The infrared, electronic (visible and ultraviolet), and mass spectra of the planar dithiophosphinato complexes, M[S2PX2]2 (M = Ni, Pd, Pt; X = CH3, CsHa, OC2H5, F, and CF3, except in the case of this latter substituent the M = Pt complex), are examined in the context of the electronic effects of the substituents and their relationship to the analogous pseudotetrahedral complexes of Mn, Fe, Co, Zn, Cd, and Hg. The novel complex formulated as Pt2S6P4(CF3)8 representing a "sulfur deficient" dimer is described. All the normal complexes are diamagnetic and monomeric in solution. The substituents which represent a range of inductive and -bonding possibilities fall in the spectrochemical order OC2H5 ~F > CH3 CeH5 ~CF3.A correlation has been found between the metal-sulfur stretching frequencies in the infrared and the first electronic transition, and this correlation has been compared with previous correlations of M-S bond lengths with ligand field strength. The Ni[S2P(CHs)2]2 complex shows two reduction waves and one oxidation wave in the polarogram obtained from an acetonitrile solution.

The proton magnetic resonance spectra of some dimeric cupric complexes which are models for copper dimer units in proteins have been examined. The spectra are discussed in terms of a simple theory. The possibility of being able to describe the nature of dimeric copper units in proteins by the temperature-dependence of their proton magnetic resonance spectra is discussed. OX1 3PNAS part of our interest in the role of metal ions in biologically important systems we have been investigating the role of copper atoms in oxidase meta1loenzymes.l The recent suggestion 2s3 that the e.p.r. non-detectable copper atoms in such enzymes as laccase and caeruloplasmin exist in the form of spin-paired cupric dimeric units has led us to consider what properties might be associated with such a unit. Our initial studies are restricted to possible model complexes with the expressed W.

the MCD spectrum of Cr(dtp)3 at 20.38 kK which he associates with the 2Ai level. (No hint of a band at this energy is seen in the absorption spectrum.) Within the limits of the calculation we have made it does not seem possible either to move the 2Ai level near 20.38 kK (without destroying the more certain parts of the fit, i.e., the 4T2g and 4Tig manifolds) or to move the 2Aig and 4Tig levels closer than ca. 5 kK to each other. Introduction of a large and (apparently) unlikely second-

The trivalent complexes are monomeric and six-coordinated (D¡) whereas the divalent complexes are both monomeric and polymeric depending on the substituent X and the physical state of the complex. All divalent complexes appear to possess pseudotetrahedral coordination of the metal by four sulfur atoms. The results of thermogravimetric and mass spectral studies are presented and discussed. Temperature-dependent magnetic susceptibility studies reveal Curie-Weiss behavior for all paramagnetic complexes. The Fe(II) complexes are high spin with moments typical of tetrahedral coordination. Visible and ultraviolet spectral studies, interpreted on a ligand field model, permit the ordering of the ligands into the spectrochemical series according to X: F ~OC2H5 > CH3 ~C8H5 ~CF3. Metal-sulfur infrared frequencies of the M3+ complexes follow the same trend with X but the M2+ complexes do not. Oxygen for sulfur substitution occurs in many cases during preparation but is not in general stoichiometric. In one case a stoichiometric complex CoS3OP2(CH3)4 was isolated and characterized.

The preparation and characterization of dithiophosphinate complexes of oxovanadium (IV), OV(S2PX2 )2 (X = CH3, CeHs, CF3, OC2Hs, F), are described. Solution and glass epr spectra show hyperfine coupling to 31P and 51V; the former is isotropic at 77°K in the CH3, C6H6, and OC2Hs cases. Difficulties were experienced in obtaining glass spectra of X = F and CF3 Complexes and these two systems also show anomalous bulk magnetic susceptibility behavior (over the temperature range 90-303 °K) which is thought to arise from interactions between molecules through the formation of VOV chains.Infrared spectra of X = F and CFS complexes show a large reversible shift of the VO absorption between solution and solid states which substantiates this interpretation. Electronic spectra are discussed with reference to the current state of knowledge of V02 + spectra.