KURBAKOVA and I. A. EFIMENKO Institute of General and Inorganic Chemistry, U.S.S.R. Academy of Sciences, Moscow 117047, U.S.S.R. and M. MITEWA and P. R. BONTCHEV Department of Chemistry, Sofia University, 1 A. Ivanov Avenue, Sofia 1126, Bulgaria zyxwvutsrqponmlkji (Received 16 September 1990; accepted 6 November 1990) Abstract-Infrared spectra of creatinine (H&T-N-C(NH)-NH-CO-CH,) (treat), cis-Pt(creat)z(N02), and Pt(creat),(CIO,), have been recorded in the range 50-4O@Ocm- I. The fundamental vibrations for the creatinine molecule were assigned by normal coordinate analysis in the generalized valence force field approximation. The spectrum of cb-Pt(creat),(NO,), was interpreted by comparison with the creatinine vibrational modes. Additionally the Pt(creat),(ClO,), infrared spectrum has been involved to help the assignment. THE complexation ability of 2-amino-1-methyL4Gmidazolidinone (creatinine) [H,C-N-C(NH)-NH-CO-CH,] has been studied extensively because of its important role in protein metabolism [l-5]. Infrared spectroscopic data on Pt(I1) and Pd(I1) complexes with creatinine are scarce [4-61. The IR band assignment both for the ligand and complexes has been made on the basis of characteristic vibrations for these and related compounds [6-81. The purpose of the present study is to assign the IR spectra of cis-Pt(creat),(NO,)z and Pt(creat)4(C104)2 and extract information on their force fields. To assist the normal coordinate analysis, the vibrations of the creatinine ligand have been considered to first order approximation independently of those of the PtN2(N0& unit. Thus, as a first step, normal coordinate analysis of creatinine has been performed. Furthermore, the spectra of cis-Pt(creat)2(NOz)2 have been considered by treating the PtN,(NO& unit. Finally, the results thus obtained for the ligand and cis-Pt(creat)z(NOz)2 have been used in a comparative assignment of the Pt(creat),(ClO,), IR spectrum. EXPERIMENTAL The compounds were prepared as reported elsewhere [S]. The IR spectra of the solid compounds in the form of Nujol suspensions between KB plates or polyethylene windows were obtained in the range 504000 cm-’ using a Bruker Fourier spectrometer JFS-113. In addition, the IR spectrum of creatinine (200-3400 cm-‘) was recorded with CsI plates on a Perkin-Elmer 983 spectrometer. * Author to whom correspondence should be addressed, 577