SYNTHESIS, CHARACTERIZATION, AND REACTIONS OF [RH(ETA(1)-DMPP)(MU-SIGMA, ETA(4)-DMPP)(CO)](2)(BF4)(2) AND [RH(ETA(1)-DMPP)(MU-SIGMA, ETA(4)-DMPP)CL](2)

trans-(DMPP)(2)Rh(CO)Cl (DMPP = 1-phenyl-3,4-dimethylphosphole) reacts with AgBF4 to form [Rh(eta(1)-DMPP)-(mu-sigma, eta(4)-DMPP)(CO)](2) ( BF4)(2), 1. [(COE)(2)RhCl](2) (COE = cyclooctene) reacts with DMPP to form [Rh(eta(1)-DMPP)(mu-sigma, eta(4)-DMPP) Cl](2), 2. In both 1 and 2 the phospholes are bound to rhodium(I) as 2- and [4 + 2]-electron do nors. The 2-electron donor is bound through phosphorus only and the [4 + 2] donor is bound through its diene system to one rhodium and throu gh phosphorus to a second rhodium such that each rhodium atom is penta coordinate. Substitution of the chloride in 2 by N-3(-), OH-, and DMPP (the latter in the presence of AgBF4) produces 3, 4, and 5. Reaction of 2 with diphenylvinylphosphine and 2-vinylpyridine in the presence o f AgBF4 produces the [4 + 2] Diels-Alder adducts 6 and 7, respectively . New complexes were characterized by elemental analyses, infrared and H-1,C-13{H-1}, P-31{H-1}, P-31{H-1,P-31(sel)} and in some cases by H- 1{P-31} nuclear magnetic resonance spectroscopy. The structure of 7, e thyl-7-phosphabicyclo[2.2.1]hept-5-ene)(mu-sigma, eta(4)-1-phenyl-3,4- dimethylphosphole](2)(BF4) was confirmed by X-ray crystallography. It crystallized in the monoclinic P2(1)/c space group in a unit cell with the following dimensions: a = 11.460(3) Angstrom A, b = 20.088(6) Ang strom A, c = 16.002(4) Angstrom A, beta = 109.46(2)degrees, rho(calcd) = 1.519 g cm(-3), Z = 2. Refinement converged to R(F) = 0.033 for 490 7 independent observed (I greater than or equal to 3 sigma(I)) reflect ions. The dirhodium cation is centrosymmetric with considerable differ ences in the three Rh-P distances (RhP1 = 2.8336 (9) Angstrom A, RhP1' = 2.3173 (9) Angstrom A, and RhP2 = 2.2690 (9) Angstrom A. These dist ances do not correlate with the relative magnitudes of the rhodium-pho sphorus coupling constants (J(RhP1) = -13.86 Hz, (1)J(RhP1') = 172.87 Hz, and (1)J(RhP2) = 119.96 Hz. The short P1...P1' separation (3.352(9 ) Angstrom A) gives rise to a large through-space P...P coupling of 24 3.93 Hz.