BRIDGING CYAPHIDE (C-EQUIVALENT-TO-P-) AND BRIDGING ARYL ISOCYAPHIDE (C-EQUIVALENT-TO-P-R) LIGANDS - SYNTHESIS AND CHARACTERIZATION OF (X)(PET3)2PT(MU-C=P)PT(PET3)2 AND (X)(PET3)PT(MU-C=P-R)PT(PET3)I(X) (X=CL,BR, R=2,4,6-TRI-TERT-BUTYLPHENYL)

The halophosphaalkene platinum complexes, trans-(X)(PEt3)2Pt[C(= PR)X] (1a, X = Cl; lb, X = Br; R = 2,4,6-tri-tert-butylphenyl) react with P t(PEt3)4 to yield (X)(PEt3)Pt(mu-C = PR)-Pt(PEt3)2(X) (3a, X = Cl; 3b, X = Br). The molecular structure of 3a shows that it contains a semib ridging isocyaphide (C=P-R) ligand. The platinum complexes trans-(X)(P Et3)2Pt-[C(= PR)X] (1a, X = Cl; lb, X = Br; R = 2,4,6-tri-tert-butylph enyl) react with Pd(PEt3)4 to give (X)(PEt3)2Pt(C = P) (4) and (X)(PEt 3)2Pd(R) (5). Complexes 4, which are tentatively assigned a structure with a terminal cyaphide (C = P-) ligand, react with Pt(PEt3)4 to give bridging cyaphide diplatinum complexes (PEt3)2Pt(mu-C = P)Pt(PEt3)2(X ) (6a, X = Cl; 6b, X = Br). The molecular structure of 6a exhibits a b ridging C = P- ligand carbon-bonded to Pt(l) and eta2-bonded to Pt(2). In the structure of 5a, a methyl group of each of the two o-tert-buty l groups of the R ligand sits above (and below) the Pd; however, NMR s tudies suggest there is little if any agostic interaction.