gas configuration of the Ni is exceeded by one electron. In an attempt to isolate (3) N O was lost and ( I ) was re-formed. The complexes ( I ) , Hal = C1 and Br, cannot indefinitely undergo reversible addition of N O because on prolonged action of NO they are converted into the oxidation products (Bu3PO)NiHalz 141. On reaction of (Bu3P)zNiJz 121 with NO the presence of the intermediates (2) and (3) cannot be demonstrated although, as the products (4) and (5) show, they probably represent steps in the reaction.if the reaction is carried out in hexane, Bu3PI2 is precipitated and can be isolated. The IR spectrum of the mixture of (4) and (5) contains three N O bands, of which one is assigned to (4) and the two others to the cis,trans isomersIs1 of (5). The analytical results and molecular weight of the mixture lie between those of ( 4 ) and (5).Chromatographic separation of (4) and (5) has not been accomplished because of the instability of (5). However, (5) is readily converted into ( 4 ) : if the mixture of (4) and (5) is treated with PBu3 the I bridges in (5) are broken and after removal of the excess of PBu3 in a high vacuum a t 90°C analytically pure (4) is obtained in 95 % yield (calculated on the (Bu3P)zNiIz ( I ) used). Iodonitrosylbis(tri-n-butylphosphine)nickel (4) is a violet compound that is liquid at room temperature and dissolves as the monomer in benzene. Its properties closely resemble those of the compounds [ ( C~H S )~P ]~N~( N O ) N O~ 141 and [ ( C~H~~)~P ] Z N~( N O ) I [5] which have been prepared by other methods.With phosphorus, as with other elements of Period 3, the tendency to formation ofp,-hybrid bonds is very slight. Only very recently have derivatives of tervalent phosphorus with coordination number 2 been prepared "1. We set ourselves the task of synthesizing dibenzo[b,e]phosphorin (9-phospha-anthracene) ( I ) , the phosphorus analogue of acridine, by removal of HCl from 5-chloro-5,10-dihydrodibenzo[b,e]phosphorin (2) [*I. We worked out two new methods of preparing (2) : a) A solution of the di-Grignard compound from bis(o-bromopheny1)methane (3) in tetrahydrofuran was added dropwise to a solution of dichlorodiethylaminophosphine (molar ratio ca. 1 : l ) in tetrahydrofuran at -8OOC. After evaporation of the solvent the residue was extracted with cyclohexane, filtered, and gaseous HC1 was passed into the filtrate. The crude product obtained on subsequent evaporation was sublimed and recrystallized from toluene; m.p.(after sublimation) [102][103][104][105][106][107][108][109]. To confirm its structure, the product (2). which is very sensitive to hydrolysis, was oxidized in sodium hydroxide solution to (4) [*I by hydrogen peroxide. ( 3 ) =+m NaOH 0 " ' OH ( 4 )
61(2), 4 7% b) Analogously, interaction of the GIignard compound from (u-bromopheny1)phenylmethane (5) and chlorobis(diethy1amino)phosphine in tetrahydrofuran at -80 OC and treatment of the reaction mixture with cyclohexane and HCI as described in a) affords o-benzylphenyldichlorophosphine (6), b.p. 142-143 "j0.01 mm, n'," = 1.62...
