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cyclic rings can be inferred from I95Pt-'H coupling data: H(6) of the thymine ligand exhibits sidebands caused by coupling with the 195Pt isotope (J = 37 Hz), as does the NH signal (J = 20 Hz). The relative magnitudes of coupling constants indicate that the site of platinum coordination is closer to H(6) than to the NH group, caused by N(l) being the site of platination. The H(5) signal of 1-methylcytosine is coupled not only to H(6) (J = 8 Hz) but also to 195Pt (/ = 20 Hz). This is consistent with N(3)-platinum binding.22 The H( 5) and H(6) signals and the NH2 signal of 1-methylcytosine are shifted downfield upon platination. The shifts for H(5) and H(6) are relatively minor (approximately 0.1 ppm each); the NH2 signal shift, however, is substantial (1.50 and 1.75 ppm).It reflects the acidification of the amino protons on platinum coordination at N(3), which is sufficient to allow even substitution of a proton for a second platinum.23 Splitting of the cytosine amino group signal in a 1:1 ratio indicates nonequivalence of the two protons. It probably is a consequence of the increased hindrance of the NH2 group to rotation about the C4-N4 bond on platinum binding at N(3).24 The proton signals of the two NH3 groups cis to each other are nonequivalent as well and also exhibit 195Pt coupling of approximately 52 Hz each. Only the low-field satellites overlap with the N-CH3 signal of 1-methylcytosine.Acknowledgment. We thank the Natural Sciences and Engineering Research Council of Canada,

A Ruthenium Complex Having Both Linear and Bent Nitrosyl GroupsSir :The addition of small molecules to transition metal complexes and oxidative addition reactions in general have been extensively studied during the last 8 years,' with several very recent reports focusing on the oxidative addition properites of nitrosyl complexes of second and third transition series elements. 2-7 The recent communication of the synthesis of a ruthenium(0) nitrosyl analog6 of the well-studied Ir(1) complex named after Vaska, IrCl(CO)(P(C6H6)3)2,8 together with the established molecular geometry of the NO+ adducts of IrX(CO)(P(C6HS)3)2 (X = C1, 1)4,9910 prompted us to consider the possibility of obtaining a complex having both linear and bent coordinated nitrosyl groups. We now wish to report the synthesis and structural * To whom correspondence should be addressed.